Introduction
Type 1 diabetes (T1D) is an autoimmune disorder in which the immune system mistakenly attacks and destroys the β-cells in the pancreas that are responsible for producing insulin, resulting in inadequate insulin production.1–3 The immune system often targets insulin itself or components that are essential for its synthesis, like pre-proinsulin, the insulin precursor.4,5 Moreover, a combination of environmental and metabolic factors, along with genetic and epigenetic factors, contributes to the initiation and progression of this autoimmune response.6–8 Its distinctive feature is this immune-mediated destruction of pancreatic β-cells.1–3 Therefore, a person diagnosed with T1D requires continuous insulin therapy.9 Hyperglycemia, or an increase in glucose in the blood without the conjunction of insulin, can result in a lethal condition known as diabetic ketoacidosis.10,11 Although T1D is traditionally considered a childhood disease, more than half of the new cases now occur in adults, with diagnoses spanning from early childhood to well into middle age.12,13 It is crucial to distinguish between T1D and type 2 diabetes, since type 2 diabetes primarily affects older individuals and is characterized by an initial insulin resistance instead of a complete absence of insulin.14,15 Interestingly, in T1D, the immune system attacks β-cells only, leaving glucagon-producing α-cells unaffected.16,17 Non-β cells may have innate resistance to autoimmune attack, making them suitable for transformation into β-cells by innovative techniques to promote evasion from autoimmunity.18–20 In simple terms, the immune response affects specific types of cells, namely β-cells, confirming that the autoimmune mechanism in T1D has a degree of selectivity that can be utilized for future treatment approaches. In this context, the immune system’s rejection of the recipient of transplanted cells poses a significant challenge to established treatments such as islet transplantation (IT).21,22 This immune response can result in a gradual reduction of islet function over the subsequent years, and it may also prevent certain individuals from fully reducing their reliance on exogenous insulin therapy.23,24
Moreover, the worldwide shortage of organs is a major challenge that hampers progress in pancreatic IT. Annually, around 8,000 organ donations take place, yet fewer than one-third of the pancreases are considered suitable for transplantation.25,26 Although IT can provide a provisional solution for T1D, it necessitates the administration of immunosuppressive drugs to prevent graft rejection.27,28 However, these immunosuppressants can cause lymphopenia, which is associated with increased serum levels of the cytokines interleukin (IL)-7 and IL-15, contributing to the in vivo proliferation of autoreactive clusters of differentiation (CD) 8+ T cells.29,30 The resurgence of autoreactivity is likely a significant factor behind the long-term failure of islet transplants. Graft rejections, under normal circumstances, typically involve an immune response directed against donor antigens. However, in the case of T1D, the resurgence of autoimmunity is fundamentally different from these occurrences and indicates the reactivation of autoreactive T cells targeting self-antigens in the graft, thereby signifying another resurgence of the disease’s original pathogenic mechanisms. In other words, rather than the typical rejection of foreign tissue, the immune system could activate the dormant autoimmune process that originally caused β-cell destruction in T1D. This revival of autoreactive immune responses likely plays a role in the eventual failure of the islet grafts.31,32 It also underscores the complex immunological landscape that needs to be managed to achieve successful and lasting IT outcomes.
In light of these challenges, researchers are increasingly investigating the potential of pancreatic stem or progenitor cells to produce immune-tolerant β-cells, making them a logical option for T1D patients with autoimmunity. To elaborate, multiple experimental findings indicate that, under specific culture conditions or when triggered by key transcription factors, these progenitor cells can produce functional β-like cells that release insulin in response to glucose.33–35 Moreover, there is a growing focus on whether stem cell-derived β-cells are more resilient to immune attacks or can be designed to promote immune tolerance.36–38 Thus, immune modulation through stem cell-based approaches could help alleviate immune attacks, aiming to restore β-cell function and address the fundamental autoimmune response seen in T1D. Although identifying and isolating pancreatic stem cells remains technically challenging and they are available in limited quantities for research, these cells hold potential for modulating immune responses and preventing autoimmune destruction of β-cells in T1D. Pancreatic stem or progenitor cells are typically obtained from donated organs. Unlike transplanting entire organs, these cells can be expanded outside the body and may be modified for immune invisibility. Therefore, they offer a scalable and less resource-intensive solution that could alleviate the challenges associated with organ shortages.39–42 Mesenchymal stem cells release anti-inflammatory cytokines such as IL-10, transforming growth factor-beta (TGF-β), and prostaglandin E2, which may slow effector T cell growth and promote the expansion of regulatory T cells (Tregs), thereby reducing immune responses.43,44 These generate a protective environment for the neogenesis of β-cells formed from pancreatic progenitor cells to boost immunity against the immune attack.45,46 A highly small number of pancreatic stem cells in the islets can differentiate into insulin-producing β-cells. They provide the possibility to restore endogenous insulin production through immune modulation and regeneration, with minimal rejection risk.47–49
However, a significant barrier is the ambiguity regarding the existence of specific pancreatic stem cells in adults. Pancreatic regeneration mainly occurs through β-cell division rather than through stem cells that self-renew.50,51 Pancreatic progenitor cells play a critical role in building both exocrine and endocrine cells during embryonic development, but seem to lose this ability with age.52,53 Recent studies suggest that progenitor-like cells in ductal and acinar regions may generate new β-cells, especially under injury or metabolic stress.54,55 The mature pancreas lacks a dedicated stem cell niche like the intestines and bone marrow. Advances in regenerative medicine and stem cell research show that cells can be reprogrammed to act like pancreatic progenitors or stem cells from other tissues, generating functional β-cells.56–59 This has led to new diabetes treatments, such as activating progenitor cells or using patient-derived stem cells to restore insulin production.60–63
Recent studies have also highlighted the potential of senescent or damaged β-cells—cells that endure an autoimmune attack yet lose their ability to replicate or produce insulin.64,65 Although typically nonfunctional, these cells may possess significant flexibility in terms of differentiation and could potentially be reprogrammed under certain conditions. Genetic or drug-based strategies may help dysfunctional β-cells revert to a progenitor-like state, enabling them to grow and produce insulin.66–70 This concept of cellular adaptability provides optimism for restoring insulin production in individuals with T1D. Interestingly, senescent β-cells may acquire progenitor-like characteristics in the presence of appropriate signaling cues.71–74 Genetic or regulatory factors may drive the cells back to a more stem-like state and allow for the replacement and expansion of insulin-secreting cell mass.75–77 Under certain conditions, studies on animals indicate that α-cells might transdifferentiate into a cell type reminiscent of a β-cell.78,79 This suggests that, under appropriate signals, both α-cells and aged β-cells could be reprogrammed to perform the roles of insulin-producing cells. Some reprogrammed cells may arise from surviving β-cells, suggesting that senescent ones could regain a flexible, progenitor-like state to support regeneration.80,81 Hence, reprogramming senescent β-cells into functioning insulin-producing cells represents a significant breakthrough in diabetes care.82,83 This approach aims to restore β-cell function in T1D, moving beyond insulin replacement to regenerative therapies that address the disease’s root cause. If successful, reprogramming senescent β-cells into functional β-cells, either directly or after turning them into progenitor β-cells, could provide a permanent solution for restoring insulin production.84–86 This concept envisions a future in which persons with T1D will no longer rely on insulin injections.
