Expansion of transplanted islets in mice by co-transplantation with adipose tissue-derived mesenchymal stem cells

Co-culture of vascular endothelial cells enhances corticosterone production in steroid hormone-producing cells generated from adipose-derived mesenchymal stromal cells

Cell therapy for adrenocortical insufficiency can potentially provide steroid replacement in response to physiological stimuli. Previously, we reported that adipose tissue-derived stromal cells (ADSCs) are transformed into steroid-producing cells by overexpression of nuclear receptor subfamily 5 group A member 1 (NR5A1). The steroidogenic cells are characterized by the production of both adrenal and gonadal steroids. Cytotherapy for adrenocortical insufficiency requires cells with more adrenocortical characteristics. Considering the highly developed vascular network within the adrenal cortex, all adrenocortical cells are adjacent to and interact with vascular endothelial cells (VECs). In this study, NR5A1-induced steroidogenic cells derived from mouse ADSCs (NR5A1-ADSCs) were co-cultured with mouse VECs. Testosterone secretion in NR5A1-ADSCs was not altered; however, corticosterone secretion significantly increased while levels of steroidogenic enzymes significantly increased in the corticosterone synthesis pathway. Co-culture with lymphatic endothelial cells (LECs) or ADSCs, or transwell culture with NR5A1-ADSCs and VECs did not alter corticosterone production. VECs expressed higher levels of collagen and laminin than LECs. Culture in type-IV collagen and laminin-coated dishes increased corticosterone secretion in NR5A1-ADSCs. These results suggest that VECs may characterize ADSC-derived steroidogenic cells into a more corticosterone-producing phenotype, and VECs may be useful for generating adrenal steroidogenic cells from stem cells.

Unveiling therapeutic potential: Adipose tissue-derived mesenchymal stem cells and their exosomes in the management of diabetes mellitus, wound healing, and chronic ulcers

Diabetes mellitus (DM) is a pervasive global health issue with substantial morbidity and mortality, often resulting in secondary complications, including diabetic wounds (DWs). These wounds, arising from hyperglycemia, diabetic neuropathy, anemia, and ischemia, afflict approximately 15% of diabetic patients, with a considerable 25% at risk of lower limb amputations. The conventional approaches for chronic and diabetic wounds management involves utilizing various therapeutic substances and techniques, encompassing growth factors, skin substitutes and wound dressings. In parallel, emerging cell therapy approaches, notably involving adipose tissue-derived mesenchymal stem cells (ADMSCs), have demonstrated significant promise in addressing diabetes mellitus and its complications. ADMSCs play a pivotal role in wound repair, and their derived exosomes have garnered attention for their therapeutic potential. This review aimed to unravel the potential mechanisms and provide an updated overview of the role of ADMSCs and their exosomes in diabetes mellitus and its associated complications, with a specific focus on wound healing.

Progress and application of adipose-derived stem cells in the treatment of diabetes and its complications

Diabetes mellitus (DM) is a serious chronic metabolic disease that can lead to many serious complications, such as cardiovascular disease, retinopathy, neuropathy, and kidney disease. Once diagnosed with diabetes, patients need to take oral hypoglycemic drugs or use insulin to control blood sugar and slow down the progression of the disease. This has a significant impact on the daily life of patients, requiring constant monitoring of the side effects of medication. It also imposes a heavy financial burden on individuals, their families, and even society as a whole. Adipose-derived stem cells (ADSCs) have recently become an emerging therapeutic modality for DM and its complications. ADSCs can improve insulin sensitivity and enhance insulin secretion through various pathways, thereby alleviating diabetes and its complications. Additionally, ADSCs can promote tissue regeneration, inhibit inflammatory reactions, and reduce tissue damage and cell apoptosis. The potential mechanisms of ADSC therapy for DM and its complications are numerous, and its extensive regenerative and differentiation ability, as well as its role in regulating the immune system and metabolic function, make it a powerful tool in the treatment of DM. Although this technology is still in the early stages, many studies have already proven its safety and effectiveness, providing new treatment options for patients with DM or its complications. Although based on current research, ADSCs have achieved some results in animal experiments and clinical trials for the treatment of DM, further clinical trials are still needed before they can be applied in a clinical setting.

