Mesenchymal stem cell therapy in diabetes mellitus: progress and challenges. J Nucleic Acids. 2013;2013:194858. [PMID: 23762531 PMCID: PMC3666198 DOI: 10.1155/2013/194858]

Diabetic microenvironment deteriorates the regenerative capacities of adipose mesenchymal stromal cells

BACKGROUND

Type 2 diabetes is an endocrine disorder characterized by compromised insulin sensitivity that eventually leads to overt disease. Adipose stem cells (ASCs) showed promising potency in improving type 2 diabetes and its complications through their immunomodulatory and differentiation capabilities. However, the hyperglycaemia of the diabetic microenvironment may exert a detrimental effect on the functionality of ASCs. Herein, we investigate ASC homeostasis and regenerative potential in the diabetic milieu.

METHODS

We conducted data collection and functional enrichment analysis to investigate the differential gene expression profile of MSCs in the diabetic microenvironment. Next, ASCs were cultured in a medium containing diabetic serum (DS) or normal non-diabetic serum (NS) for six days and one-month periods. Proteomic analysis was carried out, and ASCs were then evaluated for apoptosis, changes in the expression of surface markers and DNA repair genes, intracellular oxidative stress, and differentiation capacity. The crosstalk between the ASCs and the diabetic microenvironment was determined by the expression of pro and anti-inflammatory cytokines and cytokine receptors.

RESULTS

The enrichment of MSCs differentially expressed genes in diabetes points to an alteration in oxidative stress regulating pathways in MSCs. Next, proteomic analysis of ASCs in DS revealed differentially expressed proteins that are related to enhanced cellular apoptosis, DNA damage and oxidative stress, altered immunomodulatory and differentiation potential. Our experiments confirmed these data and showed that ASCs cultured in DS suffered apoptosis, intracellular oxidative stress, and defective DNA repair. Under diabetic conditions, ASCs also showed compromised osteogenic, adipogenic, and angiogenic differentiation capacities. Both pro- and anti-inflammatory cytokine expression were significantly altered by culture of ASCs in DS denoting defective immunomodulatory potential. Interestingly, ASCs showed induction of antioxidative stress genes and proteins such as SIRT1, TERF1, Clusterin and PKM2.

CONCLUSION

We propose that this deterioration in the regenerative function of ASCs is partially mediated by the induced oxidative stress and the diabetic inflammatory milieu. The induction of antioxidative stress factors in ASCs may indicate an adaptation mechanism to the increased oxidative stress in the diabetic microenvironment.

Silencing of forkhead box protein O-1 (FOXO-1) enhances insulin-producing cell generation from adipose mesenchymal stem cells for diabetes therapy

AIMS

Generation of mature β-cells from MSCs has been a challenge in the field of stem cell therapy of diabetes. Adipose tissue-derived mesenchymal stem cells (Ad-MSCs) have made their mark in regenerative medicine, and provide several advantages compared to other MSCs sources. Forkhead box protein O-1 (FOXO-1) is an important transcription factor for normal development of β-cells, yet its over expression in β-cells may cause glucose intolerance. In this study, we isolated, characterized Ad-MSCs from rat epididymal fat pads, differentiated these MSCs into insulin producing cells (IPCs) and studied the role of FOXO-1 in such differentiation.

MATERIALS AND METHODS

We examined the expression of FOXO-1 and its nuclear cytoplasmic localization in the generated IPCs. Afterwards we knocked down FOXO-1 using siRNA targeting FOXO-1 (siFOXO-1). The differentiated siFOXO-1 IPCs were compared to non-targeting siRNA (siNT) IPCs regarding expression of β-cell markers by qRT-PCR and western blotting, dithizone (DTZ) staining and glucose stimulated insulin secretion (GSIS).

KEY FINDINGS

Isolated Ad-MSCs exhibited all characteristics of MSCs and can generate IPCs. FOXO-1 was initially elevated during differentiation followed by a decline towards end of differentiation. FOXO-1 was dephosphorylated and localized to the nucleus upon differentiation into IPCs. Knock down of FOXO-1 improved the expression of β-cell markers in final differentiated IPCs, improved DTZ uptake and showed increased insulin secretion upon challenging with increased glucose concentration.

SIGNIFICANCE

These results portray FOXO-1 as a hindering factor of generation of IPCs whose down-regulation can generate more mature IPCs for MSCs therapy of diabetes mellitus.

