Differentiation of rat marrow mesenchymal stem cells into pancreatic islet beta-cells

AIM: To explore the possibility of marrow mesenchymal stem cells (MSC) in vitro differentiating into functional isletlike cells and to test the diabetes therapeutic potency of Islet-like cells. METHODS: Rat MSCs were isolated from Wistar rats and cultured. Passaged MSCs were induced to differentiate into islet-like cells under following conditions: pre-induction with L-DMEM including 10 mmol/L nicotinamide+l mmol/L β-mercaptoethanol+200 mL/L fetal calf serum (FSC) for 24 h, followed by induction with serum free H-DMEM solution including 10 mmol/L nicotinamide+1 mmol/L,β-mercaptoethanol for 10 h. Differentiated cells were observed under inverse microscopy, insulin and nestin expressed in differentiated cells were detected with immunocytochemistry. Insulin excreted from differentiated cells was tested with radioimmunoassay. Rat diabetic models were made to test in vivo function of differentiated MSCs. RESULTS: Typical islet-like clustered cells were observed. Insulin mRNA and protein expressions were positive in differentiated cells, and nestin could be detected in predifferentiated cells. Insulin excreted from differentiated MSCs (446.93±102.28 IU/L) was much higher than that from pre-differentiated MSCs (2.45+0.81 IU/L (P<0.01). Injected differentiated MSCs cells could down-regulate glucose level in diabetic rats. CONCLUSION: Islet-like functional cells can be differentiated from marrow mesenchymal stem cells, which may be a new procedure for clinical diabetes stem -cell therapy, these cells can control blood glucose level in diabetic rats. MSCs may play an important role in diabetes therapy by islet differentiation and transplantation.

Preliminary Study on Biological Properties of Adult Human Bone Marrow-derived Mesenchymal Stem Cells

Objective： To establish a method of culture and expansion of adult human bone marrow-derived MSCs in vitro and to explore their biological properties. Methods： Mononuclear cells were obtained from 5 mL adult human bone marrow by density gradient centrifugation with Percoll solution. Adult human MSCs were cultured in Dulbecco＇s Modified Eagle＇s Medium with low glucose （LG-DMEM） containing 10% fetal calf serum at a density of 2×10^5 cell/cm^2. The morphocytology was observed under phase-contrast microscope. The cell growth was measured by MTT method. The flow cytometer was performed to examine the expression of cell surface molecules and cell cycle. The ultrastructure of MSCs was observed under transmission electron microscope. The immunomodulatory functions of MSCs were measured by MTT method. The effects of MSCs on the growth of K562 cells and the dynamic change of HA, IV-C, LN concentration in the culture supernatant of MSCs was also observed. Results： The MSCs harvested in this study were homogenous population and exhibited a spindle-shaped fibroblastic morphology. The cell growth curve showed that MSCs had a strong ability of proliferation. The cells were positive for CD44, while negative for hematopoietic cell surface marker such as CD3, CD4, CD7, CD13, CD14, CD15, CD19, CD22, CD33, CD34, CD45 and HLA-DR, which was closely related to graft versus host disease. Above 90% cells of MSCs were found at G0/G1 phase. The ultrastructure of MSCs indicated that there were plenty of cytoplasmic organelles. Allogeneic peripheral blood lymphocytes proliferation was suppressed by MSCs and the inhibition ratio was 60.68% （P〈0.01）. The suppressive effect was also existed in the culture supernatant of MSCs and the inhibition ratio was 9.00% （P〈0.05）. When lymphocytes were stimulated by PHA, the suppression effects of the culture supernatant were even stronger and the inhibition ratio was 20.91% （P〈0.01）. Compared with the cell growth curve of the K562 ceils alone, the K562 ceils cocultured with MSCs grew slowly and the exponential phase of growth wasn＇t significant. Seeing from the concentration curve, as time passed, the concentration of HA increased quickly, while those of IV-C and LN didn＇t change much. Conclusion： The method for culture and expansion of adult human bone marrow-derived MSCs in vitro has been successfully established in this study. MSCs were a homogenous population that had unique growth phenotype and multilineage potential. Preliminary study proved that it had the abilities of immunomodulatory function, antitumor, hematopoietic supporting and could act as seed cell of tissue engineering.

