Reversal of experimental diabetes by multiple bone marrow transplantation

A Supportive Role of Mesenchymal Stem Cells on Insulin-Producing Langerhans Islets with a Specific Emphasis on The Secretome

Type 1 Diabetes (T1D) is a chronic autoimmune disease characterized by a gradual destruction of insulin-producing β-cells in the endocrine pancreas due to innate and specific immune responses, leading to impaired glucose homeostasis. T1D patients usually require regular insulin injections after meals to maintain normal serum glucose levels. In severe cases, pancreas or Langerhans islet transplantation can assist in reaching a sufficient β-mass to normalize glucose homeostasis. The latter procedure is limited because of low donor availability, high islet loss, and immune rejection. There is still a need to develop new technologies to improve islet survival and implantation and to keep the islets functional. Mesenchymal stem cells (MSCs) are multipotent non-hematopoietic progenitor cells with high plasticity that can support human pancreatic islet function both in vitro and in vivo and islet co-transplantation with MSCs is more effective than islet transplantation alone in attenuating diabetes progression. The beneficial effect of MSCs on islet function is due to a combined effect on angiogenesis, suppression of immune responses, and secretion of growth factors essential for islet survival and function. In this review, various aspects of MSCs related to islet function and diabetes are described.

Bone marrow-derived mesenchymal stem cells transplantation downregulates pancreatic NF-κB and pro-inflammatory cytokine profile in rats with type I and type II-induced diabetes: a comparison study

Diabetes mellitus (DM) is a set of metabolic diseases defined by a persistently high blood sugar level. Mesenchymal stem cells (MSCs) are a novel potential therapeutic intervention in treatments of various diseases, which is also referred to as regenerative medicine. We aimed to compare the pro-inflammatory cytokines’ levels during bone marrow mesenchymal stem cells (BM-MSCs) transplantation in rats with induced type I (T1D) and type II diabetes (T2D). Thirty-five male Sprague dawley rats were divided into: Group I: the healthy control group, group II: untreated rats with streptozotocin (STZ)-induced T1D (65 mg/kg), group III: BM-MSCs treated rats with STZ-induced T1D, group IV: untreated rats with high-fat diet (HFD)/STZ-induced T2D (40 mg/kg), group V: BM-MSCs-treated rats with HFD/STZ-induced T2D. Biochemical, histopathological and immunohistochemical studies were applied. Our results showed that transplantation reduced hyperglycemia and increased insulin levels in both induced T1D and T2D. Also, reductions in the levels of inflammatory markers were noticed after transplantation that was coincided with nuclear factor-kappa B (NF-кB) immunohistochemical results; which showed negative or moderate cytoplasmic reactivity in treated groups III and V. These results indicated the ability of BM-MSCs transplantation to modulate the pro-inflammatory cytokine profile during treatment of both T1D and T2D.

Immunopathology of Type 1 Diabetes and Immunomodulatory Effects of Stem Cells: A Narrative Review of the Literature

Type 1 Diabetes (T1D) is a complex autoimmune disorder which occurs as a result of an intricate series of pathologic interactions between pancreatic β-cells and a wide range of components of both the innate and the adaptive immune systems. Stem-cell therapy, a recently-emerged potentially therapeutic option for curative treatment of diabetes, is demonstrated to cause significant alternations to both different immune cells such as macrophages, natural killer (NK) cells, dendritic cells, T cells, and B cells and non-cellular elements including serum cytokines and different components of the complement system. Although there exists overwhelming evidence indicating that the documented therapeutic effects of stem cells on patients with T1D is primarily due to their potential for immune regulation rather than pancreatic tissue regeneration, to date, the precise underlying mechanisms remain obscure. On the other hand, immune-mediated rejection of stem cells remains one of the main obstacles to regenerative medicine. Moreover, the consequences of efferocytosis of stem-cells by the recipients' lung-resident macrophages have recently emerged as a responsible mechanism for some immune-mediated therapeutic effects of stem-cells. This review focuses on the nature of the interactions amongst different compartments of the immune systems which are involved in the pathogenesis of T1D and provides explanation as to how stem cell-based interventions can influence immune system and maintain the physiologic equilibrium.

Inducible Pluripotent Stem Cells as a Potential Cure for Diabetes

Over the last century, diabetes has been treated with subcutaneous insulin, a discovery that enabled patients to forego death from hyperglycemia. Despite novel insulin formulations, patients with diabetes continue to suffer morbidity and mortality with unsustainable costs to the health care system. Continuous glucose monitoring, wearable insulin pumps, and closed-loop artificial pancreas systems represent an advance, but still fail to recreate physiologic euglycemia and are not universally available. Islet cell transplantation has evolved into a successful modality for treating a subset of patients with ‘brittle’ diabetes but is limited by organ donor supply and immunosuppression requirements. A novel approach involves generating autologous or immune-protected islet cells for transplant from inducible pluripotent stem cells to eliminate detrimental immune responses and organ supply limitations. In this review, we briefly discuss novel mechanisms for subcutaneous insulin delivery and define their shortfalls. We describe embryological development and physiology of islets to better understand their role in glycemic control and, finally, discuss cell-based therapies for diabetes and barriers to widespread use. In response to these barriers, we present the promise of stem cell therapy, and review the current gaps requiring solutions to enable widespread use of stem cells as a potential cure for diabetes.

Mesenchymal stem cells promote pancreatic β-cell regeneration through downregulation of FoxO1 pathway

Background

Mesenchymal stem cells (MSC) are non-haematopoietic, fibroblast-like multipotent stromal cells. In the injured pancreas, these cells are assumed to secrete growth factors and immunomodulatory molecules, which facilitate the regeneration of pre-existing β-cells. However, when MSC are delivered intravenously, their majority is entrapped in the lungs and does not reach the pancreas. Therefore, the aim of this investigation was to compare the regenerative support of hTERT-MSC (human telomerase reverse transcriptase mesenchymal stem cells) via intrapancreatic (IPR) and intravenous route (IVR).

Methods

hTERT-MSC were administered by IPR and IVR to 50% pancreatectomized NMRI nude mice. After eight days, blood glucose level, body weight, and residual pancreatic weight were measured. Proliferating pancreatic β-cells were labelled and identified with bromodeoxyuridine (BrdU) in vivo. The number of residual islets and the frequency of proliferating β-cells were compared in different groups with sequential pancreatic sections. The pancreatic insulin content was evaluated by enzyme-linked immunosorbent assay (ELISA) and the presence of hTERT-MSC with human Alu sequence. Murine gene expression of growth factors, β-cell specific molecules and proinflammatory cytokines were inspected by real-time polymerase chain reaction (RT-PCR) and Western blot.

Results

This study evaluated the regenerative potential of the murine pancreas post-hTERT-MSC administration through the intrapancreatic (IPR) and intravenous route (IVR). Both routes of hTERT-MSC transplantation (IVR and IPR) increased the incorporation of BrdU by pancreatic β-cells compared to control. MSC induced epidermal growth factor (EGF) expression and inhibited proinflammatory cytokines (IFN-γ and TNF-α). FOXA2 and PDX-1 characteristics for pancreatic progenitor cells were activated via AKT/ PDX-1/ FoxO1 signalling pathway.

Conclusion

The infusion of hTERT-MSC after partial pancreatectomy (Px) through the IVR and IPR facilitated the proliferation of autochthonous pancreatic β-cells and provided evidence for a regenerative influence of MSC on the endocrine pancreas. Moderate benefit of IPR over IVR was observed which could be a new treatment option for preventing diabetes mellitus after pancreas surgery.

Supplementary information

The online version contains supplementary material available at at 10.1186/s13287-020-02007-9.

