Effect of high glucose on extensive culturing of mesenchymal stem cells derived from subcutaneous fat, omentum fat and bone marrow

The impact of diabetic glucose concentration on viability and cardiac differentiation of mesenchymal stem cells

INTRODUCTION

Hyperglycemia may be a stumbling block for delivery of regenerative benefits of mesenchymal stem cells (MSCs) to diabetic patients with cardiovascular diseases. Our study aims to assess the viability and cardiac differentiation potential of MSCs after being exposed to diabetic glucose concentration.

METHODS

MSCs were extracted from rat bone marrow. Cells were characterized based on morphology, differentiation potential, and expression of mesenchymal specific markers. MTT assay was done to evaluate the viability of MSCs after treatment with different glucose concentrations. Case group was MSCs treated with diabetic concentration of glucose versus cells treated with PBS as the control group. Growth curve and population doubling time were calculated in both groups. Expression of GATA4 and troponin, as the early and late markers during cardiac differentiation, were measured following 5-azacytidine exposure.

RESULTS

Proliferated cells at passage three had fibroblastic-shape, was able to differentiate into adipocytes or osteocytes, and expressed CD73 and CD90. MSCs viability was gradually decreased by increasing glucose concentration. Irrespective of nicotine concentration, three-day exposure imposed more severe detrimental effects on viability compared with one-day treatment. Proliferation rate of the MSCs was lower in the case group, and they need more time for population doubling. Expression of both cardiac markers were downregulated in the case group at day three. However, their expression became higher at day seven.

CONCLUSION

Diabetic glucose concentration inhibits normal proliferation and cardiac differentiation of MSCs. This effect should be considered in stem cell therapy of cardiovascular patients who are concurrently affected by hyperglycemia, a common comorbidity in such individuals. Why carry out this study? What was learned from the study?

FINDINGS

Effects of Different Basal Cell Culture Media upon the Osteogenic Response of hMSCs Evaluated by 99mTc-HDP Labeling

The osteogenic differentiation of mesenchymal stem cells is now a standard procedure in modern bone tissue engineering. As this is a promising field for future clinical applications, many cell culture media exist to promote osteogenic differentiation. Prior to differentiation, cells must be expanded to obtain sufficient numbers for experiments. Little evidence is available regarding the optimal media combination for expansion and differentiation to maximize the osteogenic response. Therefore, human BM-MSCs (n = 6) were expanded in parallel in DMEM (Dulbecco’s Modified Eagle Medium) LG (Low Glucose) and α-MEM (Minimum Essential Media alpha-modification), followed by simultaneous monolayer differentiation toward the osteogenic lineage in: 1. DMEM LG (Low Glucose), 2. DMEM HG (High Glucose), 3. α-MEM, 4. “Bernese medium”, and 5. “Verfaillie medium”, with a corresponding negative control (total 20 groups). As a marker for osteogenic differentiation, hydroxyapatite was accessed using radioactive ^99mTc-HDP labeling and quantitative alizarin red staining. The results indicate that all media except “Bernese medium” are suitable for osteogenic differentiation, while there was evidence that DMEM LG is partly superior when used for expansion and differentiation of BM-hMSCs. Using “Verfaillie medium” after DMEM LG expansion led to the highest grade of osteogenic differentiation. Nevertheless, the difference was not significant. Therefore, we recommend using DMEM LG for robust osteogenic differentiation, as it is highly suitable for that purpose, economical compared to other media, and requires little preparation time.

The Effect of Diabetes Mellitus on IGF Axis and Stem Cell Mediated Regeneration of the Periodontium

Periodontitis and diabetes mellitus (DM) are two of the most common and challenging health problems worldwide and they affect each other mutually and adversely. Current periodontal therapies have unpredictable outcome in diabetic patients. Periodontal tissue engineering is a challenging but promising approach that aims at restoring periodontal tissues using one or all of the following: stem cells, signalling molecules and scaffolds. Mesenchymal stem cells (MSCs) and insulin-like growth factor (IGF) represent ideal examples of stem cells and signalling molecules. This review outlines the most recent updates in characterizing MSCs isolated from diabetics to fully understand why diabetics are more prone to periodontitis that theoretically reflect the impaired regenerative capabilities of their native stem cells. This characterisation is of utmost importance to enhance autologous stem cells based tissue regeneration in diabetic patients using both MSCs and members of IGF axis.

