Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093, United States; Institute of Engineering in Medicine, University of California, San Diego, La Jolla, CA, 92093, United States; Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA, 92093, United States.
Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093, United States; Institute of Engineering in Medicine, University of California, San Diego, La Jolla, CA, 92093, United States.
Biomaterials. 2019 Jun;204:59-69. doi: 10.1016/j.biomaterials.2019.03.003. Epub 2019 Mar 8.
The use of biochemical signaling to derive smooth muscle cells (SMCs) from mesenchymal stem cells (MSCs) has been explored, but the induction of a fully functional SMC phenotype remains to be a major challenge. Cell morphology has been shown to regulate MSC differentiation into various lineages, including SMCs. We engineered substrates with microgrooves to induce cell elongation to study the mechanism underlying the MSC shape modulation in SMC differentiation. In comparison to those on flat substrates, MSCs cultured on engineered substrates were elongated with increased aspect ratios for both cell body and nucleus, as well as augmented cytoskeletal tensions. Biochemical studies indicated that the microgroove-elongated cells expressed significantly higher levels of SMC markers. MicroRNA analyses showed that up-regulation of miR-145 and the consequent repression of KLF4 in these elongated cells promoted MSC-to-SMC differentiation. Rho/ROCK inhibitions, which impair cytoskeletal tension, attenuated cell and nuclear elongations and disrupted the miR-145/KLF4 regulation for SMC differentiation. Furthermore, cell traction force measurements showed that miR-145 is essential for the functional contractility in the microgroove-induced SMC differentiation. Collectively, our findings demonstrate that, through a Rho-ROCK/miR-145/KLF4 pathway, the elongated cell shape serves as a decisive geometric cue to direct MSC differentiation into functional SMCs.
已经探索了利用生化信号将间充质干细胞（MSCs）诱导为平滑肌细胞（SMCs），但诱导完全功能性 SMC 表型仍然是一个主要挑战。细胞形态已被证明可以调节 MSC 向包括 SMC 在内的各种谱系分化。我们设计了带有微凹槽的基底来诱导细胞伸长，以研究 MSC 在 SMC 分化中形态调节的机制。与在平基底上培养的细胞相比，在工程化基底上培养的 MSC 细胞的体部和核部的长宽比增加，细胞骨架张力也增加，从而变得更加细长。生化研究表明，在微凹槽中伸长的细胞表达了更高水平的 SMC 标志物。miRNA 分析表明，这些伸长细胞中 miR-145 的上调和随之而来的 KLF4 抑制促进了 MSC 向 SMC 的分化。抑制 Rho/ROCK，会削弱细胞骨架张力，从而破坏细胞和核的伸长以及 miR-145/KLF4 对 SMC 分化的调控。此外，细胞牵引力测量表明，miR-145 对于微凹槽诱导的 SMC 分化中的功能性收缩性至关重要。总之，我们的研究结果表明，通过 Rho/ROCK/miR-145/KLF4 途径，细长的细胞形态作为一个决定性的几何线索，指导 MSC 分化为功能性 SMC。
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