Human mesenchymal stem cells exhibit altered mitochondrial dynamics and poor survival in high glucose microenvironment

BACKGROUND

Mesenchymal stem cells (MSCs) are a type of stem cells that possess relevant regenerative abilities and can be used to treat many chronic diseases. Diabetes mellitus (DM) is a frequently diagnosed chronic disease characterized by hyperglycemia which initiates many multisystem complications in the long-run. DM patients can benefit from MSCs transplantation to curb down the pathological consequences associated with hyperglycemia persistence and restore the function of damaged tissues. MSCs therapeutic outcomes are found to last for short period of time and ultimately these regenerative cells are eradicated and died in DM disease model.

AIM

To investigate the impact of high glucose or hyperglycemia on the cellular and molecular characteristics of MSCs.

METHODS

Human adipose tissue-derived MSCs (hAD-MSCs) were seeded in low (5.6 mmol/L of glucose) and high glucose (25 mmol/L of glucose) for 7 d. Cytotoxicity, viability, mitochondrial dynamics, and apoptosis were deplored using specific kits. Western blotting was performed to measure the protein expression of phosphatidylinositol 3-kinase (PI3K), TSC1, and mammalian target of rapamycin (mTOR) in these cells.

RESULTS

hAD-MSCs cultured in high glucose for 7 d demonstrated marked decrease in their viability, as shown by a significant increase in lactate dehydrogenase (P < 0.01) and a significant decrease in Trypan blue (P < 0.05) in these cells compared to low glucose control. Mitochondrial membrane potential, indicated by tetramethylrhodamine ethyl ester (TMRE) fluorescence intensity, and nicotinamide adenine dinucleotide (NAD+)/NADH ratio were significantly dropped (P < 0.05 for TMRE and P < 0.01 for NAD+/NADH) in high glucose exposed hAD-MSCs, indicating disturbed mitochondrial function. PI3K protein expression significantly decreased in high glucose culture MSCs (P < 0.05 compared to low glucose) and it was coupled with significant upregulation in TSC1 (P < 0.05) and downregulation in mTOR protein expression (P < 0.05). Mitochondrial complexes I, IV, and V were downregulated profoundly in high glucose (P < 0.05 compared to low glucose). Apoptosis was induced as a result of mitochondrial impairment and explained the poor survival of MSCs in high glucose.

CONCLUSION

High glucose impaired the mitochondrial dynamics and regulatory proteins in hAD-MSCs ensuing their poor survival and high apoptosis rate in hyperglycemic microenvironment.

Impact of type 2 diabetes mellitus on the immunoregulatory characteristics of adipose tissue-derived mesenchymal stem cells

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder associated with several complications. Adipose tissue-derived mesenchymal stem cells (AT-MSCs) represent an emerging type of MSCs with high plasticity and immunoregulatory capabilities and are useful for treating inflammation-related disorders such as T2DM. However, the pathogenic microenvironment of T2DM may affect their therapeutic potential. We aimed to examine the impact of the diabetic milieu on the immunomodulatory/anti-inflammatory potential of AT-MSCs.

METHODS

We assessed the proliferation potential, cell surface expression of MSC-characteristic markers and immunomodulatory markers, along with the gene expression and protein secretion of pro-inflammatory and anti-inflammatory cytokines and adipokines in AT-MSCs derived from T2DM patients (dAT-MSCs) vs. those derived from non-diabetic volunteers (ndAT-MSCs). Furthermore, we evaluated the IFN-γ priming effect on both groups.

RESULTS

Our data revealed comparable proliferative activities in both groups. Flow cytometric analysis results showed a lower expression of CD200 and CD276 on dAT-MSCs vs. ndAT-MSCs. qPCR demonstrated upregulation of IL-1β associated with a downregulation of IL-1RN in dAT-MSCs vs. ndAT-MSCs. IFN-γ priming induced an elevation in CD274 expression associated with IDO1 and ILRN overexpression and IL-1β downregulation in both groups. ELISA analysis uncovered elevated levels of secreted IL-1β, TNF, and visfatin/NAMPT in dAT-MSCs, whereas IL-1RA and IDO levels were reduced. ELISA results were also evident in the secretome of dAT-MSCs upon IFN-γ priming.

CONCLUSIONS

This study suggests that the T2DM milieu alters the immunomodulatory characteristics of AT-MSCs with a shift towards a proinflammatory phenotype which may restrain their autologous therapeutic use. Furthermore, our findings indicate that IFN-γ priming could be a useful strategy for enhancing dAT-MSC anti-inflammatory potential.

