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

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.

Potentials of bone marrow cells-derived from naïve or diabetic mice in autoimmune type 1 diabetes: immunomodulatory, anti-inflammatory, anti hyperglycemic, and antioxidative

BACKGROUND

The scarcity of transplanted human islet tissue and the requirement for immunosuppressive drugs to prevent the rejection of allogeneic grafts have hindered the treatment of autoimmune type 1 diabetes mellitus (T1DM) through islet transplantation. However, there is hope in adoptively transferred bone marrow cells (BMCs) therapy, which has emerged as a propitious pathway for forthcoming medications. BMCs have the potential to significantly impact both replacement and regenerative therapies for a range of disorders, including diabetes mellitus, and have demonstrated anti-diabetic effects.

AIM

The main goal of this study is to evaluate the effectiveness of adoptively transferred bone marrow cells derived from either naïve mice (nBMCs) or diabetic mice (dBMCs) in treating a T1DM mice model.

METHODS

Male Swiss albino mice were starved for 16 h and then injected with streptozotocin (STZ) at a dose of 40 mg/kg body weight for 5 consecutive days to induce T1DM. After 14 days, the diabetic mice were distributed into four groups. The first group served as a diabetic control treated with sodium citrate buffer, while the other three groups were treated for two weeks, respectively, with insulin (subcutaneously at a dose of 8 U/kg/day), nBMCs (intravenously at a dose of 1 × 106 cells/mouse/once), and dBMCs (intravenously at a dose of 1 × 106 cells/mouse/once).

RESULTS

It is worth noting that administering adoptively transferred nBMCs or adoptively transferred dBMCs to STZ-induced T1DM mice resulted in a significant amelioration in glycemic condition, accompanied by a considerable reduction in the level of blood glucose and glycosylated hemoglobin % (HbA1C %), ultimately restoring serum insulin levels to their initial state in control mice. Administering nBMCs or dBMCs to STZ-induced T1DM mice led to a remarkable decrease in levels of inflammatory cytokine markers in the serum, including interferon-γ (INF-γ), tumor necrosis factor- α (TNF-α), tumor growth factor-β (TGF-β), interleukin-1 β (L-1β), interlekin-4 (IL-4), interleukin-6 (IL-6), and interleukin-10 (IL-10). Additionally, STZ-induced T1DM mice, when treated with nBMCs or dBMCs, experienced a notable rise in total immunoglobulin (Ig) level. Furthermore, there was a significant reduction in the levels of islet cell autoantibodies (ICA) and insulin autoantibodies (IAA). Furthermore, the serum of STZ-induced T1DM mice showed a significant increase in Zinc transporter 8 antigen protein (ZnT8), islet antigen 2 protein (IA-2), and glutamic acid decarboxylase antigen protein (GAD) levels. Interestingly, the administration of nBMCs or dBMCs resulted in a heightened expression of IA-2 protein in STZ-induced T1DM mice treated with nBMCs or dBMCs. Furthermore, the level of malondialdehyde (MDA) was increased, while the levels of catalase (CAT) and superoxide dismutase (SOD) were decreased in non-treated STZ-induced T1DM mice. However, when nBMCs or dBMCs were administered to STZ-induced T1DM mice, it had a significant impact on reducing oxidative stress. This was accomplished by reducing the levels of MDA in the serum and enhancing the activities of enzymatic antioxidants like CAT and SOD. STZ-induced T1DM mice displayed a significant elevation in the levels of liver enzymes ALT and AST, as well as heightened levels of creatinine and urea. Considering the crucial roles of the liver and kidney in metabolism and excretion, this research further examined the effects of administering nBMCs or dBMCs to STZ-induced T1DM mice. Notably, the administration of these cells alleviated the observed effects.

CONCLUSION

The present study suggests that utilizing adoptively transferred nBMCs or adoptively transferred dBMCs in the treatment of T1DM led to noteworthy decreases in blood glucose levels, possibly attributed to their capacity to enhance insulin secretion and improve the performance of pancreatic islets. Additionally, BMCs may exert their beneficial effects on the pancreatic islets of diabetic mice through their immunomodulatory, antioxidant, anti-inflammatory, and anti-oxidative stress properties.

