Reduction of marginal mass required for successful islet transplantation in a diabetic rat model using adipose tissue-derived mesenchymal stromal cells.

Adipose tissue-derived mesenchymal stromal cells (AT-MSCs), widely known as multipotent progenitors, release several cytokines that support cell survival and repair. There are in vitro and in vivo studies reporting the regenerative role of AT-MSCs possibly mediated by their protective effects on functional islet cells as well as their capacity to differentiate into insulin-producing cells (IPCs). On such a basis, our goal in the present study was to use three different models including direct and indirect co-cultures and islet-derived conditioned medium (CM) to differentiate AT-MSCs into IPCs and to illuminate the molecular mechanisms of the beneficial impact of AT-MSCs on pancreatic islet functionality. Furthermore, we combined in vitro co-culture of islets and AT-MSCs with in vivo assessment of islet graft function to assess whether co-transplantation of islets with AT-MSCs can reduce marginal mass required for successful islet transplantation and prolong graft function in a diabetic rat model. Our findings demonstrated that AT-MSCs are suitable for creating a microenvironment favorable for the repair and longevity of the pancreas β cells through the improvement of islet survival and maintenance of cell morphology and insulin secretion due to their potent properties in differentiation. Most importantly, hybrid transplantation of islets with AT-MSCs significantly promoted survival, engraftment and insulin-producing function of the graft and reduced the islet mass required for reversal of diabetes. This strategy might be of therapeutic potential solving the problem of donor islet material loss that currently limits the application of allogeneic islet transplantation as a more widespread therapy for type 1 diabetes.

Navaei-Nigjeh M ，Moloudizargari M ，Baeeri M ，Gholami M ，Lotfibakhshaiesh N ，Soleimani M ，Vasheghani-Farahani E ，Ai J ，Abdollahi M ... -  《-》

Adipose tissue-derived mesenchymal stromal cells efficiently differentiate into insulin-producing cells in pancreatic islet microenvironment both in vitro and in vivo.

Differentiation or reprogramming of stem cells could be achieved by remodulating the microenvironment, which regulates the fate of cells by soluble factors and contacts. By providing an in vivo-like microenvironment, directional and functional differentiation of stem cells could be achieved in vitro. In this study, the differentiation of mesenchymal stromal cells (MSCs) derived from rat tissues (adipose, rAT; bone marrow, rBM) were analyzed by in vitro and in vivo co-culture experiments. The insulin-producing capacities of islets transplanted under the renal kidney capsule with rAT- and rBM-MSCs were compared and the reduction of hyperglycemia symptoms in rat models was examined. MSCs prelabeled with green fluorescence protein were co-cultured with islets directly. The insulin production of cells was determined by immunostaining and ELISA. Streptozotocin-induced diabetic rat models were created and MSCs were co-transplanted with the islets under the kidney capsule to confirm the in vitro results. MSCs were differentiated into insulin-producing cells after 38 days of co-culture, confirmed by insulin and C-peptide stainings. In vivo functional studies revealed that the co-culture of islets with MSCs provided higher differentiation efficiency. The weight gain measurement and glucose tolerance test in the rat group co-transplanted of rAT-MSCs and islets indicate a better recovery than islet-alone transplants and co-transplants of islets and rBM-MSCs. rAT-MSCs could be considered as the cell of choice for cell-based treatment of type 1 diabetes. Because the co-transplantation of islets with MSCs increases the number of insulin-producing cells, this method was suggested for clinical applications.

Karaoz E ，Okcu A ，Ünal ZS ，Subasi C ，Saglam O ，Duruksu G ... -  《-》

Pre-culturing islets with mesenchymal stromal cells using a direct contact configuration is beneficial for transplantation outcome in diabetic mice.

We recently showed that co-transplantation of mesenchymal stromal cells (MSCs) improves islet function and revascularization in vivo. Pre-transplant islet culture is associated with the loss of islet cells. MSCs may enhance islet cell survival or function by direct cell contact mechanisms and soluble mediators. We investigated the capacity of MSCs to improve islet cell survival or β-cell function in vitro using direct and indirect contact islet-MSC configurations. We also investigated whether pre-culturing islets with MSCs improves islet transplantation outcome. The effect of pre-culturing islets with MSCs on islet function in vitro was investigated by measuring glucose-stimulated insulin secretion. The endothelial cell density of fresh islets and islets cultured with or without MSCs was determined by immunohistochemistry. The efficacy of transplanted islets was tested in vivo using a syngeneic streptozotocin-diabetic minimal islet mass model. Graft function was investigated by monitoring blood glucose concentrations. Indirect islet-MSC co-culture configurations did not improve islet function in vitro. Pre-culturing islets using a direct contact MSC monolayer configuration improved glucose-stimulated insulin secretion in vitro, which correlated with superior islet graft function in vivo. MSC pre-culture had no effect on islet endothelial cell number in vitro or in vivo. Pre-culturing islets with MSCs using a direct contact configuration maintains functional β-cell mass in vitro and the capacity of cultured islets to reverse hyperglycemia in diabetic mice.