Greb1 Transiently Accelerates Pancreatic β-Cell Proliferation in Diabetic Mice Exposed to Estradiol

Decrease of pancreatic β cells leads to diabetes. In an inducible cAMP early suppressor (ICER-Iγ) transgenic mouse model of severe type 2 diabetes with reduced insulin production and depleted β cells, supplementation with high concentrations of 17β-estradiol (E2) markedly enhances β-cell proliferation and normalizes glucose levels. The current study explored the underlying mechanisms leading to a dynamic increase of β cells and pathologic changes in diabetic mice exposed to E2. Gene expression profiling of pancreatic islets of 6-month-old ICER-transgenic mice recovering from diabetes due to elevated E2 levels identified growth regulation by estrogen in breast cancer 1 (Greb1) as a gene significantly up-regulated during the recovery phase. To substantiate this, β-cell-specific Greb1-deficient mice were generated, and Greb1 was shown to be essential for recovery of depleted β cells in diabetic mice. Graft growth and glucose lowering were observed in 50 islets with increased Greb1 expression transplanted adjacent to E2 pellets beneath the kidney capsule of streptozotocin-induced diabetic mice. Greb1 expression due to a drastic increase in exogenous or endogenous E2 was transient and closely correlated with changes in E2-related and some cell cycle-related genes. These findings provide new insights into in vivo proliferation of deficient β cells and suggest the possibility of new therapeutic approaches targeting pancreatic β cells that could revolutionize the concept of diabetes treatment, which has been considered difficult to cure completely.

Stem Cell Therapy Improves Human Islet Graft Survival in Mice via Regulation of Macrophages

Islet/β-cell transplantation offers great hope for patients with type 1 diabetes. We assessed the mechanisms of how intrahepatic coinfusion of human α-1 antitrypsin (hAAT)-engineered mesenchymal stromal cells (hAAT-MSCs) improves survival of human islet grafts posttransplantation (PT). Longitudinal in vivo bioluminescence imaging studies identified significantly more islets in the livers bearing islets cotransplanted with hAAT-MSCs compared with islets transplanted alone. In vitro mechanistic studies revealed that hAAT-MSCs inhibit macrophage migration and suppress IFN-γ-induced M1-like macrophages while promoting IL-4-induced M2-like macrophages. In vivo this translated to significantly reduced CD11c+ and F4/80+ cells and increased CD206+ cells around islets cotransplanted with hAAT-MSCs as identified by multiplex immunofluorescence staining. Recipient-derived F4/80+and CD11b+ macrophages were mainly present in the periphery of an islet, while CD11c+ and CD206+ cells appeared inside an islet. hAAT-MSCs inhibited macrophage migration and skewed the M1-like phenotype toward an M2 phenotype both in vitro and in vivo, which may have favored islet survival. These data provide evidence that hAAT-MSCs cotransplanted with islets remain in the liver and shift macrophages to a protective state that favors islet survival. This novel strategy may be used to enhance β-cell survival during islet/β-cell transplantation for the treatment of type 1 diabetes or other diseases.