Against this backdrop, this article aims to expand T1D research by critically analyzing past studies and forming hypothesis-driven insights. It explores alternative sources of insulin-producing cells, focusing on whether pancreatic stem or progenitor cells exist in islets, as adult stem cells are found in other organs. It also investigates why α-cells resist autoimmune attacks in T1D. A critical question is whether the distinctive property of their resistance to autoimmunity can help convert non-β-cell counterparts into ‘normally’ resistant β-cells. This research aims to uncover new approaches for T1D management and explore their broader societal impact.
Hence, the article opens with the search for elusive pancreatic stem cells and the inquiry into whether β-cell replication suffices for insulin regeneration. It subsequently explores the regenerative role of ductal epithelium and insights gained from single-cell transcriptomics.87,88 It focuses on the immune resistance of α-cells, their role in β-cell protection, and approaches to replicate this immunity.89,90 The final sections briefly examine important transcriptional and signaling pathways that could be utilized to combat T1D and regenerate β-cells: neurogenin-3 (NGN3), Hippo signaling pathway (Hippo)/Yes-associated protein (YAP), and glucagon-like peptide-1 (GLP-1).34,91–94
The hidden treasure island: The search for elusive pancreatic stem cells
Recent research shows that turning stem cells, like embryonic stem cells (ESCs) or induced pluripotent stem cells, into β-cells could help with cell replacement therapies.95,96 For instance, studies have indicated that researchers successfully produced glucose-responsive β-like cells from ESCs that managed blood glucose levels in diabetic mice.97–99 Initial clinical trials conducted by ViaCyte using encapsulated pancreatic progenitors derived from ESCs showed their potential for application, although some challenges related to immune responses were encountered.100 Building on this initial research, ViaCyte progressed its proprietary pancreatic endocrine cell (PEC)-01 cell line, sourced from human pluripotent stem cells, into Phase 1 and Phase 2 clinical trials (e.g., NCT02239354, NCT03163511). These clinical studies involved subcutaneous delivery of PEC-01 cells through macroencapsulation devices, such as Encaptra. While the results were encouraging regarding safety and partial engraftment, several problems arose, including limited oxygen and nutrient diffusion, excessive fibrosis growth, and insufficient insulin secretion, presenting major hurdles to achieving long-term functionality and immune compatibility. These findings underscore the need for ongoing enhancement in cell encapsulation and device innovation to optimize the survival and efficacy of transplanted cells. Vertex Pharmaceuticals, which acquired ViaCyte in 2022, recently announced favorable outcomes for its VX-880 treatment, inspired by Douglas Melton’s foundational research, indicating a revival of spontaneous insulin production and reduced reliance on insulin in patients.101,102 This approach offers major benefits, like scalability and the ability to modify cells so the immune system doesn’t attack them after transplantation, which is crucial for treating T1D. It also suggests that we can trigger pancreatic stem cells, possibly in the islets, to become insulin-producing β-cells. By changing key biological signals and the pancreatic environment, we may activate this regeneration and restore β-cell function in people with T1D.103,104 The main challenge is figuring out how to change these signals and control stem cells to encourage β-cell production while preventing immune system rejection. As a result, the quest for endogenous pancreatic stem or progenitor cells could significantly impact T1D management. If scientists could identify these cells and determine whether they have regenerative ability, there may then be the possibility of inducing the direct conversion of these cells into insulin-secreting β-cells in the pancreas of the subjects. This would usher in a new mode of replacement for β-cell functioning, which would be far more sustainable and personalized and would considerably reduce reliance on an external cell source as well as the immunorejection risk, which is currently a major hurdle for treatment.105,106 Understanding the major mechanisms governing this important process will be crucial in devising efficient therapies for T1D and ultimately restoring normal insulin production.
Replicating β-cells: A limited solution or the future of insulin regeneration
Looking back at the history of scientific inquiry, groundbreaking research by Susan Bonner-Weir and colleagues showed that the number of β-cells in the pancreas progressively increases during normal development and continues throughout adulthood.107 This growth links the formation of new, small islets to ductal progenitor cells in a process called neogenesis. Another finding was that while pancreatic cells, like β-cells, acinar cells, and ductal cells, can replicate, mature β-cells may have limited ability to do so due to two types: one that can replicate and another that has aged. It’s noteworthy that while replicating β-cells may undergo slight dedifferentiation, they do not revert to progenitor or stem cell states. During replication, these β-cells might temporarily lose their functional capabilities. This suggests that using existing β-cells to produce insulin may be less effective at regulating blood glucose than converting pancreatic progenitor cells into stable, long-lasting insulin-producing β-cells.
Subsequent studies have confirmed the concept of neogenesis, particularly during physiological conditions such as pregnancy or stress from injury, where ductal cells are implicated in the regeneration of β-cells.108–110 Notably, studies by Bonner-Weir and associates have provided histological and lineage-tracing proof demonstrating the plasticity of ductal epithelial cells in creating endocrine progenitors.111–114 Similarly, studies have shown that the activation of the Notch pathway can influence the differentiation of ductal cells into cells that produce insulin.115,116 Furthermore, research has shown that while mature β-cells are capable of limited proliferation, this process is often followed by temporary dedifferentiation.117,118 During this phase, there is a decrease in the expression of insulin and key genes associated with β-cell identity, such as pancreatic and duodenal homeobox 1 (Pdx1) and V-maf musculoaponeurotic fibrosarcoma oncogene homolog A.119–121 These findings emphasize the challenges of relying only on the replication of mature β-cells to regain function in diabetes and instead support the therapeutic strategy of employing progenitor cell populations or neogenesis to create robust, functional β-cells.
Uncovering hidden stem cells: The potential of ductal epithelium in pancreatic regeneration
Studies show that the duct epithelium in adults can still produce all the cell types in the pancreas, offering a potential source for pancreatic stem and progenitor cells.105,111–113,122 Researchers have successfully extracted potential intra-islet stem cells, marked by nestin, from both rat and human islets.123,124 One alternative concept suggests the existence of facultative or functional stem cells.125,126 This implies that a fully differentiated epithelial cell can momentarily behave like a stem cell by undergoing multiple divisions, despite not being an actual stem cell. Animal studies show that after partial pancreas removal, mature ductal cells in rats can replicate and become less differentiated, forming islet, acinar, or duct cells.127,128 Similarly, transgenic mouse models with overproduced interferon (IFN)-γ regulated by the insulin promoter have been shown to enhance neogenesis in adulthood.129,130 These experiments cause insulitis by promoting IFN γ expression through insulin, leading to continuous ductal cell growth and new islet formation.131,132 Most importantly, the new islets extend toward the ductal lumen, suggesting that pancreatic progenitor cells exist in the duct.133,134
Building on these findings, later research has further strengthened the regenerative abilities of adult pancreatic ductal epithelium. For example, studies indicate that ductal cells can transform into functional β-cells under specific conditions, such as the activation of key signaling pathways like Notch and Wingless-related integration site (Wnt).135–137 Importantly, research in transgenic mice revealed that stimulating these pathways can convert mature ductal cells into insulin-producing β-like cells, offering a possible treatment method for regenerating β-cells.138,139 Later research has also examined the role of inflammation and stress in promoting the growth of ductal progenitor cells. Research has indicated that enhancing β-cell regeneration following injury can be achieved by blocking key elements that limit progenitor cell activation, such as the TGF-β signaling pathway.140,141 Additionally, studies revealed that after partial pancreatic damage, ductal cells exhibit greater plasticity and can regenerate functional insulin-secreting cells.142,143 Recently, it has been shown that metabolic stress, such as insulin resistance caused by a high-fat diet, can stimulate the proliferation of ductal progenitor cells and enhance β-cell regeneration in diabetic models.144,145 Similarly, it was recently discovered that altering the Hippo signaling pathway in adult mice enhanced the plasticity of ductal cells and prompted the neogenesis of β-cells after pancreatic damage.146–148 These findings support the idea that the ductal epithelium serves as an essential source of progenitor cells for β-cell regeneration and suggest that adjusting specific signaling pathways might improve neogenesis and offer a possible therapy for T1D.
