Proliferation Of Adipose Tissue-derived Stem Cells Research Articles

Effects of Streptozotocin-Induced Diabetes on Proliferation and Differentiation Abilities of Mesenchymal Stem Cells Derived from Subcutaneous and Visceral Adipose Tissues.

Introduction: Accumulated evidence indicates that there are intrinsic differences between adipose tissue-derived stem cells (ASCs) obtained from different body fat depots. Here, we compared the proliferation and multipotency of subcutaneous ASCs (SC-ASCs) and epididymal ASCs (ED-ASCs) before and after induction of diabetes by streptozotocin. Methods: The adipogenic and osteogenic abilities of rat SC-ASCs and ED-ASCs were evaluated using Oil Red O and Alizarin Red staining, respectively. The expression of adipocyte (PPAR-γ, LPL) and osteoblast (ALP, SPP1) specific mRNAs was evaluated by quantitative real-time PCR. MTT test was used for determination of cell proliferation capacity. Results: The proliferation of SC-ASCs was higher than ED-ASCs, both before and after diabetes induction (P<0.05). Diabetes increased the proliferative capability of SC-ASCs (P<0.05) but not ED-ASCs. Before diabetes, both adipogenic and osteogenic differentiation of SC-ASCs were higher than ED-ASCs (P<0.05). After diabetes, both SC-ASCs and ED-ASCs were able to differentiate into adipocyte and osteoblast, but the levels of differentiation were higher in SC-ASCs than in ED-ASCs (P<0.05). Diabetes decreased the expression of PPAR-γ and LPL, but increased the SPP1 and ALP expression in both SC-ASCs and ED-ASCs. Conclusion: Our data suggested that diabetes increases the proliferation of ASCs but decreases their adipogenic differentiation. Also, SC-ASCs have higher proliferation and differentiation abilities than ED-ASCs in normal and diabetic conditions so can be more preferable for cell therapy.

Development of recombinant collagen-peptide-based vehicles for delivery of adipose-derived stromal cells.

Stem cell therapy is a promising approach for repair, remodeling and even regenerate tissue of otherwise irreparable damage, such as after myocardial infarction (aMI). A severe limitation of cardiac stem cell therapy is the generally poor retention of administered cells in the target tissue. In tissue repair the main mode of action of adipose tissue-derived stem cells (ADSC) is the production of various growth factors, cytokines, anti-inflammatory and anti-apoptotic factors that together augment repair, remodeling, and regeneration. In this experiment, we used recombinant collagen peptide (RCP) with additional integrin-binding motives and different crosslinkers. Formulated as 50-100 μm microspheres with bound ADSC, we hypothesized that this would improve ADSC retention and function. Crosslinking was performed with chemical crosslinkers (EDC and HMDIC) at high and low concentrations or by thermal treatment (DHT). ADSC adhesion, proliferation, apoptosis/necrosis, and gene expressions in two-dimensional and three-dimensional were analyzed. In addition, the effect of ADSC conditioned medium (ADSC-CM) on proapoptotic/sprouting HUVEC was examined. Our results show that all materials support cell adhesion in short time point, however, EDC-High crosslinker induced ADSC apoptosis/necrosis. Gene expression results revealed lower expression of proinflammatory genes in chemical crosslinked materials, despite EDC-High the proinflammatory genes expressions were similar or higher than TCPS. In addition, cultured ADSC on DHT crosslinked RCP showed a proinflammatory phenotype compared to TCPS. Sprouting assay results confirmed the protective effect of ADSC-CM derived from TCPS and HMDIC-High crosslinked RCP proapoptotic HUVEC. We conclude that ADSC adhere to the materials and maintain their therapeutic profile.

Hypoxia Enhances Proliferation of Human Adipose-Derived Stem Cells via HIF-1ɑ Activation.

