Effect of Structural Elements of Heparin-Mimicking Polymers on Vascular Cell Distribution and Functions: Chemically Homogeneous or Heterogeneous?

Heparin-mimicking polymers (HMPs) are artificially synthesized alternatives to heparin with comparable regulatory effects on protein adsorption and cell behavior. By introducing two major structural elements of HMPs (sulfonate- and glyco-containing units) to different areas of material surfaces, heterogeneous surfaces patterned with different HMPs and homogeneous surfaces patterned with the same HMPs can be obtained. In this work, heterogeneous HMP-patterned poly(dimethylsiloxane) (PDMS) surfaces with sulfonate-containing polySS (pS) and glyco-containing polyMAG (pM) distributed in circular patterns (with a diameter of 300 μm) were prepared (S–M and M–S). Specifically, pS and pM were distributed inside and outside the circles on S–M, respectively, and exchanged their distribution on M–S. Homogeneous HMP-patterned silicone surfaces (SM–SM) where sulfonate- and glyco-containing poly(SS-co-MAG) (pSM) were distributed uniformly were prepared. Vascular cells showed interestingly different behaviors between chemically homogeneous and heterogeneous surfaces. They tended to grow in the sulfonate-modified area on S–M and M–S and were distributed uniformly on SM–SM. Compared with M–S, S–M showed a better promoting effect on the growth of vascular cells. Among all the samples, SM–SM exhibited the highest proliferation density and an optimum spreading state of vascular cells, as well as the highest human umbilical vein endothelial cell (HUVEC) viability (∼99%) and relatively low human umbilical vein smooth muscle cell (HUVSMC) viability (∼72%). By heterogeneous or homogeneous patterning with different structural elements of HMPs, the modified silicone surfaces spatially guided vascular cell distribution and functions. This strategy provides a new surface engineering approach to the study of cell–HMP interactions.