The Secretome of Mesenchymal Stem Cells Prevents Islet Beta Cell Apoptosis via an IL-10-Dependent Mechanism

Glucose-stimulated insulin secretion (GSIS) from pancreatic islet beta-cells is central to control of mammalian fuel homeostasis. Glucose metabolism mediates GSIS in part via ATP-regulated K+ (KATP) channels, but multiple lines of evidence suggest participation of other signals. Here we investigated the role of cytosolic NADP-dependent isocitrate dehydrogenase (ICDc) in control of GSIS in beta-cells. Delivery of small interfering RNAs specific for ICDc caused impairment of GSIS in two independent robustly glucose-responsive rat insulinoma (INS-1-derived) cell lines and in primary rat islets. Suppression of ICDc also attenuated the glucose-induced increments in pyruvate cycling activity and in NADPH levels, a predicted by-product of pyruvate cycling pathways, as well as the total cellular NADP(H) content. Metabolic profiling of eight organic acids in cell extracts revealed that suppression of ICDc caused increases in lactate production in both INS-1-derived cell lines and primary islets, consistent with the attenuation of pyruvate cycling, with no significant changes in other intermediates. Based on these studies, we propose that a pyruvate cycling pathway involving ICDc plays an important role in control of GSIS.

Three novel human insulin-releasing cell lines designated 1.1B4, 1.4E7, and 1.1E7 were generated by electrofusion of freshly isolated of human pancreatic beta cells and the immortal human PANC-1 epithelial cell line. Functional studies demonstrated glucose sensitivity and responsiveness to known modulators of insulin secretion. Western blot, RT-PCR, and immunohistochemistry showed expression of the major genes involved in proinsulin processing and the pancreatic beta cell stimulus-secretion pathway including PC1/3, PC2, GLUT-1, glucokinase, and K-ATP channel complex (Sur1 and Kir6.2) and the voltage-dependent L-type Ca(2+) channel. The cells stained positively for insulin, and 1.1B4 cells were used to demonstrate specific staining for insulin, C-peptide, and proinsulin together with insulin secretory granules by electron microscopy. Analysis of metabolic function indicated intact mechanisms for glucose uptake, oxidation/utilization, and phosphorylation by glucokinase. Glucose, alanine, and depolarizing concentrations of K(+) were all able to increase [Ca(2+)](i) in at least two of the cell lines tested. Insulin secretion was also modulated by other nutrients, hormones, and drugs acting as stimulators or inhibitors in normal beta cells. Subscapular implantation of the 1.1B4 cell line improved hyperglycemia and resulted in glucose lowering in streptozotocin-diabetic SCID mice. These novel human electrofusion-derived beta cell lines therefore exhibit stable characteristics reminiscent of normal pancreatic beta cells, thereby providing an unlimited source of human insulin-producing cells for basic biochemical studies and pharmacological drug testing plus proof of concept for cellular insulin replacement therapy.

Diabetes mellitus is a complex metabolic disease that has become a global epidemic with more than 285 million cases worldwide. Major medical advances over the past decades have substantially improved its management, extending patients' survival. The latter is accompanied by an increased risk of developing chronic macro- and microvascular complications. Amongst them, diabetic retinopathy (DR) is the most common and frightening. Furthermore, during the past two decades, it has become the leading cause of visual loss. Irrespective of the type of diabetes, DR follows a well-known clinical and temporal course characterized by pericytes and neuronal cell loss, formation of acellular-occluded capillaries, occasional microaneurysms, increased leucostasis and thickening of the vascular basement membrane. These alterations progressively affect the integrity of retinal microvessels, leading to the breakdown of the blood-retinal barrier, widespread haemorrhage and neovascularization. Finally, tractional retinal detachment occurs leading to blindness. Nowadays, there is growing evidence that local inflammation and oxidative stress play pivotal roles in the pathogenesis of DR. Both processes have been associated with pericytes and neuronal degeneration observed early during DR progression. They may also be linked to sustained retinal vasculature damage that results in abnormal neovascularization. Currently, DR therapeutic options depend on highly invasive surgical procedures performed only at advanced stages of the disease, and which have proved to be ineffective to restore visual acuity. Therefore, the availability of less invasive and more effective strategies aimed to prevent or delay the onset of DR is highly desirable. Multipotent mesenchymal stromal cells, also referred to as mesenchymal stem cells (MSCs), are promising healing agents as they contribute to tissue regeneration by pleiotropic mechanisms, with no evidence of significant adverse events. Here, we revise the pathophysiology of DR to identify therapeutic targets for donor MSCs. Also, we discuss whether an MSC-based therapy could prevent or delay the onset of DR.