Unlocking pancreatic regeneration: The power of single-cell transcriptomics
Put together, while the therapeutic potential of pluripotent stem cell-derived β-like cells has been demonstrated, the existence of a dedicated endogenous pancreatic stem cell population in adult humans remains under investigation. Nevertheless, the search for such cells remains crucial, particularly in the context of T1D, where inflammation-driven β-cell loss highlights the need for regeneration and replacement strategies. A comprehensive identification of plausible cell types could ultimately lead to the discovery of true pancreatic progenitor stem cells. In this context, single-cell transcriptomics serves as an effective technology for in-depth analysis. By exploring the gene expression profiles of individual cells within the ductal epithelium and newly formed islets, single-cell RNA sequencing can effectively identify and isolate potential progenitor cells, even those exhibiting minor or transient characteristics.149,150 This method could identify markers specific to progenitor states, differentiate pathways, and assess the process of dedifferentiation or transdifferentiation occurring in pancreatic tissues.151,152 In addition, the single-cell RNA sequencing technique can deconvolute the variegated cell types existing in the ductal epithelium and help discover subgroups with stem-like properties or plasticity, especially when injury is present or inflammation is triggered in transgenic models.153,154 This ability to distinguish progenitor populations by their gene expression provides an avenue for their isolation and further study.155,156 In essence, single-cell transcriptomics helps uncover more about pancreatic progenitor cells and provides the foundation for advancing regenerative medicine.157,158 Critically, to assist readers in navigating the diverse techniques commonly employed in pancreatic β-cell regeneration, Table 1 provides a comprehensive summary of advanced experimental and translational techniques designed for the regeneration and preservation of β-cells in a T1D setting.38,149–152,157–185 Such information is crucial to the development of next-generation cell therapies for diabetes.38,157–185
Table 1Emerging techniques in β-cell regeneration and therapeutic applications in type 1 diabetes
| Technique | Purpose | Description | Therapeutic implications |
|---|
| Single-cell RNA sequencing (scRNA-seq) | Identification of progenitor/stem-like cells | Examines gene expression at the single-cell level to investigate rare or transient progenitor cell states within the pancreatic ductal epithelium149–151 | Enables the identification and isolation of potential regenerative cell types, which is an essential step in advancing targeted cell-based therapies157,158 |
| Cellular reprogramming | Regeneration of β-cells | Transforms non-β cells, such as α-cells or ductal cells, into insulin-secreting β-cells through the use of transcription factors and the modulation of signaling pathways159,160 | Provides a method to restore missing β-cells without depending on external stem cell sources161 |
| Transgenic animal models | Understanding neogenesis and immune mechanisms | Genetic modification, such as the overexpression of IFN-γ, causes damage or inflammation in the pancreas to investigate regeneration and immune reactions162 | Replicates human diseases, facilitating the identification of regeneration pathways and immune regulators 163 |
| Epigenetic profiling | Studying chromatin states and immune resilience | Investigates DNA methylation, histone modifications, and chromatin accessibility to understand the mechanisms behind α-cells’ resistance to immune attacks164,165 | May assist in reprogramming β-cells to reduce their immunogenicity and enhance their resistance to immune destruction166 |
| Molecular mimicry | β-cell protection via immune evasion | Engineered β-cells produce immune-protective molecules similar to those found in α-cells, thereby minimizing immune targeting167,168 | Decreases autoimmunity and improves the survival of β-cells following transplantation or during endogenous regeneration169 |
| Immune checkpoint modulation | Immunosuppression and β-cell protection | Introduction or activation of checkpoint inhibitors (e.g., PD-1, CTLA-4) on β-cells to prevent T-cell mediated killing170,171 | It could enhance β-cell tolerance and prolong survival in autoimmune conditions172 |
| Anti-inflammatory cytokine therapy | Modulating immune environment | Utilization of cytokines like IL-10 or TGF-β to mitigate localized inflammation and safeguard β-cells173,174 | Creates a favorable niche for β-cell regeneration and survival in T1D175 |
| Lineage tracing | Tracking cell origin and fate | Employs genetic labeling techniques to monitor the conversion of ductal or α-cells into β-cells in vivo. The labeled cells are then tracked over time in vivo to monitor their potential conversion into insulin-producing β-cells176 | Verifies the origins of neogenesis; substantiates regenerative processes in living tissues177 |
| Organoid culture systems | In vitro modeling of regeneration | Three-dimensional (3D) cultures developed from pancreatic tissue or stem cells to replicate the structural and functional characteristics of the pancreas178,179 | Facilitates the evaluation of regeneration protocols and the screening of pharmaceuticals within a regulated setting180 |
| Gene editing (e.g., CRISPR/Cas9) | Modulating gene expression in pancreatic cells | Employed to alter the expression of autoantigens, improve β-cell functionality, or replicate the protective characteristics of α-cells181,182 | Enables the development of tailored therapies and the generation of immune-resistant β-cells183 |
| Beta cell encapsulation | Encapsulation of β-cells or progenitors in a protective barrier to shield them from immune attack | Involves enclosing insulin-producing cells in a semi-permeable membrane to protect them from immune attack while allowing nutrient and insulin exchange184,185 | Long-term β-cell protection in an immune-privileged environment38 |
What α-cells know: Lessons learned to safeguard β-cells in T1D
As previously stated, T1D is an autoimmune disorder that destroys the β-cells in the pancreas, whereas the α-cells that generate glucagon typically remain unharmed. The selective preservation of β- and α-cells during immune attacks is shaped by a variety of molecular, immunological, and physiological factors that contribute to the protection of α-cells. Gaining insight into these mechanisms is crucial for understanding the onset of T1D and investigating potential treatment alternatives. A primary cause for the specific destruction of β-cells is the diverse expression of autoantigens.186,187 β-cells are responsible for producing insulin and other proteins such as glutamic acid decarboxylase and insulinoma-associated antigen-2, which are targeted by autoreactive T cells in T1D.188,189 Cytotoxic T lymphocytes (CTLs) kill the β-cells upon being activated by stimulation from major histocompatibility complex molecules.190 Notably, in contrast to the β-cells, the α-cells seem to express considerably less of these autoantigens and are, therefore, not recognizable by the immune system.191 As a result, α-cells frequently manage to evade the harmful effects that are primarily directed at the β-cells.
