Cheng Nai-Chen, Estes Bradley T, Awad Hani A, Guilak Farshid
Departments of Surgery and Biomedical Engineering, Duke University Medical Center, Durham, North Carolina 27710, USA.
Tissue Eng Part A. 2009 Feb;15(2):231-41. doi: 10.1089/ten.tea.2008.0253.
Adipose-derived adult stem cells (ASCs) have the ability to differentiate into a chondrogenic phenotype in response to specific environmental signals such as growth factors or artificial biomaterial scaffolds. In this study, we examined the hypothesis that a porous scaffold derived exclusively from articular cartilage can induce chondrogenesis of ASCs. Human ASCs were seeded on porous scaffolds derived from adult porcine articular cartilage and cultured in standard medium without exogenous growth factors. Chondrogenesis of ASCs seeded within the scaffold was evident by quantitative RT-PCR analysis for cartilage-specific extracellular matrix (ECM) genes. Histological and immunohistochemical examination showed abundant production of cartilage-specific ECM components-particularly, type II collagen-after 4 or 6 weeks of culture. After 6 weeks of culture, the cellular morphology in the ASC-seeded constructs resembled those in native articular cartilage tissue, with rounded cells residing in the glycosaminoglycan-rich regions of the scaffolds. Biphasic mechanical testing showed that the aggregate modulus of the ASC-seeded constructs increased over time, reaching 150 kPa by day 42, more than threefold higher than that of the unseeded controls. These results suggest that a porous scaffold derived from articular cartilage has the ability to induce chondrogenic differentiation of ASCs without exogenous growth factors, with significant synthesis and accumulation of ECM macromolecules, and the development of mechanical properties approaching those of native cartilage. These findings support the potential for a processed cartilage ECM as a biomaterial scaffold for cartilage tissue engineering. Additional in vivo evaluation is necessary to fully recognize the clinical implication of these observations.
脂肪来源的成体干细胞（ASCs）能够响应特定的环境信号，如生长因子或人工生物材料支架，分化为软骨形成表型。在本研究中，我们检验了一个假设，即仅由关节软骨衍生的多孔支架可诱导ASCs的软骨形成。将人ASCs接种于源自成年猪关节软骨的多孔支架上，并在无外源性生长因子的标准培养基中培养。通过对软骨特异性细胞外基质（ECM）基因进行定量RT-PCR分析，发现接种于支架内的ASCs发生了软骨形成。组织学和免疫组织化学检查显示，培养4周或6周后，软骨特异性ECM成分大量产生，尤其是II型胶原蛋白。培养6周后，接种ASCs的构建体中的细胞形态与天然关节软骨组织中的相似，圆形细胞位于支架中富含糖胺聚糖的区域。双相力学测试表明，接种ASCs的构建体的聚集模量随时间增加，在第42天达到150 kPa，比未接种的对照高出三倍多。这些结果表明，源自关节软骨的多孔支架能够在无外源性生长因子的情况下诱导ASCs的软骨形成分化，有显著的ECM大分子合成和积累，并且其力学性能的发展接近天然软骨。这些发现支持了将经过处理的软骨ECM作为软骨组织工程生物材料支架的潜力。需要进行额外的体内评估，以充分认识这些观察结果的临床意义。
