Fabrication of polymeric nanostructures with high aspect ratio for cell differentiation

The regulation of stem cell fate by using the physicochemical signals is a hot research topic in tissue engineering. Compared to biochemical growth factors, mechanical stimulation such as surface nanostructures can remodel the microenvironment in which cells are located to via their own physical properties. To fabricate bioresorbable nanostructures with an optimal design for cell differentiation, a robust and versatile process chain needs to be developed. In this work, a process chain combining self-assembled mold inserts and injection molding was proposed to fabricate nanopillars with different aspect ratios as the substrates for cell culture. Herein, the optimal parameters affecting the anodic oxidation process for mold inserts and the injection molding process for nanopillar were investigated. The injection-molded nanopillars were then applied to the differentiation experiments of bone marrow mesenchymal stem cells (BMSCs). The results showed that nanopillar structures with different aspect ratios were precisely fabricated through the process chain. Nanopillars had a significant osteogenic differentiation inducing effect on BMSCs, and the inducing effect became stronger with the increase in the aspect ratio. Compared with the addition of osteogenic inducers, nanopillar substrates exhibited a better effect in inducing differentiation and provided an alternative protocol for differentiation induction.