Regenerative medicine of pancreatic islets

The pancreas became one of the first objects of regenerative medicine, since other possibilities of dealing with the pancreatic endocrine insufficiency were clearly exhausted. The number of people living with diabetes mellitus is currently approaching half a billion, hence the crucial relevance of new methods to stimulate regeneration of the insulin-secreting β-cells of the islets of Langerhans. Natural restrictions on the islet regeneration are very tight; nevertheless, the islets are capable of physiological regeneration via β-cell self-replication, direct differentiation of multipotent progenitor cells and spontaneous α- to β- or δ- to β-cell conversion (trans-differentiation). The existing preclinical models of β-cell dysfunction or ablation (induced surgically, chemically or genetically) have significantly expanded our understanding of reparative regeneration of the islets and possible ways of its stimulation. The ultimate goal, sufficient level of functional activity of β-cells or their substitutes can be achieved by two prospective broad strategies: β-cell replacement and β-cell regeneration. The "regeneration" strategy aims to maintain a preserved population of β-cells through in situ exposure to biologically active substances that improve β-cell survival, replication and insulin secretion, or to evoke the intrinsic adaptive mechanisms triggering the spontaneous non-β- to β-cell conversion. The "replacement" strategy implies transplantation of β-cells (as non-disintegrated pancreatic material or isolated donor islets) or β-like cells obtained ex vivo from progenitors or mature somatic cells (for example, hepatocytes or α-cells) under the action of small-molecule inducers or by genetic modification. We believe that the huge volume of experimental and clinical studies will finally allow a safe and effective solution to a seemingly simple goal-restoration of the functionally active β-cells, the innermost hope of millions of people globally.

Mesenchymal Stem Cells: A Trump Card for the Treatment of Diabetes?

The advent of the new revolutionary approach based on regenerative medicine is progressively reshaping the therapeutic scenario of many different diseases, such as cardiovascular diseases and immune diseases, with encouraging results. During the last 10 years, many studies have also proposed the use of mesenchymal stem cells (MSCs), adult stem cells with several interesting properties already used in different experimental models, for the treatment of diabetes, however, reporting conflicting outcomes. These reasons have given rise to a question: are these cells a real trump card for the biomedical field? Are they really able to outclass the traditional therapies, or at least able to give an advantage over them? In this review, we will discuss the most promising results obtained with MSCs for the treatment of diabetes and its complications, we will compare the different therapeutic treatments applied as well as the most likely mechanisms of action, and overall we will give an in-depth overview of the pros and the cons of the use of MSCs for the therapy of both type-1 and type-2 diabetes.

Myeloid-Derived Growth Factor Promotes Intestinal Glucagon-Like Peptide-1 Production in Male Mice With Type 2 Diabetes

Myeloid-derived growth factor (MYDGF), which is produced by bone marrow-derived cells, mediates cardiac repair following myocardial infarction by inhibiting cardiac myocyte apoptosis to subsequently reduce the infarct size. However, the function of MYDGF in the incretin system of diabetes is still unknown. Here, loss-of-function and gain-of-function experiments in mice revealed that MYDGF maintains glucose homeostasis by inducing glucagon-like peptide-1 (GLP-1) production and secretion and that it improves glucose tolerance and lipid metabolism. Treatment with recombinant MYDGF increased the secretion and production of GLP-1 in STC-1 cells in vitro. Mechanistically, the positive effects of MYDGF are potentially attributable to the activation of protein kinase A/glycogen synthase kinase 3β/β-catenin (PKA/GSK-3β/β-catenin) and mitogen-activated protein kinase (MAPK) kinases/extracellular regulated protein kinase (MEK/ERK) pathways. Based on these findings, MYDGF promotes the secretion and production of GLP-1 in intestinal L-cells and potentially represents a potential therapeutic medication target for type 2 diabetes.

Co-Transplantation of Pancreatic Islet Cells and Mesenchymal Bone Marrow Precursors on Titanium Nickelide Scaffolds in Alloxan-Induced Diabetes Mellitus

We studied therapeutic activity of co-transplantation of allogeneic pancreatic islet cells and mesenchymal bone marrow progenitors on TiNi scaffolds in Wistar rats with experimental alloxan-induced diabetes mellitus. In preliminary experiments with co-culturing of cells in different proportions followed by their transplantation on tissue-engineered constructs, the optimum ratio of these cells was determined - 3:1. Regeneration was assessed by biochemical methods by the blood levels of glucose and glycosylated hemoglobin on days 15, 30, and 5. In the group with combined cell transplantation on TiNi scaffold, normalization of the studied biochemical parameters occurred earlier than after monotherapy with allogenic islet cells and was associated with an increase in animal lifespan. Normalization of the parameters of bone marrow hemopoiesis, in particular, the number of myelokaryocytes and erythroblasts was also noted.

Mesenchymal Stem Cells as New Therapeutic Approach for Diabetes and Pancreatic Disorders

Diabetes is a worldwide disease which actually includes different disorders related to glucose metabolism. According to different epidemiological studies, patients affected by diabetes present a higher risk to develop both acute and chronic pancreatitis, clinical situations which, in turn, increase the risk to develop pancreatic cancer. Current therapies are able to adjust insulin levels according to blood glucose peak, but they only partly reach the goal to abrogate the consequent inflammatory milieu responsible for diabetes-related diseases. In recent years, many studies have investigated the possible use of adult mesenchymal stem cells (MSCs) as alternative therapeutic treatment for diabetes, with promising results due to the manifold properties of these cells. In this review we will critically analyze the many different uses of MSCs for both diabetes treatment and for the reduction of diabetes-related disease development, focusing on their putative molecular mechanisms.

Effects of bone marrow on the microenvironment of the human pancreatic islet: A Protein Profile Approach

Stem cells are a new therapeutic modality that may support the viability and function of human organs and tissue. Our previous studies have revealed that human allogeneic bone marrow (BM) sustains pancreatic β cell function and survival. This paper examines whether BM creates a microenvironment that supports human pancreatic islets in vitro by evaluating 107 proteins in culture media from BM, islet, and islet/bone marrow (IB) with mass spectrometry. Proteins were considered up- or down-regulated if p-values < 0.05 and fold change was greater than 2 fold I VS. IB. In addition, proteins identified that were uniquely found in islets co-cultured with bone marrow, but not in islets or bone marrow. A 95% protein probability was used as a threshold. Twenty three proteins were upregulated, and sixteen proteins were downregulated. The function of each protein is listed based on the protein database, which include structural proteins (9 upregulated, 4 downregulated); anti-protease and anti-endopeptidase enzymes (8 upregulated); cation binding proteins (6 up-regulated). Six proteins were uniquely identified in islet co-cultured with bone marrow. Three are anti-proteases or anti-endopeptidases, and 1 is a structural protein. These findings suggest that BM, by changing culture media proteins, may be one of mechanisms to maintain human islet function and survival.

Stem cells to restore insulin production and cure diabetes

BACKGROUND

The advancement of knowledge in the field of regenerative medicine is increasing the therapeutic expectations of patients and clinicians on cell therapy approaches. Within these, stem cell therapies are often evoked as a possible therapeutic option for diabetes, already ongoing or possible in the near future.

AIM

The purpose of this document is to make a point of the situation on existing knowledge and therapies with stem cells to treat patients with diabetes by focusing on some of the aspects that most frequently raise curiosity and discussion in clinical practice and in the interaction with the patient. In fact, at present there are no clinically approved treatments based on the use of stem cells for the treatment of diabetes, but several therapeutic approaches have already been evaluated or are being evaluated in clinical trials.

DATA SYNTHESIS

It is possible to identify three large potential application fields: 1) the reconstruction of the β cell mass; 2) the immunomodulation in type 1 diabetes (T1D); 3) the treatment of complications. In this study we will limit the discussion to approaches that have the potential for clinical translation, deliberately omitting aspects of basic biology and preclinical data. Also, we intentionally omit the treatment of the complications that will be the subject of a future document. Finally, an overview of the Italian situation regarding the storage of cord blood cells for the therapy of diabetes will be given.