Reversal of hyperglycemia in diabetic rats by portal vein transplantation of islet-like cells generated from bone marrow mesenchymal stem cells

AIM: To study the capacity of bone marrow mesenchymal stem cells (BM-MSCs) trans-differentiating into islet-like cells and to observe the effect of portal vein transplantation of islet-like cells in the treatment of streptozotocin-induced diabetic rat. METHODS: BM-MSCs were isolated from SD rats and induced to differentiate into islet-like cells under defined conditions. Differentiation was evaluated with electron microscopy, RT-PCR, immunofluorescence and flow cytometry. insulin release after glucose challenge was tested with ELiSA. Then allogeneic islet-like cells were transplanted into diabetic rats via portal vein. Blood glucose levels were monitored and islet hormones were detected in the liver and pancreas of the recipient by immunohistochemistry. RESULTS: BM-MSCs were spheroid adherent monolayers with high CD90, CD29 and very low CD45 expression. Typical islet-like cells clusters were formed after induction. Electron microscopy revealed that secretory granules were densely packed within the cytoplasm of the differentiated cells. The spheroid cells expressed islet related genes and hormones. The insulin-positive cells accounted for 19.8% and mean fluorescence intensity increased by 2.6 fold after induction. The cells secreted a small amount of insulin that was increased 1.5 fold after glucose challenge. After transplantation, islet-like cells could locate in the liver expressing islet hormones and lower the glucose levels of diabetic rats during d 6 to d 20.CONCLUSION: Rat BM-MSCs could be transdifferentiated into islet-like cells in vitro . Portal vein transplantation of islet-like cells could alleviate the hyperglycemia of diabetic rats.

Human bone marrow-derived mesenchymal stem cells transplanted into damaged rabbit heart to improve heart function

Objective: The present study was designed to test whether transplantation of human bone marrow-derived mesen- chymal stem cells (hMSCs) in New Zealand rabbits with myocardial infarction can improve heart function; and whether engrafted donor cells can survive and transdifferentiated into cardiomyocytes. Methods: Twenty milliliters bone marrow was obtained from healthy men by bone biopsy. A gradient centrifugation method was used to separate bone marrow cells (BMCs) and red blood cells. BMCs were incubated for 48 h and then washed with phosphate-buffered saline (PBS). The culture medium was changed twice a week for 28 d. Finally, hematopoietic cells were washed away to leave only MSCs. Human MSCs (hMSCs) were premarked by BrdU 72 h before the transplantation. Thirty-four New Zealand rabbits were randomly divided into myocardial infarction (MI) control group and cell treated group, which received hMSCs (MI+MSCs) through intramyocardial injection, while the control group received the same volume of PBS. Myocardial infarction was induced by ligation of the left coronary artery. Cell treated rabbits were treated with 5×106 MSCs transplanted into the infarcted region after ligation of the coronary artery for 1 h, and the control group received the same volume of PBS. Cyclosporin A (oral solution; 10 mg/kg) was provided alone, 24 h before surgery and once a day after MI for 4 weeks. Echocardiography was measured in each group before the surgery and 4 weeks after the surgery to test heart function change. The hearts were harvested for HE staining and immunohistochemical studies after MI and cell transplantation for 4 weeks. Results: Our data showed that cardiac function was significantly improved by hMSC transplan- tation in rabbit infarcted hearts 4 weeks after MI (ejection fraction: 0.695±0.038 in the cell treated group (n=12) versus 0.554±0.065 in the control group (n=13) (P<0.05). Surviving hMSCs were identified by BrdU positive spots in infarcted region and transdifferentiated into cardiomyocytes characterized with a positive cardiac phenotype: troponin I. Conclusion: Transplan- tation of hMSCs could transdifferentiate into cardiomyocytes and regenerate vascular structures, contributing to functional im- provement.