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.

Optimization of the nutritional environment for differentiation of human-induced pluripotent stem cells using design of experiments-A proof of concept

The utilization of human-induced pluripotent stem cells (hiPSCs) in cell therapy has a tremendous potential but faces many practical challenges, including costs associated with cell culture media and growth factors. There is an immediate need to establish an optimized culture platform to direct the differentiation of hiPSCs into germ layers in a defined nutritional microenvironment to generate cost-effective and robust therapeutics. The aim of this study was to identify the optimal nutritional environment by mimicking the in vivo concentrations of three key factors (glucose, pyruvate, and oxygen) during the spontaneous differentiation of hiPSCs derived from cord blood, which greatly differ from the in vitro expansion and differentiation scenarios. Moreover, we hypothesized that the high glucose, pyruvate, and oxygen concentrations found in typical growth media could inhibit the differentiation of certain lineages. A design of experiments was used to investigate the interaction between these three variables during the spontaneous differentiation of hiPSCs. We found that lower oxygen and glucose concentrations enhance the expression of mesodermal (Brachyury, KIF1A) and ectodermal (Nestin, β-Tubulin) markers. Our findings present a novel approach for efficient directed differentiation of hiPSCs through the manipulation of media components while simultaneously avoiding the usage of growth factors thus reducing costs.

Targeting Stem Cells in Chronic Inflammatory Diseases

Mesenchymal stem cell (MSC) dysfunction is a serious complication in ageing and age-related inflammatory diseases such as type 2 diabetes mellitus. Inflammation and oxidative stress-induced cellular senescence alter the immunomodulatory ability of MSCs and hamper their pro-regenerative function, which in turn leads to an increase in disease severity, maladaptive tissue damage and the development of comorbidities. Targeting stem/progenitor cells to restore their function and/or protect them against impairment could thus improve healing outcomes and significantly enhance the quality of life for diabetic patients. This review discusses the dysregulation of MSCs' immunomodulatory capacity in the context of diabetes mellitus and focuses on intervention strategies aimed at MSC rejuvenation. Research pertaining to the potential therapeutic use of either pharmacological agents (NFкB antagonists), natural products (phytomedicine) or biological agents (exosomes, probiotics) to improve MSC function is discussed and an overview of the most pertinent methodological considerations given. Based on in vitro studies, numerous anti-inflammatory agents, antioxidants and biological agents show tremendous potential to revitalise MSCs. An integrated systems approach and a thorough understanding of complete disease pathology are however required to identify feasible candidates for in vivo targeting of MSCs.

Inhibitor of RAGE and glucose‑induced inflammation in bone marrow mesenchymal stem cells: Effect and mechanism of action

The occurrence and development of hyperglycemia‑induced inflammation is associated with increased expression of receptor for advanced glycation end products (RAGE) and inflammatory factors, including IL‑1β, TNF‑α and IL‑6. Previous studies have reported that the nucleotide‑binding oligomerization domain‑like receptor protein 3 (NLRP3) inflammasome interacts with thioredoxin‑interacting protein (TXNIP) and serves a crucial role in inflammation. FPS‑ZM1 has been identified as target inhibitor of RAGE and has been shown to exert an anti‑inflammatory effect in vitro. However, the underlying mechanism by which FPS‑ZM1 impacts high glucose (HG)‑induced inflammation in bone marrow mesenchymal stem cells (BMSCs) remains unclear. The present study explored the regulatory effect of FPS‑ZM1 on HG‑induced inflammation in BMSCs. Furthermore, the role of the TXNIP/NLRP3 inflammasome signaling pathway in the regulatory effects of FPS‑ZM1 on HG‑induced inflammation was studied. Cell viability was determined using Cell Counting Kit‑8 and western blotting was used to assess the protein expression levels of RAGE. ELISA was used to determine the levels of inflammatory markers. Reverse transcription‑quantitative PCR and western blotting were used to measure the mRNA and protein expression levels of TXNIP, caspase‑1, thioredoxin (TRX), NLRP3 and apoptosis‑related speck‑like protein containing CARD (ASC). The results revealed that in BMSCs, RAGE expression was stimulated by HG, an effect which was reversed by treatment with FPS‑ZM1. In addition, HG activated inflammatory factors, such as TNF‑α, IL‑1β and IL‑6; however, their levels were suppressed when cells were treated with FPS‑ZM1 or the TXNIP/NLRP3 pathway inhibitor, resveratrol (Res). Furthermore, FPS‑ZM1 inhibited the mRNA and protein expression levels of TXNIP, caspase‑1, NLRP3 and ASC, and promoted TRX expression, which was consistent with the effects of Res. These findings indicated that FPS‑ZM1 may attenuate HG‑induced inflammation in BMSCs. Furthermore, the TXNIP/NLRP3 inflammasome signaling pathway mediated the molecular mechanism underlying this effect.