Comparison of insulin secretion by transduced adipose-derived and endometrial-derived stem cells in 2D and 3D cultures on fibrin scaffold

Type 1 diabetes is a metabolic disorder caused by the loss or dysfunction of β-cells in the pancreas. Organ shortage is a critical concern of diabetic patients in need of beta islet transplantation. Tissue engineered islets are promising alternatives to traditional organ transplantation. Recent progress in stem cell biology and gene cloning techniques has raised hopes for the generation of insulin producing cells (IPCs) without the need of immunosuppression. The purpose of this study was to produce IPCs using human adipose-derived stem cells (hADSCs) and human endometrial-derived stem cells (hEnSCs) and also to compare the level of insulin secretion by these cells in 2D and 3D culture systems on fibrin scaffolding. Stem cells differentiation was carried out through transduction with an insulin over expression lentiviral vector. Real-time PCR and immunocytochemistry confirmed the successful transduction of both cell types. Both cell types showed comparable insulin secretion by ELISA.3D culture resulted in higher amounts of insulin secretion of the two cell types versus 2D as control. This study showed that insulin gene delivery to the stem cells could be an efficient method for producing IPCs and fibrin encapsulation enhances the functionality of these cells.

Diabetes-induced glucolipotoxicity impairs wound healing ability of adipose-derived stem cells-through the miR-1248/CITED2/HIF-1α pathway

Despite being an attractive cell type for mesenchymal stem cell (MSC) transplantation therapy for wound healing, human adipose-derived stem cells (hADSCs) from diabetes mellitus (DM) patients result in remarkable retention of stem cell activity due to diabetes-induced glucolipotoxicity. We explored the effect of diabetes and medium containing AGEs on the cell activity, phenotype, multipotency, angiogenic potential, and the therapeutic effect of hADSCs. Then, miRNA-1248 was selected by miRNA microarray analysis to further study the core molecular pathways that regulate the wound healing ability of hADSCs. hADSCs isolated from DM patients or cultured in medium containing AGEs in vitro exhibited decreased effectiveness in stem cell therapy. The expression of miRNA-1248 was decreased in the hADSCs of DM patients and hence failed to positively regulate stem cell activity, differentiation functions, and angiogenesis promotion effect. This concomitantly increased the expression of CITED2, an inhibitor of HIF-1α, thus influencing growth factors that promote angiogenesis, cellular proliferation, and wound healing. Overall, our data demonstrated that the glucolipotoxicity-impaired wound healing ability of hADSCs might occur through the miR-1248/CITED2/HIF-1α pathway. MiRNA-1248 may have potential to be used as a novel therapeutic target for wound healing in DM patients or restoring the wound healing ability of diabetic hADSCs.

Antidiabetic Effects of Bisamide Derivative of Dicarboxylic Acid in Metabolic Disorders

In clinical practice, the metabolic syndrome can lead to multiple complications, including diabetes. It remains unclear which component of the metabolic syndrome (obesity, inflammation, hyperglycemia, or insulin resistance) has the strongest inhibitory effect on stem cells involved in beta cell regeneration. This makes it challenging to develop effective treatment options for complications such as diabetes. In our study, experiments were performed on male C57BL/6 mice where metabolic disorders have been introduced experimentally by a combination of streptozotocin-treatment and a high-fat diet. We evaluated the biological effects of Bisamide Derivative of Dicarboxylic Acid (BDDA) and its impact on pancreatic stem cells in vivo. To assess the impact of BDDA, we applied a combination of histological and biochemical methods along with a cytometric analysis of stem cell and progenitor cell markers. We show that in mice with metabolic disorders, BDDA has a positive effect on lipid and glucose metabolism. The pancreatic restoration was associated with a decrease of the inhibitory effects of inflammation and obesity factors on pancreatic stem cells. Our data shows that BDDA increases the number of pancreatic stem cells. Thus, BDDA could be used as a new compound for treating complication of the metabolic syndrome such as 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.

Endothelial Progenitor Cells as Pathogenetic and Diagnostic Factors, and Potential Targets for GLP-1 in Combination with Metabolic Syndrome and Chronic Obstructive Pulmonary Disease

In clinical practice, there are patients with a combination of metabolic syndrome (MS) and chronic obstructive pulmonary disease (COPD). The pathological mechanisms linking MS and COPD are largely unknown. It remains unclear whether the effect of MS (possible obesity) has a major impact on the progression of COPD. This complicates the development of effective approaches for the treatment of patients with a diagnosis of MS and COPD. Experiments were performed on female C57BL/6 mice. Introduction of monosodium glutamate and extract of cigarette smoke was modeled to simulate the combined pathology of lipid disorders and emphysema. Biological effects of glucagon-like peptide 1 (GLP-1) and GLP-1 on endothelial progenitor cells (EPC) in vitro and in vivo were evaluated. Histological, immunohistochemical methods, biochemical methods, cytometric analysis of markers identifying EPC were used in the study. The CD31⁺ endothelial cells in vitro evaluation was produced by Flow Cytometry and Image Processing of each well with a Cytation™ 3. GLP-1 reduces the area of emphysema and increases the number of CD31⁺ endothelial cells in the lungs of mice in conditions of dyslipidemia and damage to alveolar tissue of cigarette smoke extract. The regenerative effects of GLP-1 are caused by a decrease in inflammation, a positive effect on lipid metabolism and glucose metabolism. EPC are proposed as pathogenetic and diagnostic markers of endothelial disorders in combination of MS with COPD. Based on GLP-1, it is proposed to create a drug to stimulate the regeneration of endothelium damaged in MS and COPD.

