Abstract: Objective To investigate the messenger ribonucleic acid (mRNA) expression level of tissue-type plasminogen activator (t-PA) in endothelial cells derived from adult mesenchymal stem cells (MSCs) after fluid shear stress loading which is within the physiological range. Methods After culturing in vitro, bone marrow MSCs of SD rats were seeded on slides.When it come to 80% confluence,26 slides were exposed to 5dyn/cm2 fluid shear stress for 3h in a flow chamber, and then induced to endothelial cells. Among them,13 slides constituted group Ⅰ, and the rest 13 slides set up group Ⅱ, which would be cultured for 3-4d further and passaged in 1∶3. At the same time, control group was set up, which including the cells never exposed to fluid shear stress before the endothelial differentiation. Fluid shear stress were exerting to cells in a specially made flow chamber. The expression level of t-PA mRNA of all groups were measured by real-time fluorescent quantitation reverse transcriptionpolymerase chain reaction (RTPCR). Results After endothelial differentiation for 7 days, the SD rats bone marrow MSCs acquired typical endothelial cell appearance. The t-PA mRNA expression level of group Ⅰ and group Ⅱ have an obviously enhance compared with control group(P＜0.05). The t-PA mRNA expression level of group Ⅱ step down a little (P＞0.05), but it is still significantly higher than that of control group (P＜0.05). Conclusion Fluid shear stress could provide a protective action on the endothelial cells induced from MSCs in vitro, and the effect maintains with the cells passages. This formulates a theoretical foundation to the therapeutics of atherosclerosis and selection of seed cells in vascular tissue engineering.
Objective To study the differenation of adult marrow mesenchymal stem cells(MSCs) into vascular endothelial cells in vitro and to explore inducing conditions. Methods MSCs were isolated from adult marrow mononuclear cells by attaching growth. MSCs were divided into 4 groups to induce: the cells seeded at a density of 5×103/cm2 in 2% and 15% FCS LDMEM respectively (group1 and group 2)， at a density of 5×104/cm2 in 2% and 15% FCS LDMEM respectively (group 3 and group 4); vascular endothelial growth factor(VEGF) supplemented with Bovine pituitary extract was used to induce the cell differentiation. The differentiated cells were identified by measuring surfacemarks (CD34, VEGFR2, CD31 and vWF ) on the 14th day and 21st day and performed angiogenesis in vitroon the 21st day.The cell proliferation index（PI）of different inducing conditions were measured. Results After induced in VEGF supplemented with Bovine pituitary extract, the cells of group 3 expressed the surface marks CD34, VEGFR-2, CD31 and vWF on the 14th day, the positive rates were 8.5%, 12.0%, 40.0% and 30.0% respectively, and on the 21st day the positive ratesof CD34 and VEGFR2 increased to 15.5％ and 20.0％, while the other groups did not express these marks; the induced cells of group 3 showed low proliferating state(PI was 10.4%) and formed capillary-like structure in semisolid medium. Conclusion Adult MSCs can differentiate into vascular endothelial cellsafter induced by VEGF and Bovine pituitary extract at high cell densities and low proliferatingconditions，suggesting that adult MSCs will be ideal seed cells forthe therapeutic neovascularization and tissue engineering.
