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. 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. 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. 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.

中文翻译：

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转基因血小板衍生生长因子-BB过表达间充质基质细胞在核心减压过程中对兔类固醇相关股骨头坏死的影响

大约三分之一因早期股骨头坏死 (ONFH) 而接受核心减压 (CD) 的患者经历了疾病的进展，随后需要进行全髋关节置换术 (THA)。因此，确定辅助治疗以优化 CD 期间的骨再生是一个未满足的临床需求。血小板衍生生长因子 (PDGF)-BB 在细胞生长和分化中起着核心作用。本研究的目的是表征经过基因改造以在体外过表达 PDGF-BB (PDGF-BB-MSCs) 的间充质基质细胞 (MSCs)，并评估它们在 CD 时注射到骨隧道中时的治疗效果。类固醇相关 ONFH 的体内兔模型。体外研究：在巨细胞病毒 (CMV) 或磷酸甘油酸 (PGK) 启动子的控制下，使用携带人 PDGF-BB 基因的慢病毒载体转导兔 MSC。评估未修饰的 MSC、CMV-PDGF-BB-MSC 和 PGK-PDGF-BB-MSC 的增殖率、PDGF-BB 表达水平和成骨分化能力。体内研究： 24 只雄性新西兰白兔接受了 20 毫克/千克甲基强的松龙肌肉内 (IM) 注射。4 周后，兔子被分为四组：CD 组、水凝胶 [HG，（一种胶原-海藻酸盐混合物）] 组、MSC 组和 PGK-PDGF-BB-MSC 组。八周后，兔子被处死，股骨被收获，并进行了显微CT、机械测试和组织学分析。体外研究：在第 3 天和第 7 天，PGK-PDGF-BB-MSCs 比未修饰的 MSCs (P < 0.001) 和 CMV-PDGF-BB-MSCs (P < 0.05) 增殖更快。CMV-PDGF-BB-MSCs 表现出更高的 PDGF-BB 表达比 PGK-PDGF-BB-MSCs (P < 0.01)。然而，与 CMV-PDGF-BB-MSC 相比，PGK-PDGF-BB-MSC 在 14 天时表现出更强的碱性磷酸酶染色（P < 0.01），并在 28 天时表现出更大的成骨分化（P = 0.07）。体内：与 CD 组相比，PGK-PDGF-BB-MSC 组具有更高的骨矿物质密度 (BMD) 趋势（P = 0.074）。与其他治疗组相比，PGK-PDGF-BB-MSC 组的空腔隙数量显着减少（P < 0.001），破骨细胞密度更高（P < 0.01），血管生成更多（P < 0.01）。