Cell Based Therapy for Type 1 Diabetes: Should We Take Hyperglycemia Into Account?

Diabetes mellitus is characterized by long standing hyperglycemia leading to numerous life-threatening complications. For type 1 diabetes mellitus, resulting from selective destruction of insulin producing cells by exaggerated immune reaction, the only effective therapy remains exogenous insulin administration. Despite accurate compliance to treatment of certain patients, transient episodes of hyperglycemia cannot be completely eliminated by this symptomatic treatment. Novel immunotherapeutic approaches based on tolerogenic dendritic cells, T regulatory cells and mesenchymal stem cells (MSCs) have been tested in clinical trials, endeavoring to directly modulate the autoimmune destruction process in pancreas. However, hyperglycemia itself affects the immune system and the final efficacy of cell-based immunotherapies could be affected by the different glycemic control of enrolled patients. The present review explores the impact of hyperglycemia on immune cells while providing greater insight into the molecular mechanisms of high glucose action and subsequent metabolic reprogramming of different immune cells. Furthermore, over-production of mitochondrial reactive oxygen species, formation of advanced glycation end products as a consequence of hyperglycemia and their downstream signalization in immune cells are also discussed. Since hyperglycemia in patients with type 1 diabetes mellitus might have an impact on immune-interventional treatment, the maintenance of a tight glucose control seems to be beneficial in patients considered for cell-based therapy.

Cdc42 Promotes ADSC-Derived IPC Induction, Proliferation, And Insulin Secretion Via Wnt/β-Catenin Signaling

PURPOSE

Type 1 diabetes mellitus (T1DM) is characterized by irreversible islet β cell destruction. Accumulative evidence indicated that Cdc42 and Wnt/β-catenin signaling both play a critical role in the pathogenesis and development of T1DM. Further, bio-molecular mechanisms in adipose-derived mesenchymal stem cells (ADSCs)-derived insulin-producing cells (IPCs) remain largely unknown. Our aim was to investigate the underlying mechanism of Cdc42/Wnt/β-catenin pathway in ADSC-derived IPCs, which may provide new insights into the therapeutic strategy for T1DM patients.

METHODS

ADSC induction was accomplished with DMSO under high-glucose condition. ML141 (Cdc42 inhibitor) and Wnt-3a (Wnt signaling activator) were administered to ADSCs from day 2 until the induction finished. Morphological changes were determined by an inverted microscope. Dithizone staining was employed to evaluate the induction of ADSC-derived IPCs. qPCR and Western blotting were employed to measure the mRNA and protein expression level of islet cell development-related genes and Wnt signaling-related genes. The proliferation ability of ADSC-derived IPCs was also detected with a cell counting kit (CCK) assay. The expression and secretion of Insulin were detected with immunofluorescence test and enzyme-linked immunosorbent assay (ELISA) respectively.

RESULTS

During induction, morphological characters of ADSCs changed into spindle and round shape, and formed islet-line cell clusters, with brown dithizone-stained cytoplasm. Expression levels of islet cell development-related genes were up-regulated in ADSC-derived IPCs. Wnt-3a promoted Wnt signaling markers and islet cell development-related gene expression at mRNA and protein levels, while ML141 played a negative effect. Wnt-3a promoted ADSC-derived IPC proliferation and glucose-stimulated insulin secretion (GSIS), while ML141 played a negative effect.

CONCLUSION

Our research demonstrated that DMSO and high-glucose condition can induce ADSCs into IPCs, and Wnt signaling promotes the induction. Cdc42 may promote IPC induction, IPC proliferation and insulin secretion via Wnt/β-catenin pathway, meaning that Cdc42 may be regarded as a potential target in the treatment of T1DM.