Differentiation of insulin-producing cells (IPCs) from stem cells has been widely studied as an alternative source for cell transplantation therapy in diabetes. Mesenchymal stem cells (MSCs) are a useful therapeutic option for islet transplants due to their immunomodulatory properties and differentiation potential. In this study, we introduce a method for in vitro differentiation of pancreatic MSCs into IPCs. Research-grade pancreas from cadaveric donors was used to isolate islets, and the COBE remnant after islet purification was used for the generation of pancreatic MSCs. The remnant tissue was cultured in RPMI medium and plastic to isolate tissue-resident MSCs. Surface marker expression analysis and differentiation assays were performed to characteristically confirm that the cells obtained were in fact MSCs. Osteogenic, adipogenic and chondrogenic differentiation of MSCs were induced by StemPro® differentiation kits. The protocol for the differentiation of IPCs from stem cells was adopted from Pagliuca et al. 2014. Similarly, we have treated the pancreatic MSCs with molecules and growth factors at different stages of development to produce IPCs. The insulin secretion from differentiated IPCs also analyzed at all stages. The culture of remnant tissue after islet isolation resulted in plastic-adherent cells of fibroblast-like morphology after 3 passages. Flow cytometry analysis showed homogeneous expression of markers (CD90, CD73, CD29, CD105) and negative expression of CD14, CD34, and CD45 as classically characterized by cultured MSCs. Interestingly, there was a significant increase in insulin levels up to 5 and 100 folds in the media at developmental stages S5 (P= 0.0686) and S6 (P <0.0001) respectively. Our results reveal that MSCs can be directly differentiated into IPCs. Human pancreas-derived MSCs may serve as an alternative source of insulin-producing beta cells that can be transplanted to type 1 diabetes patients. Disclosure J. Kalivarathan: None. P. Saravanan: None. M.F. Levy: None. M.A. Kanak: None.

Immunosuppression in sepsis is hypothesized to result from the increased expression of the immune checkpoint molecules programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1). PD-1 and PD-L1 blockade therapies have been reported to increase survival in septic animals. Currently, the interleukin (IL)-10 within mesenchymal stem cell (MSC) secretome is known for its immunomodulatory capacity. To study the effect of IL-10 within MSC secretome on the expression of immune checkpoints in the rat model of sepsis. Methods: We used 48 male Rattus norvegicus rats in this research and divided them into four groups: sham (rats without sepsis induction and treatment), control (sepsis-induced rats without treatment), T1 (sepsis-induced rats treated with 150 μL of secreted IL-10 from MSC), and T2 (sepsis-induced rats treated with 300 μL of secreted IL-10 from MSC). Forty-eight hours after sepsis induction, we terminated the rats and collected the blood to examine the PD-1 and PD-L1 expression levels. We found a decrease in the relative expression of PD-1 in the septic rat group given 150 μL and 300 μL of secreted IL-10 from MSC compared to the control group, but the decrease was not significant. We also found a decrease in the relative expression of PD-L1 mRNA in the septic rat group given 150 μL and 300 μL of secreted IL-10 from MSC compared to the control group. Administering secreted IL-10 from MSC reduces the expression of PD-1 and PD-L1 in sepsis. These findings suggest that MSC secretome can improve the immunosuppression in sepsis.

Introduction: Osteoarthritis (OA) is a leading cause of disability, characterized by cartilage degeneration. Current therapies primarily alleviate symptoms rather than address cartilage damage. This systematic review evaluates the potential of mesenchymal stem cell (MSC) secretome as a regenerative treatment for OA. Method: A comprehensive literature search was conducted across EMBASE, Medline, Google Scholar and PLOS One databases using specific keywords related to MSCs and OA. Inclusion criteria focused on studies published from 2019 to 2024, while exclusion criteria eliminated reviews and non-experimental articles. The PRISMA guidelines were followed for screening and synthesis. Results: The review identified several studies demonstrating that MSC-derived secretome significantly improves clinical outcomes in OA. For instance, umbilical cord-derived MSC secretome showed enhanced cartilage repair and favorable biomarker changes with a favorable safety profile, indicating no adverse effects. Discussion: Findings suggest that MSC secretome offers a regenerative strategy targeting cartilage degeneration, contrasting with conventional therapies. The secretome's rich composition of bioactive molecules supports cartilage health and promotes tissue repair. However, variability in methodologies and limited sample sizes highlight the need for standardized protocols and larger randomized controlled trials. Conclusion: MSC secretome represents a promising therapeutic approach for OA, addressing the underlying pathology rather than merely alleviating symptoms. Continued research is essential to optimize treatment protocols and fully harness the potential of MSC secretome in improving OA management.