Adipose Tissue-Derived Mesenchymal Stromal Cells Modulate Inflammatory Response and Improve Allograft Islet Transplant in Mice Model of Type 1 Diabetes

OBJECTIVE

Type 1 diabetes mellitus (T1DM) is an autoimmune disease where immune cells attack insulin-producing beta cells. Islet transplantation is a promising treatment for T1DM. This study aims to evaluate the effects of adipose tissue-derived mesenchymal stem cells (AT-MSCs) in combination with pancreatic islet transplantation using hydrogel.

METHODS

T1DM mouse model was established using streptozotocin (STZ). Islets and AT-MSCs were co-embedded in a hydrogel and transplanted into diabetic mice. Five groups with six animals in each (control, hydrogel alone, AT-MSCs embedded hydrogel, islet embedded in hydrogel, and islet + AT-MSCs co-imbedded into a hydrogel) were evaluated in terms of blood glucose, insulin levels and serum and lavage cytokine production.

RESULTS

During 32 days, blood glucose levels decreased from over 400 mg/dl to less than 150 mg/dl in the transplanted mice. Analysis showed increased transformation growth factor beta (TGF-β1) and IL-4 levels, while IL-17 and IFN-γ levels significantly decreased in the MSC-treated groups.

CONCLUSION

These findings suggest that using AT-MSCs with hydrogel could be a beneficial alternative for enhancing pancreatic islet engraftment and function.

Islet Like Cells Induced from Umbilical Cord Mesenchymal Stem Cells with Neonatal Bovine Pancreatic Mesenchymal Exosomes for Treatment of Diabetes Mellitus

To investigate the safety and efficacy of the islet-like cell (cell) induced from human umbilical cord mesenchymal stem cell (UCMSC) with different methods for the treatment of diabetic animal model. UCMSCs were induced to βcells with cytokines (CY) and neonatal bovine pancreatic mesenchymal cell exosomes (Ex) combined with CY (EX+CY). The insulin secretion of UCMSC and βcell was measured with ELISA when the cells were growing in different concentrations of glucose media for different times. UCMSCs (4×105) and the same number of cells prepared with two methods were transplanted to type I diabetic rat models. UCMSCs could be induced into islet βcells by CY or EX+CY in vitro. The insulin secretion of the prepared β cells growing in 25.0 mM glucose medium was over 5-fold of that in 6.0 mM glucose. The transplantation of the βcells to type I diabetic rat models could reduce the blood glucose and prolong the survival time. The β cells induced by EX+CY had much more significant effects on decreasing blood glucose and increasing survival time (p<0.01). The cells did not affect blood sugar level and had no serious side-effects in human health. UCMSC could be induced to islet βcells with either CY or EX+CY. The transplantation of the induced islet βcells could reduce blood glucose and prolong the survival time of diabetic animal models. Although the cells induced with EX+CY had more significant effects on diabetic rats, they did not affect blood glucose level and had no serious side-effects in human health.

Efficacy of adipose-derived mesenchymal stem cell therapy in the treatment of chronic micro- and macrovascular complications of diabetes

Diabetes mellitus is a highly prevalent disease characterized by hyperglycaemia that damages the vascular system, leading to micro- (retinopathy, neuropathy, nephropathy) and macrovascular diseases (cardiovascular disease). There are also secondary complications of diabetes (cardiomyopathy, erectile dysfunction or diabetic foot ulcers). Stem cell-based therapies have become a promising tool targeting diabetes symptoms and its chronic complications. Among all stem cells, adipose-derived mesenchymal stem cells (ADMSCs) are of great importance because of their abundance, non-invasive isolation and no ethical limitations. Characteristics that make ADMSCs good candidates for cell-based therapy are their wide immunomodulatory properties and paracrine activities through the secretion of an array of growth factors, chemokines, cytokines, angiogenic factors and anti-apoptotic molecules. Besides, after transplantation, ADMSCs show great ex vivo expansion capacity and differentiation to other cell types, including insulin-producing cells, cardiomyocytes, chondrocytes, hepatocyte-like cells, neurons, endothelial cells, photoreceptor-like cells, or astrocytes. Preclinical studies have shown that ADMSC-based therapy effectively improved visual acuity, ameliorated polyneuropathy and foot ulceration, arrested the development and progression of diabetic kidney disease, or alleviated the diabetes-induced cardiomyocyte hypertrophy. However, despite the positive results obtained in animal models, there are still several challenges that need to be overcome before the results of preclinical studies can be translated into clinical applications. To date, there are several clinical trials or ongoing trials using ADMSCs in the treatment of diabetic complications, most of them in the treatment of diabetic foot ulcers. This narrative review summarizes the most recent outcomes on the usage of ADMSCs in the treatment of long-term complications of diabetes in both animal models and clinical trials.

