Preventive effects of siRNA targeting PPARγ gene on steroid-induced osteonecrosis in rabbits

Abstract

Purposes/Aim: Glucocorticoid steroids can induce expression of PPARg gene and enhance adipogenesis by bone marrow mesenchymal stem cells (BMSCs), which may result in osteonecrosis of the femoral head. Currently, there are no medications available to prevent steroid-induced osteonecrosis. We hypothesized that siRNA targeting PPARg gene may prevent steroid-induced adipogenesis and osteonecrosis in rabbit. The purpose of this study was to evaluate the preventive effects of siRNA targeting PPARg gene on steroid-induced adipogenesis and osteonecrosis. Methods: Forty-eight healthy New Zealand rabbits were randomized into four groups with Group M treated with dexamethasone only, Group S with dexamethasone and a recombinant adenovirus shuttle vector carrying siRNA targeting PPARg gene, Group Con with dexamethasone and a vector carrying irrelative sequence, and Group N with no treatment serving as control. Expressions of the PPARg, osteocalcin and Runx2 genes, as well as histopathologic changes were evaluated. Results: The levels of PPARg gene expression were decreased while the levels of osteocalcin and Runx2 gene expression were increased in rabbits treated with dexamethasone and recombinant adenovirus shuttle vector carrying siRNA targeting PPARg gene (Group S), compared to rabbits treated either with dexamethasone alone (Group M) or with both dexamethasone and a vector carrying irrelative sequence (Group Con). The marrow necrosis, adipocyte hypertrophy and proliferation, diminished hematopoiesis, thinner and sparse trabeculae, and increased empty osteocyte lacunae in the femoral head were observed in Group M and Group Con rabbits. However, no such changes were seen in Group S rabbits that were treated with dexamethasone and a recombinant adenovirus shuttle vector carrying siRNA targeting PPARg gene. Conclusion: siRNA targeting PPARg gene can inhibit adipogenic differentiation of BMSCs and prevent steroid-induced osteonecrosis in rabbit. The inhibition of bone-marrow adipogenesis and concomitant enhancement of osteogenesis with RNAi may provide a novel approach to the prevention of steroid-induced osteonecrosis.

Osthole stimulates bone formation, drives vascularization and retards adipogenesis to alleviate alcohol‐induced osteonecrosis of the femoral head

“…Intramedullary fat deposition is revealed as a critical pathological feature in the progress of ONFH, characterized by enlarged cellular size and increased number of adipocytes . The strengthened capacity of adipogenesis in ethanol‐induced ONFH has been revealed in several animal models . Notably, promoted adipogenic differentiation led to disordered osteogenic differentiation, and the accumulation of adipocytes might lead to a high intramedullary pressure and impair brittle blood circulation in the femoral heads .…”

“…The strengthened capacity of adipogenesis in ethanol‐induced ONFH has been revealed in several animal models . Notably, promoted adipogenic differentiation led to disordered osteogenic differentiation, and the accumulation of adipocytes might lead to a high intramedullary pressure and impair brittle blood circulation in the femoral heads . Moreover, fat emboli in vessels and sinusoids can also indirectly induce intravascular coagulation via the complement signalling pathways and deposition of immune complex, whereas antithrombotic reagents have protective effects to promote circulation and ameliorate ONFH .…”

Animal models of steroid-induced osteonecrosis of the femoral head—a comprehensive research review up to 2018

“…Many mechanisms for the pathogenesis of SONFH have been proposed, but no consensus yet exists as to the exact mechanism. Glucocorticoids directly inhibit differentiation of osteogenic progenitors to osteoblasts while simultaneously promoting adipocyte formation and deposition [8][9][10]. Liu et al [8] found that impaired osteogenic differentiation associated with connexin43/microRNA-206 is implicated in SONFH.…”

“…Fan et al [9] found that hypoxia inducible factor prolyl hydroxylase inhibitor prevents SONFH in rabbits by promoting angiogenesis and inhibiting apoptosis. Li et al [10] found that small interfering RNA (siRNA) that targets the PPARγ gene inhibits adipocytic differentiation of bone marrow mesenchymal stems cells (BMSCs) and prevents SONFH in rabbits.…”

Differential proteomic screening and identification for non-traumatic necrotic femoral osseous tissue

“…Hypoxia and ischemia cause damage to the mitochondrial function, increased oxygen free radicals, and decrease the activity of the ATP synthetase (26). The ATP synthetase on the cytomembrane surface is highly ectopic (27) in the intermediate and advanced stages. It participates in the repair process through a certain negative feedback mechanism and signal transduction.…”