Therapeutic potential of Mesenchymal Stem Cells for the treatment of diabetic peripheral neuropathy

Type-1 Diabetes is generally treated with exogenous insulin administration. Despite treatment, a very common long term consequence of diabetes is the development of a disabling and painful peripheral neuropathy. The transplantation of pancreatic islets is an advanced alternative therapeutic approach, but its clinical application is still very limited, mainly because of the great number of islets required to complete the procedure and of their short-term survival. An intriguing method to improve the performance of pancreatic islets transplantation is the co-transplantation of Mesenchymal Stem Cells (MSCs), adult stem cells already known to support the survival of different cellular populations. In this proof-of-concept study, we demonstrated using an in vivo model of diabetes, the ability of allogenic MSCs to reduce the number of pancreatic islets necessary to achieve glycemic control in diabetic rats, and overall their positive effect on diabetic neuropathy, with the reduction of all the neuropathic signs showed after disease induction. The cutback of the pancreatic islet number required to control glycemia and the regression of the painful neuropathy make MSC co-transplantation a very promising tool to improve the clinical feasibility of pancreatic islet transplantation for diabetes treatment.

Mesenchymal stem cell therapy in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM), which is characterized by the combination of relative insulin deficiency and insulin resistance, cannot be reversed with existing therapeutic strategies. Transplantation of insulin-producing cells (IPCs) was once thought to be the most promising strategy for treating diabetes, but the pace from the laboratory to clinical application has been obstructed due to its drawbacks. Mesenchymal stem cells (MSCs) harbor differentiation potential, immunosuppressive properties, and anti-inflammatory effects, and they are considered an ideal candidate cell type for treatment of DM. MSC-related research has demonstrated exciting therapeutic effects in glycemic control both in vivo and in vitro, and these results now have been translated into clinical practice. However, some critical potential problems have emerged from current clinical trials. Multi-center, large-scale, double-blind, and placebo-controlled studies with strict supervision are required before MSC transplantation can become a routine therapeutic approach for T2DM. We briefly review the molecular mechanism of MSC treatment for T2DM as well as the merits and drawbacks identified in current clinical trials.

Autologous bone marrow-derived mononuclear cells transplantation in type 2 diabetes mellitus: effect on β-cell function and insulin sensitivity

BACKGROUND

Insulin resistance and insulin deficiency are the cardinal defects in the pathogenesis of type 2 diabetes mellitus (T2DM). Despite the plethora of anti-diabetic medications, drugs specifically targeting the β-cells are still desired. Stem cell therapy has emerged as a novel therapeutics strategy to target β-cells; however, their mechanism of action has not been well defined. This study aims to examine the efficacy and safety of autologous bone marrow-derived mononuclear cells (ABM-MNCs) transplantation in T2DM, and explores the mechanistic insights into stem cells action through metabolic studies.

METHODS

Seven T2DM patients with the duration of disease ≥5 years, receiving triple oral anti-diabetic drugs along with insulin (≥0.4 IU per kg per day) and HbA1c ≤ 7.5% (≤58.0 mmol/mol) were enrolled for ABM-MNCs administration through a targeted approach. The primary end-point was a reduction in insulin requirement by ≥50% from baseline, while maintaining HbA1c < 7.0% (<53.0 mmol/mol) with improvement in insulin secretion, and/or insulin sensitivity after ABM-MNCs transplantation.

RESULTS

Six out of 7 (90%) patients achieved the primary end-point. At 6 months, there was a significant reduction in insulin requirement by 51% as compared to baseline (p < 0.003). This was accompanied by a significant increase in the 2nd phase C-peptide response during hyperglycemic clamp (p = 0.018), whereas there were no significant alterations in insulin sensitivity and glucose disposal rate during hyperinsulinemic-euglycemic clamp relative to the baseline. Other measures of β-cell indices like HOMA-β, and stimulated C-peptide response to glucagon and mixed meal tolerance test were non-contributory.

CONCLUSION

ABM-MNCs transplantation results in significant reduction in insulin doses and improvement in C-peptide response in patients with T2DM. Metabolic studies may be more useful than conventional indices to predict β-cell function in patients with advanced duration of T2DM. Trial registration-Clinicaltrials.gov NCT01759823.

Intravenous vs intraperitoneal transplantation of umbilical cord mesenchymal stem cells from Wharton's jelly in the treatment of streptozotocin-induced diabetic rats

AIM

To evaluate the efficiency of mesenchymal stem cells isolated from Wharton's jelly (WJ-MSCs) through either the intravenous or intraperitoneal transplantations into streptozotocin (STZ)-induced diabetic rats as a therapy for type 1 diabetes mellitus (T1DM).

METHODOLOGY

A rat model with STZ induction was established and the rats were divided into 3 groups: a tail vein injection group, an intraperitoneal injection group and a STZ control group. Following transplantation, blood glucose levels were monitored weekly then the pancreatic tissues were collected to examine the pancreatic islets by histopathology and morphometric studies.

RESULTS

Intravenous transplantation of WJ-MSCs ameliorated hyperglycemia at day 7 after transplantation, with sustained decreased fasting blood glucose (FBG) levels until day 56. Further, these cells ameliorated at least partially the damage induced by STZ in the pancreas and produced a similar morphology to normal islets. On the contrary, intraperitoneal transplantation of WJ-MSCs failed to maintain normoglycemia or ameliorate the damaged pancreas in STZ-injected rats.

CONCLUSION

These findings conclude that the intravenous administration method was effective in transplanting WJ-MSCs for the treatment of T1DM, whereas the intraperitoneal transplantation showed no therapeutic effect in our animal experiments.

Effect of mesenchymal stem cells transplantation on glycaemic profile & their localization in streptozotocin induced diabetic Wistar rats

BACKGROUND & OBJECTIVES

Bone marrow is a rich source of adult stem cells that can differentiate into various cell types. Administration of mesenchymal stem cells (MSCs) in irradiated diabetic rat model has transiently shown to decrease blood glucose level. This study examines the effect of high dose and multiple injections of MSCs on glycemic profile, their localization and regeneration of islet in diabetic Wistar rat.

METHODS

The study was carried out in male Wistar rats categorized into three groups (n=6, in each group): Group 1 as control, group 2 streptozotocin (STZ) (50 mg/kg) induced diabetic group and group 3 experimental group; 5-bromo-2-deoxyuridine (BrdU) labelled allogenic MSCs were injected in the non-irradiated diabetic rat of the experimental group through tail vein. The blood glucose profile was subsequently monitored at regular intervals. Rats were sacrificed on day 45 and pancreas was examined for localization of BrdU labelled stem cells by immunofluorescence and islet-neogenesis by immunohistochemistry .

RESULTS

There was a significant reduction in blood glucose level after administration of MSCs in the experimental group (P<0.001). The presence of BrdU labelled MSCs in islet suggested their localization in the pancreas. Co-expression of anti-BrdU and anti-insulin antibody indicated trans-differentiation / fusion into insulin producing cells evidenced by significant increase in total number of islet (P=0.004) and insulin positive cells ( P<0.0001) in experimental group.

INTERPRETATION & CONCLUSIONS

Our results showed that the MSCs administration in non-irradiated diabetic Wistar rat reduced hyperglycaemia and was accompanied by increased islet-neogenesis, possibly through trans-differentiation/fusion.

A comparison of Wharton's jelly and cord blood as a source of mesenchymal stem cells for diabetes cell therapy

AIM

In this study, we investigated the differences between mesenchymal stem cells (MSCs), isolated from umbilical cord blood (UCB-MSCs) and Wharton's jelly (WJ-MSCs) as sources of diabetes mellitus cell therapy.