Objective To establish a model of the human marrow mesenchymal stem cells (hMSCs) cultured under the hypoxic condition in adults and to investigate the biological features of MSCs under hypoxia.Methods The bone marrow was obtained by aspiration at the posterior superior iliac spine in 3 healthy adult subjects. hMSCs were isolated by the gradient centrifugation and were cultured in the DMEM-LG that contained 20％ fetal bovine serum. The serial subcultivation was performed 10-14 days later. The second passage of the hMSCs were taken, and they were divided into the following 4 groups according to the oxygen concentrations and the medium types: the normoxic group（20％O2, DMEM-LG, Group A）, the hypoxic group（1％O2, DMEM-LG,Group B）, the normoxic osteoblast induction group（20％O2, conditioned medium, Group C）, and the hypoxic osteoblast induction group（1％O2, conditioned medium, Group D）. The biological features of the cultured hMSCs under hypoxia were assessed bythe cell count, the MTT method, the colony forming unit-fibroblast, the real-time RT-PCR, and the alkaline phosphatase (ALP) activity, and the alizarinred staining. Results The hMSCs cultured in the Group B and Group D had a significantly higher proliferation rate than those in the Group A (Plt;0.01), and the culture effect was not influenced by the medium type. The hMSCs in the Group B had a significantly higher level of the colony-forming unit capability than the hMSCs cultured in the Group A(Plt;0.01). After the induction, hMSCs in the Group B had a decreasednumber of the osteoblasts than hMSCs in the Group C. The hMSCs in the Group D had a gradually-increasedactivity of ALP, which was significantly lower than that in the Group C(Plt;0.01). The RT-PCR examination revealed that ALP,osteocalcin, and mRNA expressions of collagen type Ⅰ and osteonectin in the Group Csignificantly increased （P＜0.01). By comparisonamong the 3 groups, after the 4-week culture the obvious calcium salt deposit and the red-stained calcium nodus could be observed.ConclusionHypoxia can promote the proliferation rate of hMSCs, enhance the colonyforming ability and inhibit the differentiation of the osteoblasts.
Objective To investigate the effect of the synthetic bone morphogenetic protein 2 (BMP-2)derived peptide on the osteogenic induction in the marrow mesenchymal stem cells (MSCs）and to evaluate the osteoinductivity and dosedependence of the BMP-2 derived peptide in vitro. Methods MSCs of 4-week old Wistar rats were separated and cultured. In the 3rd passage, the conditional culture medium was changed, in which the BMP-2-derived peptide in the following doses was added: 300,200, 100, 50, and 0 μg/ml, respectively (Groups A-E). The activity of alkaline phosphatase (ALP）and the amount of calciumdeposition were meassured at 5，10，15 and 20 days during the culture with the conditional culture medium. The real-time fluorescent quantitative polymerase chain reaction (FQ-PCR) was performed to measure the mRNA expressions of collagen type Ⅰ, osteopontin (OPN), and osteocalcin（OCN）and to measure the osteoinductivity of the BMP-2-derived peptide in the different concentrations.Results Under the inverted phase contrast microscope, MSCs cultured in the conditional culture medium for 3-4 days were changed in shape, from long fusiform to short fusiform or polygon. As the concentration of the BMP-2-derived peptide increased, the time for MSCs to change into the osteoblasts decreased. There was a significantly greater level of the ALP activity and amount of the calcium deposition in Groups A and B than in the other groups（Plt;0.05）. However,there was no significant difference between Group A and Group B （Pgt;0.05）. Theresult of FQPCR showed that after MSCs were cultured in the different doses of theconditional culture medium for 14 days, the mRNA expressions of collagen type Ⅰ, OPN andOCN were at higher levels. An increasing order in the level of the cycle threshold (Ct) was found in the following groups: Agt;Bgt;Cgt;D. Almost no expression was found in Group E. The Ct levels were significantly greater in Groups A and B thanin Groups C and D（Plt;0.05）. However, there was no significant difference between Group A and Group B （Pgt;0.05）.ConclusionThe BMP-2-derived peptide can greatly promote differentiation of MSCs into the osteoblasts, the promotion of osteogenesis has a dosedependent pattern, and the best inducing dosage is 200 μg/ml.
Objective To explore the effect of the platelet-rich plasma (PRP) on proliferation and osteogenic differentiation of the bone marrow mesenchymal stem cells (MSCs) in China goat in vitro. Methods MSCs from the bone marrow of China goat were cultured. The third passage of MSCs were treated with PRP in the PRP group (the experimental group), but the cells were cultured with only the fetal calf serum (FCS) in the FCS group (the control group). The morphology and proliferation of the cells were observed by an inverted phase contrast microscope. The effect of PRP on proliferation of MSCs was examined by the MTT assay at 2,4,6 and 8 days. Furthermore, MSCs were cultured withdexamethasone（DEX）or PRP; alkaline phosphatase (ALP) and the calcium stainingwere used to evaluate the effect of DEX or PRP on osteogenic differatiation of MSCs at 18 days. The results from the PRP group were compared with those from the FCS group. Results The time for the MSCs confluence in the PRP group was earlier than that in the FCS group when observed under the inverted phase contrast microscope. The MTT assay showed that at 2, 4, 6 and 8 days the mean absorbance values were 0.252±0.026, 0.747±0.042, 1.173±0.067, and 1.242±0.056 in the PRP group, but 0.137±0.019, 0.436±0.052, 0.939±0.036, and 1.105±0.070 in the FCS group. The mean absorbance value was significantly higher in the PRP group than in the FCS group at each observation time (P＜0.01). Compared with the FCS group, the positive-ALP cells and the calcium deposition were decreased in the PRP group; however, DEX could increase boththe number of the positiveALP cells and the calcium deposition. Conclusion The PRP can promote proliferation of the MSCs of China goats in vitro but inhibit osteogenic differentiation.
