BACKGROUND: Schwann calls are seed cells for constructing tissue engineered peripheral nerves. But their in vitro isolation, culture and purification are difficult. Acellular nerve allografts (ANA) have a great effect on repairing peripheral nerve defects, and it can induce marrow stromal cells (MSCs) into Schwann-like calls. Accordingly, MSCs can be used as seed calls theoretically in constructing tissue engineered peripheral nerves, instead of Schwann cells OBJECTIVE: To observe the repairing effect of tissue engineered peripheral nerves constructed with MSCs on sciatic nerve defects and to assess the feasibility of repairing peripheral nerve defects with MSCs as seed calls. DESIGN, TIME AND SE'I-rlNG: A randomized control animal experiment was conducted in the laboratory of Basic Medicine Collage of Dali Collage from July to December in 2008.MATERIALS: A total of 30 SD rats were divided randomly into 3 groups, with 10 in each group. In MSCs+ ANA group, end-to-end anastomosis were performed with 10/0 non traumatic suture to broken ends of rat sciatic nerves and tissue engineered nerves cultured using MSCs combined with ANA; In ANA group, ANA were bridged to broken ends of sciatic nerves; In METHODS: The 10ram sciatic nerve defects in rats were repaired using MSCs-constructed tissue engineered peripheral nerves, whose repairing effects were evaluated at week 12 post transplant through sciatic function index (SFI), gastrocnemius wet weight recovery rate, S-100 immunohistochemical staining and electron microscope observation, etc. MAIN OUTCOME MEASURES: Morphological changes of calls were observed during the culture of compounds; SFI and gastrocnemius wet weight recovery rates were detected after transplantation; New myelinization, axon growth and nerve fiber distdbuUon were observed with toluidine blue staining; Schwann calls growth and nerve fiber regeneration were observed with transmission electron microscope combined with S-100 protein immunohistochemical staining method.RESULTS: The detection results showed that SFI and gastrocnemius wet weight recovery rate were higher in the MSCs+ ANA group than in the ANA group (P < 0.05). Compared the ANA group, the MSCs+ ANA group had more S-100 proteins expressed in its compounds obviously, and the number, the diameter of its myelinated nerve fibers as well as its myelin sheath thickness were all greater than those of the ANA group (P < 0.05). The repairing effect of the MSCs+ ANA group was close to that of the autotransplantation group.CONCLUSION: MSCs-constructed tissue engineered nerves have a better effect on repairing peripheral nerve defects than ANA, and MSCs as seed cells have a high value in peripheral nerve tissue engineering.

Objective: To investigate the association between inflammatory cytokines and ventricular remodeling after acute myocardial infarction (AMI) in rats, and the effects of simvastain on inflammatory cytokines and ventricular remodeling after AMI thereof. Methods: After AMI was produced in female SD rats, the animals were divided into control group,simvastain group and sham-operated group. After transthoracic echocardiography, TNF-α, IL-6 and P Ⅲ NP of the serum and cardiac muscle were measured by radioimmunology technology. The comparative heart weight and infarct sizes were calculated.Results: Compared with the control group, the LVDd and LVDs decreased significantly (P ＜ 0.05), LVEF,LVFS and posterior wall thicking increased significantly (P ＜ 0.05) in simvastain group. The values of TNF-α, IL-6 and P Ⅲ NP increased significantly in simvastain and control group compared with those of sham-operated group(P ＜ 0.05 or P ＜ 0.01 ). The values ot TNF-α, IL-6 and pⅢ NP decreased significantly in simvastain group compared with those of the control group (P ＜ 0.05). The comparative heart weight and infarct size decreased significantly in simvastain group compared with those of the control group (P ＜ 0.05). Conclusion: Simvastain can ameliorate the ventricular remodeling and improve cardiac performance after AMI by restraining the overexpression of inflammatory cytokines.

This study was amied to construct CXCR4 gene modified bone marrow mesenchymal stem cells (MSCs), and investigate the effect of CXCR4 expression on MSCs migration. The retrovirus vector pMSCV-CXCR4-IRES-GFP that expresses human CXCR4 gene was cloned,the MSCs were transduced by the virus, and the expression of OXCR4 was analyzed by FACS, RT-PCR and immunofluorescence staining. The migration assay was performed using Transwell method in the presence of SDF-1. FACS results showed that 46% of the transduced MSCs were CXCR4 positive, and 57% were GFP positive. The expression of CXCR4 in MSCs was also confirmed by RT-PCR and immunostaining. The migration of MSCs was induced by SDF-1 and was strongly dependent on CXCR4 expression. The concentration of SDF-1 had effect on the migration and the transmigration rate of CXCR4 modified; the amount of MSCs was 5-fold higher than that of untransduced MSCs when the optimal concentration rose to 50 ng/ml. These data indicate that SDF-1/CXCR4 plays an important role in MSCs migration ,and the CXCR4 genetic modification approach could be applied to enhance cell homing, and engraftment in MSCs therapy.
Bone Marrow Cells ; cytology ; Cell Movement ; Cells, Cultured ; Chemokine CXCL12 ; pharmacology ; Genetic Vectors ; genetics ; Humans ; Mesenchymal Stromal Cells ; cytology ; metabolism ; Receptors, CXCR4 ; biosynthesis ; genetics ; Retroviridae ; genetics ; metabolism ; Transduction, Genetic ; Transfection

Bone marrow mesenchymal stem cells (MSCs) are considered as a promising cell source to treat the acute myocardial infarction. However, over 90% of the stem cells usually die in the first three days of transplantation. Survival potential, migration ability and paracrine capacity have been considered as the most important three factors for cell transplantation in the ischemic cardiac treatment. We hypothesized that stromal-derived factor-1 (SDF-1)/CXCR4 axis plays a critical role in the regulation of these processes. In this study, apoptosis was induced by exposure of MSCs to H(2)O(2) for 2 h. After re-oxygenation, the SDF-1 pretreated MSCs demonstrated a significant increase in survival and proliferation. SDF-1 pretreatment also enhanced the migration and increased the secretion of pro-survival and angiogenic cytokines including basic fibroblast growth factor and vascular endothelial growth factor. Western blot and RT-PCR demonstrated that SDF-1 pretreatment significantly activated the pro-survival Akt and Erk signaling pathways and up-regulated Bcl-2/Bax ratio. These protective effects were partially inhibited by AMD3100, an antagonist of CXCR4.We conclude that the SDF-1/CXCR4 axis is critical for MSC survival, migration and cytokine secretion.
Animals ; Apoptosis ; Apoptosis Regulatory Proteins ; genetics ; metabolism ; Bone Marrow Cells ; metabolism ; physiology ; Cell Hypoxia ; Cell Movement ; Chemokine CXCL12 ; genetics ; pharmacology ; physiology ; Cytokines ; metabolism ; Gene Expression ; L-Lactate Dehydrogenase ; metabolism ; MAP Kinase Signaling System ; Male ; Mesenchymal Stem Cells ; metabolism ; physiology ; Proto-Oncogene Proteins c-akt ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, CXCR4 ; metabolism