BackgroundAdipose tissue-derived stem cells (ASCs) have been recently isolated from human subcutaneous adipose tissue. ASCs may be useful in regenerative medicine as an alternative to bone marrow-derived stem cells. Changes in the oxygen concentration influence physiological activities, such as stem cell proliferation. However, the effects of the oxygen concentration on ASCs remain unclear. In the present study, the effects of hypoxia on ASC proliferation were examined.MethodsNormal human adipose tissue was collected from the lower abdomen, and ASCs were prepared with collagenase treatment. The ASCs were cultured in hypoxic (1%) or normoxic (20%) conditions. Cell proliferation was investigated in the presence or absence of inhibitors of various potentially important kinases. Hypoxia inducible factor (HIF)-1α expression and MAP kinase phosphorylation in the hypoxic culture were determined with western blotting. In addition, the mRNA expression of vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF)-2 in hypoxic or normoxic conditions were determined with real-time RT-PCR. The effects of these growth factors on ASC proliferation were investigated. Chromatin immunoprecipitation (ChIP) of the HIF–1α-binding hypoxia responsive element in FGF–2 was performed. HIF–1α was knocked down by siRNA, and FGF–2 expression was investigated.ResultsASC proliferation was significantly enhanced in the hypoxic culture and was inhibited by ERK and Akt inhibitors. Hypoxia for 5–15 minutes stimulated the phosphorylation of ERK1/2 among MAP kinases and induced HIF–1α expression. The levels of VEGF and FGF–2 mRNA and protein in the ASCs were significantly enhanced in hypoxia, and FGF–2 increased ASC proliferation. The ChIP assay revealed an 8-fold increase in the binding of HIF–1α to FGF–2 in hypoxia. HIF–1α knockdown by siRNA partially inhibited the FGF–2 expression of ASCs induced by hypoxia.ConclusionASC proliferation was enhanced by hypoxia. HIF–1α activation, FGF–2 production, and the ERK1/2 and Akt pathway were involved in this regulatory mechanism.

Efficient and sustained IGF-1 expression in the adipose tissue-derived stem cells mediated via a lentiviral vector.

The adipose tissue-derived stem cells (ADSCs) represent a significant area of the cell therapy. Genetic modification of ADSCs may further improve their therapeutic potential. Here, we aimed to generate a lentiviral vector expressing insulin-like growth factor-I (IGF-1) and investigate the impact of IGF-1 transduction on the properties of cultured ADSCs. Isolated rat ADSCs were assessed by flow cytometric analysis. IGF-1 was cloned and inserted into the pLenO-DCE plasmid to acquire pLenO-DCE-IGF-1 plasmid. Lentivirus was enveloped with pRsv-REV, pMDlg-pRRE and pMD2G plasmids in 293T cells. The ADSCs were transfected with the vectors. And then IGF-1-induced anti-apoptosis was evaluated by annexin V-FITC. Besides, proliferation of cells was detected by MTT assay and EdU. Moreover, Akt phosphorylation was evaluated by Western blotting analysis. Stable expression of IGF-1 in ADSCs was confirmed. ADSCs were positive for CD90 and CD29, but negative for CD31, CD34 and CD45. The transduction of IGF-1 to the ADSCs caused a dramatic increase in P-Akt expression. Over-expression of IGF-1 in ADSCs could improve the paracine of IGF-1 in a time-dependent manner, but could not promote the proliferation of ADSCs. This study indicated that lentiviral vectors offered a promising mean of delivering IGF-1 to the ADSCs. Lentiviral-mediated over-expression of therapeutic IGF-1 gene in ADSCs could prolong the anti-apoptosis effect of IGF-1, which might be induced by the activation of the PI3K/Akt pathway. And our data would improve the efficacy of ADSC-based therapies.