Platelet-rich plasma counteracts detrimental effect of high-glucose concentrations on mesenchymal stem cells from Bichat fat pad

Diabetic patients display increased risk of periodontitis and failure in bone augmentation procedures. Mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP) represent a relevant advantage in tissue repair process and regenerative medicine. We isolated MSCs from Bichat's buccal fat pad (BFP) and measured the effects of glucose and PRP on cell number and osteogenic differentiation potential. Cells were cultured in the presence of 5.5-mM glucose (low glucose [LG]) or 25-mM glucose (high glucose [HG]). BFP-MSC number was significantly lower when cells were cultured in HG compared with those in LG. Following osteogenic differentiation procedures, calcium accumulation, alkaline phosphatase activity, and expression of osteogenic markers were significantly lower in HG compared with LG. Exposure of BFP-MSC to PRP significantly increased cell number and osteogenic differentiation potential, reaching comparable levels in LG and in HG. Thus, high-glucose concentrations impair BFP-MSC growth and osteogenic differentiation. However, these detrimental effects are largely counteracted by PRP.

Mesenchymal stem cells in obesity: insights for translational applications

Obesity is now a major public health problem worldwide. Lifestyle modification to reduce the characteristic excess body adiposity is important in the treatment of obesity, but effective therapeutic intervention is still needed to control what has become an obesity epidemic. Unfortunately, many anti-obesity drugs have been withdrawn from market due to adverse side effects. Bariatric surgery therefore remains the most effective therapy for severe cases, although such surgery is invasive and researchers continue to seek new control strategies for obesity. Mesenchymal stem cells (MSCs) are a major source of adipocyte generation, and studies have been conducted into the potential roles of MSCs in treating obesity. However, despite significant progress in stem cell research and its potential applications for obesity, adipogenesis is a highly complex process and the molecular mechanisms governing MSC adipogenesis remain ill defined. In particular, successful clinical application of MSCs will require extensive identification and characterization of the transcriptional regulators controlling MSC adipogenesis. Since obesity is associated with the incidence of multiple important comorbidities, an in-depth understanding of the relationship between MSC adipogenesis and the comorbidities of obesity is also necessary to evaluate the potential of effective and safe MSC-based therapies for obesity. In addition, brown adipogenesis is an attractive topic from the viewpoint of therapeutic innovation and future research into MSC-based brown adipogenesis could lead to a novel breakthrough. Ongoing stem cell studies and emerging research fields such as epigenetics are expected to elucidate the complicated mechanisms at play in MSC adipogenesis and develop novel MSC-based therapeutic options for obesity. This review discusses the current understanding of MSCs in adipogenesis and their potential clinical applications for obesity.

