Atelocollagen-based Hydrogels Crosslinked with Oxidised Polysaccharides as Cell Encapsulation Matrix for Engineered Bioactive Stromal Tissue.

Tissue stroma is responsible for extracellular matrix (ECM) formation and secretion of factors that coordinate the behaviour of the surrounding cells through the microenvironment created. It's inability to spontaneously regenerate makes it a good candidate for research studies such as testing various tissue engineered products capable of replacing the stroma in order to assure normal tissue regeneration and function. In this study, a bioactive stroma was obtained considering two main components: 1) the artificial ECM formed using atelocollagen-oxidized polysaccharides hydrogels in which the polysaccharide compound (oxidised gellan or pullulan) has the role of crosslinker and 2) encapsulated stromal cells (dermal fibroblasts, ovarian theca-interstitial and granulosa cells). The cell-hosting ability of the hydrogels is demonstrated by a good diffusion of globular proteins (albumin) while the fibrillar morphology proves to be optimal for cell adhesion. These structural properties and cytocompatibility of the components maintain good cell viability and cell encapsulation for more than 12 days. Nevertheless, the results indicate some differences favouring the gellan crosslinked hydrogels. Ovarian stromal cells functionality was maintained as indicated by hormone secretion, confirming cell-cell signalling in encapsulated and co-culture conditions. In vivo implantation shows the regenerative potential of the cell-populated hydrogels as they are integrated into the natural tissue. The possibility of cryopreserving the hydrogel-cell system, while maintaining both cell viability and hydrogel structural integrity underlines the potential of these ready-to-use hydrogels as bioactive stroma for multipurpose tissue regeneration.

Evaluation of polyurethane based on cellulose derivative-ketoprofen biosystem for implant biomedical devices.

A polyether-urethane based on polytetrahydrofuran containing hydroxypropyl cellulose for biomedical applications was tested for its biocompatibility. Ketoprofen was incorporated (3% and 6%) in the polyurethane matrix as an anti-inflammatory drug. Dynamic vapour sorption method was employed for testing the water sorption/desorption behaviour of these materials with the determination of the surface isotherms, surface parameters and the kinetic curves of sorption/desorption processes. Cytotoxicity testing in vitro for quantifying cell proliferation was employed, and the results evidence noncytotoxicity for the studied polyurethane-drug systems. In vivo biocompatibility study was performed on 200 g weight male rats. It was found that after implantation of the polyether-urethane samples a reduced acute inflammation occurred, especially for polyurethane samples with added ketoprofen.