METHODS

After isolation, both cell types were induced to differentiate into insulin producing cells, then the differentiated cells were assessed genetically and functionally. UCB-MSCs and WJ-MSCs were transplanted in the tail veins of streptozotocin-induced diabetic rats. Blood glucose levels were monitored post-transplantation.

RESULTS & CONCLUSION

Wharton's jelly was more homogeneous, can better differentiate into insulin producing cells in vitro and better control hyperglycemia in diabetic rats in vivo, as compared with UCB. These results indicate that WJ-MSCs represent a potential source of cells in the field of diabetes mellitus cell therapy.

Comparisons of Differentiation Potential in Human Mesenchymal Stem Cells from Wharton's Jelly, Bone Marrow, and Pancreatic Tissues

Background. Type 1 diabetes mellitus results from autoimmune destruction of β-cells. Insulin-producing cells (IPCs) differentiated from mesenchymal stem cells (MSCs) in human tissues decrease blood glucose levels and improve survival in diabetic rats. We compared the differential ability and the curative effect of IPCs from three types of human tissue to determine the ideal source of cell therapy for diabetes. Methods. We induced MSCs from Wharton's jelly (WJ), bone marrow (BM), and surgically resected pancreatic tissue to differentiate into IPCs. The in vitro differential function of these IPCs was compared by insulin-to-DNA ratios and C-peptide levels after glucose challenge. In vivo curative effects of IPCs transplanted into diabetic rats were monitored by weekly blood glucose measurement. Results. WJ-MSCs showed better proliferation and differentiation potential than pancreatic MSCs and BM-MSCs. In vivo, WJ-IPCs significantly reduced blood glucose levels at first week after transplantation and maintained significant decrease till week 8. BM-IPCs reduced blood glucose levels at first week but gradually increased since week 3. In resected pancreas-IPCs group, blood glucose levels were significantly reduced till two weeks after transplantation and gradually increased since week 4. Conclusion. WJ-MSCs are the most promising stem cell source for β-cell regeneration in diabetes treatment.

Effects of autologous bone marrow-derived stem cell mobilization on acute tubular necrosis and cell apoptosis in rats

The aim of this study was to investigate the effects of stem cell factor (SCF) and granulocyte colony-stimulating factor (G-CSF) on bone marrow-derived stem cell (BMSC) mobilization in rat models of renal ischemia/reperfusion (I/R) injury. In addition, the effects of SCF and G-CSF on cellular apoptosis were explored in order to determine the protective mechanism of the two factors against renal I/R injury. A unilateral renal I/R injury model was established for the model and treatment groups. The treatment and treatment control groups were subcutaneously injected with SCF (200 µg/kg/day) and G-CSF (50 µg/kg/day) 24 h after the establishment of the model for five consecutive days. The total number of leukocytes in the peripheral blood and the cellular percentages of cluster of differentiation (CD)34⁺, renal CD34⁺ and apoptotic cells were detected. The total number of leukocytes in the peripheral blood and the percentages of CD34⁺ cells in the treatment and treatment control groups reached maximum levels on the fifth postoperative day and were significantly higher than those in the normal control and model groups. The number of renal CD34⁺ cells in the treatment group was significantly increased compared with that in the treatment control and model groups. The apoptotic indices (AIs) of the model and treatment groups were higher than those of the normal control and treatment control groups. The AI of the model group was significantly higher than that of the treatment group. In conclusion, the combined application of SCF and G-CSF can mobilize sufficient numbers of BMSCs and cause cellular 'homing' to the injured site, thus inhibiting apoptosis and promoting the repair of renal tubular injury.

Transplantation of insulin-producing cells to treat diabetic rats after 90% pancreatectomy

AIM: To investigate the effects of transplantation of insulin-producing cells (IPCs) in the treatment of diabetic rats after 90% pancreatectomy.

METHODS: Human umbilical cord mesenchymal stem cells (UCMSCs) were isolated and induced into IPCs using differentiation medium. Differentiated cells were examined by dithizone (DTZ) staining, reverse transcription-polymerase chain reaction (RT-PCR), and real-time RT-PCR. C-peptide release, both spontaneously and after glucose challenge, was measured by ELISA. IPCs were then transplanted into Sprague-Dawley rats after 90% pancreatectomy and blood glucose levels and body weight were measured.

RESULTS: The differentiated cells were positive for DTZ staining and expressed pancreatic β-cell related genes. C-peptide release by the differentiated cells increased after glucose challenge (380.6 ± 15.32 pmol/L vs 272.4 ± 15.32 pmol/L, P < 0.05). Further, in the cell transplantation group, blood sugar levels were significantly lower than in the sham group 2 wk after transplantation (18.7 ± 2.5 mmol/L vs 25.8 ± 1.25 mmol/L, P < 0.05). Glucose tolerance tests showed that 45 min after intraperitoneal glucose injection, blood glucose levels were significantly lower on day 56 after transplantation of IPCs (12.5 ± 4.7 mmol/L vs 42.2 ± 9.3 mmol/L, P < 0.05).

CONCLUSION: Our results show that UCMSCs can differentiate into islet-like cells in vitro under certain conditions, which can function as IPCs both in vivo and in vitro.

Efficacy and safety of autologous bone marrow-derived stem cell transplantation in patients with type 2 diabetes mellitus: a randomized placebo-controlled study

There is a growing interest in cell-based therapies in T2DM as β-cell failure is progressive and inexorable with the advancing duration of disease. This prospective, randomized, single-blinded placebo-controlled study evaluates the efficacy and safety of autologous bone marrow-derived stem cell transplantation (ABMSCT) in T2DM. Twenty-one patients with triple oral antidiabetic drug failure and requiring insulin ≥0.4 IU per kg per day with HbA1c <7.5% were randomly assigned to an intervention (n = 11) and control group (n = 10) and followed for 12 months. Patients in the intervention group received ABMSCT through a targeted approach, and after 12 weeks, a second dose of stem cells was administered through the antecubital vein after mobilization with G-CSF, while the control group underwent a sham procedure. The primary end point was a reduction in insulin requirement by ≥50% from baseline while maintaining HbA1c <7%. Nine out of the 11 (82%) patients in the intervention group achieved the primary end point, whereas none of the patients in the control group did over the study period (p = 0.002). The insulin requirement decreased by 66.7% in the intervention group from 42.0 (31.0‐64.0) IU per day to 14.0 (0.0‐30.0) IU per day (p = 0.011), while in controls it decreased by 32.1% from 40.5 (31.8‐44.3) IU per day to 27.5 (23.5‐33.3) IU per day (p = 0.008) at 12 months. The reduction in insulin requirement was significantly more in the intervention group compared to controls at both 6 (p = 0.001) and 12 months (p = 0.004). There was a modest but nonsignificant increase in HbA1c (%) in cases from 6.9% (6.4‐7.2%) to 7.1% (6.6‐7.5%) as well as in controls from 6.9% (6.2‐7.0%) to 7.0% (6.9‐7.5%). Ten out of 11 (91%) patients could maintain HbA1c <7% in the intervention group, whereas 6 out of 10 did (60%) in the control group (p = 0.167). The glucagon-stimulated C-peptide significantly increased in treated cases compared to controls (p = 0.036). The decrease in insulin requirement positively correlated with stimulated C-peptide (r = 0.8, p = 0.001). In conclusion, ABMSCT results in a significant decrease in the insulin dose requirement along with an improvement in the stimulated C-peptide levels in T2DM. However, a greater number of patients with a longer duration of follow-up are required to substantiate these observations.

