Human chondrocyte morphology, its dedifferentiation, and fibronectin conformation on different PLLA microtopographies

Surfaces of poly(L-lactic acid) (PLLA) of well-defined microtopography were prepared by making use of the semicrystalline character of PLLA. Different thermal treatments before isothermal crystallization (which include nucleation steps) permit to obtain a controlled number of simultaneously growing spherulites, which, in the end, modulate the topography at the microscale. Four qualitatively different surfaces were prepared. The dynamics of primary human chondrocyte adhesion and cytoskeleton organization was investigated on the different surfaces. Chondrocyte morphology is shown to be influenced by the microtopography of the system as obtained by scanning electron microscopy and atomic force microscopy (AFM). The cytoplasmatic distribution of a focal adhesion protein, tensin, is followed as a function of time. Since the effect of surface topography on cell morphology is a consequence of the process of interaction between the extracellular matrix (ECM) proteins, adsorbed on the surface of the material, and related cell adhesion molecules, the conformation of one ECM protein, fibronectin, adsorbed on the different substrates was investigated by means of AFM.