Objective To investigate the therapeutic effects of transplanting allogeneic marrow mesenchymal stem cells (MSCs) via subarachnoid space on spinal cord injury(SCI) and the T cell subpopulation. Methods Density gradient centrifugation was used to isolate and expand MSCs from bone marrow of 10 six-week-old SD rats. The SCI model was produced by weightbeating from 60 eight-week-old female SD rats. Forty survival SCI rats,which BBB scores were zero, were divided randomly into 2 groups:experimental group(group A) and control group(group B). In addition, 20 normal eightweekold SD ratswere used as blank group (group C). In group A, 1 ml cells suspention containing MSCs(the 6th generation, 2×106/ml) was injected via subarachnoid space. Ingroup B, equal volume of L-DMEM was injected in the same way. The BBB score was obtained after 1st,2nd and 3rd weeks of injection. At the same time,T cell subpopulation was detected by flow cytometry. Results The BBB score in group A was better than that in group B, but fewer than that in group C in the 3rd week. CD4+T cells in group A were less than those in groups B and C in the 1st, 2nd, and 3rd weeks. CD8+T cells in group A were less than those in groups B and C in the 2nd and 3rd weeks. The ratio of CD4+/CD8+T cells in group A was less than those in groups B and C in the 1st week. Above differences showed statistically significant difference(P＜0.05). However, there were no statistically significant differences in the ratio of CD4+/CD8+T cells between group A and groups B, C in the 2nd and 3rd weeks (P＞0.05). Conclusion The above results suggest that allogeneic MSCs transplantation via subarachnoid space is beneficial to SCI to some extend, do not result in rejection in vivo. Furthermore, it can lead to immunosuppression in short time. So, it provides clues to apply MSCs to treat SCI and other diseases.
Objective To review the advances in repair of spinal cord injury by transplantation of marrow mesenchymal stem cells(MSCs). Methods The related articles in recent years were extensively reviewed,the biological characteristic of MSCs,the experimental and clinical studies on repair of spinal cord injury by transplantation of MSCs,the machanisms of immigration and therapy and the problems were discussed and analysed. Results The experimental and clinical studies demonstrated that the great advances was made in repair of spinal cord injury by transplantation of MSCs. After transplantation, MSCs could immigrate to the position of spinal cord injury, and differentiate into nervelike cells and secrete neurotrophic factors.So it could promote repair of injuryed spinal cord and recovery of neurologicalfunction. Conclusion Transplantation of MSCs was one of effective ways in repair of spinal cord injury, but many problems remain to be resolved.