Protection of mouse pancreatic islet function by co‑culture with hypoxia pre‑treated mesenchymal stromal cells

Ectogenic pancreatic islet transplantation has long been discussed as having the potential to reverse diabetes. The aim of the present study was to evaluate the therapeutic efficacy of co‑transplantation with hypoxia pretreated mesenchymal stem cells (MSCs) and islets in a diabetic mouse model. MSCs were isolated from femoral and tibial bone marrow aspirates from female BALB/c donor mice. MSC proliferation rates and the expression levels of vascular endothelial growth factor A (VEGFA), interleukin (IL)‑6, monocyte chemoattractant protein (MCP)‑1 and matrix metalloproteinase (MMP)‑9 were measured in hypoxic conditions. Subsequently, a streptozotocin‑induced diabetic model was established in BALB/c mice. Glucose tolerance and diabetes reversal rate following co‑transplantation of hypoxia pre‑cultured MSCs and islets were demonstrated at different conditions during transplantation. The present study results demonstrated that MSCs increased their proliferation rate and the secretion of growth‑related cytokines, including VEGFA, IL‑6, MCP‑1 and MMP‑9 in a hypoxic environment. In the diabetes animal model, fewer islets (~250) were required to reverse the impaired glucose tolerance condition in Islets + Hypoxia cultured MSCs transplant group compared with the Islets‑only group (~400 islets) and the Islets + Normal cultured MSCs group (~300 islets). Hypoxia‑cultured MSC co‑transplantation accelerated glycemic utilization following glucose intake. In subjects with hyperglycemia control for islet only transplantation group, MSCs pre‑cultured in hypoxic condition prior to co‑transplantation may potentially improve islet tissue regeneration.

Phenolic compounds apigenin, hesperidin and kaempferol reduce in vitro lipid accumulation in human adipocytes

BACKGROUND

Adipocytes derived from human mesenchymal stem cells (MSCs) are widely used to investigate adipogenesis. Taking into account both the novelty of these MSCs and the scarcity of studies focused on the effects of phenolic compounds, the aim of the present study was to analyze the effect of apigenin, hesperidin and kaempferol on pre-adipocyte and mature adipocytes derived from this type of cells. In addition, the expression of genes involved in TG accumulation was also measured.

METHODS

Pre-adipocytes were cultured from day 0 to day 8 and mature adipocytes for 48 h with the polyphenols at doses of 1, 10 and 25 µM.

RESULTS

Apigenin did not show an anti-adipogenic action. Pre-adipocytes treated with hesperidin and kaempferol showed reduced TG content at the three experimental doses. Apigenin did not modify the expression of the main adipogenic genes (c/ebpβ, c/ebpα, pparγ and srebp1c), hesperidin inhibited genes involved in the three phases of adipogenesis (c/ebpβ, srebp1c and perilipin) and kaempferol reduced c/ebpβ. In mature adipocytes, the three polyphenols reduced TG accumulation at the dose of 25 µM, but not at lower doses. All compounds increased mRNA levels of atgl. Apigenin and hesperidin decreased fasn expression. The present study shows the anti-adipogenic effect and delipidating effects of apigenin, hesperidin and kaempferol in human adipocytes derived from hMSCs. While hesperidin blocks all the stages of adipogenesis, kaempferol only inhibits the early stage. Regarding mature adipocytes, the three compounds reduce TG accumulation by activating, at least in part, lipolysis, and in the case of hesperidin and apigenin, also by reducing lipogenesis.

CONCLUSIONS

The present study shows for the first time the anti-adipogenic effect and delipidating effect of apigenin, hesperidin and kaempferol in human adipocytes derived from MSCs for the first time.

Lipopolysaccharide treatment induces genome-wide pre-mRNA splicing pattern changes in mouse bone marrow stromal stem cells

BACKGROUND

Lipopolysaccharide (LPS) is a gram-negative bacterial antigen that triggers a series of cellular responses. LPS pre-conditioning was previously shown to improve the therapeutic efficacy of bone marrow stromal cells/bone-marrow derived mesenchymal stem cells (BMSCs) for repairing ischemic, injured tissue.

RESULTS

In this study, we systematically evaluated the effects of LPS treatment on genome-wide splicing pattern changes in mouse BMSCs by comparing transcriptome sequencing data from control vs. LPS-treated samples, revealing 197 exons whose BMSC splicing patterns were altered by LPS. Functional analysis of these alternatively spliced genes demonstrated significant enrichment of phosphoproteins, zinc finger proteins, and proteins undergoing acetylation. Additional bioinformatics analysis strongly suggest that LPS-induced alternatively spliced exons could have major effects on protein functions by disrupting key protein functional domains, protein-protein interactions, and post-translational modifications.