Differentiation of hepatocytoid cell induced from whole-bone-marrow method isolated rat myeloid mesenchymal stem cells

AIM： To explore the expansion and differentiation of hepatocytoid cell induced from myeloid mesenchymal stem cell （MSC） in vib＇o, in order to find suitable resource of hepatocytes for bioartiflcial liver or liver transplantation. METHODS： The rat myeloid MSC was isolated and divided into three groups which were cultured by Friedensteion method, and then were induced by culture fluid, culture fluid plus cholestatic serum and culture fluid plus hepatocyte growth factor （HGF）, respectively. Hepatocytoid cell as well as expression of CK18 and AFP was observed by immunohistochemistry. RESULTS： After the induction for 21 d, hepatocytoid cell was observed, and its expression of CK18 and AFP was detected by immunohistochemistry in MSC cultured with cholestatic serum. Furthermore, on the 35^th d, albumin mRNA was expressed in the cell, suggesting the inducing effect was similar to that by HGF.CONCLUSION： Rat myeloid MSC can differentiate into hepatocyte lineage under appropriate condition. This method is easy to operate.

Comparison of biological characteristics of marrow mesenchymal stem cells in hepatitis B patients and normal adults

AIM: To establish a culture system of marrow mesenchymal stem cells (MSCs)from hepatitis B patients and normal adults and to compare their biological characteristics. METHODS: MSCs were isolated from bone marrow in 34 male hepatitis B patients and 15 male normal adults and cultivated in vitro. Their biological characteristics including surface markers, shapes and appearances, growth curves, first passage time and passage generations were compared. RESULTS: Cultivation achievement ratio of hepatitis B patients was lower than that of normal adults, no statistical significance (82.35% vs 100%, P > 0.05). Compared with MSCs of normal adults, MSCs of hepatitis B patients presented a statistical lower growth curve, longer first passage time (13.0 ± 1.6 d vs 11.4 ± 1.5 d, P < 0.05), fewer passaging generation numbers (10.5 ± 1.4 generations vs 12.3 ± 1.7 generations, P < 0.05), though both shared same appearances, shapes and surface markers. MSCs in hepatitis B patients would expand, spread out and age more easily and there were more refractive particles in the cytoplasm. CONCLUSION: MSCs from hepatitis B patients can be cultured in vitro. Although their appearance, shape and surface marker are similar to those of MSCs from normal adults, there are differences in their biological characteristics.

Local signals in stem cell-based bone marrow regeneration

The cellular basis of bone marrow （BM） tissue development and regeneration is mediated through hematopoietic stem cells （HSCs） and mesenchymal stem cells （MSCs）. Local interplays between hematopoietic cells and BM stromal cells （BMSCs） determine the reconstitution of hematopoiesis after myelosuppression. Here we review the BM local signals in control of BM regeneration after insults. Hematopoietic growth factors （HGFs） and cytokines produced by BMSCs are primary factors in regulation ofBM hematopoiesis. Morphogens which are critical to early embryo development in multiple species have been added to the family of HSCs regulators, including families of Wnt proteins, Notch ligands, BMPs, and Hedgehogs. Global gene expression analysis of HSCs and BMSCs has begun to reveal signature groups of genes for both cell types. More importantly, analysis of global gene expression coupled with biochemical and biological studies of local signals during BM regeneration have strongly suggested that HGFs and cytokines may not be the primary local regulators for BM recovery, rather chemokines （SDF- 1, FGF-4） and angiogenic growth factors （VEGF-A, Ang- 1） play instructive roles in BM reconstitution after myelosuppression. A new direction of management of BM toxicity is emerging from the identification of BM regenerative regulators.