PVDF film tethered with RGD-click-poly(glycidyl methacrylate) brushes by combination of direct surface-initiated ATRP and click chemistry for improved cytocompatibility

To enhance the cytocompatibility of polyvinylidene fluoride (PVDF) films, arginine–glycine–aspartic acid (RGD) peptide-click-poly(glycidyl methacrylate) (PGMA) polymer brushes were grafted onto the PVDF surface by the combination of surface-initiated atom transfer radical polymerization (ATRP) and click reaction. The direct initiation of the secondary fluorine atoms of PVDF backbone allowed for grafting of the PGMA brushes containing reactive epoxy groups. Subsequent introduction of the azide groups onto the side chain of PGMA brushes was achieved by the ring-open reaction of the epoxy groups with sodium azide. The cell adhesive RGD peptide was finally conjugated onto the PGMA brushes via alkyne-azide click reaction. Kinetic studies revealed that the PGMA chain growth from the PVDF surface was consistent with a “controlled” process, and that the amount of immobilized RGD peptide on the PGMA brushes increased with the concentration of the pendant azide groups. The specificity of cellular interactions of adipose tissue-derived stem cells (ASCs) on the functionalized PVDF films was investigated. Results demonstrated that cell adhesion and proliferation of ASCs were significantly improved on the RGD-immobilized PVDF substrates, and this improvement was positively correlated with the surface concentration of covalently-bonded RGD peptide. With the inherent superior chemical and mechanical properties of PVDF films and the biocompatible nature of cell-adhesive peptides, surface functionalized PVDF films are potentially useful for biomedical and tissue engineering applications.

VEGF-Mediated Proliferation of Human Adipose Tissue-Derived Stem Cells

Human adipose tissue-derived stem cells (ADSCs) are an attractive multipotent stem cell source with therapeutic applicability across diverse fields for the repair and regeneration of acute and chronically damaged tissues. In recent years, there has been increasing interest in ADSC for tissue engineering applications. However, the mechanisms underlying the regulation of ADSC proliferation are not fully understood. Here we show that 47 transcripts are up-regulated while 23 are down-regulated in ADSC compared to terminally differentiated cells based on global mRNA profiling and microRNA profiling. Among the up-regulated genes, the expression of vascular endothelial growth factor (VEGF) is fine-tuned by miR-199a-5p. Further investigation indicates that VEGF accelerates ADSC proliferation whereas the multipotency of ADSC remains stable in terms of adipogenic, chondrogenic and osteogenic potentials after VEGF treatment, suggesting that VEGF may serve as an excellent supplement for accelerating ADSC proliferation during in vitro expansion.

Permanent activation of HMGA2 in lipomas mimics its temporal physiological activation linked to the gain of adipose tissue

In this study the activation of HMGA2 and overexpression by FGF1-driven stimulation of adipose tissue derived stem cells (ADSCs) in adipose tissue tumors were analyzed. In addition, the expression of HMGA2 and PPAR-gamma mRNA were quantified in canine subcutaneous abdominal adipose tissue from normal and overweight purebred dogs. ADSCs and adipose tissue explants stimulated with FGF1 followed by gene expression analyses of HMGA2 and p14(Arf) using Western-blot and qRT-PCR. Furthermore, canine subcutaneous white adipose tissue (WAT) were analyzed by qRT-PCR for their expression of HMGA2 and PPAR-gamma. ADSCs and adipose tissue explants are able to execute a HMGA2 response upon FGF1 stimulation. FGF1 enhances proliferation of ADSCs by a HMGA2-dependent mechanism. In lipomas increase of HMGA2 is accompanied by increased expression of p14(Arf) . Furthermore, a significantly elevated level of HMGA2 in overweight dogs and a negative correlation between the expression of HMGA2 and PPAR-gamma in subcutaneous cWAT were noted. These results suggest that WAT contains cells that as essential part of adipogenesis up-regulate HMGA2 resulting from growth factor stimulation. In subgroups of lipoma, constitutive activation of HMGA2 due to rearrangements replaces the temporal response triggered by growth factors.