Angiogenic and Restorative Abilities of Human Mesenchymal Stem Cells Were Reduced Following Treatment With Serum From Diabetes Mellitus Type 2 Patients

This experiment investigated the impact of serum from patients with type 2 diabetes mellitus on the angiogenic behavior of human mesenchymal stem cells in vitro. Changes in the level of Ang-1, Ang-2, cell migration, and trans-differentiation into pericytes and endothelial lineage were monitored after 7 days. The interaction of mesenchymal stem cells with endothelial cells were evaluated using surface plasmon resonance technique. Paracrine restorative effect of diabetic stem cells was tested on pancreatic β cells. Compared to data from FBS and normal serum, diabetic serum reduced the stem cell survival and chemotaxis toward VEGF and SDF-1α (P < 0.05). Diabetic condition were found to decline cell migration rate and the activity of MMP-2 and -9 (P < 0.05). The down-regulation of VEGFR-2 and CXCR-4 was observed with an increase in the level of miR-1-3p and miR-15b-5p at the same time. The paracrine angiogenic potential of diabetic stem cells was disturbed via the changes in the dynamic of Ang-1, Ang-2, and VEGF. Surface plasmon resonance analysis showed that diabetes could induce an aberrant increase in the interaction of stem cells with endothelial cells. After treatment with diabetic serum, the expression of VE-cadherin and NG2 and ability for uptake of Dil-Ac-LDL were reduced (P < 0.01). Conditioned media prepared from diabetic stem cells were unable to decrease fatty acid accumulation in β-cells (P < 0.05). The level of insulin secreted by β-cells was not affected after exposure to supernatant from diabetic or non-diabetic mesenchymal stem cells. Data suggest diabetes could decrease angiogenic and restorative effect of stem cells in vitro. J. Cell. Biochem. 119: 524-535, 2018. © 2017 Wiley Periodicals, Inc.

O-GlcNAcylation: a bridge between glucose and cell differentiation

Glucose is the major energy supply and a critical metabolite for most cells and is especially important when cell is differentiating. High or low concentrations of glucose enhances or inhibits the osteogenic, chondrogenic and adipogenic differentiation of cell via the insulin, transforming growth factor‐β and peroxisome proliferator‐activated receptor γ pathways, among others. New evidence implicates the hexosamine biosynthetic pathway as a mediator of crosstalk between glucose flux, cellular signalling and epigenetic regulation of cell differentiation. Extracellular glucose flux alters intracellular O‐GlcNAcylation levels through the hexosamine biosynthetic pathway. Signalling molecules that are important for cell differentiation, including protein kinase C, extracellular signal‐regulated kinase, Runx2, CCAAT/enhancer‐binding proteins, are modified by O‐GlcNAcylation. Thus, O‐GlcNAcylation markedly alters cell fate during differentiation via the post‐transcriptional modification of proteins. Furthermore, O‐GlcNAcylation and phosphorylation show complex interactions during cell differentiation: they can either non‐competitively occupy different sites on a substrate or competitively occupy a single site or proximal sites. Therefore, the influence of glucose on cell differentiation via O‐GlcNAcylation offers a potential target for controlling tissue homoeostasis and regeneration in ageing and disease. Here, we review recent progress establishing an emerging relationship among glucose concentration, O‐GlcNAcylation levels and cell differentiation.

Genetic modification of human mesenchymal stem cells helps to reduce adiposity and improve glucose tolerance in an obese diabetic mouse model

Introduction

Human mesenchymal stem cells (MSCs) are multipotent cells that can differentiate into fat, muscle, bone and cartilage cells. Exposure of subcutaneous abdominal adipose tissue derived AD-MSCs to high glucose (HG) leads to superoxide accumulation and up-regulation of inflammatory molecules. Our aim was to inquire how HG exposure affects MSCs differentiation and whether the mechanism is reversible.

Methods

We exposed human adipose tissue derived MSCs to HG (25 mM) and compared it to normal glucose (NG, 5.5 mM) exposed cells at 7, 10 and 14 days. We examined mitochondrial superoxide accumulation (Mitosox-Red), cellular oxygen consumption rate (OCR, Seahorse) and gene expression.

