Department of Biomedical Engineering, Columbia University, 622 West 168th Street, New York, NY 10032, USA.
Tissue Eng Part A. 2013 Oct;19(19-20):2188-200. doi: 10.1089/ten.TEA.2012.0352. Epub 2013 Jun 25.
Formation of tissue-engineered cartilage is greatly enhanced by mechanical stimulation. However, direct mechanical stimulation is not always a suitable method, and the utilization of mechanisms underlying mechanotransduction might allow for a highly effective and less aggressive alternate means of stimulation. In particular, the purinergic, adenosine 5'-triphosphate (ATP)-mediated signaling pathway is strongly implicated in mechanotransduction within the articular cartilage. We investigated the effects of transient and continuous exogenous ATP supplementation on mechanical properties of cartilaginous constructs engineered using bovine chondrocytes and human mesenchymal stem cells (hMSCs) encapsulated in an agarose hydrogel. For both cell types, we have observed significant increases in equilibrium and dynamic compressive moduli after transient ATP treatment applied in the fourth week of cultivation. Continuous ATP treatment over 4 weeks of culture only slightly improved the mechanical properties of the constructs, without major changes in the total glycosaminoglycan (GAG) and collagen content. Structure-function analyses showed that transiently ATP-treated constructs, and in particular those based on hMSCs, had the highest level of correlation between compositional and mechanical properties. Transiently treated groups showed intense staining of the territorial matrix for GAGs and collagen type II. These results indicate that transient ATP treatment can improve functional mechanical properties of cartilaginous constructs based on chondrogenic cells and agarose hydrogels, possibly by improving the structural organization of the bulk phase and territorial extracellular matrix (ECM), that is, by increasing correlation slopes between the content of the ECM components (GAG, collagen) and mechanical properties of the construct.
机械刺激极大地促进了组织工程软骨的形成。然而，直接的机械刺激并不总是一种合适的方法，利用机械转导的机制可能会提供一种高效且侵袭性较小的替代刺激方法。特别是，嘌呤能、三磷酸腺苷（ATP）介导的信号通路强烈参与了关节软骨中的机械转导。我们研究了短暂和持续外源性 ATP 补充对牛软骨细胞和人骨髓间充质干细胞（hMSC）包埋在琼脂糖水凝胶中构建的软骨构建体的机械性能的影响。对于这两种细胞类型，我们观察到在培养的第四周进行短暂的 ATP 处理后，平衡和动态压缩模量都有显著增加。在培养的 4 周内持续的 ATP 处理仅略微改善了构建体的机械性能，而对总糖胺聚糖（GAG）和胶原含量没有重大影响。结构-功能分析表明，短暂接受 ATP 处理的构建体，特别是基于 hMSC 的构建体，在组成和机械性能之间具有最高的相关性。短暂处理组的 GAG 和 II 型胶原的基质区带染色强烈。这些结果表明，短暂的 ATP 处理可以改善基于软骨细胞和琼脂糖水凝胶的软骨构建体的功能性机械性能，可能通过改善整体相和基质细胞外基质（ECM）的结构组织来实现，即通过增加 ECM 成分（GAG、胶原）的含量与构建体机械性能之间的相关斜率。