CONCLUSION

Although it is still to be determined whether such proteome modifications improve BMSC therapeutic efficacy, our comprehensive splicing characterizations provide greater understanding of the intracellular mechanisms that underlie the therapeutic potential of BMSCs.

Therapeutic potential of human embryonic stem cells in type 2 diabetes mellitus

AIM: To evaluate the safety and efficacy of human embryonic stem cells (hESCs) for the management of type 2 diabetes mellitus (T2DM).

METHODS: Patients with a previous history of diabetes and its associated complications were enrolled and injected with hESC lines as per the defined protocol. The patients were assessed using Nutech functional score (NFS), a numeric scoring scale to evaluate the patients for 11 diagnostic parameters. Patients were evaluated at baseline and at the end of treatment period 1 (T1). All the parameters were graded on the NFS scale from 1 to 5. Highest possible grade (HPG) of 5 was considered as the grade of best improvement.

RESULTS: Overall, 94.8% of the patients showed improvement by at least one grade of NFS at the end of T1. For all the 11 parameters evaluated, 54% of patients achieved HPG after treatment. The four essential parameters (improvement in glycated hemoglobin (HbA1c) and insulin level, and fall in number of other oral hypoglycemic drugs with and without insulin) are presented in detail. For HbA1c, 72.6% of patients at the end of T1 met the World Health Organization cut off value, i.e., 6.5% of HbA1c. For insulin level, 65.9% of patients at the end of T1 were able to achieve HPG. After treatment, the improvement was seen in 16.3% of patients who required no more than two medications along with insulin. Similarly, 21.5% of patients were improved as their dosage regimen for using oral drugs was reduced to 1-2 from 5.

CONCLUSION: hESC therapy is beneficial in patients with diabetes and helps in reducing their dependence on insulin and other medicines.

Mesenchymal Stem Cells and Metabolic Syndrome: Current Understanding and Potential Clinical Implications

Metabolic syndrome is an obesity-based, complicated clinical condition that has become a global epidemic problem with a high associated risk for cardiovascular disease and mortality. Dyslipidemia, hypertension, and diabetes or glucose dysmetabolism are the major factors constituting metabolic syndrome, and these factors are interrelated and share underlying pathophysiological mechanisms. Severe obesity predisposes individuals to metabolic syndrome, and recent data suggest that mesenchymal stem cells (MSCs) contribute significantly to adipocyte generation by increasing the number of adipocytes. Accordingly, an increasing number of studies have examined the potential roles of MSCs in managing obesity and metabolic syndrome. However, despite the growing bank of experimental and clinical data, the efficacy and the safety of MSCs in the clinical setting are still to be optimized. It is thus hoped that ongoing and future studies can elucidate the roles of MSCs in metabolic syndrome and lead to MSC-based therapeutic options for affected patients. This review discusses current understanding of the relationship between MSCs and metabolic syndrome and its potential implications for patient management.

Clinical Efficacy of Stem Cell Therapy for Diabetes Mellitus: A Meta-Analysis

BACKGROUND

Stem cell therapy is a promising therapeutic modality for advanced diabetes mellitus (DM). This study presents a meta-analysis of relevant clinical trials to determine the efficacy of stem cell therapy in DM. We aim to critically evaluate and synthesize clinical evidence on the safety and efficiency of different types of stem cell therapy for both T1DM and T2DM.

METHODS AND FINDINGS

We pooled participant-level data from twenty-two eligible clinical trials that satisfied our inclusion criteria, with a total of 524 patients. There were significant differences in the outcome based on the type and source of the infused cells. Out of all T1DM patients who received CD34+ hematopoietic stem cell (HSC) infusion, 58.9% became insulin independent for a mean period of 16 months, whereas the results were uniformly negative in patients who received umbilical cord blood (UCB). Infusion of umbilical cord mesenchymal stem cells (UC-MSCs) provided significantly beneficial outcome in T1DM, when compared to bone-marrow mesenchymal stem cells (BM-MSCs) (P<0.0001 and P = 0.1557). Administration of stem cell therapy early after DM diagnosis was more effective than intervention at later stages (relative risk = 2.0, P = 0.0008). Adverse effects were observed in only 21.72% of both T1DM and T2DM stem cell recipients with no reported mortality. Out of all poor responders, 79.5% were diagnosed with diabetic ketoacidosis.

CONCLUSIONS

Stem cell transplantation can represent a safe and effective treatment for selected patients with DM. In this cohort of trials, the best therapeutic outcome was achieved with CD34+ HSC therapy for T1DM, while the poorest outcome was observed with HUCB for T1DM. Diabetic ketoacidosis impedes therapeutic efficacy.