Valproic Acid, a Histone Deacetylase Inhibitor, Decreases Proliferation of and Induces Specific Neurogenic Differentiation of Canine Adipose Tissue-Derived Stem Cells

ABSTRACTAdipose tissue-derived stem cells (ADSCs) isolated from adult tissue have pluripotent differentiation and self-renewal capability. The tissue source of ADSCs can be obtained in large quantities and with low risks, thus highlighting the advantages of ADSCs in clinical applications. Valproic acid (VPA) is a widely used antiepileptic drug, which has recently been reported to affect ADSC differentiation in mice and rats; however, few studies have been performed on dogs. We aimed to examine the in vitro effect of VPA on canine ADSCs. Three days of pretreatment with VPA decreased the proliferation of ADSCs in a dose-dependent manner; VPA concentrations of 4 mM and above inhibited the proliferation of ADSCs. In parallel, VPA increased p16 and p21 mRNA expression, suggesting that VPA attenuated the proliferative activity of ADSCs by activating p16 and p21. Furthermore, the effects of VPA on adipogenic, osteogenic or neurogenic differentiation were investigated morphologically. VPA pretreatment markedly promoted neurogenic differentiation, but suppressed the accumulation of lipid droplets and calcium depositions. These modifications of ADSCs by VPA were associated with a particular gene expression profile, viz., an increase in neuronal markers, that is, NSE, TUBB3 and MAP2, a decrease in the adipogenic marker, LPL, but no changes in osteogenic markers, as estimated by reverse transcription-PCR analysis. These results suggested that VPA is a specific inducer of neurogenic differentiation of canine ADSCs and is a useful tool for studying the interaction between chromatin structure and cell fate determination.

Body mass index affects proliferation and osteogenic differentiation of human subcutaneous adipose tissue-derived stem cells

BackgroundObesity is associated with a higher risk of developing cancer and co-morbidities that are part of the metabolic syndrome. Adipose tissue is recognized as an endocrine organ, as it affects a number of physiological functions, and contains adipose tissue-derived stem cells (ASCs). ASCs can differentiate into cells of multiple lineages, and as such are applicable to tissue engineering and regenerative medicine. Yet the question of whether ASC functionality is affected by the donor’s body mass index (BMI) still exists.ResultsASCs were isolated from patients having different BMIs (BMI-ASCs), within the ranges of 18.5-32.8. It was hypothesized that overweight BMI-ASCs would be more compromised in early adipogenic and osteogenic potential, and ability to form colonies in vitro. BMI was inversely correlated with ASC proliferation and colony forming potential as assessed by CyQUANT proliferation assay (fluorescence- based measurement of cellular DNA content), and colony forming assays. BMI was positively correlated with early time point (day 7) but not later time point (day 15) intracytoplasmic lipid accumulation as assessed by Oil-Red-O staining. Alizarin red staining and RT-PCR for alkaline phosphatase demonstrated that elevated BMI resulted in compromised ASC mineralization of extracellular matrix and decreased alkaline phosphatase mRNA expression.ConclusionsThese data demonstrate that elevated BMI resulted in reduced ASC proliferation, and potentially compromised osteogenic capacity in vitro; thus BMI is an important criterion to consider in selecting ASC donors for clinical applications.

Efficacy of cyclosporine A-nanoparticles emulsion combined with stem cell transplantation therapy for acute myocardial infarction

To evaluate the efficacy of cyclosporine A-nanoparticles emulsion (CsA-NP) combined with adipose tissue-derived stem cells (ASCs)transplantation therapy for acute myocardial infarction (AMI) in a miniswine model. CsA-NP emulsion was prepared by the high-pressure homogenization method. Models were performed by coronary angioplasty for percutaneous balloon occlusion of left anterior descending artery (LAD). A total of 17 miniswines survived after AMI were divided into four groups: control group (n=5), CsA-NP group (n=4), ASCs group (n=4), and CsA-NP+ASCs group (n=4). ASCs or saline were delivered by intracoronary injection one week after AMI.Before cell transplantation and 8 weeks after cell transplantation, delayed-enhanced magnetic resonance imaging (DE-MRI) was performed to evaluate cardiac function and viability. The infarcted myocardium and implanted cells were histologically studied. Eight weeks after treatment, the left ventricular ejection fraction (LVEF)significantly increased in the CsA-NP+ASCs group when compared with the ASCs group [(53.6 ± 2.4)% vs. (48.3 ± 1.8)%, P<0.05]; meanwhile, the infarct size significantly decreased [(6.2 ± 1.7)cm(3) vs.(7.5 ± 0.6) cm(3), P<0.05] and the thickness of the ventricular wall significantly increased (P<0.05). Histology showed that the number of surviving cells increased nearly by three times in the CsA-NP+ASCs group, and the expressions of the cardiomyocyte specific markers (cTnT and α-actin) were detected. Histological samples also showed that CsA-NP+ASCs group reduced fibrotic tissue, and down-regulated the activation of Caspase-3. The CsA-NP+ASCs combination therapy can enhance the viability of ASCs by improving LVEF and preventing LV expansion, which may be explained that CsA-NP has the anti-apoptotic effect and can promote the survivals and proliferation of ASCs.