Efficiency of Bone Marrow-Derived Mesenchymal Stem Cells and Hesperetin in the Treatment of Streptozotocin-Induced Type 1 Diabetes in Wistar Rats

Type 1 diabetes mellitus (T1DM) was established to be ameliorated by islet transplantation, but the shortage of the transplanted human islet tissue and the use of immunosuppressive drugs to inhibit the rejection of allogeneic grafts make this type of therapy is limited. Nowadays, therapy with stem cells is one of the most promising future treatments. This kind of therapy could have a profound impact on both replacement, as well as regenerative therapies, to improve or even cure various disorders, including diabetes mellitus. Flavonoids have also been shown to possess anti-diabetic effects. Thus, this study aims to evaluate the effectiveness of the bone marrow-derived mesenchymal stem cells (BM-MSCs) and hesperetin in the treatment of a T1DM rat model. T1DM was induced in male Wistar rats that had been starved for 16 h via intraperitoneal injection of STZ at a dose of 40 mg/kg body weight (b.wt.). After 10 days of STZ injection, the diabetic rats were allocated into four groups. The first diabetic animal group was considered a diabetic control, while the other three diabetic animal groups were treated for six weeks, respectively, with hesperetin (given orally at a dose of 20 mg/kg b.wt.), BM-MSCs (injected intravenously at a dose of 1 × 10⁶ cells/rat/week), and their combination (hesperetin and BM-MSCs). The use of hesperetin and BM-MSCs in the treatment of STZ-induced diabetic animals significantly improved the glycemic state, serum fructosamine, insulin and C-peptide levels, liver glycogen content, glycogen phosphorylase, glucose-6-phosphatase activities, hepatic oxidative stress, and mRNA expressions of NF-κB, IL-1β, IL-10, P53, and Bcl-2 in pancreatic tissue. The study suggested the therapy with both hesperetin and BM-MSCs produced marked antihyperglycemic effects, which may be mediated via their potencies to ameliorate pancreatic islet architecture and insulin secretory response, as well as to decrease hepatic glucose output in diabetic animals. The improvement effects of hesperetin and BM-MSCs on the pancreatic islets of diabetic rats may be mediated via their antioxidant, anti-inflammatory, and antiapoptotic actions.

Species-dependent impact of immunosuppressive squalene-gusperimus nanoparticles and adipose-derived stem cells on isolated human and rat pancreatic islets

Transplantation of pancreatic islets is a promising approach to controlling glucose levels in type 1 diabetes mellitus (T1DM), but islet survival is still limited. To overcome this, islet co-culture with mesenchymal stromal cells (MSCs) together with safe immunosuppressive agents like squalene-gusperimus nanoparticles (Sq-GusNPs) may be applied. This could support islet survival and engraftment. Here, we studied how Sq-GusNPs and adipose-derived stem cells (ASCs) influence islets response under pro-inflammatory conditions. Through qRT-PCR, we studied the expression of specific genes at 24 hours in human and rat islets and ASCs in co-culture under indirect contact with or without treatment with Sq-GusNPs. We characterized how the response of islets and ASCs starts at molecular level before impaired viability or function is observed and how this response differs between species. Human islets and ASCs responses showed to be principally influenced by NF-κB activation, whereas rat islet and ASCs responses showed to be principally mediated by nitrosative stress. Rat islets showed tolerance to inflammatory conditions due to IL-1Ra secretion which was also observed in rat ASCs. Human islets induced the expression of cytokines and chemokines with pro-angiogenic, tissue repair, and anti-apoptotic properties in human ASCs under basal conditions. This expression was not inhibited by Sq-GusNPs. Our results showed a clear difference in the response elicited by human and rat islets and ASCs in front of an inflammatory stimulus and Sq-GusNPs. Our data support the use of ASCs and Sq-GusNP to facilitate engraftment of islets for T1DM treatment.