Results

HG increased reactive superoxide (ROS) accumulation noted by day 7 both in cytosol and mitochondria. The OCR between the NG and HG exposed groups however did not change until 10 days at which point OCR of HG exposed cells were reduced significantly. We noted that HG exposure upregulated mRNA expression of adipogenic (PPARG, FABP-4, CREBP alpha and beta), inflammatory (IL-6 and TNF alpha) and antioxidant (SOD2 and Catalase) genes. Next, we used AdSOD2 to upregulate SOD2 prior to HG exposure and thereby noted reduction in superoxide generation. SOD2 upregulation helped reduce mRNA over-expression of PPARG, FABP-4, IL-6 and TNFα. In a series of separate experiments, we delivered the eGFP and SOD2 upregulated MSCs (5 days post ex-vivo transduction) and saline intra-peritoneally (IP) to obese diabetic (db/db) mice. We confirmed homing-in of eGFP labeled MSCs, delivered IP, to different inflamed fat pockets, particularly omental fat. Mice receiving SOD2-MSCs showed progressive reduction in body weight and improved glucose tolerance (GTT) at 4 weeks, post MSCs transplantation compared to the GFP-MSC group (control).

Conclusions

High glucose evokes superoxide generation, OCR reduction and adipogenic differentiation. Mitochondrial superoxide dismutase upregulation quenches excess superoxide and reduces adipocyte inflammation. Delivery of superoxide dismutase (SOD2) using MSCs as a gene delivery vehicle reduces inflammation and improves glucose tolerance in vivo. Suppression of superoxide production and adipocyte inflammation using mitochondrial superoxide dismutase may be a novel and safe therapeutic tool to combat hyperglycemia mediated effects.

Adipose-derived mesenchymal stem cells improve glucose homeostasis in high-fat diet-induced obese mice

INTRODUCTION

Effective therapies for obesity and diabetes are still lacking. The aim of this study was to evaluate whether a single intravenous infusion of syngeneic adipose-derived mesenchymal stem cells (ASCs) can reduce obesity, lower insulin resistance, and improve glucose homeostasis in a high-fat diet-induced obese (DIO) mouse model.

METHODS

Seven-week-old C57BL/6 mice were fed a high-fat diet for 20 weeks to generate the DIO mouse model. Mice were given a single intravenous infusion of ex vivo expanded syngeneic ASCs at 2 × 10(6) cells per mouse. DIO or CHOW mice injected with saline were used as controls. Body weights, blood glucose levels, glucose, and insulin tolerance test results were obtained before and 2 and 6 weeks after cell infusion. Triglyceride (TG), high-density lipoprotein (HDL), and insulin levels in serum were measured. Expressions of genes related to insulin resistance, including peroxisome proliferator-activated receptor γ (PPARγ) and insulin receptor (InsR), and inflammation (IL-6, F4/80, and nucleotide-binding oligomerization domain containing 2, or NOD2), were measured in livers at mRNA level by real-time-polymerase chain reaction analysis. Beta-cell mass in pancrheases from CHOW, DIO, and DIO + ASC mice was quantified. GFP(+) ASCs were injected, and the presence of GFP(+) cells in livers and pancreases was determined.

RESULTS

DIO mice that had received ASCs showed reduced body weights, reduced blood glucose levels, and increased glucose tolerance. ASC treatment was found to reduce TG levels and increase serum HDL levels. In livers, less fat cell deposition was observed, as were increased expression of InsR and PPARγ and reduction in expressions of IL-6 and F4/80. Treated mice showed well-preserved pancreatic β-cell mass with reduced expression of F4/80 and TNF-α compared with DIO controls. GFP(+) cells were found in liver and pancreas tissues at 1 and 2 weeks after cell injection.

CONCLUSIONS

ASC therapy is effective in lowering blood glucose levels and increasing glucose tolerance in DIO mice. The protective effects of ASCs arise at least in part from suppression of inflammation in the liver. In addition, ASCs are associated with better-preserved pancreatic β-cell mass.

Diazoxide preconditioning of endothelial progenitor cells from streptozotocin-induced type 1 diabetic rats improves their ability to repair diabetic cardiomyopathy

