Diabetes mellitus (DM) is a metabolic disease characterized by persistent hyperglycemia, resulting from defects in insulin secretion or impaired insulin action. In cases of severe pancreatic cell dysfunction and deficiency, the primary treatment remains lifelong insulin injections. A potential alternative is allogeneic pancreatic cell transplantation from a donor, which can stabilize glucose levels. However, the scarcity of donor material and the risk of immune rejection limit the widespread use of this approach. An alternative solution involves using in vitro-derived insulin-producing cells generated through the differentiation of pluripotent stem cells (PSCs), which could overcome the shortage of transplantable material. Furthermore, patient-specific cells—obtained directly from the patient via reprogramming of blood or skin cells into induced pluripotent stem cells (iPSCs)—would avoid immune rejection. Advances in this field have led to the active development and optimization of PSC differentiation into hormone-producing cells worldwide, with more than hundred patients dosed in clinical trials with ESC-derived cells and the single trial of iPSC-derived cells. This review highlights recent progress and prospects in generating insulin-producing cells from human PSCs, their applications in therapy development and disease modeling, as well as the current challenges and potential solutions.

The treatment of type 1 diabetes through pancreatic islet transplantation faces significant limitations, including donor organ shortages and poor islet survival due to post-transplantation loss of extracellular matrix support and inadequate vascularization. Developing biocompatible scaffolds that mimic the native islet microenvironment could substantially improve transplantation outcomes. This study aimed to create and evaluate decellularized (DCL) matrices from porcine organs as potential platforms for islet transplantation. Porcine lung and pancreatic tissues were decellularized using four different protocols combining detergents (Triton X-100, SDS and SDC) with optimized incubation times. The resulting matrices were characterized through DNA quantification and histological staining (H&E and Van Gieson). Islet viability was assessed in vitro using Live/Dead staining after 3 and 7 days of culture on the matrices. In vivo biocompatibility was evaluated by implanting matrices into rat omentum or peritoneum, with histological analysis at 1-, 4-, and 8 weeks post-transplantation. Protocols 3 (for lung tissue) and 4 (for pancreas tissue) demonstrated optimal decellularization efficiency with residual DNA levels below 8%, while preserving the collagen and elastin networks. In vitro, islets cultured on decellularized lung matrix had maintained 95% viability by day 7, significantly higher than the controls (60%) and pancreatic matrix (83%). The omentum showed superior performance as an implantation site, exhibiting minimal inflammation and fibrosis compared to the peritoneum sites throughout the 8-week study period. These findings establish DCL as a promising scaffold for islet transplantation due to its superior preservation of ECM components and excellent support of islet viability. This work provides a significant step toward developing effective tissue-engineered therapies for diabetes treatment.

FLIM (Fluorescence Lifetime Imaging Microscopy) is a powerful tool that could be used in the future to diagnose islet cell recovery after therapy. The identification of appropriate FLIM parameters is required to determine islet quality and islet cell metabolism throughout the organ under various conditions of insulin deficiency. The aim of the work was to identify key FLIM parameters, changes of which are characteristic of pancreatic pathologies. The τm, τ1, τ2, α1, α2 and α1/α2 of free and bound forms of NAD(P)H of the islet cells of animals (rats and pigs) and of humans with and without pathologies were measured and analyzed. The data were confirmed by IHC and histological studies. We identified three FLIM parameters in islet cells from animals with streptozotocin (STZ)-induced diabetes mellitus (DM) and from humans with chronic pancreatitis + type 2 diabetes (T2D), which differ in the same way: τm and α2 take lower values compared to the nonpathological islet cells, while α1/α2 takes higher values. In islet cells from patients with adenocarcinoma (PDAC) and chronic pancreatitis, these parameters had reverse tendency relative to the norm or did not differ. Thus, minimally invasive and non-contrast FLIM methods may, in the future, be used to diagnose pathological islet cells.

Allogeneic cell replacement therapy for diabetes using induced pluripotent stem cell (iPSC)-derived pancreatic progenitors (PPs) is currently limited by immune rejection. Alginate encapsulation and the genetic ablation of HLA-I via β2-microglobulin (B2M) knockout represent distinct strategies to reduce immune recognition and to protect the transplanted cells. We generated encapsulated B2M-knockout pancreatic progenitors (IPS-∆B2M-PPs) and evaluated their immunogenicity in vitro using each of: peripheral blood mononuclear cell (PBMC) co-culture, natural killer cell (NK cell) degranulation, T-cell activation, and rat macrophage adhesion. In vivo studies were also performed to assess capsule biocompatibility and structural stability, following transplantation into rat omentum. While the B2M knockout did not compromise differentiation to pancreatic lineage, encapsulation largely prevented NK cell degranulation regardless of the encapsulated cell type, although T-cells did show residual activation after 7 days of co-culture with encapsulated progenitors, albeit significantly reduced in comparison with non-encapsulated controls. IPS-∆B2M-PP-containing capsules showed reduced macrophage adhesion in vitro compared to wild-type progenitors, while Interleukin-1β (IL-1β) secretion by the macrophages remained negligible. In vivo, all capsules formed a myofibroblastic zone without giant foreign-body cells; IPS-∆B2M-PP implants exhibited the thinnest fibrotic capsules and minimal lymphocytic infiltration. No capsule deformation was observed at 2 weeks or 1 month, indicating preserved structural stability. Although this characterizes both the local tissue response to the biomaterial and capsule stability, it does not establish immune evasion or reduced immunogenicity of the encapsulated cells in vivo. Overall, this study demonstrates the feasibility of combining B2M knockout with alginate encapsulation and suggests a potential additional protective role for B2M deletion under conditions of compromised capsule integrity that requires further investigation.