GW24-e1001 Effects of advanced glycation end products on function and angiogenesis of adipose tissue-derived stem cells and protective effects of Danhong injection

ObjectivesTo investigate the effects of Nε-(carboxymethyl) Lysine albumin (CMLs), a primary advanced glycation end products isoform in diabetic body, on function and angiogenesis of adipose tissue-derived stem cells (ADSCs) and...

Methylcellulose Based Thermally Reversible Hydrogel System for Tissue Engineering Applications

The thermoresponsive behavior of a Methylcellulose (MC) polymer was systematically investigated to determine its usability in constructing MC based hydrogel systems in cell sheet engineering applications. Solution-gel analyses were made to study the effects of polymer concentration, molecular weight and dissolved salts on the gelation of three commercially available MCs using differential scanning calorimeter and rheology. For investigation of the hydrogel stability and fluid uptake capacity, swelling and degradation experiments were performed with the hydrogel system exposed to cell culture solutions at incubation temperature for several days. From these experiments, the optimal composition of MC-water-salt that was able to produce stable hydrogels at or above 32 °C, was found to be 12% to 16% of MC (Mol. wt. of 15,000) in water with 0.5× PBS (~150mOsm). This stable hydrogel system was then evaluated for a week for its efficacy to support the adhesion and growth of specific cells in culture; in our case the stromal/stem cells derived from human adipose tissue derived stem cells (ASCs). The results indicated that the addition (evenly spread) of ~200 µL of 2 mg/mL bovine collagen type -I (pH adjusted to 7.5) over the MC hydrogel surface at 37 °C is required to improve the ASC adhesion and proliferation. Upon confluence, a continuous monolayer ASC sheet was formed on the surface of the hydrogel system and an intact cell sheet with preserved cell–cell and cell–extracellular matrix was spontaneously and gradually detached when the grown cell sheet was removed from the incubator and exposed to room temperature (~30 °C) within minutes.

DiI Labeling of Human Adipose-Derived Stem Cells: Evaluation of DNA Damage, Toxicity and Functional Impairment

Introduction: Adipose tissue-derived stem cells (ASCs) have become the primary focus of tissue engineering research. To understand their functions and behavior in in vitro and in vivo models, it is mandatory to track the implanted cells and distinguish them from the resident or host cells. A common labeling method is the use of fluorescent dyes, e.g. the lipophilic carbocyanine dye, DiI. This study aimed to analyze potential DNA damage, toxicity and impairment of the functional properties of human ASCs after labeling with DiI. Methods: Cytotoxicity was measured using the MTT assay and DNA damage was determined by means of the comet assay. Potential apoptotic effects were determined using the annexin V-propidium iodide test. Differentiation potential was evaluated by trilineage differentiation procedures in labeled and unlabeled ASCs. Proliferation as well as migration capability was analyzed, and the duration and stability of DiI labeling in ASCs during in vitro expansion was observed over a period of 35 days. Results: DiI labeling did not cause genotoxic effects 15, or 30 min or 24 h after the labeling procedure, and there were no cytotoxic effects until 72 h afterwards. No impairment of proliferation or migration capability or differentiation potential could be determined. However, after 35 days, only 37% of labeled cells could be detected using the fluorescence microscope, which indicates a decrease in staining stability during in vitro expansion. Conclusion: DiI is a convenient method for ASCs labeling which causes no toxic effects and does not impair the proliferation, migration or differentiation potential of ASCs after the labeling procedure.