A Biological Pacemaker Restored by Autologous Transplantation of Bone Marrow Mesenchymal Stem Cells

Objective：To restore cardiac autonomic pace function by autologous trans- plantation and committed differentiation of hone marrow mesenchymal stern cells, and explore the technique for the treatment of sick sinus syndrome. Methods ： Mesenchymal stern cells isolated from canine bone marrow were culture-expanded and differentiated in vitro by 5-azacytidine. The models of sick sinus syndrome in canines were established by ablating sinus node with radio-frequency technique. Differentiated mesenchymal stem cells labeled by BrdU were autologously transplanted into sinus node area through direct injection. The effects of autologous transplantation of mesenchymal stern cells on cardiac autonomic pace function in sick sinus syndrome models were evaluated by electrocardiography, pathologic and immunohistochemical staining technique. Results：There was distinct improvement on pace function of sick sinus syndrome animal models while differentiated mesenchymal stem cells were auto-transplanted into sinus node area. Mesenchymal stern cells transplanted in sinus node area were differentiated into similar sinus node cells and endothelial cells in vivo, and established gap junction with native cardiomyocytes. Conclusion ： The committed- induced mesenchymal stern cells transplanted into sinus node area can differentiate into a- nalogous sinus node cells and improve pace function in canine sick sinus syndrome models.

Treatment of osteonecrosis of femoral head with BMSCsseeded bio-derived bone materials combined with rhBMP-2 in rabbits

Objective： To evaluate the effect of autologous bone marrow mesenchymal stem cells （BMSCs） seeded bio-derived bone materials （BBM） combined with recombinant human bone morphogenetic protein-2 （rhBMP-2） in repairing defect of osteonecrosis of femoral head （ONFH）. Methods： Early-stage osteonecrosis in the left hip was induced in 36 adult New Zealand white rabbits （provided by the Animal Center of Guangxi Medical University, Nanning, China） after core decompression and delivery of liquid nitrogen into the femoral head. Then the animals were divided into three groups according to the type of implants for bone repair： 12 rabbits with nothing （Group Ⅰ, the blank control group）, 12 with BBM combined with rhBMP-2 （Group Ⅱ）, and 12 with BMSCs-seeded BBM combined with rhBMP-2 （Group Ⅲ）. At 4, 8, and 12 weeks after surgery, X-ray of the femoral head of every 4 rabbits in each group was taken, and then they were killed and the femoral heads were collected at each time point, respectively. Gross observation was made on the femoral heads. After hematoxylin and eosin staining, Lane-sandhu scores of X-ray and bone densitometry were calculated and the histomorphometric measurements were made for the new bone trabeculae. Results： At 12 weeks after surgery, two femoral heads collapsed in Group Ⅰ, but none in Group Ⅱ or Group Ⅲ. X-ray examination showed that the femoral heads in Group I had defect shadow or collapsed while those in Group II had a low density and those in Group III presented with a normal density. Histologically, the defects of femoral heads were primarily filled with no new bone but fibrous tissues in Group Ⅰ. In contrast, new bone regeneration and fibrous tissues occurred in Group II and only new bone regeneration occurrd in Group Ⅲ. Lane-sandhu scores of X-ray, bone mineral density and rate of new bone in trabecular area in Group Ⅲ were higher significantly than those of the other two groups. Conclusions： Our findings indicate a superior choice of repairing the experimental defect of OFH with BMSCsseeded BBM combined with rhBMP-2.

Induction of corneal epithelial progenitors from bone-marrow mesenchymal stem cells of rhesus monkeys in vitro

Bioengineered corneas are substitutes for human donor tissue that are designed to treat severe dis-ease affecting ocular surfaces. However,a shortage of candidate seed cells for bioengineering corneas is still a problem. Bone-marrow mesenchymal stem cells (MSCs) are capable of multilineage differen-tiation. Therefore,we determined whether MSCs differentiate into corneal epithelial cells (ECs). We applied three exoteric-microenvironmental systems to induce MSCs to become ECs. Induced MSC were identified by means of morphologic examination,immunocytochemical analysis,and flow cytometry. MSCs grown in one microenvironment had characteristics similar to those of corneal epithelial pro-genitors. Induced MSCs expressed markers for EC,including integrin β1,Cx43,Pax6,and P63. MSCs were successfully induced to become corneal epithelial progenitors. Therefore,the use of MSCs may hold substantial promise for reconstructing the ocular surface after corneal injury.

