School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia.
Biomaterials. 2010 May;31(14):3858-67. doi: 10.1016/j.biomaterials.2010.01.090. Epub 2010 Feb 11.
Chondrogenic differentiation of human adult adipose-derived stem cells was studied in vitro for the development of engineered cartilage tissue. Cells cultured under dynamic conditions in polyglycolic acid (PGA) scaffolds produced substantially higher glycosaminoglycan (GAG) and total collagen levels than cells in pellet cultures. This result reflects the importance of cell attachment and cell-scaffold interactions in stem cell differentiation and chondrogenesis. Although gene expression levels for both aggrecan and collagen type II were up-regulated significantly in PGA cultures treated with transforming growth factor beta1 (TGF-beta1), synthesis of GAG but not collagen type II was enhanced in tissue constructs when TGF-beta1 was added to the medium. Bone morphogenetic protein-6 (BMP-6) in the presence of TGF-beta1 was effective in improving GAG and total collagen production when the cells were pre-treated with fibroblast growth factor-2 (FGF-2) prior to scaffold seeding. Extending the culture duration from 2 to 5 weeks did not improve cartilage development in PGA scaffolds; loss of cells from the constructs suggested that the rate of scaffold degradation exceeded the rate of replacement by ECM during the 5-week period. Stem cells in PGA scaffolds were cultured in perfusion-type recirculation bioreactors operated with periodic medium flow reversal. The highest levels of GAG and collagen type II accumulation were achieved in the bioreactor cultures after the seeding cell density was increased from 2x10(7) to 4x10(7) cells per scaffold.
研究了人脂肪间充质干细胞在体外的软骨分化，以开发工程化软骨组织。在聚乙醇酸（PGA）支架中进行动态培养的细胞产生的糖胺聚糖（GAG）和总胶原水平明显高于微团培养的细胞。这一结果反映了细胞附着和细胞-支架相互作用在干细胞分化和软骨发生中的重要性。尽管在 TGF-β1 处理的 PGA 培养物中，聚集蛋白聚糖和 II 型胶原的基因表达水平均显著上调，但当 TGF-β1 添加到培养基中时，仅增强了 GAG 的合成，而不是 II 型胶原的合成。在 TGF-β1 存在的情况下，骨形态发生蛋白-6（BMP-6）在细胞用成纤维细胞生长因子-2（FGF-2）预处理后接种支架之前，可有效提高 GAG 和总胶原的产生。将培养时间从 2 周延长至 5 周并不会改善 PGA 支架中的软骨发育；从构建体中丢失的细胞表明，在 5 周的时间内，支架降解的速度超过了 ECM 的替代速度。在周期性介质流反转的灌注式再循环生物反应器中培养 PGA 支架中的干细胞。在接种细胞密度从 2x10(7)增加到 4x10(7)个细胞/支架后，在生物反应器培养物中达到了最高水平的 GAG 和 II 型胶原积累。