Adipose Tissue-Derived Stem Cells Treated with Estradiol Enhance Survival of Autologous Fat Transplants

Autologous fat transplantation (AFT) is a common and important operation in plastic surgery for soft tissue defects and adipose tissue-derived stem cells (ADSCs) are considered as a promising supplement to decrease absorption and subsequent side effects due to the ability of multiple differentiation and production of vascular endothelial growth factor (VEGF). The capacities of ADSCs can be further enhanced by treatment with 17-β estradiol (E2). Therefore, we hypothesized that E2 may promote the potential of ADSCs for AFT. In this study, ADSCs were extracted from three female patients by liposuction. In vitro studies showed that E2 supplementation at an optimal concentration of 10(-8) M resulted in enhanced proliferation, VEGF production, and adipogenic differentiation of human ADSCs, and reduced apoptosis rate in a serum-free environment. In addition, a nude mice model of fat transplantation was utilized to demonstrate the efficacy of ADSC for survival ratio in vivo. These results using the volume of fat tissues after 12 weeks compared original volume, revealed that the addition of E2-treated ADSCs induced a significantly higher tissue survival ratio (76.9 ± 1.9%) when compared with the ADSC-free system (55.5 ± 1.5%). Furthermore, increased capillary formation stained with hematoxylin-eosin (H&E) was observed in ADSCs systems after treatment with E2. Therefore, this study demonstrated E2 could promote the capacities of ADSCs about aspects of adipogenic differentiation, growth factor secretion and apoptosis reduction in vitro, vascularization improvement in vivo, and then enhanced the survival ratio of AFT.

Differentiation potential of human mesenchymal stem cells derived from adipose tissue and bone marrow to sinus node-like cells

Adult mesenchymal stem cells (MSCs) hold great promise for the repair of heart defects. Both bone marrow-derived mesenchymal stem cells (BMSCs) and adipose tissue-derived stem cells (ASCs) are multipotent and may be induced by 5-azacytidine to differentiate into cardiomyocytes. However, the differentiation potential of human MSCs into sinus node-like cells has not been studied extensively. The aim of this study was to analyze the differences in proliferation and phenotype of ASCs and BMSCs from the same donors and to evaluate their capacity to differentiate into sinus node-like cells in vitro. Five passaged cells from bone marrow and adipose tissue were treated with 10 µM 5-azacytidine for 48 h and further cultured in complete medium for 4 weeks. A comparative study of cultured ASCs and BMSCs was carried out, and the morphological parameters, proliferative capacity, expression of surface markers and differentiation potential to sinus node-like cells were characterized. No morphologic differences were observed between ASCs and BMSCs. Flow cytometric analysis revealed that ASCs and BMSCs both expressed CD29, CD44, CD90 and CD105 and did not express CD34 and CD14, while CD49d, CD106 and CD34 were differentially expressed. Growth curves and doubling time determined with the Cell Counting Kit-8 (CCK-8) demonstrated that ASCs had a stronger proliferative ability than BMSCs. Histological immuofluorescence staining suggested that ASCs and BMSCs were capable of differentiating into sinus node-like cells and that the positive expression ratios of cTNI were higher in ASCs compared to BMSCs at 4 weeks. Expression of the HCN2 and HCN4 genes was detected by reverse transcriptase polymerase chain reaction, and the results revealed that the expression of the HCN genes appeared earlier in ASC-derived sinus node-like cells. ASCs expressed HCN2 and HCN4 shortly after induction with 5-azacytidine for 2 weeks, although BMSCs expressed these genes after 4 weeks. The expression levels of HCN2 and HCN4 mRNA in ASC-derived cells were higher compared to those of BMSCs at 4 weeks. In conclusion, ASCs may be a better candidate as a novel source of cell therapy in sinus bradycardia disorders than BMSCs.