Acceptance of Murine Islet Allografts Without Immunosuppression in Inguinal Subcutaneous White Adipose Tissue Pretreated With bFGF

Prevention of immune rejection without immunosuppression is the ultimate goal of transplant immunobiology. One way to achieve this in cellular transplantation, such as with islet transplantation, is to create a favorable local environment at the transplant site. In the current study, we found that C57BL/6 mice with streptozotocin-induced diabetes remained normoglycemic for >1 year after transplantation of BALB/c islets without immunosuppression when the inguinal subcutaneous white adipose tissue (ISWAT) was the site of transplantation and when the site was pretreated with basic fibroblast growth factor. Mechanistically, mesenchymal stem cells (MSCs) expanded in the ISWAT after the treatment was found to produce transforming growth factor-β (TGF-β), and prevention of islet allograft rejection could be achieved by cotransplantation with syngeneic MSCs isolated from the ISWAT after the treatment, which was abolished by anti-TGF-β antibody treatment. Importantly, TGF-β-producing cells remained present at the site of cotransplantation up to the end of observation period at 240 days after transplantation. These findings indicate that prevention of islet allograft rejection without immunosuppression is feasible with the use of syngeneic TGF-β-producing MSCs expanded in the ISWAT after the treatment with bFGF, providing a novel strategy for prevention of islet allograft rejection without immunosuppression.

Human Hemangioblast-Derived Mesenchymal Stem Cells Promote Islet Engraftment in a Minimal Islet Mass Transplantation Model in Mice

Islet transplantation can restore glycemic control in patients with type 1 diabetes. Using this procedure, the early stages of engraftment are often crucial to long-term islet function, and outcomes are not always successful. Numerous studies have shown that mesenchymal stem cells (MSCs) facilitate islet graft function. However, experimental data can be inconsistent due to variables associated with MSC generation (including donor characteristics and tissue source), thus, demonstrating the need for a well-characterized and uniform cell product before translation to the clinic. Unlike bone marrow- or adipose tissue-derived MSCs, human embryonic stem cell-derived-MSCs (hESC-MSCs) offer an unlimited source of stable and highly-characterized cells that are easily scalable. Here, we studied the effects of human hemangioblast-derived mesenchymal cells (HMCs), (i.e., MSCs differentiated from hESCs using a hemangioblast intermediate), on islet cell transplantation using a minimal islet mass model. The co-transplantation of the HMCs allowed a mass of islets that was insufficient to correct diabetes on its own to restore glycemic control in all recipients. Our in vitro studies help to elucidate the mechanisms including reduction of cytokine stress by which the HMCs support islet graft protection in vivo. Derivation, stability, and scalability of the HMC source may offer unique advantages for clinical applications, including fewer islets needed for successful islet transplantation.

White Adipose Tissue as a Site for Islet Transplantation

Although islet transplantation is recognized as a useful cellular replacement therapy for severe diabetes, surgeons face difficulties in islet engraftment. The transplant site is a pivotal factor that influences the engraftment. Although the liver is the current representative site for clinical islet transplantation, it is not the best site because of limitations in immunity, inflammation, and hypoxia. White adipose tissue, including omentum, is recognized as a useful candidate site for islet transplantation. Its effectiveness has been evaluated in not only various basic and translational studies using small and large animals but also in some recent clinical trials. In this review, we attempt to shed light on the characteristics and usefulness of white adipose tissue as a transplant site for islets.

White Adipose Tissue as a Site for Islet Transplantation

Although islet transplantation is recognized as a useful cellular replacement therapy for severe diabetes, surgeons face difficulties in islet engraftment. The transplant site is a pivotal factor that influences the engraftment. Although the liver is the current representative site for clinical islet transplantation, it is not the best site because of limitations in immunity, inflammation, and hypoxia. White adipose tissue, including omentum, is recognized as a useful candidate site for islet transplantation. Its effectiveness has been evaluated in not only various basic and translational studies using small and large animals but also in some recent clinical trials. In this review, we attempt to shed light on the characteristics and usefulness of white adipose tissue as a transplant site for islets.