Type 1 diabetes mellitus (DM) is a strong risk factor for the development of diabetic cardiomyopathy (DCM) which is the leading cause of morbidity and mortality in the type 1 diabetic patients. Stem cells may act as a therapeutic agent for the repair of DCM. However, deteriorated functional abilities and survival of stem cells derived from type 1 diabetic subjects need to be overcome for obtaining potential outcome of the stem cell therapy. Diazoxide (DZ) a highly selective mitochondrial ATP-sensitive K(+) channel opener has been previously shown to improve the ability of mesenchymal stem cells for the repair of heart failure. In the present study, we evaluated the effects of DZ preconditioning in improving the ability of streptozotocin-induced type 1 diabetes affected bone marrow-derived endothelial progenitor cells (DM-EPCs) for the repair of DCM in the type 1 diabetic rats. DM-EPCs were characterized by immunocytochemistry, flow cytometry, and reverse transcriptase PCR for endothelial cell-specific markers like vWF, VE cadherin, VEGFR2, PECAM, CD34, and eNOS. In vitro studies included preconditioning of DM-EPCs with 200 μM DZ for 30 min followed by exposure to either 200 μM H2O2 for 2 h (for oxidative stress induction) or 30 mM glucose media (for induction of hyperglycemic stress) for 48 h. Non-preconditioned EPCs with and without exposure to H2O2 and 30 mM high glucose served as controls. These cells were then evaluated for survival (by MTT and XTT cell viability assays), senescence, paracrine potential (by ELISA for VEGF), and alteration in gene expression [VEGF, stromal derived factor-1α (SDF-1α), HGF, bFGF, Bcl2, and Caspase-3]. DZ preconditioned DM-EPCs demonstrated significantly increased survival and VEGF release while reduced cell injury and senescence. Furthermore, DZ preconditioned DM-EPCs exhibited up-regulated expression of prosurvival genes (VEGF, SDF-1α, HGF, bFGF, and Bcl2) on exposure to H2O2, and VEGF and Bcl2 on exposure to hyperglycemia while down regulation of Caspase-3 gene. Eight weeks after type 1 diabetes induction, DZ preconditioned, and non-preconditioned DM-EPCs were transplanted into left ventricle of diabetic rats (at a dose of 2 × 10(6) DM-EPCs/70 μl serum free medium). After 4 weeks, DZ preconditioned DM-EPCs transplantation improved cardiac function as assessed by Millar's apparatus. There was decrease in collagen content estimated by Masson's trichrome and sirius red staining. Furthermore, reduced cell injury was observed as evidenced by decreased expression of Caspase-3 and increased expression of prosurvival genes Bcl2, VEGF, and bFGF by semi-quantitative real-time PCR. In conclusion, the present study demonstrated that DZ preconditioning enhanced EPCs survival under oxidative and hyperglycemic stress and their ability to treat DCM.

Human adult stem cells maintain a constant phenotype profile irrespective of their origin, Basal media, and long term cultures

The study aims to identify the phenotypic marker expressions of different human adult stem cells derived from, namely, bone marrow, subcutaneous fat, and omentum fat, cultured in different media, namely, DMEM-Low Glucose, Alpha-MEM, DMEM-F12 and DMEM-KO and under long term culture conditions (>P20). We characterized immunophenotype by using various hematopoietic, mesenchymal, endothelial markers, and cell adhesion molecules in the long term cultures (Passages-P1, P3, P5, P9, P12, P15, and P20.) Interestingly, data revealed similar marker expression profiles irrespective of source, basal media, and extensive culturing. This demonstrates that all adult stem cell sources mentioned in this study share similar phenotypic marker and all media seem appropriate for culturing these sources. However, a disparity was observed in the markers such as CD49d, CD54, CD117, CD29, and CD106, thereby warranting further research on these markers. Besides the aforesaid objective, it is understood from the study that immunophenotyping acts as a valuable tool to identify inherent property of each cell, thereby leading to a valuable cell based therapy.

Combined influence of basal media and fibroblast growth factor on the expansion and differentiation capabilities of adipose-derived stem cells

BACKGROUND

Interest in adipose-derived stem cells (ASCs) has increased in recent years due to their multi-linage differentiation capabilities. While much work has been done to optimize the differentiation media, few studies have focused on examining the influence of different expansion media on cell behavior. In this study, three basal media (low glucose Dulbecco's modified Eagle's medium (DMEM), high glucose DMEM and DMEM-F12) supplemented with or without fibroblast growth factor 2 (FGF) were examined to assess their suitability for expanding ASCs.