α-cell resilience: A key to β-cell regeneration and protection in T1D
Immunological stresses are not confined to the expression of antigens; rather, they inhibit normal β-cell function.192 In addition, activated T cells produce inflammatory cytokines like IFN-γ and tumor necrosis factor alpha during any autoimmune response or condition.193,194 This eventually leads to the endoplasmic reticulum inability to withstand oxidative stresses and subsequent cell death.195,196 Given their substantial metabolic needs and high levels of insulin production, β-cells face a greater risk.197,198 In contrast, α-cells demonstrate greater resilience to these cytokines, largely due to their different gene expression profiles and reduced reliance on insulin production.199 Additionally, α-cells boast a stronger anti-apoptotic signaling route that balances oxidative stress and lowers responses to endoplasmic reticulum stress, thereby allowing these cells to sustain the inflammatory atmosphere typical of T1D.200 Under certain conditions, α-cells can transdifferentiate into β-cells, enabling them to adapt and compensate for the loss of β-cells.201,202 Though presumably not to the extent found in humans, this points toward the relatively plastic characteristics of α-cells compared to the more inflexible nature of β-cells. Differences might also arise in the vascular system as well as in the microenvironment within pancreatic islets, affecting immune responses.203,204 α-cells are generally located at the periphery of islets and may be exposed to different levels of cytokines and immune cells than β-cells, which are situated centrally and are more directly involved in glucose regulation, making them more susceptible to immune attacks.205 It is possible that the entire immune system is directed against the β-cells, considering their important function, insulin, in overall glucose regulation. As a major hormone regulating various functions in the body, insulin has strong immunogenic properties, making β-cells apparent immunological targets.206 Glucagon secreted by α-cells is also a regulator of glucose, although its effects are secondary to those of insulin, and thus immune responses against α-cells are toned down.207 Additionally, research indicates that α-cells might influence immune reactions within the islet microenvironment, which could aid in their survival.208
Immune resistance in pancreatic β-cells could potentially be enhanced by adopting strategies employed by α-cells in T1D, which have evolved mechanisms to evade immune-mediated destruction. One option could be molecular mimicry: modifying β-cells to express the protective molecules expressed by α-cells, thereby decreasing their immunogenicity.209–211 In addition, α-cells employ immune checkpoint regulators, such as programmed cell death protein 1 (PD-1) and cytotoxic T-lymphocyte antigen 4 (CTLA-4), to shield themselves from T-cell attacks; therefore, encouraging similar regulatory molecules in β-like cells may fortify them against autoimmunity.212,213 Recognizing and increasing the levels of anti-inflammatory cytokines like IL-10 and TGF-β could also enable β-cells to withstand immune challenges, akin to α-cells.214,215 For instance, in the non-obese diabetic mouse model for T1D, it has been noted that IL-10 therapy reduces β-cell damage and the infiltration of immune cells into the pancreas.216,217 Furthermore, IL-10 enhances the Treg response, which is crucial for maintaining immune tolerance.218 Preclinical studies, particularly in non-obese diabetic mice, have shown that IL-10–mediated enhancement of Tregs can delay or prevent diabetes onset, underscoring its potential as a therapeutic target for preserving β-cell function in T1D.219,220 In contrast, a lack of IL-10 accelerates the onset of diabetes and alters intestinal immunity.221
Another promising avenue is the downregulation or modified presentation of major β-cell autoantigens, such as insulin or glutamic acid decarboxylase-65, to reduce their visibility to autoreactive T cells.222,223 Furthermore, epigenetic profiling of α-cells has revealed a more compact and immune-inactive chromatin state around key inflammatory gene loci, which may underlie their reduced immunogenicity.224–227 Understanding and recreating such epigenetic states in β-cells could serve as a strategy to reprogram their immune profile.228,229 These are strategies that can be applied in principle but require large-scale experimental verification before being turned into clinical processes.
In summary, during T1D, α-cells resist immune stress based on a low autoantigen expression profile, higher resistance against inflammatory stimuli, and activation of pathways that inhibit cell death. The possibility that α-cells may transdifferentiate into β-cells could allow for certain regenerative strategies. Strategies such as immune checkpoint modulation, molecular mimicry, and the use of anti-inflammatory cytokines could help protect or restore β-cell function, though further research is required. The immune-mediated destruction of β-cells in T1D involves intricate interactions concerning antigen presentation, immune targeting, cellular stress, and renewal. In this context of autoimmunity, α-cells demonstrate resilience, presenting opportunities to minimize β-cell loss through their adaptability and informing future T1D therapies.
Reversing T1D: Transcriptional and NGN3 signaling pathways in β-cell regeneration
As mentioned earlier, although current T1D management includes insulin replacement, new regenerative therapies aim to replenish endogenous β-cell mass through cellular reprogramming. They rely on an accurate understanding of the molecular mechanisms that govern pancreatic development, lineage determination, and β-cell maturation. Key transcription factors, initially identified during embryonic development and currently utilized to guide stem or progenitor cells toward a β-cell identity, continue to be vital for the future of this area.230,231 Simultaneously, pathways such as Wnt/β-catenin and Hippo/YAP provide crucial signals for the proliferation, survival, and differentiation of progenitor cells.232,233 By adjusting these signaling and transcriptional networks, scientists aim to reprogram non-β-cell types or increase β-cell numbers, ultimately offering a route to insulin independence in T1D. In addition to the aforementioned transcription factors, Table 2 includes a comprehensive list of key transcription factors and signaling pathways that play a role in β-cell reprogramming and regeneration.234–271 This table will serve as a reference throughout the article, highlighting their roles in promoting β-cell regeneration, protecting against β-cell impairment, and facilitating the conversion of non-β-cells into insulin-producing cells. These elements hold significant therapeutic potential for diabetes treatment. In essence, Table 2 outlines the essential transcription factors and pathways involved in this regenerative process, along with their therapeutic significance. This introduction lays the foundation for the subsequent discussion on key signaling pathways, including NGN3, Hippo/YAP, and GLP-1.
Table 2Key transcription factors and signaling pathways in β-cell reprogramming and regeneration
| Transcription factor/signaling pathway | Function in β-cell reprogramming/regeneration | Therapeutic implications |
|---|
| Pdx1 (pancreatic and duodenal homeobox 1) | Master regulator of β-cell differentiation and maintenance. Promotes insulin secretion and β-cell identity234 | Potential therapeutic target for β-cell regeneration in T1D. Can enhance endogenous β-cell regeneration or reprogram non-β-cells into functional β-cells235 |
| NGN3 (neurogenin 3) | Induces pancreatic endocrine differentiation and promotes β-cell lineage specification236 | Targeting NGN3 could induce the generation of new β-cells from pancreatic progenitors or ductal cells, offering promising treatments for T1D237 |