Theoretical and Practical Issues That Are Relevant When Scaling Up hMSC Microcarrier Production Processes

The potential of human mesenchymal stem cells (hMSCs) for allogeneic cell therapies has created a large amount of interest. However, this presupposes the availability of efficient scale-up procedures. Promising results have been reported for stirred bioreactors that operate with microcarriers. Recent publications focusing on microcarrier-based stirred bioreactors have demonstrated the successful use of Computational Fluid Dynamics (CFD) and suspension criteria (N S1u , N S1) for rapidly scaling up hMSC expansions from mL- to pilot scale. Nevertheless, one obstacle may be the formation of large microcarrier-cell-aggregates, which may result in mass transfer limitations and inhomogeneous distributions of stem cells in the culture broth. The dependence of microcarrier-cell-aggregate formation on impeller speed and shear stress levels was investigated for human adipose derived stromal/stem cells (hASCs) at the spinner scale by recording the Sauter mean diameter (d 32) versus time. Cultivation at the suspension criteria provided d 32 values between 0.2 and 0.7 mm, the highest cell densities (1.25 × 10(6) cells mL(-1) hASCs), and the highest expansion factors (117.0 ± 4.7 on day 7), while maintaining the expression of specific surface markers. Furthermore, suitability of the suspension criterion N S1u was investigated for scaling up microcarrier-based processes in wave-mixed bioreactors for the first time.

CdSe/ZnS Quantum Dots-Labeled Mesenchymal Stem Cells for Targeted Fluorescence Imaging of Pancreas Tissues and Therapy of Type 1 Diabetic Rats

Mesenchymal stem cells (MSCs) have been used for therapy of type 1 diabetes mellitus. However, the in vivo distribution and therapeutic effects of transplanted MSCs are not clarified well. Herein, we reported that CdSe/ZnS quantum dots-labeled MSCs were prepared for targeted fluorescence imaging and therapy of pancreas tissues in rat models with type 1 diabetes. CdSe/ZnS quantum dots were synthesized, their biocompatibility was evaluated, and then, the appropriate concentration of quantum dots was selected to label MSCs. CdSe/ZnS quantum dots-labeled MSCs were injected into mouse models with type 1 diabetes via tail vessel and then were observed by using the Bruker In-Vivo F PRO system, and the blood glucose levels were monitored for 8 weeks. Results showed that prepared CdSe/ZnS quantum dots owned good biocompatibility. Significant differences existed in distribution of quantum dots-labeled MSCs between normal control rats and diabetic rats (p < 0.05). The ratios of the fluorescence intensity (RFI) analysis showed an accumulation rate of MSCs in the pancreas of rats in the diabetes group which was about 32 %, while that in the normal control group rats was about 18 %. The blood glucose levels were also monitored for 8 weeks after quantum dots-labeled MSC injection. Statistical differences existed between the blood glucose levels of the diabetic rat control group and MSC-injected diabetic rat group (p < 0.01), and the MSC-injected diabetic rat group displayed lower blood glucose levels. In conclusion, CdSe/ZnS-labeled MSCs can target in vivo pancreas tissues in diabetic rats, and significantly reduce the blood glucose levels in diabetic rats, and own potential application in therapy of diabetic patients in the near future.

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.

Effect of 17β-estradiol on mediators involved in mesenchymal stromal cell trafficking in cell therapy of diabetes

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) have shown great promise for cell therapy of a wide range of diseases such as diabetes. However, insufficient viability of transplanted cells reaching to damaged tissues has limited their potential therapeutic effects. Expression of estrogen receptors on stem cells may suggest a role for 17β-estradiol (E2) in regulating some functions in these cells. There is evidence that E2 enhances homing of stem cells. Induction of hypoxia-inducible factor-1α (HIF-1α) by E2 and the profound effect of HIF-1α on migration of cells have previously been demonstrated. We investigated the effect of E2 on major mediators involved in trafficking and subsequent homing of MSCs both in vitro and in vivo in diabetic rats.

METHODS

E2 has been selected to improve the poor migration capacity of MSCs toward sites of injury. MSCs were incubated with different concentrations of E2 for varying periods of time to investigate whether estradiol treatment could be effective to enhance the efficiency of MSC transplantation.

RESULTS

E2 significantly enhanced the viability of the cells that were blocked by ICI 182,780 (estrogen receptor antagonist). E2 also increased HIF-1α, CXC chemokine receptor 4 and C-C chemokine receptor 2 protein and messenger RNA levels measured by Western blot and reverse transcription-polymerase chain reaction. The enzymatic activity of matrix metalloproteinase 2 and metalloproteinase 9 was elevated in E2-treated cells through the use of gelatin zymography. Finally, the improved migration capacity of E2-treated MSCs was evaluated with the use of a Boyden chamber and in vivo migration assays.