N,N'-Diphenyl-1,4-phenylenediamine Antioxidant's Potential Role in Enhancing the Pancreatic Antioxidant, Immunomodulatory, and Anti-Apoptotic Therapeutic Capabilities of Adipose-Derived Stem Cells in Type I Diabetic Rats

Mesenchymal stem cells (MSCs) are considered to be a promising therapeutic protocol for diabetes mellitus (DM) management. The latter is attributed to their differentiation potentiality to pancreatic β-cells, angiogenesis, and immune-modulatory capabilities by releasing various paracrine factors. Interestingly, antioxidant co-administration increased the MSCs' hypoglycemic and regenerative activities. Thus, this study aims to evaluate the therapeutic implication of type 1 DM after the co-administration of adipose tissue-derived-MSCs (AD-MSCs) and N,N'-d iphenyl-1,4-phenylenediamine (DPPD), compared to the single injection of either of them alone. In our four week long experiment, six rat groups were used as control, DPPD (250 mg/kg, i.p.), STZ-diabetic (D), D+DPPD, D+AD-MSCs (1 × 10⁶ cell/rat, i.p.), and D+AD-MSCs+DPPD groups. Within this context, a single injection of AD-MSCs or DPPD into diabetic rats showed significant pancreatic anti-inflammatory, immunomodulation, antioxidant, and anti-apoptotic capacities, superior to AD-MSCs injection. However, AD-MSCs and DPPD co-administration into diabetic rats manifested the highest hypoglycemic and pancreatic regenerative activities in managing diabetes compared to the single shot of AD-MSCs or DPPD. These results highlight the synergetic role of DPPD as an antioxidant in enhancing AD-MSCs' therapeutic applications.

Isolation and characterization of farm pig adipose tissue-derived mesenchymal stromal/stem cells

Adipose tissue-derived mesenchymal stromal/stem cells (ASCs) are considered important tools in regenerative medicine and are being tested in several clinical studies. Porcine models are frequently used to obtain adipose tissue, due to the abundance of material and because they have immunological and physiological similarities with humans. However, it is essential to understand the effects and safe application of ASCs from pigs (pASCs) as an alternative therapy for diseases. Although minipigs are easy-to-handle animals that require less food and space, acquiring and maintaining them in a bioterium can be costly. Thus, we present a protocol for the isolation and proliferation of ASCs isolated from adipose tissue of farm pigs. Adipose tissue samples were extracted from the abdominal region of the animals. Because the pigs were not raised in a controlled environment, such as a bioterium, it was necessary to carry out rigorous procedures for disinfection. After this procedure, cells were isolated by mechanical dissociation and enzymatic digestion. A proliferation curve was performed and used to calculate the doubling time of the population. The characterization of pASCs was performed by immunophenotyping and cell differentiation in osteogenic and adipogenic lineages. The described method was efficient for the isolation and cultivation of pASCs, maintaining cellular attributes, such as surface antigens and multipotential differentiation during in vitro proliferation. This protocol presents the isolation and cultivation of ASCs from farm pig as an alternative for the isolation and cultivation of ASCs from minipigs, which require strictly controlled maintenance conditions and a more expensive process.

Reprogramming adipose mesenchymal stem cells into islet β-cells for the treatment of canine diabetes mellitus

BACKGROUND

Islet transplantation is an excellent method for the treatment of type I diabetes mellitus. However, due to the limited number of donors, cumbersome isolation and purification procedures, and immune rejection, the clinical application is greatly limited. The development of a simple and efficient new method to obtain islet β-cells is a key problem that urgently requires a solution for the treatment of type I diabetes mellitus.

METHODS

In this study, Pbx1, Rfx3, Pdx1, Ngn3, Pax4 and MafA were used to form a six-gene combination to efficiently reprogram aMSCs (adipose mesenchymal stem cells) into ra-βCs (reprogrammed aMSCs-derived islet β-cells), and the characteristics and immunogenicity of ra-βCs were detected. Feasibility of ra-βCs transplantation for the treatment of diabetes mellitus in model dogs and clinical dogs was detected.