Therapeutic efficacy of umbilical cord-derived mesenchymal stem cells in patients with type 2 diabetes

Type 2 diabetes (T2D) is characterized by progressive and inexorable β-cell dysfunction, leading to insulin deficiency. Novel strategies to preserve the remaining β-cells and restore β-cell function for the treatment of diabetes are urgently required. Mesenchymal stem cells (MSCs) have been exploited in a variety of clinical trials aimed at reducing the burden of immune-mediated disease. The aim of the present clinical trial was to assess the safety and efficacy of umbilical cord-derived MSC (UCMSC) transplantation for patients with T2D. The safety and efficacy of UCMSC application were evaluated in six patients with T2D during a minimum of a 24-month follow-up period. Following transplantation, the levels of fasting C-peptide, the peak value and the area under the C-peptide release curve increased significantly within one month and remained high during the follow-up period (P<0.05). Three of the six patients became insulin free for varying lengths of time between 25 and 43 months, while the additional three patients continued to require insulin injections, although with a reduced insulin requirement. Fasting plasma glucose and 2-h postprandial blood glucose levels were relatively stable in all the patients following transplantation. There was no immediate or delayed toxicity associated with the cell administration within the follow-up period. Therefore, the results indicated that transplantation of allogeneic UCMSCs may be an approach to improve islet function in patients with T2D. There were no safety issues observed during infusion and the long-term monitoring period.

Differentiated mesenchymal stem cells ameliorate cardiovascular complications in diabetic rats

Cardiovascular manifestations are one of the major complications of type 1 diabetes mellitus (T1DM) and supersede the slow progression of DM in most cases as the leading cause of mortality. There have been many studies and trials in regenerating the functional β-cells of islets from mesenchymal stem cells (MSCs) with varied success. The effect of MSCs ex vivo differentiated to mimic functional insulin-secreting β-cells of islets and their impact on restoration of diabetic complications and transplantation via systemic delivery have not been well studied. In the current study, bone marrow MSCs differentiated to insulin-secreting β-cells are used to treat STZ-induced diabetic rats. The post-homing effects of the differentiated MSCs (dMSCs) were endogenous with definite reversal of diabetic parameters. Consequently, the altered cardiac functions like heart beat rate, left ventricular performance, contractility index and physiological body weight gain due to hyperglycemia were amelorated into normacy. The primary onset cardiac perfomance and the endothelial activation were well evidenced by high fibrinogen levels and systolic blood pressure (SBP) being reversed on the treatment by dMSCs. Further high basal [Ca(2+)]c in isolated endothelial cells and thereby increased ROS confirmed the endothelial activation. The levels of pro-apoptotic makers p53 and Bax were highly expressed in the diabetic groups indicating oxidative stress through ROS induced by high cytosolic calcium skewing the cells towards apoptosis. The expression of the anti-apoptotic marker Bcl-2 was observed to be low in the diabetic group further augmenting the stress state of endothelial cells (ECs) in T1DM. Restoration of [Ca(2+)]c chelates ROS and the subsequent reversal of pro- and anti-apoptotic markers after the successful treatment of dMSCs proved that endogenous reconstitution of insulin secretion improves diabetic-induced cardiac manifestations.

Mesenchymal Stem Cells: Rising Concerns over Their Application in Treatment of Type One Diabetes Mellitus

Type 1 diabetes mellitus (T1DM) is an autoimmune disorder that leads to beta cell destruction and lowered insulin production. In recent years, stem cell therapies have opened up new horizons to treatment of diabetes mellitus. Among all kinds of stem cells, mesenchymal stem cells (MSCs) have been shown to be an interesting therapeutic option based on their immunomodulatory properties and differentiation potentials confirmed in various experimental and clinical trial studies. In this review, we discuss MSCs differential potentials in differentiation into insulin-producing cells (IPCs) from various sources and also have an overview on currently understood mechanisms through which MSCs exhibit their immunomodulatory effects. Other important issues that are provided in this review, due to their importance in the field of cell therapy, are genetic manipulations (as a new biotechnological method), routes of transplantation, combination of MSCs with other cell types, frequency of transplantation, and special considerations regarding diabetic patients' autologous MSCs transplantation. At the end, utilization of biomaterials either as encapsulation tools or as scaffolds to prevent immune rejection, preparation of tridimensional vascularized microenvironment, and completed or ongoing clinical trials using MSCs are discussed. Despite all unresolved concerns about clinical applications of MSCs, this group of stem cells still remains a promising therapeutic modality for treatment of diabetes.

MSC microvesicles for the treatment of lung disease: a new paradigm for cell-free therapy

SIGNIFICANCE

Bronchopulmonary dysplasia (BPD), also known as chronic lung disease of infancy, is a major complication of preterm birth that, despite improvements in neonatal respiratory support and perinatal care, remains an important cause of morbidity and mortality, often with severe adverse neurodevelopmental sequelae. Even with major advances in our understanding of the pathogenesis of this disease, BPD remains essentially without adequate treatment.

RECENT ADVANCES

Cell-based therapies arose as a promising treatment for acute and chronic lung injury in many experimental models of disease. Currently, more than 3000 human clinical trials employing cell therapy for the treatment of diverse diseases, including cardiac, neurologic, immune, and respiratory conditions, are ongoing or completed. Among the treatments, mesenchymal stem cells (MSCs) are the most studied and have been extensively tested in experimental models of BPD, pulmonary hypertension, pulmonary fibrosis, and acute lung injury.

CRITICAL ISSUES

Despite the promising potential, MSC therapy for human lung disease still remains at an experimental stage and optimal transplantation conditions need to be determined. Although the mechanism of MSC action can be manifold, accumulating evidence suggests a predominant paracrine, immunomodulatory, and cytoprotective effect.

FUTURE DIRECTIONS

The current review summarizes the effect of MSC treatment in models of lung injury, including BPD, and focuses on the MSC secretome and, specifically, MSC-derived microvesicles as potential key mediators of therapeutic action that can be the focus of future therapies.

Exosomes: vehicles of intercellular signaling, biomarkers, and vectors of cell therapy

Mesenchymal stem cells (MSCs), whose mechanism of action is predominantly paracrine, are being widely tested for the treatment of a variety of human diseases. No one factor has been proven sufficient to mediate the therapeutic effects of MSCs. However, exosomes--membrane vesicles secreted by many cells, including MSCs--are appealing candidates as vectors of their efficacy. Exosomes can transport and deliver a large cargo of proteins, lipids, and nucleic acids and can modify cell and organ function. In addition to their key role as vehicles of intercellular communication, exosomes are increasingly recognized as biomarkers and prognosticators of disease. Moreover, they have the potential to be used as vehicles of gene and drug delivery for clinical application. This article reviews the biogenesis of exosomes, their molecular composition, and their role as messengers of intercellular communication, focusing on their potential as therapeutic vectors for stem cell therapy.

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

BACKGROUND AIMS

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

Co-transplantation of UC-MSCs and CB-MNCs at a ratio of 1:4 could efficiently reverse hyperglycemia and repair pancreatic tissue.

Bone marrow mesenchymal stem cells promote the repair of islets from diabetic mice through paracrine actions

Transplantation of bone marrow mesenchymal stem cells (MSCs) has been shown to effectively lower blood glucose levels in diabetic individuals, but the mechanism has not been adequately explained. We hypothesized that MSCs exert beneficial paracrine actions on the injured islets by releasing biologically active factors. To prove our hypothesis, we tested the cytoprotective effect of conditioned medium from cultured MSCs on isolated islets exposed to STZ in vitro and on mice islets after the experimental induction of diabetes in vivo. We assessed islet regeneration in the presence of conditioned medium and explored the possible mechanisms involved. Transplantation of MSCs can ameliorate hyperglycemia in diabetic mice by promoting the regeneration of β cells. Both β cell replication and islet progenitors differentiation contribute to β cell regeneration. MSC transplantation resulted in increases in pAkt and pErk expression by islets in vivo. Treatment with MSC-CM promoted islet cell proliferation and resulted in increases in pAkt and pErk expression by islets in vitro. The MSC-CM-mediated induction of β cell proliferation was completely blocked by the PI3K/Akt inhibitor LY294002 but not by the MEK/Erk inhibitor PD98059. Together, these data suggest that the PI3K/Akt signal pathway plays a critical role in β cell proliferation after MSC transplantation.

