CONICET | Buscador de Institutos y Recursos Humanos

Cellularized collagen hydrogels are commonly obtained using the method developed by Bell et al., (1979), consisting in the neutralization of diluted acid soluble collagen solutions extemporary prior to fibroblast addition. One of the main limitations in using those types of collagen gels as biomedical materials is related to their strong contraction upon ageing. Following typical approaches in material science, we prepared silica-collagen hybrid and composite hydrogels with the aim of reducing this contraction effect. Our process rely on the addition of small amounts of soluble silicates or silica colloids to cold acidified collagen solutions, followed by neutralization and cell suspension addition. Cell viability during 21 days was estimated by MTT tests. The remodelling activity of the cells was monitored by the gelatine hydrolysis activity of the MMP-2 enzyme. Immuno-histological methods as well as RT-PCR techniques were used to study the behaviour of cells within the silica-collagen hydrogels. In parallel, SEM and TEM observations, combined with mechanical testing and DSC measurements, were performed to investigate the effect of silica on the structural evolution of the collagen matrix. To get a better understanding of silica-collagen interactions in the presence of fibroblasts, the diffusion of silica nanoparticles in acellularized and cellularized collagen hydrogels of various concentrations was also studied. At this stage, it is possible to conclude that silica nanoparticles i) efficiently slow down collagen hydrogel contraction while preserving fibroblast viability and activity over a 3 weeks period; ii) interact with collagen as a function of their size and surface charge; iii) influence fibroblast behaviour either indirectly by modifying the cell/collagen interface or directly by being uptaken by immobilized cells