FINDINGS

Flow cytometry, colony-forming unit assays (CFU-Fs) and differentiation assays were utilized to study cell behavior. High glucose media CFU-Fs produced fewest colonies while the addition of FGF increased colony size. By passage 2, the majority of cells were positive for CD44, 45, 73, 90 and 105 and negative for CD14, 31 and 45, indicating a mesenchymal phenotype. A sub-population of CD34 positive cells was present among passage 2 cells; however, by passage 4 the cells were negative for CD34. FGF has a negative effective on passage 4 ASC adipogenesis and high glucose media plus FGF-enhanced osteogenic capacity of passage 4 ASCs. FGF supplemented basal media were most suitable for chondrogenesis. High glucose media plus FGF appeared to be the most beneficial for priming ASCs to induce a keratocyte phenotype.

CONCLUSIONS

These findings demonstrate the reciprocal effect FGF and basal media have on ASCs. This research has implications for those interested regenerating bone, cartilage, cornea or adipose tissues.

Immunogenicity of allogeneic mesenchymal stem cells transplanted via different routes in diabetic rats

Due to their hypoimmunogenicity and unique immunosuppressive properties, mesenchymal stem cells (MSCs) are considered one of the most promising adult stem cell types for cell therapy. Although many studies have shown that MSCs exert therapeutic effects on several acute and subacute conditions, their long-term effects are not confirmed in chronic diseases. Immunogenicity is a major limitation for cell replacement therapy, and it is not well understood in vivo. We evaluated the immunogenicity of allogeneic MSCs in vivo by transplanting MSCs into normal and diabetic rats via the tail vein or pancreas and found that MSCs exhibited low immunogenicity in normal recipients and even exerted some immunosuppressive effects in diabetic rats during the initial phase. However, during the later stage in the pancreas group, MSCs expressed insulin and MHC II, eliciting a strong immune response in the pancreas. Simultaneously, the peripheral blood mononuclear cells in the recipients in the pancreas group were activated, and alloantibodies developed in vivo. Conversely, in the tail vein group, MSCs remained immunoprivileged and displayed immunosuppressive effects in vivo. These data indicate that different transplanting routes and microenvironments can lead to divergent immunogenicity of MSCs.

Enhancing effect of glucose microspheres in the viability of human mesenchymal stem cell suspensions for clinical administration

PURPOSE

A critical limiting factor of cell therapy is the short life of the stem cells. In this study, glucose containing alginate microspheres were developed and characterized to provide a sustained release system prolonging the viability of human mesenchymal stem cells (hMSCs) in a suspension for clinical application.

METHODS

The glucose microspheres were satisfactorily elaborated with alginate by emulsification/internal gelation method. Particle size was evaluated by light diffraction and optical microscopy. Shape and surface texture by scanning electron microscopy (SEM). Zeta potential, infrared spectra and release studies were also conducted. Also, rheological properties and stability of hMSCs suspensions with microspheres were tested. The viability of hMSCs was determined by trypan blue dye exclusion staining.

RESULTS

Microspheres of 86.62 μm, spherical shaped and -32.54 mV zeta potential with excellent stability, good encapsulation efficiency and providing an exponential release of glucose were obtained. hMSCs had better survival rate when they were packed with glucose microspheres. Microspheres maintained the aseptic conditions of the cell suspension without rheological, morphological or immunophenotypic disturbances on hMSCs.

CONCLUSIONS

Developed microspheres were able to enhance the functionality of hMSC suspension. This strategy could be broadly applied to various therapeutic approaches in which prolonged viability of cells is necessary.

