Department of Orthopedic Surgery, UCLA, Los Angeles, California, USA.
J Cell Biochem. 2011 Jun;112(6):1673-84. doi: 10.1002/jcb.23082.
Stimulation of bone formation by osteoinductive materials is of great clinical importance in spinal fusion surgery, repair of bone fractures, and in the treatment of osteoporosis. We previously reported that specific naturally occurring oxysterols including 20(S)-hydroxycholesterol (20S) induce the osteogenic differentiation of pluripotent mesenchymal cells, while inhibiting their adipogenic differentiation. Here we report the characterization of two structural analogues of 20S, Oxy34 and Oxy49, which induce the osteogenic and inhibit the adipogenic differentiation of bone marrow stromal cells (MSC) through activation of Hedgehog (Hh) signaling. Treatment of M2-10B4 MSC with Oxy34 or Oxy49 induced the expression of osteogenic differentiation markers Runx2, Osterix (Osx), alkaline phosphatase (ALP), bone sialoprotein (BSP), and osteocalcin (OCN), as well as ALP enzymatic activity and robust mineralization. Treatment with oxysterols together with PPARγ activator, troglitazone (Tro), inhibited mRNA expression for adipogenic genes PPARγ, LPL, and aP2, and inhibited the formation of adipocytes. Efficacy of Oxy34 and Oxy49 in stimulating bone formation in vivo was assessed using the posterolateral intertransverse process rat spinal fusion model. Rats receiving collagen implants with Oxy 34 or Oxy49 showed comparable osteogenic efficacy to BMP2/collagen implants as measured by radiography, MicroCT, and manual inspection. Histological analysis showed trabecular and cortical bone formation by oxysterols and rhBMP2 within the fusion mass, with robust adipogenesis in BMP2-induced bone and significantly less adipocytes in oxysterol-induced bone. These data suggest that Oxy34 and Oxy49 are effective novel osteoinductive molecules and may be suitable candidates for further development and use in orthopedic indications requiring local bone formation.
骨诱导材料刺激骨形成在脊柱融合手术、骨折修复和骨质疏松症治疗中具有重要的临床意义。我们之前报道过,特定的天然存在的氧化固醇,包括 20(S)-羟胆固醇(20S),诱导多能间充质细胞的成骨分化,同时抑制其脂肪生成分化。在这里,我们报告了两种 20S 的结构类似物,Oxy34 和 Oxy49 的特征,它们通过激活 Hedgehog(Hh)信号诱导骨髓基质细胞(MSC)的成骨分化和抑制脂肪生成分化。用 Oxy34 或 Oxy49 处理 M2-10B4 MSC 诱导成骨分化标志物 Runx2、Osterix(Osx)、碱性磷酸酶(ALP)、骨涎蛋白(BSP)和骨钙素(OCN)的表达,以及 ALP 酶活性和强有力的矿化。用氧化固醇与过氧化物酶体增殖物激活受体γ 激活剂曲格列酮(Tro)一起处理,抑制了脂肪生成基因 PPARγ、LPL 和 aP2 的 mRNA 表达,并抑制了脂肪细胞的形成。通过后外侧横突间大鼠脊柱融合模型评估了 Oxy34 和 Oxy49 在体内刺激骨形成的功效。在胶原植入物中加入 Oxy 34 或 Oxy49 的大鼠在放射学、MicroCT 和人工检查中显示出与 BMP2/胶原植入物相当的成骨功效。组织学分析显示,在融合块中,氧化固醇和 rhBMP2 形成了小梁骨和皮质骨,BMP2 诱导的骨中有明显的脂肪生成,而氧化固醇诱导的骨中脂肪细胞明显较少。这些数据表明,Oxy34 和 Oxy49 是有效的新型骨诱导分子,可能适合进一步开发和用于需要局部骨形成的骨科适应证。