| MAFA (V-maf avian musculoaponeurotic fibrosarcoma oncogene homolog A) | Regulates insulin expression in β-cells and aids in maintaining their function. Important for maintaining β-cell function during stem cell differentiation238 | Therapeutic application in augmenting insulin production or improving β-cell survival in diabetes239 |
| NEUROD1 (neurogenic differentiation 1) | It is a basic helix-loop-helix (bHLH) transcription factor. Works downstream of NGN3; critical for terminal differentiation and functional maintenance of β-cells240 | Utilization in cell-based therapies or reprogramming protocols may help restore β-cell mass in diabetes, especially when used in combination with Pdx1, MAFA, or NGN3241 |
| PAX4 (paired box gene 4) | Promotes β-cell fate over α-cell fate during endocrine progenitor differentiation; supports β-cell survival242 | Conversion of pancreatic stem cells or non-β-cells into insulin-producing β-cells: a potential strategy for β-cell restoration in T1D244 |
| ARX (aristaless-related homeobox) | Antagonistic to PAX4; promotes α-cell fate—needs to be suppressed to favor β-cell lineage244 | Downregulation or inhibition of ARX in pancreatic stem cells or progenitors can enhance β-cell differentiation by shifting the endocrine fate toward insulin-producing β-cells as opposed to glucagon-producing α-cells245 |
| ISL1 (ISL LIM homeobox 1) | Supports pancreatic endocrine development and insulin gene transcription246 | Promotes endocrine lineage commitment and β-cell maturation; has the potential to enhance functional β-cell generation from stem cells for T1D therapy247 |
| FOXO1 (forkhead box O1) | A transcription factor that regulates β-cell fate by balancing proliferation, maintenance, and differentiation from progenitor or stem cells248 | Modulating FOXO1 activity may enhance β-cell regeneration and function, offering a potential strategy for restoring β-cell mass in T1D249 |
| Sox9 (SRY-box transcription factor 9) | Regulates pancreatic progenitor cell fate and is critical in ductal cell differentiation250 | Targeting Sox9 could aid in reprogramming ductal cells into β-cells, a potential therapeutic approach for restoring β-cell mass in T1D250,251 |
| GATA4 | Critical for β-cell survival and differentiation, it contributes to maintaining β-cell identity252 | Therapeutic modulation of GATA4 can potentially enhance stem cell-derived β-cell generation in T1D253 |
| HNF1β & HNF4α (hepatocyte nuclear factors) | Key in early pancreas development and glucose regulation; mutations associated with maturity-onset diabetes of the young (MODY)254 | Potential therapeutic modulation of HNF1β and HNF4α can promote β-cell neogenesis from stem cells by regulating pancreatic development and insulin expression255 |
| YAP/TAZ (Yes-associated protein/transcriptional coactivator with PDZ-binding motif) | Part of the Hippo signaling pathway, it regulates β-cell proliferation and regeneration256 | Therapeutic modulation of YAP/TAZ signaling potentially promotes β-cell proliferation, regeneration, and differentiation from stem cells, offering a strategy for restoring β-cell mass in diabetes257 |
| Wnt (Wingless/Integrated)/β-catenin pathway | Regulates β-cell differentiation and proliferation. Important for the expansion of the β-cell population258 | Therapeutic activation of Wnt/β-catenin signaling may enhance β-cell regeneration and promote stem cell differentiation into β-cells for T1D treatment259 |
| Tcf7l2 (T-cell factor 7-like 2) | Involved in Wnt/β-catenin signaling and promotes β-cell proliferation and survival260 | Activating Tcf7l2 signaling may offer potential for stimulating β-cell regeneration from stem cells in T1D therapy261 |
| Notch signaling pathway | Modulates endocrine differentiation, influencing β-cell identity and function262 | Manipulating Notch signaling could enhance β-cell regeneration and reprogramming of progenitor cells263 |
| JAK/STAT (Janus kinase/signal transducer and activator of transcription) pathway | Involved in cell survival and immune response regulation. Plays a role in β-cell regeneration264 | Targeting JAK/STAT could enhance β-cell survival and regeneration, particularly in inflammation-driven β-cell loss in T1D265 |
| TGF-β (transforming growth factor beta) pathway | Inhibits β-cell proliferation and differentiation but also regulates their function266 | TGF-β pathway inhibition may enhance the differentiation of pancreatic progenitor cells into β-cells, overcoming differentiation barriers267 |
| SMAD pathway | Regulates β-cell differentiation and expansion. Plays a role in TGF-β signaling in β-cells268 | Targeting SMAD signaling may overcome β-cell growth inhibition and enhance differentiation of pancreatic stem cells into functional β-cells for T1D therapy269 |
| GLP-1 (Glucagon-like peptide-1) | Enhances β-cell proliferation, survival, and function270 | Therapeutic GLP-1 analogs can promote β-cell regeneration and support stem cell-derived β-cell maturation in diabetes271 |
In principle, T1D reversal needs to be poised to undertake therapeutic intervention directed at the repair of pancreatic insulin-producing β-cells that were destroyed in T1D patients.272 This notion forms an important part of current research attempting to understand the underlying mechanisms of T1D pathology, thereby offering hope for new therapeutic avenues and even a cure. The regeneration of β-cells is considered the ultimate objective of T1D therapy, which could transform the approach to managing the disease or possibly eliminate it altogether. Achieving β-cell regeneration presents significant possibilities for novel therapies.273 If scientists succeed in finding ways to regenerate or substitute these lost cells, it could result in groundbreaking treatments for T1D. A noteworthy strategy for generating functional β-cells involves transforming pancreatic stem cells into insulin-producing cells.274,275 Various crucial signaling pathways play a vital role in guiding these stem cells to differentiate into β-cells, providing researchers with several targets for therapeutic approaches.266,276 NGN3 is one of the major signaling pathways involved in this process, and it is important in the development of pancreatic endocrine tissue.277,278 NGN3 is a transcription factor that directs progenitor cells to differentiate into hormone-secreting cells, including β-cells. Pancreatic stem or progenitor cells are rendered insulin-secreting β-cells by NGN3 expression, which can bring about the restoration of insulin production in T1D patients.236,237
To further elaborate, recent studies have highlighted the essential function of NGN3 in reinstating endocrine differentiation in the adult pancreas during instances of injury or regenerative cues.279,280 Models of pancreatic damage or diabetes suggest that brief activation of NGN3 in ductal or acinar cells can reactivate an endocrine differentiation pathway and produce insulin-secreting cells.281,282 Induced NGN3 expression in pancreatic duct cells has been shown to lead to the formation of glucose-responsive β-like cells in mouse models.283,284 Moreover, lineage-tracing investigations have confirmed that reactivated adult ductal epithelium serves as a source of endocrine progenitors when stimulated with NGN3.285,286 Importantly, NGN3 has been integrated with other key transcription factors, such as Pdx1 and V-maf musculoaponeurotic fibrosarcoma oncogene homolog A, in reprogramming strategies to convert non-β pancreatic cells or even intestinal cells into functional β-cells.287,288 Moreover, organoid and stem cell-derived pancreatic progenitor models have demonstrated that NGN3 induction is a vital step for committing to the endocrine lineage, and its appropriate expression significantly enhances the effectiveness of generating insulin-positive cells in vitro.289,290 Collectively, this information highlights that NGN3 is essential not only in embryonic development but can also be utilized in adult regenerative contexts to restore β-cell mass and function, suggesting potential treatments for diabetes.