Extension of Survival in Bilaterally Adrenalectomized Mice by Implantation of SF-1/Ad4BP-Induced Steroidogenic Cells

Mesenchymal stroma/stem cells (MSCs) exist in adult tissues, such as adipose tissue and bone marrow, and differentiate into cells of multiple lineages. In previous studies, we found that MSCs differentiate into steroidogenic cells by forced expression of steroidogenic factor 1 (SF-1)/adrenal 4 binding protein (Ad4BP), the master regulator of steroidogenesis and differentiation of pituitary gonadotrophs, adrenal glands, and gonads. In this study, SF-1/Ad4BP-induced steroidogenic cells derived from mouse adipose tissue-derived MSCs (ADSCs) were implanted under the kidney capsule of bilateral adrenalectomized (bAdx) mice. bAdx mice did not survive after 7 days. However, 4 of 9 bAdx mice implanted with SF-1/Ad4BP-induced steroidogenic cells, 1 of 10 bAdx mice transplanted with control ADSCs, and bAdx mice transplanted with an adrenal gland survived for 30 days. Plasma corticosterone levels in bAdx mice implanted with SF-1/Ad4BP-induced steroidogenic cells and control ADSCs were 5.41 ± 2.26 ng/mL (mean ± SEM) and undetectable at 7 days after implantation, respectively. After removal of the kidney bearing the graft from the surviving mice at 30 days after implantation, plasma corticosterone was not detected in any of the samples. Immunohistochemical staining revealed SF-1/Ad4BP-positive cells under the capsule of the kidney. Although we performed an adrenocorticotropin (ACTH) loading test on bAdx mice implanted with SF-1/Ad4BP-induced steroidogenic cells, ACTH responsiveness was not observed. Implantation of steroidogenic cells derived from ADSCs into bAdx mice increased the basal plasma corticosterone level and extended the survival of bAdx mice, suggesting the capability of restoring steroidogenic cells by cell transplantation therapy for adrenal insufficiency.

Class I and II Histone Deacetylase Inhibitor LBH589 Promotes Endocrine Differentiation in Bone Marrow Derived Human Mesenchymal Stem Cells and Suppresses Uncontrolled Proliferation

Mesenchymal stem cells are useful tools employed in clinical and preclinical medicine. Their beneficial potential in especially degenerative as well as autoimmune diseases is a constant focus of research. Regarding diabetes mellitus, transplantation of stem cells is seen as a possible therapeutic approach to overcome the loss of endocrine pancreatic cells. It was reported that co-transplantation of mesenchymal stem cells with pancreatic islet cells improves function and survival of the graft. However, these multipotent progenitors may be able to form tumors, especially under immunosuppressed conditions. Histone deacetylase inhibitors might offer the potential to overcome this issue. These small molecules can induce cell differentiation and control proliferation. Their potential to control lineage development of stem cells has been distinctly demonstrated in the treatment of cancer, mainly in hematopoietic neoplasias.In this study, we demonstrate that human bone marrow-derived mesenchymal stem cells exhibit low carcinogenic potential in an immunosuppressed condition in vivo. Further, the effect of histone deacetylase inhibitors LBH589, MS-275, and MGCD0103 was examined after normalizing histone deacetylase activities in culture. Interestingly, transcripts of insulin gene enhancer protein and paired-box-gene 6, two markers of pancreatic endocrine differentiation were constitutively expressed in the cell line. The broad spectrum inhibitor of class I and class II histone deacetylases LBH589 upregulated the expression of these transcription factors in a significant way, whereas addition of selective class I histone deacetylase inhibitors MS-275 and MGCD0103 did not result in significant changes in gene expression.In conclusion, we deliver evidence that a combined class I and II histone deacetylase inhibition is able to modulate the transcripts of differentiation markers of mesenchymal stem cells. The treatment holds the capability to facilitate endocrine differentiation in future approaches to replace endocrine cells by stem cell therapy.