Mesenchymal stem cells (MSCs) are capable of crossing germinative layer borders and are obtainable in high numbers via in vitro cultures. Therefore, many researchers have searched for diverse sources of MSCs. Recently the generation of glucose-responsive insulin-producing cells (IPCs) from MSCs has shown immense potential for the treatment of type 1 diabetes mellitus (T1DM) due to a lack of pancreas donors. In this study, we compared the growth potency of four kinds of MSCs derived from bone marrow, Wharton's jelly, adipose tissue, and the periosteum. In addition, in vitro differentiation of these MSCs into IPCs was also investigated. After 2weeks of IPCs differentiation, we compared the expression of the insulin gene and protein using RT-qPCR and immunofluorescence staining. Only IPCs derived from periosteum-derived progenitor cells (PDPCs) showed a response to glucose concentration. Glucose stimulated insulin secretion was conclusive evidence of the potential functionality of IPCs. Therefore, PDPCs are a promising alternative stem cell source for IPCs differentiation.

Pancreatic-derived factor (PANDER) is an islet-specific cytokine present in both pancreatic alpha- and beta-cells, which, in vitro, induces beta-cell apoptosis of primary islet and cell lines. In this study, we investigated whether PANDER is secreted by pancreatic alpha- and beta-cells and whether PANDER secretion is regulated by glucose and other insulin secretagogues. In mouse-derived insulin-secreting beta-TC3 cells, PANDER secretion in the presence of stimulatory concentrations of glucose was 2.8 +/- 0.4-fold higher (P < 0.05) than without glucose. Insulin secretion was similarly increased by glucose in the same cells. The total concentration of secreted PANDER in the medium was approximately 6-10 ng/ml (0.3-0.5 nmol/l) after a 24-h culture with glucose. L-Glucose failed to stimulate PANDER secretion in beta-TC3 cells. KCl stimulated PANDER secretion 2.1 +/- 0.1-fold compared with control without glucose. An L-type Ca2+ channel inhibitor, nifedipine, completely blocked both glucose- or KCl-induced insulin and PANDER secretion. In rat-derived INS-1 cells, glucose (20 mmol/l) stimulated PANDER secretion 4.4 +/- 0.9-fold, while leucine plus glutamine stimulated 4.4 +/- 0.7-fold compared with control without glucose. In mouse islets overexpressing PANDER, glucose (20 mmol/l) stimulated PANDER secretion 3.2 +/- 0.5-fold (P < 0.05) compared with basal (3 mmol/l glucose). PANDER was also secreted by alpha-TC3 cells but was not stimulated by glucose. Mutations of cysteine 229 or of cysteines 91 and 229 to serine, which may form one disulfide bond, and truncation of the COOH-terminus or NH2-terminus of PANDER all resulted in failure of PANDER secretion, even though these mutant or truncated PANDERs were highly expressed within the cells. In conclusion, we found that 1) PANDER is secreted from both pancreatic alpha- and beta-cells, 2) glucose stimulates PANDER secretion dose dependently in beta-cell lines and primary islets but not in alpha-cells, 3) PANDER is likely cosecreted with insulin via the same regulatory mechanisms, and 4) structure and conformation is vital for PANDER secretion.

Proteomic analysis of the secretome of human bone marrow-derived mesenchymal stem cells primed by pro-inflammatory cytokines

The Effect of Vitamin D Supplementation on Glycemic Control and Body Mass Index in the Obese, Vitamin D Deficient Adult with Type 2 Diabetes Mellitus: A Systematic Review Protocol