Importantly, the Wnt/β-catenin signaling pathway, along with NGN3, affects cell fate, growth, and differentiation levels throughout pancreatic development.291,292 When activated, this pathway promotes the self-renewal and proliferation of pancreatic progenitor cells, resulting in a greater number of potential β-cell precursors. Furthermore, this pathway is essential for maintaining stem cells in a progenitor-like state, which is crucial for their transformation into β-cells.293 Inducing Wnt signaling in β-cells is crucial for their continued proliferation and differentiation into functional β-cells, as it has been shown to be effective in promoting regeneration. Recent studies indicate that activating canonical Wnt/β-catenin signaling enhances the levels of key β-cell transcription factors such as Pdx1 and NK6 homeobox 1, which are vital for maintaining β-cell identity and facilitating insulin secretion.294,295 Additionally, modifying Wnt signaling in pancreatic organoid cultures has significantly improved the effectiveness of endocrine lineage specification, indicating its potential therapeutic benefit in β-cell replacement therapy.296,297
Key pathways in β-cell regeneration: Hippo/YAP, GLP-1, growth differentiation factor 11 (GDF11), and beyond
Another important pathway in β-cell regeneration is the Hippo/YAP signaling pathway, which plays a crucial role in pancreatic tissue repair.298,299 Typically, the Hippo pathway limits cell growth to maintain organ size. However, when this pathway is inhibited, it activates YAP, promoting the growth, survival, and advancement of β-cells.298,300 The triggering of YAP via the inhibition of the Hippo pathway underlines the core aspect of pancreatic stem cell differentiation and maturation to β-cells for tissue repair and regeneration through accelerated development.[299,301] Hormones, in addition to these signaling pathways, also trigger β-cell regeneration. The action of GLP-1 not only augments the secretion of insulin from β-cells and favors their growth and survival,302,303 it has been reported that GLP-1 is capable of increasing the mass and functionality of β-cells, particularly when those cells are under stress in the milieu of T1D.304,305 For instance, numerous studies indicate that GLP-1 improves β-cell mass and functionality, especially in T1D situations where β-cells face immune-related damage.306,307 The use of GLP-1 or GLP-1R agonists (GLP-1RAs) in T1D animal models has led to a significant increase in β-cell mass and improved insulin secretion, even with ongoing immune challenges.308,309 Additionally, it has been shown that GLP-1 enhances β-cell survival in diabetes by reducing inflammation and oxidative stress, key factors behind β-cell impairment and loss in T1D.310,311
In addition to benefiting mature β-cells, GLP-1 stimulates pancreatic progenitor cells to develop into insulin-producing β-cells.312 These regenerative processes are thought to be partly influenced by GLP-1’s regulation of central signaling routes, such as the phosphatidylinositol 3-kinase/protein kinase B pathway, which is crucial for cell survival and proliferation.313,314 The protective role of GLP-1 against β-cell apoptosis has been further substantiated by evidence showing that GLP-1RAs can counteract the negative effects of inflammatory cytokines commonly increased in the diabetic setting, such as tumor necrosis factor alpha and IL-1β, which are recognized as inducers of β-cell apoptosis.315,316 Scientists are thus using GLP-1 or GLP-1RAs to aid in β-cell regeneration from stem cells, potentially leading to improved insulin secretion and the development of new β-cells.317,318 Alongside these effects on β-cell growth and longevity, recent findings have also suggested that GLP-1 plays a role in enhancing the functional efficacy of β-cells, particularly under metabolic stress conditions. The administration of GLP-1 in animal models exhibiting insulin resistance has resulted in elevated insulin secretion and enhanced glucose tolerance, indicating that GLP-1 preserves β-cell function even during periods of metabolic stress on β-cells.319,320 This is particularly significant in T1D, where β-cell function is often compromised due to autoimmune damage and where the regeneration or maintenance of functional β-cells is essential for reinstating normal glucose balance. Moreover, GLP-1’s effect on β-cell regeneration extends beyond β-cell proliferation and survival to also enhance β-cell plasticity.295,321 Studies have shown that GLP-1RAs can convert α-cells into insulin-producing β-like cells in diabetic mice, thereby reinforcing the therapeutic promise of GLP-1 in promoting the regeneration of β-cells in diabetes.295 These findings suggest that GLP-1 could be a very potent therapeutic agent for increasing β-cell mass as well as improving the functional incorporation of newly generated β-cells into the pancreatic islet. In summary, these investigations highlight the multifaceted role of GLP-1 in enhancing β-cell regeneration and functionality, particularly in stressful environments such as T1D, and support its use as a potential treatment strategy for β-cell replacement and diabetes management.
On the other hand, GDF11, a probable candidate for β-cell regeneration, is yet another TGF-β family member.322 It stimulates pancreatic stem cells to become active β-cells.323,273 Several studies have shown that GDF11 increased both β-cell mass and glucose regulation in animals, suggesting that it might have a role in therapy for T1D.324 Furthermore, the tissue-rejuvenating properties of GDF11 may be especially advantageous for elderly individuals, as their capacity for pancreatic tissue regeneration usually declines with age.325,326
Together, these pathways, NGN3 activation, Wnt/β-catenin signaling, the Hippo/YAP pathway, GLP-1, and GDF11, create an important framework for regenerative medicine to reverse T1D effects. Figure 1 provides an overview of the integrated signaling pathways that regulate pancreatic β-cell regeneration and maintain their functional homeostasis. By manipulating these pathways, we may trigger β-cell regeneration in the pancreas and restore normal insulin production. These strategies offer hope for T1D patients and could change how diabetes is treated. However, alongside these regenerative approaches, it is essential to address the ongoing risk of autoimmune relapse, which remains an important obstacle. Various mechanisms have been proposed to either prevent or control such relapses, but this topic still requires more detailed investigation, which is beyond the scope of this narrative review. These strategies include inducing immune tolerance, such as using antigen-specific therapies aimed at re-educating the immune system rather than suppressing it entirely, and immune modulation with agents like anti-CD3 monoclonal antibodies, CTLA-4-Ig, and anti-CD20 treatments that target autoreactive T cells or boost Treg activity.327,328 Also, β-cell encapsulation techniques provide a physical barrier that shields transplanted β-cells from immune attack while allowing the exchange of nutrients and insulin.329,330 Advances in β-cell genetic engineering, employing methods like clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (hereinafter referred to as Cas9) to modify genes, aim to reduce their immunogenicity or produce local immunomodulatory factors, offering hope for longer-lasting β-cell survival.331,332 What’s more, combining immune modulation and β-cell replacement therapies may offer the most promising approach to achieve a cure and prevent relapses, eventually leading to sustained remission from T1D.333,334
Finally, besides stem cell–based approaches for β-cell replacement, a novel and highly promising strategy is emerging that aims to stimulate endogenous pancreatic cell regeneration.94,335 Therapies employing glucagon receptor (GCGR) monoclonal antibodies, such as evogliptin, leverage the glucagon signaling pathway—aligning with the classical view of diabetes as a bi-hormonal disease.336–338 GCGR monoclonal antibodies exert their effects by inhibiting glucagon action, leading to physiological changes characterized by elevated circulating amino acids and increased levels of gut-derived hormones such as GLP-1.339–341 These changes promote α-cell proliferation and facilitate the transdifferentiation of α-cells into insulin-producing β-like cells. Preclinical studies in rodent and non-human primate models have demonstrated substantial improvements in glycemic control and increases in functional β-cell mass, even in the absence of exogenous stem cell input.342,343 Early-phase clinical trials in individuals with T1D have reported reduced insulin requirements and improved glycemic regulation following administration of GCGR monoclonal antibodies.341 While further large-scale and long-term studies are necessary to confirm these findings, GCGR-targeted therapy represents a compelling endogenous regeneration strategy that could complement or potentially substitute for stem cell transplantation, particularly in patients retaining a functional α-cell population. Notably, Table 3 offers a comprehensive overview of current strategies for pancreatic β-cell regeneration, outlining their progression from basic research to clinical application.122,341,344–360 It summarizes available approaches—such as stem cell-derived islet cells, autologous and allogeneic transplantation, endogenous regeneration, gene editing, and encapsulation technologies—and organizes them by source, developmental stage, significant clinical trials or references, main benefits, and key challenges. The goal is to help readers understand the full translational pipeline and the clinical potential and challenges of these therapies for the treatment of T1D.
