Systematically organized nanopillar arrays reveal differences in adhesion and alignment properties of BMSC and Saos-2 cells.

Polymeric test surfaces of P(L-D,L)LA and of a P(L-D,L)LA:PLGA blend decorated with 25 nanopillar covered fields, were used to investigate differences in growth of bone marrow stem cells (BMSC) and osteosarcoma cells (Saos-2). The fields were populated with pillars (ca. 900 nm tall, 200 nm×200 nm area) separated systematically from each other with 1-10 μm gaps. Saos-2 cells populated fields decorated with pillars 1 μm apart but they avoided pillar-free surfaces. In contrast, BMSCs avoided fields with interpillar distances <2 μm. Both BMSCs and Saos-2 cells aligned in the direction of the shorter distance when at least one of the interpillar distances was greater than 1.5 μm. Coating the P(L-D,L)LA surfaces with cell adhesive protein fibronectin enabled the BMSC to populate fields with high pillar density which they had avoided when uncoated. Decreasing the stiffness of the film surface by using a blend of (P(L-D,L)LA and PLGA) made them more acceptable for attachment by the BMSC cells.