Dynamic cell culturing and its application to micropatterned, elastin-like protein-modified poly(N-isopropylacrylamide) scaffolds

In this study a tissue engineering scaffold was constructed from poly(N-isopropylacrylamide) (pNIPAM) to study the influence of strain on cell proliferation and differentiation. The effect of surface chemistry and topography on bone marrow mesenchymal stem cells was also investigated. Micropatterned pNIPAM films (channels with 10 μm groove width, 2 μm ridge width, 20 μm depth) were prepared by photopolymerization. The films were chemically modified by adsorption of a genetically engineered and temperature sensitive elastin-like protein (ELP). Dynamic conditions were generated by repeated temperature changes between 29 °C and 37 °C. ELP presence on the films enhanced initial cell attachment two fold (Day 1 cell number on films with ELP and without ELP were 27.6 × 104 and 13.2 × 104, respectively) but had no effect on proliferation in the long run. ELP was crucial for maintaining the cells attached on the surface in dynamic culturing (Day 7 cell numbers on the films with and without ELP were 81.4 × 104 and 12.1 × 104, respectively) and this enhanced the ability of pNIPAM films to transfer mechanical stress on the cells. Dynamic conditions improved cell proliferation (Day 21 cell numbers with dynamic and with static groups were 180.4 × 104 and 157.7 × 104, respectively) but decreased differentiation (Day 14 specific ALP values on the films of static and dynamic groups were 6.6 and 3.5 nmol/min/cell, respectively). Thus, a physically and chemically modified pNIPAM scaffold had a positive influence on the population of the scaffolds under dynamic culture conditions.