RESULTS

In this study, aMSCs were efficiently reprogrammed into ra-βCs using a six-gene combination. The ra-βCs showed islet β-cell characteristics. The immunogenicity of ra-βCs was detected and remained low in vitro and increased after transplantation. The cotransplantation of ra-βCs and aMSCs in the treatment of a model and clinical cases of canine diabetes mellitus achieved ideal therapeutic effects.

CONCLUSIONS

The aMSCs were efficiently reprogrammed into ra-βCs using a six-gene combination. The cotransplantation of ra-βCs and aMSCs as a treatment for canine diabetes is feasible, which provides a theoretical basis and therapeutic method for the treatment of canine diabetes.

Bone marrow mesenchymal stromal cells for diabetes therapy: touch, fuse, and fix?

Bone marrow mesenchymal stromal cells (BM-MSCs) have anti-inflammatory and pro-survival properties. Naturally, they do not express human leukocyte antigen class II surface antigens and have immunosuppressive capabilities. Together with their relatively easy accessibility and expansion, they are an attractive tool for organ support in transplantation and regenerative therapy. Autologous BM-MSC transplantation alone or together with transplanted islets improves β-cell function, graft survival, and glycemic control in diabetes. Albeit MSCs’ capacity to transdifferentiate into β-cell is limited, their protective effects are mediated mainly by paracrine mechanisms through BM-MSCs circulating through the body. Direct cell–cell contact and spontaneous fusion of BM-MSCs with injured cells, although at a very low rate, are further mechanisms of their supportive effect and for tissue regeneration. Diabetes is a disease of long-term chronic inflammation and cell therapy requires stable, highly functional cells. Several tools and protocols have been developed by mimicking natural fusion events to induce and accelerate fusion in vitro to promote β-cell-specific gene expression in fused cells. BM-MSC-islet fusion before transplantation may be a strategy for long-term islet survival and improved function. This review discusses the cell-protective and anti-inflammatory characteristics of BM-MSCs to boost highly functional insulin-producing cells in vitro and in vivo, and the efficacy of their fusion with β-cells as a path to promote β-cell regeneration.

Obesity Affects the Proliferative Potential of Equine Endometrial Progenitor Cells and Modulates Their Molecular Phenotype Associated with Mitochondrial Metabolism

The study aimed to investigate the influence of obesity on cellular features of equine endometrial progenitor cells (Eca EPCs), including viability, proliferation capacity, mitochondrial metabolism, and oxidative homeostasis. Eca EPCs derived from non-obese (non-OB) and obese (OB) mares were characterized by cellular phenotype and multipotency. Obesity-induced changes in the activity of Eca EPCs include the decline of their proliferative activity, clonogenic potential, mitochondrial metabolism, and enhanced oxidative stress. Eca EPCs isolated from obese mares were characterized by an increased occurrence of early apoptosis, loss of mitochondrial dynamics, and senescence-associated phenotype. Attenuated metabolism of Eca EPCs OB was related to increased expression of pro-apoptotic markers (CASP9, BAX, P53, P21), enhanced expression of OPN, PI3K, and AKT, simultaneously with decreased signaling stabilizing cellular homeostasis (including mitofusin, SIRT1, FOXP3). Obesity alters functional features and the self-renewal potential of endometrial progenitor cells. The impaired cytophysiology of progenitor cells from obese endometrium predicts lower regenerative capacity if used as autologous transplants.

Adipose-derived stem cells alleviate liver injury induced by type 1 diabetes mellitus by inhibiting mitochondrial stress and attenuating inflammation

Background

Type 1 diabetes mellitus (T1D) is a worldwide health priority due to autoimmune destruction and is associated with an increased risk of multiorgan complications. Among these complications, effective interventions for liver injury, which can progress to liver fibrosis and hepatocellular carcinoma, are lacking. Although stem cell injection has a therapeutic effect on T1D, whether it can cure liver injury and the underlying mechanisms need further investigation.

Methods

Sprague–Dawley rats with streptozotocin (STZ)-induced T1D were treated with adipose-derived stem cell (ADSC) or PBS via the tail vein formed the ADSC group or STZ group. Body weights and blood glucose levels were examined weekly for 6 weeks. RNA-seq and PCR array were used to detect the difference in gene expression of the livers between groups.