Objective To investigate the effect of homograft of marrow mesenchymal stem cells (MSCs) seeded onto poly-L-lactic acid (PLLA)/gelatin on repair of articular cartilage defects. Methods The MSCs derived from36 Qingzilan rabbits, aging 4 to 6 months and weighed 2.5-3.5 kg were cultured in vitroand seeded onto PLLA/gelatin. The MSCs/ PLLA/gelatin composite was cultured and transplanted into full thickness defects on intercondylar fossa. Thirty-six healthy Qingzilan rabbits were made models of cartilage defects in the intercondylar fossa. These rabbits were divided into 3 groups according to the repair materials with 12 in each group: group A, MSCs and PLLA/gelatin complex(MSCs/ PLLA/gelatin); group B, only PLLA/gelatin; and group C, nothing. At 4,8 and 12 weeks after operation, the gross, histological and immunohistochemical observations were made, and grading scales were evaluated. Results At 12 weeks after transplantation, defect was repaired and the structures of the cartilage surface and normal cartilage was in integrity. The defects in group A were repaired by the hylinelike tissue and defects in groups B and C were repaired by the fibrous tissues. Immunohistochemical staining showed that cells in the zones of repaired tissues were larger in size, arranged columnedly, riched in collagen Ⅱ matrix and integrated satisfactorily with native adjacent cartilages and subchondral bones in group A at 12 weeks postoperatively. In gross score, group A(2.75±0.89) was significantly better than group B (4.88±1.25) and group C (7.38±1.18) 12 weeks afteroperation, showing significant differences (P＜0.05); in histological score, group A (3.88±1.36) was better than group B (8.38±1.06) and group C (13.13±1.96), and group B was better than group C, showing significant differences (P＜0.05). Conclusion Transplantation of mesenchymal stem cells seeded onto PLLA/gelatin is a promising way for the treatment of cartilage defects.
Objective To explore the effect of age and gene therapyon the differentiation of marrow mesenchymal stem cells （MSCs） of the rats. Methods MSCs from the young (1-month-old), adult (9-month-old), and the aged(24monthold) rats were expanded in culture and infected with adenovirus mediated human bone morphogenetic protein 2 gene (Ad-BMP-2). The expression of BMP-2 and osteoblastic markers such as alkaline phosphatase(ALP), collagen Ⅰ(Col Ⅰ), bone sialoprotein(BSP) and osteopontin(OPN) were assayed during the process of differentiation. Their abilities to induce ectopic bone formation in nude mice were also tested. Results There was no significant difference in the expression of BMP-2 among the 3 groups. ALP activity assay and semi-quantitative reverse transcription polymerase chain reaction(RT-PCR) demonstrated that there were no significant differences in the expression of osteoblastic markers ALP, Col-Ⅰ, OPN and BSP amongthe 3 groups. Histomorphometric analysis indicated that there were no significant differences in the volume of the newly formed ectopic bones in nude mice amongthe 3 groups. Conclusion MSCs obtained from the aged ratscan restore their osteogenic activity following human BMP-2 gene transduction, therefore provides an alternative to treating the aged bone disease.
Objective To evaluate the effect of Schwann cell (SC) on the proliferation of marrow mesenchymal stem cells (MSCs) and provide evidence for application of SC in construction of the tissue engineered vessels.Methods SC and MSCs were harvested from SD rats(weight 40 g). SC were verified immunohstochemically by the S-100 staining, and MSCs were verified by CD 44, CD 105, CD 34 and CD 45. The 3rd passages of both the cells were cocultured in the Transwell system and were amounted by the 3H-TDR integration technique at 1, 3, 5 and 7 days,respectively. The results were expressed by the CPM(counts per minute, CPM) values. However, MSCs on both the layers were served as the controls. The Westernblot was performed to assess the expression of the vascular endothelial growth factor (VEGF), its receptor Flk-1, and the associated receptor neuropilin 1(NRP-1) in SC, the trial cells, and the controls. Results SC had a spindle shape in the flasks, and more than 90% of SC had a positive reaction for the S-100 staining.MSCs expressed CD44 and CD105, and had a negativesignal in CD 34 and CD 45. The CPM values of MSCs in the trial groups were 2 411.00±270.84，3 016.17±241.57，6 570.83±2 848.27 and 6 375.8±1 431.28at 1, 3, 5 and 7 days, respectively. They were significantly higher in their values than the control group (2 142.17±531.63，2 603.33±389.64，2 707.50±328.55，2 389.00±908.01), especially at 5 days （P＜0.05）. The Western blot indicated that VEGF was expressedobviously in both the SC group and the cocultured MSCs grou,p and was less visible in the control cells. The expressions of Flk-1 and NRP-1 inthe cocultured MSCs were much ber than in the controls. Conclusion SC can significantly promote the proliferation of MSCs when they are cocultured. The peak time of the proliferation effect appeared at 5 days. This effect may be triggered by the up-regulation of VEGF in MSCs, which also leads to the upregulation of Flk-1 and NRP-1 .