Imaging cell interactions with native and crosslinked polyelectrolyte multilayers.

The adhesion of primary chondrocytes to polyelectrolyte multilayer films, made of poly(l-lysine) (PLL) and hyaluronan (HA), was investigated for native and crosslinked films, either ending by PLL or HA. Crosslinking the film was achieved by means of a water-soluble carbodiimide in combination with N-hydroxysulfosuccinimide. The adhesion of macrophages and primary chondrocytes was investigated by microscopical techniques (optical, confocal, and atomic), providing useful information on the cell/film interface.

New physically and chemically crosslinked hyaluronate (HA)-based hydrogels for cartilage repair.

When dissolved in aqueous solutions, sodium hyaluronate substituted with low amounts of alkyl chains [amphiphilic hyaluronate (HA)] can give rise to hydrogels thanks to intermolecular reversible hydrophobic interactions, leading to a three-dimensional (3D) network. Such hydrogels possess shear-thinning properties and can thus be injected in cartilage defect to promote chondrocyte proliferation and cartilage repair. However, these hydrogels are only physically crosslinked and can progressively loose their 3D structure when they are in contact with aqueous fluids.

Layer by layer buildup of polysaccharide films: physical chemistry and cellular adhesion aspects.

The formation ofpolysaccharide films based on the alternate deposition of chitosan (CHI) and hyaluronan (HA) was investigated by several techniques. The multilayer buildup takes place in two stages: during the first stage, the surface is covered by isolated islets that grow and coalesce as the construction goes on. After several deposition steps, a continuous film is formed and the second stage of the buildup process takes place.

Induction of heat shock protein 70 (Hsp70) by proteasome inhibitor MG 132 protects articular chondrocytes from cellular death in vitro and in vivo.

The aim of this work was to determine whether Hsp70 overexpression via proteasome inhibitor MG132 was able to protect chondrocytes towards mono-iodoacetate (MIA) cytotoxicity both in vitro and in vivo. In vitro, overexpression of Hsp70 via MG132 was significantly able to protect chondrocytes from MIA toxicity (MTT/LDH analyses). Hsp70 essentially mediated this chondroprotective effect as demonstrated by antisense strategy.