Orthopaedic Research Laboratories, Department of Surgery, Division of Orthopaedic Surgery, 375 MSRB, Box 3093, Duke University Medical Center, Durham, North Carolina 27710, USA.
J Biomed Mater Res A. 2010 Jun 1;93(3):994-1003. doi: 10.1002/jbm.a.32589.
Adipose-derived stem cells (ASCs) are multipotent progenitors that can be chondrogenically induced by growth factors such as bone morphogenetic protein 6 (BMP-6). We hypothesized that nonviral transfection of a BMP-6 construct (pcDNA3-BMP6) would induce chondrogenic differentiation of ASCs encapsulated in alginate beads and that differentiation would be enhanced by the presence of the synthetic glucocorticoid dexamethasone (DEX) or the combination of epidermal growth factor (EGF), fibroblast growth factor-2 (FGF-2), and transforming growth factor beta-1 (TGF-beta1), collectively termed expansion factors (EFs). Chondrogenesis was assessed using quantitative real-time polymerase chain reaction for types I, II, and X collagen, aggrecan, and BMP6. Immunohistochemistry was performed with antibodies for types I, II, and X collagen and chondroitin-4-sulfate. BMP6 overexpression alone induced a moderate chondrogenic response. The inclusion of EFs promoted robust type II collagen expression but also increased type I and X collagen deposition, consistent with a hypertrophic chondrocyte phenotype. Early gene expression data indicated that DEX was synergistic with BMP-6 for chondrogenesis, but immunohistochemistry at 28 days showed that DEX reduced glycosaminoglycan accumulation. These results suggest that chondrogenic differentiation of ASCs depends on complex interactions among various growth factors and media supplements, as well as the concentration and duration of growth factor exposure.
脂肪来源的干细胞（ASCs）是多能祖细胞，可以通过生长因子如骨形态发生蛋白 6（BMP-6）诱导软骨分化。我们假设非病毒转染 BMP-6 构建体（pcDNA3-BMP6）将诱导包裹在藻酸盐珠中的 ASCs 的软骨分化，并且分化将通过存在合成糖皮质激素地塞米松（DEX）或表皮生长因子（EGF）、成纤维细胞生长因子-2（FGF-2）和转化生长因子β-1（TGF-β1）的组合增强，统称为扩增因子（EFs）。使用 I 型、II 型和 X 型胶原、聚集蛋白和 BMP6 的定量实时聚合酶链反应评估软骨形成。使用针对 I 型、II 型和 X 型胶原和软骨素-4-硫酸盐的抗体进行免疫组织化学染色。单独的 BMP6 过表达诱导适度的软骨生成反应。包含 EFs 促进了强有力的 II 型胶原表达，但也增加了 I 型和 X 型胶原的沉积，与肥大软骨细胞表型一致。早期基因表达数据表明，DEX 与 BMP-6 协同促进软骨生成，但 28 天时的免疫组织化学显示 DEX 减少了糖胺聚糖的积累。这些结果表明，ASCs 的软骨分化取决于各种生长因子和培养基补充之间的复杂相互作用，以及生长因子暴露的浓度和持续时间。