Intraportal injection of insulin-producing cells generated from human bone marrow mesenchymal stem cells decreases blood glucose level in diabetic rats

We studied the process of trans-differentiation of human bone marrow mesenchymal stem cells (hBM-MSCs) into insulin-producing cells. Streptozotocin (STZ)-induced diabetic rat model was used to study the effect of portal vein transplantation of these insulin-producing cells on blood sugar levels. The BM-MSCs were differentiated into insulin-producing cells under defined conditions. Real-time PCR, immunocytochemistry and glucose challenge were used to evaluate in vitro differentiation. Flow cytometry showed that hBM-MSCs were strongly positive for CD44, CD105 and CD73 and negative for hematopoietic markers CD34, CD38 and CD45. Differentiated cells expressed C-peptide as well as β-cells specific genes and hormones. Glucose stimulation increased C-peptide secretion in these cells. The insulin-producing, differentiated cells were transplanted into the portal vein of STZ-induced diabetic rats using a Port-A catheter. The insulin-producing cells were localized in the liver of the recipient rat and expressed human C-peptide. Blood glucose levels were reduced in diabetic rats transplanted with insulin-producing cells. We concluded that hBM-MSCs could be trans-differentiated into insulin-producing cells in vitro. Portal vein transplantation of insulin-producing cells alleviated hyperglycemia in diabetic rats.

Two distinct mechanisms mediate the involvement of bone marrow cells in islet remodeling: neogenesis of insulin-producing cells and support of islet recovery

We have recently reported that small-sized bone marrow cells (BMCs) isolated by counterflow centrifugal elutriation and depleted of lineage markers (Fr25lin(-)) have the capacity to differentiate and contribute to regeneration of injured islets. In this study, we assess some of the characteristics of these cells compared to elutriated hematopoietic progenitors (R/O) and whole BMCs in a murine model of streptozotocin-induced chemical diabetes. The GFP(bright)CD45(+) progeny of whole BMCs and R/O progenitors progressively infiltrate the pancreas with evolution of donor chimerism; are found at islet perimeter, vascular, and ductal walls; and have a modest impact on islet recovery from injury. In contrast, Fr25lin(-) cells incorporate in the islets, convert to GFP(dim)CD45(-)PDX-1(+) phenotypes, produce proinsulin, and secrete insulin with significant contribution to stabilization of glucose homeostasis. The elutriated Fr25lin(-) cells express low levels of CD45 and are negative for SCA-1 and c-kit, as removal of cells expressing these markers did not impair conversion to produce insulin. BMCs mediate two synergistic mechanisms that contribute to islet recovery from injury: support of islet remodeling by hematopoietic cells and neogenesis of insulin-producing cells from stem cells.

Making surrogate β-cells from mesenchymal stromal cells: perspectives and future endeavors

Generation of surrogate β-cells is the need of the day to compensate the short supply of islets for transplantation to diabetic patients requiring daily shots of insulin. Over the years several sources of stem cells have been claimed to cater to the need of insulin producing cells. These include human embryonic stem cells, induced pluripotent stem cells, human perinatal tissues such as amnion, placenta, umbilical cord and postnatal tissues involving adipose tissue, bone marrow, blood monocytes, cord blood, dental pulp, endometrium, liver, labia minora dermis-derived fibroblasts and pancreas. Despite the availability of such heterogonous sources, there is no substantial breakthrough in selecting and implementing an ideal source for generating large number of stable insulin producing cells. Although the progress in derivation of β-cell like cells from embryonic stem cells has taken a greater leap, their application is limited due to controversy surrounding the destruction of human embryo and immune rejection. Since multipotent mesenchymal stromal cells are free of ethical and immunological complications, they could provide unprecedented opportunity as starting material to derive insulin secreting cells. The main focus of this review is to discuss the merits and demerits of MSCs obtained from human peri- and post-natal tissue sources to yield abundant glucose responsive insulin producing cells as ideal candidates for prospective stem cell therapy to treat diabetes.

Recent advances in mesenchymal stem cell immunomodulation: the role of microvesicles

Mesenchymal stem cells are the most widely used cell phenotype for therapeutic applications, the main reasons being their well-established abilities to promote regeneration of injured tissues and to modulate immune responses. Efficacy was reported in the treatment of several animal models of inflammatory and autoimmune diseases and, in clinical settings, for the management of disorders such as GVHD, systemic lupus erythematosus, multiple sclerosis, and inflammatory bowel disease. The effects of mesenchymal stem cells are believed to be largely mediated by paracrine signals, and several secreted molecules have been identified as contributors to the net biological effect. Recently, it has been recognized that bioactive molecules can be shuttled from cell to cell packed in microvesicles, tiny portions of cytoplasm surrounded by a membrane. Coding and noncoding RNAs are also carried in such microvesicles, transferring relevant biological activity to target cells. Several reports indicate that the regenerative effect of mesenchymal stem cells can be reproduced by microvesicles isolated from their culture medium. More recent evidence suggests that the immunomodulatory effects of mesenchymal stem cells are also at least partially mediated by secreted microvesicles. These findings allow better understanding of the mechanisms involved in cell-to-cell interaction and may have interesting implications for the development of novel therapeutic tools in place of the parent cells.

Co-transplantation of bone marrow-derived endothelial progenitor cells improves revascularization and organization in islet grafts

Bone marrow-derived early endothelial progenitor cells (BM-EPCs) are a clinical tool for enhancing revascularization. However, the therapeutic efficacy of co-transplantation of BM-EPC with islets has not been investigated. In this study, marginal mass islets were co-transplanted with or without BM-EPCs under the kidney capsules of syngeneic streptozotocin-induced diabetic mice. Using green fluorescent protein transgenic (GFP-Tg) mice as BM-EPC and islet donors or recipients, the role of EPCs in revascularization was assessed for graft morphology, vascular density and fate of EPCs by immunohistochemistry. Islet-EPC co-transplantation improved the outcome of islet transplantation as measured by glucose tolerance, serum insulin level and diabetes reversal rate, compared with transplantation of islets alone. Between groups, the morphology of islet grafts showed significant differences in size and composition of grafted endocrine tissues. Significantly more vessel density derived from donors and recipients was detected with islet-EPC co-transplantation. Abundant GFP-Tg mice-derived BM-EPCs (GFP-EPCs) were observed in or around islet grafts and incorporated into CD31-positive capillaries. Remaining GFP-EPCs expressed VEGF. In conclusion, co-transplantation of islets with BM-EPCs could improve the outcome of marginal mass islet transplantation by promoting revascularization and preserving islet morphology.

β-Cell regeneration mediated by human bone marrow mesenchymal stem cells

Bone marrow mesenchymal stem cells (BMSCs) have been shown to ameliorate diabetes in animal models. The mechanism, however, remains largely unknown. An unanswered question is whether BMSCs are able to differentiate into β-cells in vivo, or whether BMSCs are able to mediate recovery and/or regeneration of endogenous β-cells. Here we examined these questions by testing the ability of hBMSCs genetically modified to transiently express vascular endothelial growth factor (VEGF) or pancreatic-duodenal homeobox 1 (PDX1) to reverse diabetes and whether these cells were differentiated into β-cells or mediated recovery through alternative mechanisms. Human BMSCs expressing VEGF and PDX1 reversed hyperglycemia in more than half of the diabetic mice and induced overall improved survival and weight maintenance in all mice. Recovery was sustained only in the mice treated with hBMSCs-VEGF. However, de novo β-cell differentiation from human cells was observed in mice in both cases, treated with either hBMSCs-VEGF or hBMSCs- PDX1, confirmed by detectable level of serum human insulin. Sustained reversion of diabetes mediated by hBMSCs-VEGF was secondary to endogenous β-cell regeneration and correlated with activation of the insulin/IGF receptor signaling pathway involved in maintaining β-cell mass and function. Our study demonstrated the possible benefit of hBMSCs for the treatment of insulin-dependent diabetes and gives new insight into the mechanism of β-cell recovery after injury mediated by hBMSC therapy.