Fewer Islets Survive from a First Transplant than a Second Transplant: Evaluation of Repeated Intraportal Islet Transplantation in Mice

Beta cell replacement is an exciting field where new beta cell sources and alternative sites are widely explored. The liver has been the implantation site of choice in the clinic since the advent of islet transplantation. However, in most cases, repeated islet transplantation is needed to achieve normoglycemia in diabetic recipients. This study aimed to investigate whether there are differences in islet survival and engraftment between a first and a second transplantation, performed 1 week apart, to the liver. C57BL/6 mice were accordingly transplanted twice with an initial infusion of syngeneic islets expressing green fluorescent protein (GFP). The second islet transplant was performed 1 week later and consisted of islets isolated from non-GFP C57BL/6-mice. Animals were sacrificed either 1 day or 1 month after the second transplantation. A control group received a saline infusion instead of GFP-expressing islets, 1 week later obtained a standard non-GFP islet transplant, and was subsequently sacrificed 1 month later. Islet engraftment in the liver was assessed by immunohistochemistry and serum was analyzed for angiogenic factors induced by the first islet transplantation. Almost 70% of islets found in the liver following repeated islet transplantation originated from the second transplantation. The vascular density in the transplanted non-GFP-expressing islets did not differ depending on whether their transplantation was preceded by a primary islet transplantation or saline administration only nor did angiogenic factors in serum prior to the transplantation of non-GFP islets differ between animals that had received a previous islet transplantation or a saline infusion. We conclude that first islet transplantation creates, by unknown mechanisms, favorable conditions for the survival of a second transplant to the liver.

Regenerative and Transplantation Medicine: Cellular Therapy Using Adipose Tissue-Derived Mesenchymal Stromal Cells for Type 1 Diabetes Mellitus

Type 1 diabetes mellitus (T1DM) is caused by the autoimmune targeting of pancreatic β-cells, and, in the advanced stage, severe hypoinsulinemia due to islet destruction. In patients with T1DM, continuous exogenous insulin therapy cannot be avoided. However, an insufficient dose of insulin easily induces extreme hyperglycemia or diabetic ketoacidosis, and intensive insulin therapy may cause hypoglycemic symptoms including hypoglycemic shock. While these insulin therapies are efficacious in most patients, some additional therapies are warranted to support the control of blood glucose levels and reduce the risk of hypoglycemia in patients who respond poorly despite receiving appropriate treatment. There has been a recent gain in the popularity of cellular therapies using mesenchymal stromal cells (MSCs) in various clinical fields, owing to their multipotentiality, capacity for self-renewal, and regenerative and immunomodulatory potential. In particular, adipose tissue-derived MSCs (ADMSCs) have become a focus in the clinical setting due to the abundance and easy isolation of these cells. In this review, we outline the possible therapeutic benefits of ADMSC for the treatment of T1DM.

Improved islet recovery and efficacy through co-culture and co-transplantation of islets with human adipose-derived mesenchymal stem cells

Islet transplantation is an established clinical procedure for select patients with type 1 diabetes and severe hypoglycemia to stabilize glycemic control. Post-transplant, substantial beta cell mass is lost, necessitating multiple donors to maintain euglycemia. A potential strategy to augment islet engraftment is the co-transplantation of islets with multipotent mesenchymal stem cells to capitalize upon their pro-angiogenic and anti-inflammatory properties. Herein, we examine the in vitro and in vivo effect of co-culturing murine islets with human adipose-derived mesenchymal stem cells (Ad-MSCs). Islets co-cultured with Ad-MSCs for 48 hours had decreased cell death, superior viability as measured by membrane integrity, improved glucose stimulated insulin secretion and reduced apoptosis compared to control islets. These observations were recapitulated with human islets, albeit tested in a limited capacity. Recipients of marginal mouse islet mass grafts, co-transplanted with Ad-MSCs without a co-culture period, did not reverse to normoglycemia as efficiently as islets alone. However, utilizing a 48-hour co-culture period, marginal mouse islets grafts with Ad-MSCs achieved a superior percent euglycemia rate when compared to islets cultured and transplanted alone. A co-culture period of human islets with human Ad-MSCs may have a clinical benefit improving engraftment outcomes.