Influence of Egr-1 in cardiac tissue-derived mesenchymal stem cells in response to glucose variations

Mesenchymal stem cells (MSCs) represent a promising cell population for cell therapy and regenerative medicine applications. However, how variations in glucose are perceived by MSC pool is still unclear. Since, glucose metabolism is cell type and tissue dependent, this must be considered when MSCs are derived from alternative sources such as the heart. The zinc finger transcription factor Egr-1 is an important early response gene, likely to play a key role in the glucose-induced response. Our aim was to investigate how short-term changes in in vitro glucose concentrations affect multipotent cardiac tissue-derived MSCs (cMSCs) in a mouse model of Egr-1 KO (Egr-1^−/−). Results showed that loss of Egr-1 does not significantly influence cMSC proliferation. In contrast, responses to glucose variations were observed in wt but not in Egr-1^−/− cMSCs by clonogenic assay. Phenotype analysis by RT-PCR showed that cMSCs Egr-1^−/− lost the ability to regulate the glucose transporters GLUT-1 and GLUT-4 and, as expected, the Egr-1 target genes VEGF, TGFβ-1, and p300. Acetylated protein levels of H3 histone were impaired in Egr-1^−/− compared to wt cMSCs. We propose that Egr-1 acts as immediate glucose biological sensor in cMSCs after a short period of stimuli, likely inducing epigenetic modifications.

Cardiac regeneration and diabetes

The prevalence of diabetes continues to increase world-wide and is a leading cause of morbidity, mortality, and rapidly rising health care costs. Although strict glucose control combined with good pharmacological and non-pharmacologic interventions can increase diabetic patient life span, the frequency and mortality of myocardial ischemia and infarction remain drastically increased in diabetic patients. Therefore, more effective therapeutic approaches are urgently needed. Over the past 15 years, cellular repair of the injured adult heart has become the focus of a rapidly expanding broad spectrum of pre-clinical and clinical research. Recent clinical trials have achieved favorable initial endpoints with improvements in cardiac function and clinical symptoms following cellular therapy. Due to the increased risk of cardiac disease, cardiac regeneration may be one strategy to treat patients with diabetic cardiomyopathy and/or myocardial infarction. However, pre-clinical studies suggest that the diabetic myocardium may not be a favorable environment for the transplantation and survival of stem cells due to altered kinetics in cellular homing, survival, and in situ remodeling. Therefore, unique conditions in the diabetic myocardium will require novel solutions in order to increase the efficiency of cellular repair following ischemia and/or infarction. This review briefly summarizes some of the recent advances in cardiac regeneration in non-diabetic conditions and then provides an overview of some of the issues related to diabetes that must be addressed in the coming years.

Downregulated microRNA-32 expression induced by high glucose inhibits cell cycle progression via PTEN upregulation and Akt inactivation in bone marrow-derived mesenchymal stem cells

MicroRNAs regulate a host of physiological and pathological processes in mesenchymal stem cells (MSCs), although no published studies describe changes in microRNA expression or function in MSCs under in vitro hyperglycemic conditions. By using a microRNA microarray approach, we have identified that miRNA-32-5p expression is significantly reduced under hyperglycemic conditions in rat bone marrow-derived MSCs. Expression of miRNA-32-5p targets the 3'-untranslated region of the mRNA encoding phosphatase and tensin homologs deleted on chromosome 10 (PTEN), a negative regulator of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway. Exposure to high glucose levels reduced miR-32-5p expression, induced PTEN expression, and inhibited activation of the PI3K/Akt signaling pathway of MSCs. Conversely, overexpression of miR-32-5p inhibited the expression of PTEN, ameliorated the inhibitory effect of high glucose levels on the PI3K/Akt signaling pathway, and promoted cell cycle progression from G0/G1 to G2/M and S phases. Our study indicates that exposure of MSCs to hyperglycemic conditions reduces miR-32-5p expression and disturbs cell cycle progression through a PTEN-mediated inhibitory effect on the PI3K/Akt signaling pathway. In summary, MiR-32-5p is a potentially important therapeutic agent for preventing MSC dysfunction under hyperglycemic conditions.

Adipose tissue regeneration: a state of the art

Adipose tissue pathologies and defects have always represented a reconstructive challenge for plastic surgeons. In more recent years, several allogenic and alloplastic materials have been developed and used as fillers for soft tissue defects. However, their clinical use has been limited by further documented complications, such as foreign-body reactions potentially affecting function, degradation over time, and the risk for immunogenicity. Tissue-engineering strategies are thus being investigated to develop methods for generating adipose tissue. This paper will discuss the current state of the art in adipose tissue engineering techniques, exploring the biomaterials used, stem cells application, culture strategies, and current regulatory framework that are in use are here described and discussed.