Mechanism of vascular endothelial cell-derived exosomes modified with vascular endothelial growth factor in steroid-induced femoral head necrosis

Abstract

Steroid-induced avascular necrosis of the femoral head (SANFH) is an intractable orthopedic disease. This study investigated the regulatory effect and molecular mechanism of vascular endothelial cell (VEC)-derived exosomes (Exos) modified with vascular endothelial growth factor (VEGF) in osteogenic and adipogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in SANFH. VECs were cultured in vitro and transfected with adenovirus Adv-VEGF plasmids. Exos were extracted and identified. In vitro/vivo SANFH models were established and treated with VEGF-modified VEC-Exos (VEGF-VEC-Exos). The internalization of Exos by BMSCs, proliferation and osteogenic and adipogenic differentiation of BMSCs were determined by the uptake test, cell counting kit-8 (CCK-8) assay, alizarin red staining, and oil red O staining. Meanwhile, the mRNA level of VEGF, the appearance of the femoral head, and histological analysis were assessed by reverse transcription quantitative polymerase chain reaction and hematoxylin-eosin staining. Moreover, the protein levels of VEGF, osteogenic markers, adipogenic markers, and mitogen-activated protein kinase (MAPK)/extracellular regulated protein kinases (ERK) pathway-related indicators were examined by Western blotting, along with evaluation of the VEGF levels in femur tissues by immunohistochemistry. Glucocorticoid (GC) induced adipogenic differentiation of BMSCs and inhibited osteogenic differentiation. VEGF-VEC-Exos accelerated the osteogenic differentiation of GC-induced BMSCs and inhibited adipogenic differentiation. VEGF-VEC-Exos activated the MAPK/ERK pathway in GC-induced BMSCs. VEGF-VEC-Exos promoted osteoblast differentiation and suppressed adipogenic differentiation of BMSCs by activating the MAPK/ERK pathway. VEGF-VEC-Exos accelerated bone formation and restrained adipogenesis in SANFH rats. VEGF-VEC-Exos carried VEGF into BMSCs and motivated the MAPK/ERK pathway, thereby promoting osteoblast differentiation of BMSCs in SANFH, inhibiting adipogenic differentiation, and alleviating SANFH.

The role and applications of extracellular vesicles in osteoporosis

“… 127 Studies have shown that EVs secreted by ECs (EC-EVs) can improve the activity and functions of osteocytes induced by steroids. 128 , 129 Mechanistically, EC-EVs play an antiosteoporotic role by inhibiting osteocyte ferroptosis. 129 A similar phenomenon occurs when EVs are derived from endothelial progenitor cells (EPCs), which can reverse osteoporosis induced by large doses.…”

Unraveling the Role of Endothelial Dysfunction in Osteonecrosis of the Femoral Head: A Pathway to New Therapies

“…( Table 1 ). For example, the activation of MAPK/ERK, SMAD, Wnt/β-catenin, and cAMP signaling is facilitated by the secretion of exosomes and cytokines derived from endothelial cells, which foster the formation of osteoblasts and chondrocytes [ 24 , 25 , 26 , 27 , 28 , 29 ]. By modulating histone lactylation, endothelial cell-derived metabolites like lactate stimulate the osteogenic differentiation of mesenchymal stem cells [ 30 ].…”