Transplantation of insulin-producing cells from umbilical cord mesenchymal stem cells for the treatment of streptozotocin-induced diabetic rats

Background

Although diabetes mellitus (DM) can be treated with islet transplantation, a scarcity of donors limits the utility of this technique. This study investigated whether human mesenchymal stem cells (MSCs) from umbilical cord could be induced efficiently to differentiate into insulin-producing cells. Secondly, we evaluated the effect of portal vein transplantation of these differentiated cells in the treatment of streptozotocin-induced diabetes in rats.

Methods

MSCs from human umbilical cord were induced in three stages to differentiate into insulin-producing cells and evaluated by immunocytochemistry, reverse transcriptase, and real-time PCR, and ELISA. Differentiated cells were transplanted into the liver of diabetic rats using a Port-A catheter via the portal vein. Blood glucose levels were monitored weekly.

Results

Human nuclei and C-peptide were detected in the rat liver by immunohistochemistry. Pancreatic β-cell development-related genes were expressed in the differentiated cells. C-peptide release was increased after glucose challenge in vitro. Furthermore, after transplantation of differentiated cells into the diabetic rats, blood sugar level decreased. Insulin-producing cells containing human C-peptide and human nuclei were located in the liver.

Conclusion

Thus, a Port-A catheter can be used to transplant differentiated insulin-producing cells from human MSCs into the portal vein to alleviate hyperglycemia among diabetic rats.

In vitro reprogramming of rat bone marrow-derived mesenchymal stem cells into insulin-producing cells by genetically manipulating negative and positive regulators

Islet cell replacement therapy represents the most promising approach for the cure of type 1 diabetes if autoimmunity to β cells is under control. However, this potential is limited by a shortage of pancreas donors. To address the donor shortage problem, we determined whether bone marrow-derived mesenchymal stem cells (bmMSCs) can be directly reprogrammed to islet lineages by simultaneously forced suppression and over-expression of key regulator genes that play critical roles during pancreas development. Here, we report that rat bmMSCs were converted in vitro into insulin-producing cells by suppressing two-repressor genes repressor element-1 silencing transcription factor/neuronal restrictive silencing factor (Rest/Nrsf) and sonic hedgehog (Shh) and by over-expressing pancreas and duodenal transcription factor 1 (Pdx1). The reprogrammed bmMSCs expressed both genes and proteins specific for islet cells. These converted cells were capable of releasing insulin in a glucose-responsive manner. Our study suggests that bmMSCs may ultimately be reprogrammed to functional insulin-secreting cells.

Transplantation of insulin-producing cells derived from umbilical cord stromal mesenchymal stem cells to treat NOD mice

Diabetes mellitus can be treated with islet transplantation, although there is a scarcity of donors. This study investigated whether human mesenchymal stem cells (MSCs) from umbilical cord stroma could be induced to differentiate into insulin-producing cells and the effects of retro-orbital injection of human insulin-producing cells for the treatment of nonobese diabetic (NOD) mice. MSCs were isolated from human umbilical cord stroma and induced to differentiate into insulin-producing cells using differentiation medium. Differentiated cells were evaluated by immunocytochemistry, RT-PCR, and real-time PCR. C-peptide release, both spontaneous and after glucose challenge, was measured by ELISA. Insulin-producing cells were then transplanted into NOD mice. Blood glucose levels and body weights were monitored weekly. Human nuclei and C-peptide were detected in mouse livers by immunohistochemistry. Pancreatic β-cell development-related genes were expressed in the differentiated insulin-producing cells. Differentiated cells' C-peptide release in vitro increased after glucose challenge. Further, in vivo glucose tolerance tests showed that blood sugar levels decreased after the cells' transplantation into NOD mice. After transplantation, insulin-producing cells containing human C-peptide and human nuclei were located in the liver. Thus, we demonstrated that differentiated insulin-producing cells from human umbilical cord stromal MSCs transplanted into NOD mice could alleviate hyperglycemia in diabetic mice.

Bone marrow and pancreatic islets: an old story with new perspectives

In the past years, in the field of β-cell replacement for diabetes therapy, the easy availability of bone marrow (BM) and the widely consolidated clinical experience in the field of hematology have contributed to the development of strategy to achieve donor-specific transplantation tolerance. Recently, the potential role of BM in diabetes therapy has been reassessed from a different point of view. Diverse groups investigated the contribution of BM cells to β-cell replacement as direct differentiation into insulin-producing cells. More importantly, while direct differentiation is highly unlikely, a wide array of experimental evidences indicates that cells of BM origin are capable of facilitating the survival or the endogenous regeneration of β-cells through an as yet well-defined regeneration process. These new experimental in vitro and in vivo data will expand in the near future the clinical trials involving BM or BM-derived cells to cure both type 1 and type 2 diabetes in humans. In this review we recapitulate the history of use of BM in diabetes therapy and we provide clinically relevant actual information about the participation of BM and BM-derived stem cells in islet cell regeneration processes. Furthermore, new aspects such as employing BM as "feeder tissue" for pancreatic islets and new clinical use of BM in diabetes therapy are discussed.

Lack of evidence for recipient precursor cells replenishing β-cells in transplanted islets

Bone marrow and tissue precursor cells have been postulated to replenish grafts of transplanted islets. Several investigators have reported that bone marrow cells can promote the regeneration of injured islets. In this study, we investigated the potential of recipient-derived precursor cells to form new pancreatic endocrine cells in islet grafts transplanted under the kidney capsule. Mouse insulin promoter (MIP)-green fluorescence protein (GFP) mice, which express GFP only in β-cells, or β-actin GFP mice, which express GFP ubiquitously, were used to determine if the recipient-derived cells differentiate into β-cells or other types of endocrine cells. We transplanted MIP-GFP islets into wild-type mice, wild-type islets into MIP-GFP mice, β-actin GFP islets into wild-type mice, and wild-type islets into β-actin GFP mice. β-Actin GFP bone marrow cells were then injected into wild-type mice to evaluate the potential role of bone marrow stem cells to provide new islet cells to the graft. No β-cells with green fluorescence were seen in the graft when wild-type islets were transplanted into MIP-GFP mice. When wild-type islets were transplanted into β-actin GFP mice, no β-cells with GFP staining could be identified in the grafts. Similarly, no endocrine cells with GFP staining could be identified in the grafts after injection of β-actin GFP bone marrow cells into wild-type islet-transplanted wild-type mice. This study provides further support for the concept that recipient precursor cells do not produce new β-cells in grafts of transplanted islets.