Table 3Bench-to-bedside strategies for pancreatic β-cell regeneration
| Strategy | Approach/cell source | Development stage | Pivotal trials/references | Key advantages | Major challenges |
|---|
| Stem cell–derived β-cells | Differentiation from hESCs/iPSCs (e.g., VX-880) | Phase 1/2 Clinical Trials | The FORWARD study (VX-880) accomplished insulin independence within a year, with many participants experiencing a reduction in severe hypoglycemia344,345 | Unlimited availability; expandable; significant glucose regulation | Immune rejection: transplantation requires immunosuppression |
| Islet allotransplantation | Donor-derived islets (Donislecel/Lantidra) | FDA-approved since June 2023 | Donislecel received FDA approval with 21 out of 30 patients insulin independent for over a year; serious adverse events occurred in about 90%346,347 | Immediate glycemic restoration; no cell engineering needed | Limited donors, necessity for continuous immunosuppression, and adverse events |
| Autologous iPSC-derived β-cells | Patient-derived iPSCs to β-cells | Preclinical / Early clinical | Proof-of-concept studies are ongoing; it is not yet in late-stage trials348,349 | Personalized; lower immune rejection risk | High cost, time-consuming, and QC and maturation challenges |
| Endogenous regeneration (drug-induced) | GCGR (glucagon receptor antagonist) mAb (volagidemab), GLP-1 analogs, GABA (gamma-aminobutyric acid) | Phase 1/2 Clinical Trials | Volagidemab Phase 2 study: Decrease in HbA1c, reduced insulin usage, yet primary endpoint not achieved341 | Non-invasive; stimulates α-to-β conversion | Effects limited; safety issues with off-target outcomes; primary goals not achieved |
| Direct lineage reprogramming | α-cells/ductal cells → β-cells via TFs | Preclinical | Classic studies122,350 | Uses endogenous plasticity | In vivo efficiency low; off-target reprogramming |
| MSC/HSC therapies | Immunomodulation, β-cell mass preservation | Phase 1/2 Clinical Trials | MSC trials in new-onset T1D show immune regulation351,352 | Delay autoimmune degradation | Limited β-cell regeneration |
| Encapsulation technologies | Immune-shielding of transplanted β-cells | Clinical Trials (ViaCyte PEC-Encap) | NCT02239354 trials are ongoing353,354 | Protects grafts without global immunosuppression | Fibrosis, diffusion limits, vascularization |
| Gene editing (CRISPR/Cas9) | β-cells engineered for hypoimmunity | Preclinical / Early trials | VCTX210 for universal stem-cell islets355,356 | Precision modifications; potential to avoid rejection | Regulatory and ethical challenges |
| Organoids & 3D bioprinting | Scaffold-based islet cluster constructs | Preclinical | Studies by Sun Lab and Kaminiski Lab357,358 | Improved maturation and insulin response | Complex fabrication; vascularization issues |
| Combined β-cell + immunotherapy | β-cell therapy plus immunomodulators | Preclinical / Early trials | Ongoing combo trials like Teplizumab + islet therapy359,360 | Targets regeneration and autoimmunity | Risk of immune adverse events |
Major technical hurdles hindering the clinical translation of stem cell therapy for T1D
Stem cell–based therapies represent a promising avenue for a long-term cure for T1D. However, their clinical translation faces several technical and biological hurdles. A major challenge lies in scaling up the production of insulin-producing beta-like cells from pluripotent stem cells.361,362 This process requires complex, multi-step differentiation protocols that are difficult to standardize and scale under Good Manufacturing Practice conditions. Additional issues include batch-to-batch variability, high reagent costs, and the need for tightly controlled culture environments, all of which contribute to inconsistent outcomes and elevated production costs, ultimately impacting therapy accessibility and affordability.363–365
Another significant obstacle is immune rejection. Since T1D is an autoimmune disease, even autologous or human leukocyte antigen (HLA)-matched allogeneic cells may be susceptible to immune attack.366,367 Encapsulation strategies have been developed to offer immunoprotection. Microencapsulation uses semi-permeable biomaterials such as alginate, chitosan hydrogel, or agarose to allow the exchange of essential molecules while preventing immune cell infiltration.61,368 However, inconsistencies in biomaterial composition can affect their mechanical properties and stability, leading to variable foreign body responses and potential graft failure.369,370 Macroencapsulation devices like the PEC-Direct enable direct vascularization, supporting graft survival and functional integration, but they do not provide immune shielding, necessitating lifelong immunosuppression.329,371 Moreover, macroencapsulation is associated with limited nutrient and oxygen diffusion, risk of cell aggregation and central necrosis, and suboptimal vascularization, all of which impair islet viability and function.372,373 Gene-editing strategies such as CRISPR have also been explored to reduce immune recognition by deleting HLA molecules or immune-activating surface proteins.374,375 While promising, these approaches raise valid concerns about off-target effects and long-term genomic stability.
Importantly, a persistent limitation in the field is the functional immaturity of stem cell–derived beta-like cells.376,377 These cells often exhibit fetal-like phenotypes characterized by poor glucose responsiveness and inadequate insulin secretion. Contributing factors may include incomplete differentiation, altered ion channel expression, and insufficient vascularization at transplantation sites, particularly ectopic locations lacking the appropriate pancreatic microenvironment.378,379 This suboptimal glucose-stimulated insulin secretion limits their ability to tightly regulate glycemia, undermining their therapeutic efficacy.380,381
Furthermore, differentiation protocols often generate heterogeneous cell populations, including off-target or incompletely differentiated cells. These may express markers of non-β-cell pancreatic or extrapancreatic lineages, raising concerns about ectopic hormone production, inappropriate signaling, or unintended paracrine interactions.382,383 Residual undifferentiated pluripotent stem cells within the graft pose a significant tumorigenic risk, such as teratoma formation, especially in long-term applications.384,385 These concerns highlight the necessity for rigorous purification and safety validation protocols before clinical use.
Although the study of immune checkpoint pathways, such as PD-1 and CTLA-4 ligands, offers promising avenues for immunomodulation in T1D, a critical appraisal reveals that their clinical translation is considerably more complex than initially anticipated. These pathways have been extensively studied in the context of cancer immunotherapy, primarily to reinvigorate exhausted T cells.386,387 However, in T1D, they may be more appropriately applied to restrain autoreactive immune responses targeting pancreatic β-cells. Despite this potential, checkpoint blockade carries significant risks, including off-target immune activation and systemic immune dysregulation, which could exacerbate existing autoimmunity or precipitate immune-related adverse events in other organ systems.388,389 Moreover, their efficacy in preserving or restoring endogenous β-cell mass in T1D remains unproven, particularly when used in isolation.
Parallel investigations into β-cell regeneration have focused on transcription factors such as NGN3, a key regulator of endocrine lineage specification during pancreatic development. Reactivation of NGN3 in adult pancreatic tissue holds theoretical promise for the de novo generation of insulin-producing cells.51,390 However, the therapeutic modulation of NGN3 and associated pathways (e.g., Notch, Wnt/β-catenin) is inherently challenging. NGN3 expression is tightly regulated in both temporal and spatial dimensions, and its ectopic or sustained activation can lead to aberrant differentiation or tumorigenesis.391,392 Additionally, successful regeneration requires a careful balance between progenitor cell proliferation and proper β-cell maturation and function, an outcome not yet reliably achieved by current approaches.393,394 Therefore, while these signaling pathways represent compelling therapeutic targets, their clinical implementation must prioritize safety and necessitate a nuanced understanding of their context-dependent activity in the diabetic pancreas.
Taken together, these intersecting biological, engineering, and regulatory challenges underscore the complexity of translating stem cell–based therapies into safe, scalable, and effective treatments for T1D.395,396 Addressing these issues will require sustained interdisciplinary innovation across both research and clinical practice.
