Biomimetic-scaffolds recapitulating native microarchitecture improved long-term survival and function of stem-cell-derived β-cells transplanted in subcutaneous space for treating type1 diabetes

Introduction: : β-cell replacement therapy (βCRT) offers significant promise for restoring long-term glycemic control in individuals with type 1 diabetes (T1D). Despite the potential of stem cell-derived β-cell clusters as an unlimited cell source, clinical outcomes using subcutaneous islet encapsulation have been disappointing. Traditional micro- and macro-encapsulation strategies primarily focus on immune protection, neglecting the critical role of the cellular microenvironment. They impair cell-cell communication, restrict nutrient and oxygen access, promote ischemic stress, and lead to metabolic waste accumulation overall that contribute to graft failure. Emerging evidence highlights the pivotal influence of the microenvironment on β-cell survival and function. In this study, we engineer biomimetic scaffolds designed to recreate the native pancreatic niche and evaluate their impact on β-cell long-term viability and function for βCRT.

Materials and

Methods: : We engineered two biomimetic scaffold platforms designed to mimic the 3D microarchitecture in the native pancreas for islets: a microporous scaffold (MPS) with a stochastic pore structure, and a microwell scaffold (MWS) featuring an ordered array of wells. Both scaffolds were fabricated from biocompatible and biodegradable polycaprolactone using advanced microfabrication techniques, including photolithography, soft lithography, and phase inversion. They were subsequently integrated with stem cell-derived β-cell (sc-β) clusters at the final stage of differentiation. The resulting biomimetic cell–scaffold constructs (β-MPS and β-MWS) were systematically characterized using electron microscopy and immunofluorescence imaging to assess their ability to recapitulate key features of the native islet microenvironment. Scaffold performance was evaluated through in vitro analyses of sc-β cell viability, gene expression, metabolic activity, and glucose-stimulated insulin secretion, followed by in vivo studies using bioluminescence imaging and intraperitoneal glucose tolerance testing to assess cell survival and functional efficacy.

Results, Conclusions, and Discussions:: Results and

Discussion:
The sc-β clusters on β-MPS and β-MWS retained native morphology and avoided aggregation, in contrast to controls (Fig. A). Viability was significantly higher on both scaffold types (p < 0.05) (Fig. B), and clusters exhibited enhanced maturation, marked by increased expression of INS (Fig. C), along with key β cell transcription factors NKX6.1, and MAFA. sc-β clusters on biomimetic scaffolds reconstituted key extracellular matrix components, including basal membrane structures (Fig. D). Metabolic profiling revealed a pronounced shift toward oxidative metabolism, with scaffold-supported sc-β clusters showing a 5-fold increase in mitochondrial respiration relative to controls (Fig. E). Functionally, these sc-β clusters on β-MPS and β-MWS demonstrated nearly a ~3-fold increase in glucose-stimulated insulin secretion and exhibited significantly improved dynamic responsiveness to glucose fluctuations (Fig. F).

In vivo, scaffold-supported sc-β clusters displayed a ~4.5-fold increase in short- and long-term survival post-transplantation, with β-MWS yielding the most robust results (Fig. G). In particular, sc-β clusters on β-MWS exhibited ~1.5-fold greater insulin secretion and improved glucose tolerance, establishing this architecture as the most effective for long-term function (Fig. H). These data underscore the role of scaffold-guided microenvironments in enhancing β-cell viability, metabolic performance, and endocrine function across in vitro and in vivo settings.

Conclusion:
Our findings highlight the pivotal role of biomimetic scaffolds in sustaining β-cell function. Native islet physiology is governed by spatially organized biochemical and mechanical cues; features replicated in our engineered β-MPS and β-MWS scaffolds. Both platforms significantly enhanced sc-β survival, oxidative metabolism, and glucose-responsive insulin secretion, with β-MWS showing superior outcomes. These scaffolds are compatible with encapsulation strategies or standalone use alongside localized immunomodulation and are well-suited for implantation at clinically relevant, yet inhospitable, subcutaneous sites. By integrating biomimetic architecture with stem cell–derived β-cell technology for transplantation, this approach offers a compelling path toward scalable, durable β-cell replacement therapy for type 1 diabetes.

Acknowledgements and/or References (Optional):: Breakthrough T1D (formerly JDRF), Diabetes Research Connections