ABSTRACT
ObjectiveTo study the role of alpha smooth muscle actin (α-SMA) positive cells (pericytes)in early myocardial ischemia.MethodsThirty healthy female Wistar rats were randomly divided by body weight into normal control group and subcutaneous multi-point injection of isoprenaline(Isp) group.Five rats were anesthetized after 0,2,4,6,12,24 and 48 h in each group.Blood was taken in eyeballs and,serum was separated,heart was taken and fixed in 4％ paraformaldehyde solution.The myocardial enzymes [serum apartate aminotransferase ( AST ),lactate dehydrogenase (LDH),creatine kinase (CK),creatine kinase isoenzymes (CK-MB)] were determined by biochemical automatic analyzer,the expression of α-SMA and vimentin in myocardial tissue was detected by immunohistochemical staining and changes of pericytes in early myocardial ischemia was observed by morphometric analysis.ResultsThe level of myocardial enzymes AST[(160.25 ± 3.86),(172.60 ± 8.82),(192.20 ± 25.35)U/L],and LDH[(1466.25 ± 643.38),(1645.20 ± 326.83),(1701.60 ± 640.06)U/L],12,24 and 48 h after subcutaneous injection of Isp,were higher than that[(129.18 ± 19.65),(849.45 ± 248.54)U/L,all P ＜ 0.05] of the control group.The level of CK[(1097.60 ± 301.57),(1247.20 ± 243.84),(1263.75 ± 271.22),(1448.00 ± 647.00),(1268.40 ± 479.81)U/L],and CK-MB[(217.12 ± 35.89),(229.08 ± 97.11),(251.70 ± 46.82),(318.80 ±77.76),(249.04 ±:98.54)U/L],4,6,12,24 and 48 h after subcutaneous injection of Isp,were higher than that [(713.45 ± 146.30),(147.05 ± 25.75)U/L,all P ＜ 0.05] of the control group.The number of α-SMA positive cells(61.00 ± 17.25),4 h after Isp injection,was significantly increased compared with that(28.20 ± 5.81,18.20 ± 2.17) of 24 and 48 h after Isp injection.The number of α-SMA positive cells in 48 h group was less than that(50.00 ± 3.61,P ＜ 0.05) of 6 h group.The number of vimentin positive cells in 6,12,24,48 h groups (4.17 ± 2.49,5.24 ± 2.84,8.37 ± 2.18,7.73 ± 2.49) were higher than that(1.88 ± 1.85,2.21 ± 1.54) of the control group and 4 h group(all P ＜ 0.05).Compared with 24 and 48 h groups,the level of vimentin protein was increased in 6 and 12 h groups(P ＜ 0.05).ConclusionThe number of pericytes in early myocardial ischemia is higher than that of other mesenthymal cells,and pericytes may be the main effector cells in the generation and development of myocardial fibrosis.
ABSTRACT
<p><b>OBJECTIVE</b>To establish an immortalized marrow mesenchymal stem cell line to facilitate advances in cartilage engineering research.</p><p><b>METHODS</b>Human telomerase reverse transcriptase (hTERT) cDNA was transferred into primary human marrow mesenchymal stem cells (hMSC) by retroviral vector pLEGFP-C1-hTERT. Subsequently G418 resistant cell clone was screened and expanded for further studies. hMSC biomarkers and hTERT expression were confirmed by examination. Transfected hMSC was induced to differentiate into chondrocyte using TGF-P1 and dexamethasone.</p><p><b>RESULTS</b>Up-regulated hTERT expression was detected in transfected hMSC. hMSC-hTERT cells could be induced to differentiate into chondrocyte. Higher telomerase activity in transfected cells was maintained for 50 population doublings so far. Collagen II could be detected in induced transfected hMSC by immunocytochemical and hybridization in situ.</p><p><b>CONCLUSIONS</b>Ectopic expression of hTERT can effectively immortalize hMSC in vitro. Immortalized hMSC can be induced to differentiate into chondrocyte under certain condition. It may be an ideal target of further studies in cartilage engineering.</p>