Limitations
While advancements in regenerative medicine for T1D have led to some beneficial therapeutic solutions, there are still challenges in translating recent progress into clinical practice. A significant challenge is that β-like cells derived from stem cells continue to show functional immaturity; they typically display a fetal-like characteristic with restricted glucose responsiveness and compromised insulin secretion. Producing these cells on a large scale while adhering to Good Manufacturing Practice standards is technically challenging, frequently hindered by inconsistencies in differentiation efficiency, elevated costs, and prolonged protocols. Immune rejection continues to be a significant obstacle—autologous or HLA-matched cells can still face the risk of autoimmune reactivation. Although encapsulation technologies and gene-editing strategies have demonstrated potential, they bring about further complications, including limited nutrient diffusion, fibrotic overgrowth, and unintended genetic consequences. Additionally, existing differentiation protocols tend to result in mixed cell populations, which raises the likelihood of inappropriate hormone release and the potential for tumor formation. Reprogramming approaches encounter challenges related to stability, effectiveness, and safety, as excessive expression of lineage-defining transcription factors may result in partial conversion or oncogenic transformation. Immunotherapy techniques, like checkpoint blockade, are limited by their systemic immune system effects and their restricted ability to prevent recurrent β-cell autoimmunity. Additionally, one of the most significant obstacles is the insufficient integration of transplanted or reprogrammed β-like cells within the host pancreatic environment. Adequate vascularization, nerve supply, and cell-to-cell communication are vital for the long-term survival and functionality of these cells, yet these features are not adequately replicated in existing models.
Future directions
In the future, strategies aimed at regeneration for T1D will need to move beyond traditional models by embracing a more comprehensive, systems-level approach that integrates stem cell biology, immunoengineering, developmental endocrinology, and tissue bioengineering. A key aim in these regenerative efforts will be to elucidate the processes through which immature β-like cells develop into glucose-responsive, functionally effective insulin-producing cells. The developmental environment can be mimicked using biomimetic scaffolds alone, ECM hydrogels by themselves, or possibly through vascularized organ-on-chip systems, which may provide the necessary biochemical and mechanical cues for proper islet development and functionality.397,398 These culture systems might also have the capability to facilitate the co-differentiation of supporting islet-resident cell types, such as endothelial cells, pericytes, or pancreatic stellate cells, which play essential supportive roles by providing angiocrine signals, paracrine signals, and immune modulation.399,400
Concurrently, studies that utilize single-cell multi-omics and spatial transcriptomics for lineage tracing and fate mapping are necessary to gain a clearer understanding of the identity, plasticity, and differentiation capacity of adult pancreatic progenitor and non-β-cell lineages. This is important for developing more informed in situ regenerative therapy strategies, such as activating dormant progenitor-like states or orchestrating transdifferentiation pathways of either α-, δ-, or acinar cells into insulin-secreting cells through the application of transcription factor combinations or epigenetic modifiers. Moreover, reprogramming techniques should not only achieve lineage conversion but also guarantee that they encourage lasting phenotypic stability and controlled growth, as any improper growth could lead to hyperplasia or neoplasia.399,400
Understanding these strategies within the realm of immunology by combining tolerogenic and regenerative elements will be essential. There are emerging possibilities with tissue-engineered islets that are encapsulated with immunoregulatory ligands, local administration of checkpoint modulator-based methods to promote antigen-specific tolerance, and hybrid encapsulation systems that can release immunosuppressive cytokines or utilize agents like TGF-β or immune checkpoint agonists such as CTLA-4-Ig in optimal spatiotemporal release patterns. Furthermore, using neo-self signaling pathways to reprogram designed β-cells can help them evade immune recognition by showcasing “don’t-eat-me” signals like CD47 or create synthetic immunomodulatory networks to promote immune effector evasion, while simultaneously allowing host surveillance to overpower foreign pathogens.401,402
A critical yet underutilized area of research is the neuroendocrine regulation of regenerated β-cells.403,404 Successful biofunctionality requires the secretion of insulin triggered by hyperglycemia, along with autonomic nerve input and endocrine coordination with systemic hormones.405,406 There is an urgent need for research focused on the reorganization of neurovascular networks and how this may influence β-cell function and longevity. Similarly, it is essential to develop closed-loop systems that integrate biosensors to facilitate the smart delivery of various trophic and immunomodulatory factors capable of promoting regeneration in response to mechanical stimulation.407,408
Moreover, predictive modeling driven by artificial intelligence and based on individualized immunogenetic, transcriptomic, and metabolic information can be employed to categorize patients, anticipate the reactivation of autoimmunity, and customize regenerative strategies to improve their effectiveness and safety.409,410 Gene-editing technologies like base editors or prime editors could allow for precise modifications of loci associated with autoimmune susceptibility or even changes to β-cell immunogenicity while minimizing the risk of genotoxic effects.411,412 It will also be essential for ethical and regulatory frameworks to evolve in order to ensure that the ramifications of these personalized and potentially heritable treatments are safe, fair, and monitored for long-term safety.
Ultimately, future clinical trials need to implement adaptive and decentralized designs that allow for real-time biomarker analysis, immune profiling, and comprehensive multi-omics evaluations focusing not only on glycemic control but also on immune compatibility, graft integration, and the β-cell stress response.413,414 Collaborative global consortia and partnerships between the public and private sectors will be crucial for standardizing differentiation methods, potency evaluations, and long-term safety outcomes, which will help transition the field from a proof-of-concept stage to large-scale and equitable treatments. In conclusion, the path ahead necessitates collaboration among bioengineering, immunology, systems biology, and patient-centered precision medicine to create effective, safe, and sustainable cures for T1D.
Conclusions
Regenerative medicine aims to transform conventional T1D treatment by enabling the restoration of functional insulin-secreting β-cells. A particularly promising therapeutic strategy involves cellular reprogramming, which seeks to convert adult non-β pancreatic cells—such as α-cells or ductal epithelial cells—into insulin-producing β-like cells, potentially bypassing the need for exogenous stem cell sources. This approach leverages the inherent plasticity of pancreatic cell lineages and is driven by key developmental signaling pathways, including NGN3, Wnt/β-catenin, and Hippo/YAP. Recent advances, such as single-cell RNA sequencing and lineage tracing technologies, are critical for identifying rare progenitor subsets, mapping dynamic cell fate transitions, and confirming the fidelity and functionality of reprogrammed cells. Additionally, 3D pancreatic organoid models provide physiologically relevant platforms for assessing reprogramming efficiency, β-cell maturation, and disease modeling. Another major opportunity lies in engineering β-cells with immune-evasive properties, inspired by the natural immune privilege of α-cells. Epigenetic profiling has uncovered protective chromatin configurations and methylation landscapes in α-cells, which may be recapitulated in β-cells using CRISPR/Cas9 genome editing to downregulate autoantigen expression and enhance cell survival. Concurrently, immune-modulatory approaches, such as PD-1/CTLA-4 immune checkpoint inhibition and administration of anti-inflammatory cytokines (e.g., IL-10, TGF-β), are being developed to promote a localized immune-tolerant microenvironment. Nonetheless, several critical knowledge gaps impede clinical translation, including incomplete understanding of the molecular determinants of stable β-cell identity post-reprogramming; the long-term functionality and glucose responsiveness of reprogrammed cells under physiological stress; the mechanisms of immune escape; and the integration of engineered cells within native islet architecture, innervation, and vasculature. Moreover, issues of scalability, ethical considerations, and regulatory complexity must be systematically addressed to advance these innovations toward durable, clinically viable therapies for T1D.
Declarations
Funding
This research was supported by Bandhan, Kolkata, India.
Conflict of interest
The authors have nothing to declare.
Authors’ contributions
Conceptualization, formal analysis, original draft preparation, project supervision, project administration, funding acquisition (SKC), and writing—review and editing (SKC, DC). Both authors have approved the final version and publication of the manuscript.