Cellular Stemness Maintenance of Human Adipose-Derived Stem Cells on ZnO Nanorod Arrays

Ever-growing tissue regeneration and other stem cell therapies cause pressing need for large population of self-renewable stem cells. However, stem cells gradually lose their stemness after long-term in vitro cultivation. In this study, a ZnO nanorod (ZnO NR) array is used to maintain the stemness of human adipose-derived stem cells (hADSCs). The results prove that after culturing hADSCs on ZnO NRs for 3 weeks, the stemness genes and protein expression level are higher than that on culture plates and ZnO film. ZnO NRs can maintain stemness of hADSCs without inhibiting the cell proliferation and oriented differentiation capabilities. KLF4 (Kruppel-like factor 4) is a Zn2+-binding gene that plays a vital role in cell proliferation and differentiation. Sustained Zn2+ release and the increased expression of KLF4 can be detected, suggesting that ZnO NRs have efficiently released Zn2+ for stemness maintenance. Taken together, the nanotopography of ZnO NRs and the Zn2+ release synergistically facilitate stemness maintenance. This study has provided a powerful tool for directing cell fate, maintaining stemness, and realizing the expansion of stem cells in vitro, which will open a new route for the manufacture of large populations of stem cells and fulfilling the growing demand for the cell therapy market.