Human placenta-derived mesenchymal stem cells and islet-like cell clusters generated from these cells as a novel source for stem cell therapy in diabetes

Placental tissue holds great promise as a source of cells for regenerative medicine due to its plasticity, and easy availability. Human placenta-derived mesenchymal stem cells (hPDMSCs) have the potential to differentiate into insulin-producing cells. Upon transplantation, they can reverse experimental diabetes in mice. However, it is not known whether culture-expanded undifferentiated hPDMSCs are capable of restoring normoglycemia upon transplantation in streptozotocin (STZ)-induced diabetic mice. Hence we prepared long-term cultures of hPDMSCs from the chorionic villi of full-term human placenta. Flow cytometry analyses and immunocytochemistry study revealed bonafide mesenchymal nature of the isolated hPDMSCs. These cultures could differentiate into adipogenic, oesteogenic, chondrogenic, and neuronal lineages on exposure to lineage-specific cocktails. Furthermore, we showed that hPDMSCs can form islet-like cell clusters (ILCs) on stepwise exposure to serum-free defined media containing specific growth factors and differentiating agents. qRT-PCR showed the expression of insulin, glucagon, and somatostatin in undifferentiated hPDMSCs and in ILCs. Differentiated ILCs were found to express human insulin, glucagon, and somatostatin by immunocytochemistry. Additionally, ILCs also showed abundance of pancreatic transcription factors ngn3 and isl1. Both undifferentiated hPDMSCs and ILCs exihibited insulin secretion in response to glucose. Transplantation of hPDMSCs or ILCs derived from hPDMSCs in STZ-induced diabetic mice led to restoration of normoglycemia. Our results demonstrate, for the first time, reversal of hyperglycemia by undifferentiated hPDMSCs and ILCs derived from hPDMSCs. These results suggest human placenta-derived MSCs as an alternative source for cell replacement therapy in diabetes.

Mesenchymal stem cells prevent acute rejection and prolong graft function in pancreatic islet transplantation

BACKGROUND

Pancreatic islet transplantation is a promising cell-based therapy for type 1 diabetes (insulin-dependent diabetes mellitus), a disease triggered by the immune response against autoantigens of beta-cells. However, the recurrence of immune response after transplantation and the diabetogenic and growth-stunting side effects of immunosuppressants are major challenges to the application of islet transplantation. Mesenchymal stem cells (MSCs) have recently been reported to modulate the immune response in allogeneic transplantation.

METHODS

The ability of MSCs, either syngeneic or allogeneic to recipients, to prevent acute rejection and improve glycemic control was investigated in rats with diabetes given a marginal mass of pancreatic islets through the portal vein.

RESULTS

Reduced glucose levels and low-grade rejections were observed up to 15 days after transplantation upon triple-dose administration of MSCs, indicating that MSCs prolong graft function by preventing acute rejection. The efficacy of MSCs was associated with a reduction of pro-inflammatory cytokines and was independent of the administration route. Efficacy was similar for MSCs whether syngeneic or allogeneic to recipients and comparable to that of immunosuppressive therapy.

CONCLUSIONS

The results show that MSCs modulate the immune response through a down-regulation of pro-inflammatory cytokines, suggesting that MSCs may prevent acute rejection and improve graft function in portal vein pancreatic islet transplantation.

Bone marrow transplantation temporarily improves pancreatic function in streptozotocin-induced diabetes: potential involvement of very small embryonic-like cells

BACKGROUND

The role of bone marrow (BM)-derived cells in pancreatic beta-cell regeneration remains unresolved. We examined whether BM-derived cells are recruited to the site of moderate pancreatic injury and contribute to beta-cell regeneration.

METHODS

Low-dose streptozotocin (STZ) treatment was used to induce moderate pancreatic damage and hyperglycemia. Enhanced green fluorescent protein-positive (EGFP) BM chimeras were evaluated for beta-cell regeneration after STZ treatment.

RESULTS

To test the hypothesis that pancreatic tissue injury induces a stromal cell-derived factor (SDF)-1 gradient to chemoattract the stem cells, we evaluated the expression of mRNA for SDF-1 in damaged pancreatic tissue. SDF-1 was significantly increased in the pancreas after damage, peaking at day 10. The majority of BM cells expressing mRNA for pancreatic development markers were detected in the subpopulation of CD45/Sca-1/Lin very small embryonic-like (VSEL) cells. VSEL cells mobilized from BM to peripheral blood in response to pancreatic damage, peaking in peripheral blood at day 5, and were enriched in the pancreas 10 to 15 days after STZ treatment. To confirm a role for BM-derived cells in pancreatic beta-cell regeneration, we prepared EGFP-->B6 chimeras. In the EGFP chimeras, EGFP cells were detected around duct and islets and were positive for insulin after STZ treatment. However, STZ-induced hyperglycemia was reduced only transiently (49-77 days) after pancreatic injury.

CONCLUSIONS

These data suggest that VSEL cells are mobilized into injured pancreatic tissue and contribute to beta-cell regeneration. Transplantation of BM-derived cells improves the function of injured pancreas, although the response is not sufficient to restore sustained normoglycemia.

Efficacy of autologous bone marrow-derived stem cell transplantation in patients with type 2 diabetes mellitus

Progressive and inexorable beta-cell dysfunction is the hallmark of type 2 diabetes mellitus (T2DM) and beta-cell regeneration using stem cell therapy may prove to be an effective modality. A total of 10 patients (8 men) with T2DM for >5 years, failure of triple oral antidiabetic drugs, currently on insulin (> or = 0.7 U/kg/day) at least for 1 year, and glutamic acid decarboxylase antibody negative were included. Patients on stable doses of medications for past 3 months were recruited. Primary end points were reduction in insulin requirement by > or = 50% and improvement in glucagon-stimulated C-peptide levels at the end of 6 months of autologous bone marrow-derived stem cell transplantation (SCT), while secondary end points were a change in weight and HbA1c and lipid levels as compared to baseline. Seven patients were responders and showed a reduction in insulin requirement by 75% as compared to baseline. Mean duration to achieve the primary objective was 48 days. Three patients were able to discontinue insulin completely, although it was short-lived in one. Mean HbA1c reduction was 1% and 3 of the 7 responders had HbA1c value <7%. A significant weight loss of 5.5 kg was noted in the responders, whereas, nonresponders gained 2.2 kg of weight. However, weight loss did not correlate with reduction in insulin requirement (r = 0.68, P = 0.06). There was a significant improvement in both fasting and glucagon-stimulated C-peptide level in the group (P = 0.03) and responders (P = 0.03). HOMA-B increased significantly in the whole group (P = 0.02) and responders (P = 0.04) whereas, HOMA-IR did not change significantly (P = 0.74). Reduction in insulin doses correlated with stimulated C-peptide response at the baseline (r = 0.83, P = 0.047) and mononuclear cell count of infused stem cells (r = 0.57, P = 0.04). No serious adverse effects were noted. Our observations indicate that SCT is a safe and effective modality of treatment to improve beta-cell function in patients with T2DM. However, further large-scale studies are needed to substantiate these observations.

Preventive effects of syngeneic bone marrow transplantation on diabetic nephropathy in mice

Treatment with autologous bone marrow transplantation (ABMT) can change the natural history of diabetes in patients with new-onset Type 1 diabetes (T1D). Effects of syngeneic bone marrow transplantation (syn-BMT) on diabetic nephropathy were studied in streptozotocin-induced diabetic mice. Diabetic mice received sibling's bone marrow on days 3, 10, 20, or 40 after T1D onset, respectively. Renal pathology, levels of oxidative stress, and the expressions of angiotensinogen (AGT), monocyte chemoattractant protein-1 (MCP-1) and transforming growth factor beta 1 (Tgf-beta1) mRNA were investigated. Treatment with syn-BMT when disease was early-onset reduced mesangial area expansion and kidney enlargement; besides, if it is given on day 10, syn-BMT attenuated glomerular hypertrophy. Oxidative stress factors such as catalase (CAT) and superoxide radical anion O(2-) (O(2-)) were markedly maintained by syn-BMT compared to mice without treatment. In diabetic mice without treatment, renal AGT and MCP-1 mRNA were increased, while they were effectively suppressed by syn-BMT. But it showed no changes or even increment in Tgf-beta1 mRNA after syn-BMT. Syn-BMT, if applied when disease was early-onset, ameliorated diabetic renal injury. These preventive effects could be partly via maintaining oxidative stress and expression of AGT and MCP-1 in kidney in streptozotocin-diabetic mice.