Biological features of mesenchymal stem cells from human bone marrow

Objective To study the biological characteristics of mesenchymal stem cells (MSCs) from human bone marrow. Methods A culture of mesenchymal stem cells was initiated from bone marrow low-density mononuclear cells separated by Percoll Centrifugation and maintained in low-glucose Dulbecco's modified Eagle's medium (DMEM) with 10% selected fetal calf serum. Cell growth pattern and its responses to cytokines were evaluated by trypan blue exclusion and MTT test, respectively. Cell cycle and surface antigenic features were analyzed by flow cytometry technique. Cytochemistry characteristics of MSCs were determined. Results Easy-handling methods to isolate and culture expand MSCs were developed in this study. MSCs were unique in their phenotypes. They were positive for CD29, CD44, CD166, and negative for CD34, CD45, HLA-DR and Ulex europaeus. Cytochemistry evaluation showed that MSCs were homogeneously positive for acid α-naphthl acetate esterase (ANAE), glycogen (periodic acid Schiff reaction, PAS), and negative for acid phosphatase (ACP) and the Sudan black reaction (SB). Around 5% of them were positive for alkaline phosphatase (ALP). The cells had a population doubling time of 30 hours and cell cycle analysis showed that approximately 10% of them were in S phase. MSCs grew at significantly different rates when incubated in the presence of various recombinant human cytokines, of which interferon γ, tumor necrosis factor α, stem cell factor and insulin-like growth factor promoted the proliferation of MSCs dramatically, while others tested had no effects on cell growth. Conclusions MSCs are a homogenous population of cells that have unique growth, phenotypical and cytochemical characteristics. Furthermore, the diverse responses of MSCs to different cytokines provide a clue for the selection of optimal expansion and maintenance of MSCs.

Effect of type I collagen on the adhesion, proliferation, and osteoblastic gene expression of bone marrow-derived mesenchymal stem cells

Objective: To investigate the effects of porous poly lactide-co-glycolide (PLGA) modified by type I collagen on the adhesion, proliferation, and differentiation of rabbit marrow-derived mesenchymal stem cells (MSCs). Methods: The third generation MSCs isolated from mature rabbits by density gradient centrifugation were cultured at different initial concentrations on 0.3 cm×1.2 cm×2.0 cm 3-D porous PLGA coated by type I collagen in RPMI 1640 containing 10% fetal calf serum, while cultured on PLGA without type I collagen as control. The cells adhesive and proliferative behavior at 7, 14, and 21 days after inoculation was assessed by determining the incorporation rate of [3H]-TdR. In order to examine MSCs differentiation, the expression of osteoblasts marker genes, osteocalcin (OCN), alkaline phosphatase (ALP), osteopontin (OPN) mRNA, were evaluated by reverse transcription-polymerase chain reaction (RT-PCR), and further more, the cell morphology at 21 days was also observed by scanning electron microscope (SEM). Results: Type I collagen promoted cell adhesion on PLGA. The valve was significantly higher than controls (6 h, 2144 cpm±141cpm vs. 1797 cpm±118 cpm, P=0.017; 8 h, 2311 cpm±113 cpm vs. 1891 cpm±103 cpm, P=0.01). The cells which cultured on PLGA coated with type I collagen showed significantly higher cell proliferation than controls on the 7th day (1021 cpm±159 cpm vs. 451 cpm±67 cpm, P=0.002), the 14th day (1472 cpm±82 cpm vs. 583 cpm±67 cpm, P<0.001) and 21th day (1728 cpm±78 cpm vs. 632 cpm±55 cpm, P<0.001). Osteoblasts markers, OCN, ALP, OPN mRNA, were all detected on PLGA coated by type I collagen on the 21th day, but OCN, OPN mRNA could not be found in controls. Spindle and polygonal cells well distributed on the polymer coated by type I collagen while cylindric or round cells in controls. Conclusions: Type I collagen is effective in promoting the adhesion, proliferation and differentiation of MSCs on PLGA.