Effect of bone marrow mesenchymal stem cells modified with Toll-like receptor 4 on cardiac function in rats after acute myocardial infarction

Abstract

Objective To investigate the effect of bone marrow mesenchymal stem cells (BMSCs) modified with Toll-like receptor 4 (TLR4) on cardiac function in rats after acute myocardial infarction. Methods BMSCs were isolated from rat bone marrow and then cultured in vitro. The recombinant lentivirus vector carrying the target gene (Lv-EGFP-TLR4) and empty virus vector (Lv-EGFP) were transfected into BMSCs respectively. The expression of TLR4 in the supernatant of BMSCs cells transfected with Lv-EGFP-TLR4 was detected by ELISA. Adult SD rats were randomly divided into 3 groups (n=18): control group, Lv-EGFP-BMSCs group and Lv-EGFP-TLR4-BMSCs group. Lv-EGFP-BMSCs and Lv-EGFP-TLR4-BMSCs were injected into the periphery of myocardial infarction in rats, respectively. The control group was injected with the same amount of PBS. On the 7th day of transplantation, the expression of EGFP positive cells was tracked by fluorescence microscopy, and the expression of TLR4 was detected by Western blotting. Cardiac function was measured by echocardiography on 28 d after transplantation. Myocardial collagen fibrosis was observed by HE and MASSON staining. Serum levels of procollagen type Ⅰ carboxyl terminal peptide (PICP) and procollagen type Ⅲ amino terminal peptide (PⅢNT) were measured by ELISA. Results After transfection of BMSCs with Lv-EGFP-TLR4, the expression of TLR4 was increased significantly in the supernatant of BMSCs, and reached 31.55 pg/mL in 48 h after transfection. On the 7th day of cell transplantation, the green fluorescence intensity of BMSCs labeled with EGFP in infarct area was significantly higher in Lv-EGFP-TLR4-BMSCs group than in Lv-EGFP-BMSCs group, and no EGFP expression was seen in control group, and the expression of TLR4 protein was also significantly higher than that in Lv-EGFP-BMSCs group (P < 0.01). On the 28th day of cell transplantation, the Lv-EGFP-TLR4-BMSCs group showed significantly higher left ventricular ejection fraction and short-axis shortening rate when compared with the Lv-EGFP-BMSCs group, but left ventricular end-systolic diameter (LVDs, 5.41±0.71) and left ventricular end-diastolic diameter (LVDd, 7.11±0.79) were statistically decreased than the other group (6.66±0.91, 8.06±0.9, P < 0.01) The Lv-EGFP-TLR4-BMSCs group also had significantly lower serum levels of PICP (72.88 vs 83.79 μg/L) and PⅢNT (7.33 vs 9.51 μg/L) than those in Lv-EGFP-BMSCs group (P < 0.05). The severity of myocardial fibrosis in Lv-EGFP-TLR4-BMSCs group was also significantly lower than that in Lv-EGFP-BMSCs group. Conclusion Transplantation of TLR4 modified BMSCs can treat myocardial infarction, attenuate the severity of myocardial fibrosis, and thereby improve the cardiac function of myocardial infarction rats.

Keywords

• toll-like receptor 4
• bone marrow mesenchymal stem cells
• acute myocardial infarction
• cardiac function