Résumé
Objective: To investigate the effects of secreted protein acidic and rich in cysteine (SPARC) peptide on ultramicrostructure and extracellular matrix secretion of human mesangial cells cultured in vitro. Methods: Human mesangial cells (HMC) were incubated at the presence of SPARC peptide (50 μg/ml)for 48 h and 96 h separately; HMC cultured without SPARC peptide was taken as control. The cell ultramicrostructure was observed by transmission electron microscope. Real-time fluorescent quantitative PCR (RT-PCR) was used to detect mRNA levels of collagen type I (Col I), collagen type IV (Col IV), fibronectin (FN), and laminin (LN) 96 hours after culture, and the results were compared between the 2 groups. The secreted levels of Col I, Col IV, FN, and LN protein were measured and compared by enzyme-linked immunosorbent assay (ELISA) in the 2 groups. Results: There was no obvious change in HMC in the control group. After cultured for 48 hours, a few HMC in experimental group showed initial appearance of apoptosis; after cultured for 96 h, a great number of HMC had a typical apoptotic appearance and there were typical apoptotic bodies under electron microscope. RT-PCR showed that, compared with the control group, the experimental group had significantly decreased levels of Col I, Col IV and FN mRNA (P<0.05, P<0.0l); ELISA results showed that the secretions of Col I, ColIV, and FN protein in the experimental group were greatly lower than those in the control garoup (P<.05, P<0.01). Conclusion: SPARC peptide can effectively induce apoptosis of human mesangial cells and down regulate the secretion of extracellular matrix in vitro.