Results

In this study, we found that ADSCs injection alleviated hepatic oxidative stress and injury and improved liver function in rats with T1D; potential mechanisms included cytokine activity, energy metabolism and immune regulation were potentially involved, as determined by RNA-seq. Moreover, ADSC treatment altered the fibroblast growth factor 21 (FGF21) and transforming growth factor β (TGF-β) levels in T1D rat livers, implying its repair capacity. Disordered intracellular energy metabolism, which is closely related to mitochondrial stress and dysfunction, was inhibited by ADSC treatment. PCR array and ingenuity pathway analyses suggested that the ADSC-induced suppression of mitochondrial stress is related to decreased necroptosis and apoptosis. Moreover, mitochondria-related alterations caused liver inflammation, resulting in liver injury involving the T lymphocyte-mediated immune response.

Conclusions

Overall, these results improve our understanding of the curative effect of ADSCs on T1D complications: ADSCs attenuate liver injury by inhibiting mitochondrial stress (apoptosis and dysfunctional energy metabolism) and alleviating inflammation (inflammasome expression and immune disorder). These results are important for early intervention in liver injury and for delaying the development of liver lesions in patients with T1D.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02760-z.

AD-MSCs and BM-MSCs Ameliorating Effects on The Metabolic and Hepato-renal Abnormalities in Type 1 Diabetic Rats

Diabetes mellitus (DM) is one of the most serious threats in the 21th century throughout the human population that needs to be addressed cautiously. Nowadays, stem cell injection is considered among the most promising protocols for DM therapy; owing to its marked tissues and organs repair capability. Therefore, our 4 weeks study was undertaken to elucidate the probable beneficial effects of two types of adult mesenchymal stem cells (MSCs) on metabolism disturbance and some tissue function defects in diabetic rats. Animals were classified into 4 groups; the control group, the diabetic group, the diabetic group received a single dose of adipose tissue-derived MSCs and the diabetic group received a single dose of bone marrow-derived MSCs. Herein, both MSCs treated groups markedly reduced hyperglycemia resulting from diabetes induction via lowering serum glucose and rising insulin and C-peptide levels, compared to the diabetic group. Moreover, the increased lipid fractions levels were reverted back to near normal values as a consequence to MSCs injection compared to the diabetic untreated rats. Furthermore, both MSCs types were found to have hepato-renal protective effects indicated through the decreased serum levels of both liver and kidney functions markers in the treated diabetic rats. Taken together, our results highlighted the therapeutic benefits of both MSCs types in alleviating metabolic anomalies and hepato-renal diabetic complications.

Islet transplantation into brown adipose tissue can delay immune rejection

Type 1 diabetes is an autoimmune disease characterized by insulin-producing β cell destruction. Although islet transplantation restores euglycemia and improves patient outcomes, an ideal transplant site remains elusive. Brown adipose tissue (BAT) has a highly vascularized and antiinflammatory microenvironment. Because these tissue features can promote islet graft survival, we hypothesized that islets transplanted into BAT will maintain islet graft and BAT function while delaying immune-mediated rejection. We transplanted syngeneic and allogeneic islets into BAT or under the kidney capsule of streptozotocin-induced diabetic NOD.Rag and NOD mice to investigate islet graft function, BAT function, metabolism, and immune-mediated rejection. Islet grafts within BAT restored euglycemia similarly to kidney capsule controls. Islets transplanted in BAT maintained expression of islet hormones and transcription factors and were vascularized. Compared with those in kidney capsule and euglycemic mock-surgery controls, no differences in glucose or insulin tolerance, thermogenic regulation, or energy expenditure were observed with islet grafts in BAT. Immune profiling of BAT revealed enriched antiinflammatory macrophages and T cells. Compared with the kidney capsule control, there were significant delays in autoimmune and allograft rejection of islets transplanted in BAT, possibly due to increased antiinflammatory immune populations. Our data support BAT as an alternative islet transplant site that may improve graft survival.