Background & Objective: Thin endometrium (<7 mm) impairs receptivity and reduces pregnancy rates in Assisted Reproductive Technology (ART). Conventional therapies such as estrogen, vasodilators, Granulocyte Colony-Stimulating Factor (G-CSF), and platelet-rich plasma (PRP) showed inconsistent efficacy. Mesenchymal Stem Cell (MSC) secretome has emerged as a promising regenerative strategy. The narrative review was conducted with aim to synthesize evidence on the therapeutic potential of MSCs secretome for the treatment of thin endometrium.Materials & Methods: This narrative review was conducted through search in databases of PubMed, Scopus, and Google Scholar for studies up to 2025 using the keywords of “thin endometrium,” “mesenchymal stem cells,” “secretome,” and “exosomes.” Preclinical and clinical studies were included, with emphasis on human trials reporting endometrial thickness, receptivity, and pregnancy outcomes.Results: Preclinical studies demonstrate that the MSCs secretome enhances angiogenesis, modulates immune tolerance, reduces fibrosis, and promotes endometrial repair. Early clinical studies using bone marrow–, umbilical cord–, adipose tissue–, and menstrual blood–derived MSCs or their secretome report increased endometrial thickness and improved implantation, with some pregnancies and live births achieved. Safety data are favorable, particularly for secretome-derived extracellular vesicles, which avoid risks linked to cell transplantation.Conclusion: MSC secretome, based therapy offers a promising cell-free approach to manage thin endometrium through multimodal regenerative effects. While preliminary clinical findings are encouraging, larger controlled trials are needed to confirm the efficacy, optimize delivery, and establish long-term safety.

In recent years, major effort has been made to differentiate embryonic stem cells, pancreatic ductal epithelial multipotent progenitor cells, and bone marrow stem cells into insulin secreting cells. Our previous work has also demonstrated the feasibility of inducing mesenchymal stem cells (MSC) to insulin secreting cells through overexpression of Pdx-1, a pancreas and islet-specific transcription factor that plays a major role in differentiation of islet β-cells during development (Yuan et al. in Mol Biol Rep 37:4023-4031, 2010). However, the levels of insulin secretion among these differentiated MSC were quite variable. The purpose of this study is to address the issue whether the insulin secretion level from the differentiated MSC lines are determined by the expression level of the Pdx-1 transgene. To do so, we have generated several differentiated MSC lines with stable transfection of the Pdx-1 gene. Using RT-PCR analysis and insulin secretion assay, we have analyzed Pdx-1 mRNA levels and insulin secretion from these stable MSC lines. Our results showed that Pdx-1 expression is absolutely required for the differentiation of MSC lines to insulin secreting cell lines. Furthermore, we demonstrated that the level of Pdx-1 expression is closely correlated with level of insulin mRNA and insulin secretion level in differentiated MSC stable cell lines. These findings suggest that the level of Pdx-1 expression plays a key role in induction of MSCs to insulin secreting cells.

Exploiting the impact of the secretome of MSCs isolated from different tissue sources on neuronal differentiation and axonal growth

While mesenchymal stem cells (MSCs) have gained enormous attention due to their unique properties of self-renewal, colony formation, and differentiation potential, the MSC secretome has become attractive due to its roles in immunomodulation, anti-inflammatory activity, angiogenesis, and anti-apoptosis. However, the precise stimulation and efficient production of the MSC secretome for therapeutic applications are challenging problems to solve. Here, we report on Acoustofluidic Interfaces for the Mechanobiological Secretome of MSCs: AIMS. We create an acoustofluidic mechanobiological environment to form reproducible three-dimensional MSC aggregates, which produce the MSC secretome with high efficiency. We confirm the increased MSC secretome is due to improved cell-cell interactions using AIMS: the key mediator N-cadherin was up-regulated while functional blocking of N-cadherin resulted in no enhancement of the secretome. After being primed by IFN-γ, the secretome profile of the MSC aggregates contains more anti-inflammatory cytokines and can be used to inhibit the pro-inflammatory response of M1 phenotype macrophages, suppress T cell activation, and support B cell functions. As such, the MSC secretome can be modified for personalized secretome-based therapies. AIMS acts as a powerful tool for improving the MSC secretome and precisely tuning the secretory profile to develop new treatments in translational medicine.

Mesenchymal stem cells (MSCs) have the potential to be a viable therapy against various diseases due to their paracrine effects, such as secretion of immunomodulatory, trophic and protective factors. These cells are known to be distributed within various organs and tissues. Although they possess the same characteristics, MSCs from different sources are believed to have different secretion potentials and patterns, which may influence their therapeutic effects in disease environments. We characterized the protein secretome of adipose (AD), bone marrow (BM), placenta (PL), and Wharton’s jelly (WJ)-derived human MSCs by using conditioned media and analyzing the secretome by mass spectrometry and follow-up bioinformatics. Each MSC secretome profile had distinct characteristics depending on the source. However, the functional analyses of the secretome from different sources showed that they share similar characteristics, such as cell migration and negative regulation of programmed cell death, even though differences in the composition of the secretome exist. This study shows that the secretome of fetal-derived MSCs, such as PL and WJ, had a more diverse composition than that of AD and BM-derived MSCs, and it was assumed that their therapeutic potential was greater because of these properties.