Zhu Caihong, Li Jun, Liu Chen, Zhou Pinghui, Yang Huilin, Li Bin
Department of Orthopaedics, The First Affiliated Hospital, Orthopaedic Institute, Soochow University, 188 Shizi St, Suzhou, Jiangsu 215006, China.
Department of Orthopaedics, The First Affiliated Hospital, Orthopaedic Institute, Soochow University, 188 Shizi St, Suzhou, Jiangsu 215006, China.
Acta Biomater. 2016 Jan;29:228-238. doi: 10.1016/j.actbio.2015.09.039. Epub 2015 Oct 9.
Annulus fibrosus (AF) injuries commonly lead to substantial deterioration of the intervertebral disc (IVD). While tissue engineering has recently evolved into a promising approach for AF regeneration, it remains challenging due to the cellular, biochemical, and mechanical heterogeneity of AF tissue. In this study, we explored the use of AF-derived stem cells (AFSCs) to achieve diversified differentiation of cells for AF tissue engineering. Since the differentiation of stem cells relies significantly on the elasticity of the substrate, we synthesized a series of biodegradable poly(ether carbonate urethane)urea (PECUU) materials whose elasticity approximated that of native AF tissue. When AFSCs were cultured on electrospun PECUU fibrous scaffolds, the gene expression of collagen-I in the cells increased with the elasticity of scaffold material, whereas the expression of collagen-II and aggrecan genes showed an opposite trend. At the protein level, the content of collagen-I gradually increased with substrate elasticity, while collagen-II and GAG contents decreased. In addition, the cell traction forces (CTFs) of AFSCs gradually decreased with scaffold elasticity. Such substrate elasticity-dependent changes of AFSCs were similar to the gradual transition in the genetic, biochemical, and biomechanical characteristics of cells from inner to outer regions of native AF tissue. Together, findings from this study indicate that AFSCs, depending on the substrate elasticity, have strong tendencies to differentiate into various types of AF-like cells, thereby providing a solid foundation for the tissue engineering applications of AFSCs.
Repairing the annulus fibrosus (AF) of intervertebral disc (IVD) is critical for the treatment of disc degeneration disease, but remains challenging due to the significant heterogeneity of AF tissue. Previously, we have identified rabbit AF-derived stem cells (AFSCs), which are AF tissue-specific and hold promise for AF regeneration. In this study, we synthesized a series of poly(ether carbonate urethane)ureas of various elasticity (or stiffness) and explored the potential of induced differentiation of AFSCs using electrospun PECUU scaffolds. This work has, for the first time, found that AFSCs are able to present different gene expression patterns simply as a result of the elasticity of scaffold material. Therefore, our findings will help supplement current knowledge of AF tissue regeneration and may benefit a diversified readership from scientific, engineering, and clinical settings whose work involves the biology and tissue engineering of IVD.
纤维环（AF）损伤通常会导致椎间盘（IVD）严重退变。虽然组织工程学最近已发展成为一种有前景的AF再生方法，但由于AF组织的细胞、生化和力学异质性，它仍然具有挑战性。在本研究中，我们探索了利用AF来源的干细胞（AFSCs）实现用于AF组织工程的细胞多样化分化。由于干细胞的分化很大程度上依赖于基质的弹性，我们合成了一系列可生物降解的聚（醚碳酸酯聚氨酯）脲（PECUU）材料，其弹性接近天然AF组织。当AFSCs在电纺PECUU纤维支架上培养时，细胞中I型胶原蛋白的基因表达随支架材料弹性增加，而II型胶原蛋白和聚集蛋白聚糖基因的表达呈现相反趋势。在蛋白质水平上，I型胶原蛋白的含量随基质弹性逐渐增加，而II型胶原蛋白和糖胺聚糖的含量则下降。此外，AFSCs的细胞牵引力（CTFs）随支架弹性逐渐降低。AFSCs的这种依赖于基质弹性的变化类似于天然AF组织从内部到外部区域细胞的遗传、生化和生物力学特性的逐渐转变。总之，本研究结果表明，AFSCs根据基质弹性具有强烈的分化为各种类型AF样细胞的倾向，从而为AFSCs的组织工程应用提供了坚实的基础。
修复椎间盘（IVD）的纤维环（AF）对于椎间盘退变疾病的治疗至关重要，但由于AF组织的显著异质性，仍然具有挑战性。此前，我们已鉴定出兔AF来源的干细胞（AFSCs），它们是AF组织特异性的，对AF再生具有前景。在本研究中，我们合成了一系列具有不同弹性（或刚度）的聚（醚碳酸酯聚氨酯）脲，并探索了使用电纺PECUU支架诱导AFSCs分化的潜力。这项工作首次发现，AFSCs仅由于支架材料的弹性就能呈现不同的基因表达模式。因此，我们的研究结果将有助于补充当前关于AF组织再生的知识，并可能使来自科学、工程和临床领域的多样化读者群体受益，他们的工作涉及IVD的生物学和组织工程。