CONCLUSIONS

Our data support that conditioning of MSCs with E2 promotes migration of cells in cultured MSCs in vitro and in a diabetic rat model in vivo through regulation of major mediators of cell trafficking.

A modified method of insulin producing cells' generation from bone marrow-derived mesenchymal stem cells

Type 1 diabetes mellitus is a result of autoimmune destruction of pancreatic insulin producing β-cells and so far it can be cured only by insulin injection, by pancreas transplantation, or by pancreatic islet cells' transplantation. The methods are, however, imperfect and have a lot of disadvantages. Therefore new solutions are needed. The best one would be the use of differentiated mesenchymal stem cells (MSCs). In the present study, we investigated the potential of the bone marrow-derived MSCs line for in vitro differentiation into insulin producing cells (IPSs). We applied an 18-day protocol to differentiate MSCs. Differentiating cells formed cell clusters some of which resembled pancreatic islet-like cells. Using dithizone we confirmed the presence of insulin in the cells. What is more, the expression of proinsulin C-peptide in differentiated IPCs was analyzed by flow cytometry. For the first time, we investigated the influence of growth factors' concentration on IPCs differentiation efficiency. We have found that an increase in the concentration of growth factors up to 60 ng/mL of β-FGF/EGF and 30 ng/mL of activin A/β-cellulin increases the percentage of IPCs. Further increase of growth factors does not show any increase of the percentage of differentiated cells. Our findings suggest that the presented protocol can be adapted for differentiation of insulin producing cells from stem cells.

Mesenchymal stem cells: Potential role in corneal wound repair and transplantation

Corneal diseases are a major cause of blindness in the world. Although great progress has been achieved in the treatment of corneal diseases, wound healing after severe corneal damage and immunosuppressive therapy after corneal transplantation remain problematic. Mesenchymal stem cells (MSCs) derived from bone marrow or other adult tissues can differentiate into various types of mesenchymal lineages, such as osteocytes, adipocytes, and chondrocytes, both in vivo and in vitro. These cells can further differentiate into specific cell types under specific conditions. MSCs migrate to injury sites and promote wound healing by secreting anti-inflammatory and growth factors. In addition, MSCs interact with innate and acquired immune cells and modulate the immune response through their powerful paracrine function. Over the last decade, MSCs have drawn considerable attention because of their beneficial properties and promising therapeutic prospective. Furthermore, MSCs have been applied to various studies related to wound healing, autoimmune diseases, and organ transplantation. This review discusses the potential functions of MSCs in protecting corneal tissue and their possible mechanisms in corneal wound healing and corneal transplantation.

Comparison of human mesenchymal stem cells derived from dental pulp, bone marrow, adipose tissue, and umbilical cord tissue by gene expression

AIMS

Our aims were to characterize human mesenchymal stem cells isolated from various tissues by pluripotent stem cells gene expression profile.

METHODS

Four strains of dental pulp stem cells (DP-MSCs) were isolated from dental pulp tissue fragments adhered to plastic tissue culture dishes. Mesenchymal stem cells derived from umbilical cord tissue (UBC-MSCs) were isolated with the same technique. Bone marrow derived mesenchymal stem cells (BM-MSCs) were isolated from nucleated cells of bone marrow obtained by density gradient centrifugation. Human mesenchymal stem cells from adipose tissue (AT-MSCs) were isolated by collagenase digestion. All kinds of MSCs used in this study were cultivated in low glucose DMEM containing 5% or human platelet extract. All stem cell manipulation was performed in GMP conditions. Expression of 15 pluripotent stem cells genes on the level of proteins was measured by Proteome Profiler Human Pluripotent Stem Cell Array. Induction of MSCs to in vitro differentiation to adipocytes, osteoblasts, chondroblasts was achieved by cultivation of cells in appropriate differentiation medium.

RESULTS

All MSCs tested were phenotypically similar and of fibroblastoid morphology. DP-MSCs and UBC-MSCs were more proliferative than bone marrow BM-MSCs and AT-MSCs. Protein expression of 15 genes typical for pluripotent stem cells distinguished them into two groups. While the gene expression profiles of BM-MSC, AT-MSCs and UBC-MSCs were similar, DP-MSCS differed in relative gene expression on the level of their products in several genes.

CONCLUSIONS

Dental pulp mesenchymal stem cells cultivated in vitro under the same conditions as MSCs from bone marrow, adipose tissue and umbilical cord tissue can be distinguished by pluripotent stem cell gene expression profile.