Biopolymers

We designed an innovative biomaterial combining structural, mechanical and biological properties for tridimensional cell development. It consists of a tridimensional scaffold, made of biosourced and biocompatible polymers such as poly(lactic acid), whose surface is functionalized with a nanolayer of biomolecules naturally occurring in the extracellular matrix. Our biomaterial is highly tunable and scalable and thus, it may be used for a diversity of applications in vitro as well as in vivo. We focus here on cartilage engineering and tumor engineering. Surface scaffold was functionalized with hyaluronan (HA), an abundant glycosaminoglycan in both cartilage and tumors. We showed that mesenchymal stem cells (MSC) behaviors greatly depended on the composition of the polymeric scaffold and that their ability to differentiate into chondrocytes strongly varied according to the shape, the porosity, the pore diameter and the HA surface functionalization of the scaffold. Very interestingly, in porous asymmetric films which display an interconnected network of macro- and micropores and whose surface was functionalized with HA, MSC differentiate into mature chondrocytes with deposition of a hyaline cartilaginous matrix. Using porous asymmetric films, we also showed that interactions between MSC and HT-29 colorectal cancer cells strongly depended on the chain size of HA. While there was no physical interaction between the two cell types with high molecular weight HA (HMW-HA), MSC came to surround HT-29 spheroids in the presence of low molecular weight HA (LMW-HA). Moreover, with HMW-HA the microenvironment was found to be proinflammatory, while an increased secretion of proangiogenic cytokines were observed with LMW-HA.