Guo Qianping, Liu Chen, Li Jun, Zhu Caihong, Yang Huilin, Li Bin
Department of Orthopaedics, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China.
Orthopedic Institute, Soochow University, Suzhou, Jiangsu, China.
J Cell Mol Med. 2015 Jul;19(7):1582-92. doi: 10.1111/jcmm.12533. Epub 2015 Mar 6.
Tissue engineering has recently evolved into a promising approach for annulus fibrosus (AF) regeneration. However, selection of an ideal cell source, which can be readily differentiated into AF cells of various regions, remains challenging because of the heterogeneity of AF tissue. In this study, we set out to explore the feasibility of using transforming growth factor-β3-mediated bone marrow stem cells (tBMSCs) for AF tissue engineering. Since the differentiation of stem cells significantly relies on the stiffness of substrate, we fabricated nanofibrous scaffolds from a series of biodegradable poly(ether carbonate urethane)-urea (PECUU) materials whose elastic modulus approximated that of native AF tissue. We cultured tBMSCs on PECUU scaffolds and compared their gene expression profile to AF-derived stem cells (AFSCs), the newly identified AF tissue-specific stem cells. As predicted, the expression of collagen-I in both tBMSCs and AFSCs increased with scaffold stiffness, whereas the expression of collagen-II and aggrecan genes showed an opposite trend. Interestingly, the expression of collagen-I, collagen-II and aggrecan genes in tBMSCs on PECUU scaffolds were consistently higher than those in AFSCs regardless of scaffold stiffness. In addition, the cell traction forces (CTFs) of both tBMSCs and AFSCs gradually decreased with scaffold stiffness, which is similar to the CTF change of cells from inner to outer regions of native AF tissue. Together, findings from this study indicate that tBMSCs had strong tendency to differentiate into various types of AF cells and presented gene expression profiles similar to AFSCs, thereby establishing a rationale for the use of tBMSCs in AF tissue engineering.
组织工程学最近已发展成为一种用于纤维环（AF）再生的有前景的方法。然而，由于AF组织的异质性，选择一种能够容易地分化为不同区域AF细胞的理想细胞来源仍然具有挑战性。在本研究中，我们着手探索使用转化生长因子-β3介导的骨髓干细胞（tBMSCs）用于AF组织工程的可行性。由于干细胞的分化显著依赖于基质的硬度，我们用一系列弹性模量接近天然AF组织的可生物降解聚（醚碳酸酯聚氨酯）-脲（PECUU）材料制备了纳米纤维支架。我们在PECUU支架上培养tBMSCs，并将它们的基因表达谱与AF衍生干细胞（AFSCs）进行比较，AFSCs是新鉴定出的AF组织特异性干细胞。如预期的那样，tBMSCs和AFSCs中I型胶原蛋白的表达都随支架硬度增加而增加，而II型胶原蛋白和聚集蛋白聚糖基因的表达则呈现相反的趋势。有趣的是，无论支架硬度如何，PECUU支架上tBMSCs中I型胶原蛋白、II型胶原蛋白和聚集蛋白聚糖基因的表达始终高于AFSCs中的表达。此外，tBMSCs和AFSCs的细胞牵引力（CTFs）都随支架硬度逐渐降低，这与天然AF组织从内部到外部区域细胞的CTF变化相似。总之，本研究结果表明，tBMSCs具有强烈的分化为各种类型AF细胞的倾向，并呈现出与AFSCs相似的基因表达谱，从而为在AF组织工程中使用tBMSCs奠定了理论基础。
