Influences of hucMSC-exosomes on VEGF and BMP-2 expression in SNFH rats.

Abstract

To investigate the influences of human umbilical cord mesenchymal stem cell-derived exosomes (hucMSC-exosome) on steroid-induced necrosis of the femoral head (SNFH) and the expressions of vascular endothelial growth factor (VEGF) and bone morphogenetic protein-2 (BMP-2) in rats. A total of 20 male Sprague-Dawley rats were randomly divided into SNFH group and SNFH + hucMSC-exosome group using a random number table. Prednisolone acetate (24.5 mg/kg) was injected twice a week to establish the rat model of SNFH, and hucMSC-exosome in a certain dose was additionally injected into the marrow cavity in SNFH + hucMSC-exosome group. After 3 weeks, the influences of hucMSC-exosome on the pathological changes and apoptosis of the femoral head in SNFH rats were detected via hematoxylin-eosin (H&E) staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining. In addition, the expressions of cluster of differentiation 31 (CD31), VEGF, and BMP-2 in bone tissues in both groups were detected via immunohistochemical staining, and the messenger ribonucleic acid (mRNA) and protein expression levels of VEGF and BMP-2 in necrotic bone tissues in both groups were detected via Reverse Transcription-Polymerase Chain Reaction (RT-PCR) and Western blotting. The results of H&E staining revealed that the fibrous callus formation was good, the new trabecular structure was more obvious, the number of vacuum cleft declined, and there were fewer enlarged adipocytes in SNFH + hucMSC-exosome group compared with SNFH group. The results of TUNEL staining showed that the number of apoptotic cells in femoral head tissues was smaller in SNFH + hucMSC-exosome group (p<0.05). According to the results of immunohistochemistry, hucMSC-exosome could increase the expression of vascular endothelial marker CD31 in SNFH rats (p<0.05). Besides, the results of RT-PCR, immunostaining and Western blotting manifested that both the mRNA and protein levels of BMP-2 and VEGF in femoral head tissues were significantly increased in SNFH + hucMSC-exosome group (p<0.05). HucMSC-exosome can improve SNFH in rats, whose mechanism may be related to the up-regulation of VEGF and BMP-2 by exosomes.