Enhancement of Adipose-Derived Stem Cell Differentiation in Scaffolds withIGF-IGene Impregnation Under Dynamic Microenvironment

Biochemical and mechanical signals enabling cardiac regeneration can be elucidated by using in vitro tissue engineering models. We hypothesized that human insulin-like growth factor-I (IGF-I) and 3-dimensional (3D) dynamic microenvironment could enhance the survival and differentiation of adipose tissue-derived stem cells (ADSCs). In this study, ADSCs were cultured on 3D porous scaffolds with or without plasmid DNA PIRES2-IGF-I in cardiac media, in static culture dishes, and in a spinning flask bioreactor, respectively. Cell viability, formation of cardiac-like structure, expression of functional proteins, and gene expressions were tested in the cultured constructs on day 14. The results showed that dynamic microenvironment enhanced the release of plasmid DNA; the ADSCs can be transfected by the released plasmid DNA PIRES2-IGF-I in scaffold. IGF-I showed beneficial effects on cellular viability and increase of total protein and also increased the expressions of cardiac-specific proteins and genes in the grafts. It was also demonstrated that dynamic stirring environment could promote the proliferation of ADSCs. Therefore, IGF-I, expressed by ADSCs transfected by DNA PIRES2-IGF-I incorporated into scaffold, and hydrodynamic microenvironment can independently and interactively increase cellular viability and interactively increase the expression of cardiac-specific proteins and genes in the grafts. The results would be useful for developing tissue-engineered grafts for myocardial repair.

Preparation, fabrication and biocompatibility of novel injectable temperature-sensitive chitosan/glycerophosphate/collagen hydrogels

This paper introduces a novel type of injectable temperature-sensitive chitosan/glycerophosphate/collagen (C/GP/Co) hydrogel that possesses great biocompatibility for the culture of adipose tissue-derived stem cells. The C/GP/Co hydrogel is prepared by mixing 2.2% (v/v) chitosan with 50% (w/w) β-glycerophosphate at different proportions and afterwards adding 2 mg/ml of collagen. The gelation time of the prepared solution at 37°C was found to be of around 12 min. The inner structure of the hydrogel presented a porous spongy structure, as observed by scanning electron microscopy. Moreover, the osmolality of the medium in contact with the hydrogel was in the range of 310-330 mmol kg(-1). These analyses have shown that the C/GP/Co hydrogels are structurally feasible for cell culture, while their biocompatibility was further examined. Human adipose tissue-derived stem cells (ADSCs) were seeded into the developed C/GP and C/GP/Co hydrogels (The ratios of C/GP and C/GP/Co were 5:1 and 5:1:6, respectively), and the cellular growth was periodically observed under an inverted microscope. The proliferation of ADSCs was detected using cck-8 kits, while cell apoptosis was determined by a Live/Dead Viability/Cytotoxicity kit. After 7 days of culture, cells within the C/GP/Co hydrogels displayed a typical adherent cell morphology and good proliferation with very high cellular viability. It was thus demonstrated that the novel C/GP/Co hydrogel herein described possess excellent cellular compatibility, representing a new alternative as a scaffold for tissue engineering, with the added advantage of being a gel at the body's temperature that turns liquid at room temperature.

