Functionalization of poly(lactic acid) scaffold surface by aminolysis and hyaluronan immobilization: How it affects mesenchymal stem cell proliferation

Abstract

Natural polymers are often used to functionalize the surface of synthetic polymer scaffolds to improve their cytocompatibility for their use as biomaterial for tissue engineering. Here we used hyaluronan (HA), a glycosaminoglycan providing essential functions in human tissues, to functionalize the surface of poly(lactic acid) (PLA) films. PLA was first aminolyzed using hexane-1,6-diamine (HDA) to bring positive charges to the scaffold surface, then allowing HA immobilization by electrostatic interactions. Since HA interact specifically with various proteins, it should be considered as a bioactive species. Thus, we investigated the influence of both aminolysis and HA immobilization conditions on HA immobilization and on mesenchymal stem cells (MSC) proliferation. Results show that (i) there is an optimum in the number of HDA molecules grafted per surface unit to reach the highest surface concentration of hydrated HA, (ii) MSC proliferation is maximal for a low surface concentration of hydrated HA (20–100 ng·cm−2), and (iii) whatever the surface concentration of hydrated HA, the MSC proliferation level depends on aminolysis conditions. We conclude that conditions used for PLA aminolysis and HA immobilization influence MSC proliferation by affecting the organization of HA molecules on scaffold surface and consequently their ability to interact with MSC membrane receptors.