Adipose-Derived Stem Cells in the Treatment of Perianal Fistulas in Crohn's Disease: Rationale, Clinical Results and Perspectives

Between 20 to 25% of Crohn’s disease (CD) patients suffer from perianal fistulas, a marker of disease severity. Seton drainage combined with anti-TNFα can result in closure of the fistula in 70 to 75% of patients. For the remaining 25% of patients there is room for in situ injection of autologous or allogenic mesenchymal stem cells such as adipose-derived stem/stromal cells (ADSCs). ADSCs exert their effects on tissues and effector cells through paracrine phenomena, including the secretome and extracellular vesicles. They display anti-inflammatory, anti-apoptotic, pro-angiogenic, proliferative, and immunomodulatory properties, and a homing within the damaged tissue. They also have immuno-evasive properties allowing a clinical allogeneic approach. Numerous clinical trials have been conducted that demonstrate a complete cure rate of anoperineal fistulas in CD ranging from 46 to 90% of cases after in situ injection of autologous or allogenic ADSCs. A pivotal phase III-controlled trial using allogenic ADSCs (Alofisel^®) demonstrated that prolonged clinical and radiological remission can be obtained in nearly 60% of cases with a good safety profile. Future studies should be conducted for a better knowledge of the local effect of ADSCs as well as for a standardization in terms of the number of injections and associated procedures.

Adipose Tissue-Derived Stem Cells: Immunomodulatory Effects and Therapeutic Potential

Adipose-derived stem cells (ASCs) can self-renew and differentiate along multiple cell lineages. ASCs are also potently anti-inflammatory due to their inherent ability to regulate the immune system by secreting anti-inflammatory cytokines and growth factors that play a crucial role in the pathology of many diseases, including multiple sclerosis, diabetes mellitus, Crohn's, SLE, and graft-versus-host disease. The immunomodulatory effects and mechanisms of action of ASCs on pathological conditions are reviewed here.

Modeling of Ca2+ transients initiated by GPCR agonists in mesenchymal stromal cells

The integrative study that included experimentation and mathematical modeling was carried out to analyze dynamic aspects of transient Ca²⁺ signaling induced by brief pulses of GPCR agonists in mesenchymal stromal cells from the human adipose tissue (AD-MSCs). The experimental findings argued for IP₃/Ca²⁺-regulated Ca²⁺ release via IP₃ receptors (IP₃Rs) as a key mechanism mediating agonist-dependent Ca²⁺ transients. The consistent signaling circuit was proposed to formalize coupling of agonist binding to Ca²⁺ mobilization for mathematical modeling. The model properly simulated the basic phenomenology of agonist transduction in AD-MSCs, which mostly produced single Ca²⁺ spikes upon brief stimulation. The spike-like responses were almost invariantly shaped at different agonist doses above a threshold, while response lag markedly decreased with stimulus strength. In AD-MSCs, agonists and IP₃ uncaging elicited similar Ca²⁺ transients but IP₃ pulses released Ca²⁺ without pronounced delay. This suggested that IP₃ production was rate-limiting in agonist transduction. In a subpopulation of AD-MSCs, brief agonist pulses elicited Ca²⁺ bursts crowned by damped oscillations. With properly adjusted parameters of IP₃R inhibition by cytosolic Ca²⁺, the model reproduced such oscillatory Ca²⁺ responses as well. GEM-GECO1 and R-CEPIA1er, the genetically encoded sensors of cytosolic and reticular Ca²⁺, respectively, were co-expressed in HEK-293 cells that also responded to agonists in an "all-or-nothing" manner. The experimentally observed Ca²⁺ signals triggered by ACh in both compartments were properly simulated with the suggested signaling circuit. Thus, the performed modeling of the transduction process provides sufficient theoretical basis for deeper interpretation of experimental findings on agonist-induced Ca²⁺ signaling in AD-MSCs.

Mechanism of Transplanted Islet Engraftment in Visceral White Adipose Tissue

BACKGROUND

White adipose tissue (WAT) is a candidate transplantation site for islets. However, the mechanism of islet engraftment in WAT has not been fully investigated. In this study, we attempted to clarify the therapeutic effect and mechanism of islet transplantation into visceral WAT.

METHODS

Two hundred mouse islets were transplanted into epididymal WAT of syngeneic diabetic mice by wrapping islets with the tissue (fat-covered group). Mice that received intraperitoneal and renal subcapsular islet transplantations were used as negative and positive control groups, respectively.