Differentiation Enhancement of ADSC in Scaffolds With IGF-1 Gene Impregnation Under Dynamic Microenvironment*

Biochemical and mechanical signals enabling cardiac regeneration can be elucidated by using in vitro tissue engineering models. It was hypothesized that human insulin-like growth factor-1 (IGF-1) and three dimensional dynamic microenvironment could act independently and interactively to enhance the survival and differentiation of adipose tissue-derived stem cells (ADSCs) and hence the construction of engineered cardiac grafts. IGF-1 can be expressed by the ADSCs through genetic modification,which can be conveniently realized by incorporating the relevant genes into the three dimensional scaffold. ADSCs were cultured on three dimensional porous scaffolds with or without plasmid DNA PIRES2-IGF-1 in cardiac media,in dishes and in a spinning flask bioreactor respectively. Cell viability,formation of cardiac like structure,expression of functional proteins,and gene expressions were testified to the cultured constructs on day 14. The results showed that dynamic microenvironment enhanced the release of plasmid DNA; the ADSCs can be transfected by the released plasmid DNA PIRES2-IGF-1 in scaffold; IGF-1 had beneficial effects on the cellular viability and the increase of total protein; and it also increased the expressions of cardiac specific proteins and genes in the grafts. It was also demonstrated that dynamic stirring environment could promote the proliferation of ADSCs. Therefore,IGF-1,expressed by ADSCs transfected by DNA PIRES2-IGF-1 incorporated into scaffold,and hydrodynamic microenvironment can independently and interactively increase cellular viability,and interactively increased the expressions of cardiac specific proteins and genes in the grafts. The results would be useful for developing tissue engineered grafts for myocardial repair.

Promotion of stem cell proliferation by vegetable peptone.

Technical limitations and evolution of therapeutic applications for cell culture-derived products have accelerated elimination of animal-derived constituents from such products to minimize inadvertent introduction of microbial contaminants, such as fungi, bacteria or viruses. The study described here was conducted to investigate the proliferative effect of vegetable peptone on adult stem cells in the absence of serum, and its possible mechanisms of action. Cell viability and proliferation were determined using the MTT assay and Click-iT EdU flow cytometry, respectively. In addition, changes in expression of cytokine genes were analysed using MILLIPLEX human cytokine enzyme-linked immunosorbent assay kit. Viability of cord blood-derived mesenchymal stem cells (CB-MSC) and adipose tissue-derived stem cells (ADSC) increased significantly when treated with the peptone. In addition, median value of the group treated with peptone shifted to the right when compared to the untreated control group. Furthermore, quantitative analysis of the cytokines revealed that production of vascular endothelial growth factor (VEGF), transforming growth factor-beta1 (TGF-beta1), and interleukin-6 (IL-6) increased significantly in response to treatment with our vegetable peptone in both CB-MSCs and ADSCs. Our findings revealed that the vegetable peptone promotes proliferation of CB-MSCs and ADSCs. In addition, results of this study suggest that induction of stem cell proliferation by vegetable peptone is likely to be related to its induction of VEGF, TGF-beta1, and IL-6 expression.

Ex vivo expansion of adipose tissue‐derived stem cells in spinner flasks

Recent reports indicate that adipose tissue is a novel source of multipotent stem cells that can be used in cell therapy and tissue engineering. However, using the traditional cultivation of adipose tissue-derived stem cells (ADSCs), it is hard to meet the needs of clinical applications. To obtain a large number of ADSCs while retaining their stemness, we seeded ADSCs in collagen/chitosan scaffolds and compared the proliferation of ADSCs in a 3-D static environment in dishes and a 3-D dynamic environment in spinner flask. The growth dynamic parameters of ADSCs were examined using a CCK-8 kit every other day, and the variations of glucose and lactic acid concentrations were analyzed every day. After 14 days, the cells were observed under a scanning electron microscope. The surface markers (CD29, CD34, CD44, CD45, CD73, CD105, CD166 and HLA-DR), the specific transcription factors (Nanog, Oct-4, Sox-2 and Rex-1) and the multi-differentiation potential (adipogenic, osteogenic and chondrogenic) were also assayed to identify the stemness of expanded cells. The results showed that the cells in scaffolds in spinner flask could be expanded by more than 26 times, and they presented better morphology and vitality and stronger differentiation ability than the cells cultivated in scaffolds statically. All the cells maintained stem cell characteristics after proliferation. Therefore, spinner flask cultivation is an easy-to-use, inexpensive system for expanding ADSCs in 3-D scaffolds.