[Transplantation of bone marrow cells up-regulated the expressions of HSP32 and HSP70 in the acute ischemic myocardium].

OBJECTIVE

To clarify the role of Heat shock proteins (HSPs) on the cardiac function during acute myocardial infarction (AMI) after bone marrow cell implantation (BMT), we examined the expression of HSP32 and HSP70 in a rat model of myocardial infarction.

METHODS

Myocardial infarction model was induced in the inbred Lewis rats by left anterior descending artery ligation, and 5 x 10(6) of bone marrow-mononuclear cells (BM-MNCs) were injected into an ischemic zone. On days 1, 3, 7 and 14 post-infarct, the differentiations of transplanted cells and the expressions of HSP32 and HSP70 were determined by immunofluorescence or RT-PCR. The cardiac function was evaluated by echocardiography.

RESULTS

Immunofluorescence microscopy of hearts from BMT group revealed that expressions of HSP32 and HSP70 were promoted within cardiomyocytes in the infarction zone and the peri-infarct zone, and expressed within some transplanted bone marrow cells as well. RT-PCR also showed the mRNA expression levels of HSP32 and HSP70 in BMT group were significantly higher than those of the control group, peaked on day 3 post-infarct (5.0-fold and 2.9-fold, respectively, P < 0.01), and then gradually reduced. On day 7 post-infarct, cardiac function (EF and FS) was improved, more than that of the control group (14% and 22%, P < 0.05). On day 14 post-infarct, the specific markers for myocardium or vascular endothelial cells were detected in the transplanted bone marrow cells. The cardiac function was further improved in the BMT group (P < 0.01).

CONCLUSION

At the early phase after BMT, the expressions of HSP32 and HSP70 were upregulated in both transplanted cells and recipient endogenous cardiomyocytes, which improved the acute ischemic cardiac function.