The effect of genetically modified platelet-derived growth factor-BB over-expressing mesenchymal stromal cells during core decompression for steroid-associated osteonecrosis of the femoral head in rabbits

Abstract

Background Approximately one third of patients undergoing core decompression (CD) for early-stage osteonecrosis of the femoral head (ONFH) experience progression of the disease, and subsequently require total hip arthroplasty (THA). Thus, identifying adjunctive treatments to optimize bone regeneration during CD is an unmet clinical need. Platelet-derived growth factor (PDGF)-BB plays a central role in cell growth and differentiation. The aim of this study was to characterize mesenchymal stromal cells (MSCs) that were genetically modified to overexpress PDGF-BB (PDGF-BB-MSCs) in vitro and evaluate their therapeutic effect when injected into the bone tunnel at the time of CD in an in vivo rabbit model of steroid-associated ONFH. Methods In vitro studies: Rabbit MSCs were transduced with a lentivirus vector carrying the human PDGF-BB gene under the control of either the cytomegalovirus (CMV) or phosphoglycerate (PGK) promoter. The proliferative rate, PDGF-BB expression level, and osteogenic differentiation capacity of unmodified MSCs, CMV-PDGF-BB-MSCs, and PGK-PDGF-BB-MSCs were assessed. In vivo studies: Twenty-four male New Zealand white rabbits received an intramuscular (IM) injection of methylprednisolone 20 mg/kg. Four weeks later, the rabbits were divided into four groups: the CD group, the hydrogel [HG, (a collagen-alginate mixture)] group, the MSC group, and the PGK-PDGF-BB-MSC group. Eight weeks later, the rabbits were sacrificed, their femurs were harvested, and microCT, mechanical testing, and histological analyses were performed. Results In vitro studies: PGK-PDGF-BB-MSCs proliferated more rapidly than unmodified MSCs (P < 0.001) and CMV-PDGF-BB-MSCs (P < 0.05) at days 3 and 7. CMV-PDGF-BB-MSCs demonstrated greater PDGF-BB expression than PGK-PDGF-BB-MSCs (P < 0.01). However, PGK-PDGF-BB-MSCs exhibited greater alkaline phosphatase staining at 14 days (P < 0.01), and osteogenic differentiation at 28 days (P = 0.07) than CMV-PDGF-BB-MSCs. In vivo: The PGK-PDGF-BB-MSC group had a trend towards greater bone mineral density (BMD) than the CD group (P = 0.074). The PGK-PDGF-BB-MSC group demonstrated significantly lower numbers of empty lacunae (P < 0.001), greater osteoclast density (P < 0.01), and greater angiogenesis (P < 0.01) than the other treatment groups. Conclusion The use of PGK-PDGF-BB-MSCs as an adjunctive treatment with CD may reduce progression of osteonecrosis and enhance bone regeneration and angiogenesis in the treatment of early-stage ONFH.

Effect on Osteogenic Differentiation of Genetically Modified IL4 or PDGF-BB Over-Expressing and IL4-PDGF-BB Co-Over-Expressing Bone Marrow-Derived Mesenchymal Stromal Cells In Vitro

“…The injection of PDGF-BB-MSCs significantly decreased the number of empty lacunae and increased angiogenesis compared to MSCs. In addition, CD with an injection of PDGF-BB-MSCs had a trend towards greater osteogenic differentiation than the CD alone group [ 47 ]. Regarding osteogenic differentiation in our in vitro studies, the PDGF-BB-MSC group showed the best results among all eight groups.…”

Advances in experimental models of osteonecrosis of the femoral head

“…Excessive osteoclast activity is important in bone integrity loss and subsequent subchondral bone fracture. A growing literature suggests the presence of hyperactive osteoclasts in vivo ONFH models [ [115] , [116] , [117] , [118] ]. However, exogenous glucocorticoids have been proved to directly impair osteoclast function in vitro [ 119 ].…”

Regenerative medicine for osteonecrosis of the femoral head

“…As all data on gene-modified MSCs are from animal experiments, the efficiency and safety in patients are not presently known and await evaluation in clinical trials. [36][37][38] Growth factors may be directly implanted in the lesion site to enhance osteogenesis and angiogenesis. However, direct implantation of growth factors is complicated by practical problems of peptide therapy, such as an extremely short half-life and side effects with systemic or high-dose administration.…”