RESULTS

The transplant efficacy, including improvements in blood glucose and plasma insulin levels and in glucose tolerance tests, of the fat-covered group was superior to the negative control group and almost equal to the positive control group. Vessel density of engrafted islets in the fat-covered group was higher than that in the positive control group. It was speculated that the mechanism of islet engraftment in WAT might consist of trapping islets in WAT, adhesion of islets via a combination of adhesion factors (fibronectin and integrin β1), and promotion of angiogenesis in islets by expression of angiogenic factors induced by adiponectin.

CONCLUSIONS

Visceral WAT is an important candidate for islet transplantation. Adhesion factors and adiponectin might contribute to islet engraftment into WAT. Further studies to elucidate the detailed mechanism are necessary.

Advances and complications of regenerative medicine in diabetes therapy

The rapid development of technologies in regenerative medicine indicates clearly that their common application is not a matter of if, but of when. However, the regeneration of beta-cells for diabetes patients remains a complex challenge due to the plurality of related problems. Indeed, the generation of beta-cells masses expressing marker genes is only a first step, with maintaining permanent insulin secretion, their protection from the immune system and avoiding pathological modifications in the genome being the necessary next developments. The prospects of regenerative medicine in diabetes therapy were promoted by the emergence of promising results with embryonic stem cells (ESCs). Their pluripotency and proliferation in an undifferentiated state during culture have ensured the success of ESCs in regenerative medicine. The discovery of induced pluripotent stem cells (iPSCs) derived from the patients’ own mesenchymal cells has provided further hope for diabetes treatment. Nonetheless, the use of stem cells has significant limitations related to the pluripotent stage, such as the risk of development of teratomas. Thus, the direct conversion of mature cells into beta-cells could address this issue. Recent studies have shown the possibility of such transdifferentiation and have set trends for regeneration medicine, directed at minimizing genome modifications and invasive procedures. In this review, we will discuss the published results of beta-cell regeneration and the advantages and disadvantages illustrated by these experiments.

Rationale for the clinical use of adipose-derived mesenchymal stem cells for COVID-19 patients

In late 2019, a novel coronavirus (SARS-CoV-2) emerged in Wuhan, capital city of Hubei province in China. Cases of SARS-CoV-2 infection quickly grew by several thousand per day. Less than 100 days later, the World Health Organization declared that the rapidly spreading viral outbreak had become a global pandemic. Coronavirus disease 2019 (COVID-19) is typically associated with fever and respiratory symptoms. It often progresses to severe respiratory distress and multi-organ failure which carry a high mortality rate. Older patients or those with medical comorbidities are at greater risk for severe disease. Inflammation, pulmonary edema and an over-reactive immune response can lead to hypoxia, respiratory distress and lung damage. Mesenchymal stromal/stem cells (MSCs) possess potent and broad-ranging immunomodulatory activities. Multiple in vivo studies in animal models and ex vivo human lung models have demonstrated the MSC's impressive capacity to inhibit lung damage, reduce inflammation, dampen immune responses and aid with alveolar fluid clearance. Additionally, MSCs produce molecules that are antimicrobial and reduce pain. Upon administration by the intravenous route, the cells travel directly to the lungs where the majority are sequestered, a great benefit for the treatment of pulmonary disease. The in vivo safety of local and intravenous administration of MSCs has been demonstrated in multiple human clinical trials, including studies of acute respiratory distress syndrome (ARDS). Recently, the application of MSCs in the context of ongoing COVID-19 disease and other viral respiratory illnesses has demonstrated reduced patient mortality and, in some cases, improved long-term pulmonary function. Adipose-derived stem cells (ASC), an abundant type of MSC, are proposed as a therapeutic option for the treatment of COVID-19 in order to reduce morbidity and mortality. Additionally, when proven to be safe and effective, ASC treatments may reduce the demand on critical hospital resources. The ongoing COVID-19 outbreak has resulted in significant healthcare and socioeconomic burdens across the globe. There is a desperate need for safe and effective treatments. Cellular based therapies hold great promise for the treatment of COVID-19. This literature summary reviews the scientific rationale and need for clinical studies of adipose-derived stem cells and other types of mesenchymal stem cells in the treatment of patients who suffer with COVID-19.