Rackham CL ，Dhadda PK ，Chagastelles PC ，Simpson SJ ，Dattani AA ，Bowe JE ，Jones PM ，King AJ ... -  《-》

Immunomodulatory and protective effects of adipose tissue-derived mesenchymal stem cells in an allograft islet composite transplantation for experimental autoimmune type 1 diabetes.

Allogeneic islet transplantation could be an ideal alternative therapy for Type 1 Diabetes Mellitus (T1DM). Adipose Tissue-derived Mesenchymal Stem Cells (AT-MSCs) characterized by immunomodulatory and protective effects may have the potential to improve the outcome of this highly immunogenic transplant. Syngenic AT-MSCs along with allograft islets embedded in hydrogelic composite and transplanted intraperitoneally in Streptozotocin (STZ) induced diabetic C57BL/6 mice. In vitro experiments of co-imbedded islets and AT-MSCs in a hydrogel revealed AT-MSCs are able to significantly increase insulin secretion. During a 32 days of post-transplant period, blood glucose monitoring showed a decrease from over 400mg/dl to less than 150mg/dl and at the end of 32 days, mice have been dissected and assessed. Graft histopathology demonstrated that hydrogel makes an artificial immune isolation site and AT-MSCs contribute greatly to the reduction of the immune cells infiltration. Analyses of mononuclear cells isolated from Mesenteric Lymph Nodes (MLNs) and spleen showed that AT-MSCs co-transplanted with allograft decreased pro-inflammatory cytokines and increased regulatory cytokines (for both MLNs and spleen) and regulatory T cells (Treg) population (only for MLNs). In addition, real time-PCR assays revealed that transcript levels of IDO, iNOS, and PDX1, significantly increased in allograft islets in the presence of AT-MSCs. according to results, this investigation indicates that AT-MSCs can be regarded as promising complementary candidates for engineered-cell therapy using hydrogel composites in islet transplantation.

Mohammadi Ayenehdeh J ，Niknam B ，Rasouli S ，Hashemi SM ，Rahavi H ，Rezaei N ，Soleimani M ，Liaeiha A ，Niknam MH ，Tajik N ... -  《-》

Co-transplantation of mesenchymal stromal cells and cord blood cells in treatment of diabetes.

Stem cells provide a promising source for treatment of type 1 diabetes, but the treatment strategy and mechanism remain unclear. The aims of this study were to investigate whether co-transplantation of umbilical cord-derived mesenchymal stromal cells (UC-MSCs) and cord blood mononuclear cells (CB-MNCs) could reverse hyperglycemia in type 1 diabetic mice and to determine the appropriate ratio for co-transplantation. The treatment mechanism was also studied. A simple and efficient isolation method was developed to generate qualified UC-MSCs. UC-MSCs and CB-MNCs were then transplanted into type 1 diabetic mice at different ratios (UC-MSCs to CB-MNCs = 1:1, 1:4, 1:10) to observe the change in blood glucose concentration. Histology, immunohistochemistry, and human Alu polymerase chain reaction assay were performed to evaluate for the presence of donor-derived cells and the repair of endogenous islets. We also induced UC-MSCs into islet-like cells under specific culture conditions to determine their differentiate potential in vitro. Co-transplantation of UC-MSCs and CB-MNCs at a ratio of 1:4 effectively reversed hyperglycemia in diabetic mice. The detection of human Alu sequence indicated that the engraftment of donor-derived cells had homed into the recipient's pancreas and kidney. Although neither human insulin nor human nuclei antigen was detected in the regenerated pancreas, UC-MSCs could differentiate into insulin-secreted cells in vitro. Co-transplantation of UC-MSCs and CB-MNCs at a ratio of 1:4 could efficiently reverse hyperglycemia and repair pancreatic tissue.

Xiao N ，Zhao X ，Luo P ，Guo J ，Zhao Q ，Lu G ，Cheng L ... -  《-》