Flock technology is well known from textile industry. Short fibres are applied vertically on a substrate, coated with a flocking adhesive. Until now this technology has not been used in the field of biomaterials although it offers the possibility to create anisotrophic matrices with a high compressive strength despite of high porosity. Matrices presently used in matrix assisted autologous chondrocyte implantation do not show any orientation of the embedded chondrocytes. However column orientation and anisotropic direction of embedded cells and collagen fibers are thought to be necessary for proper cartilage matrix biomechanics. Combination of matrices as a guiding structure and chondrogenically differentiated mesenchymal stem cells (MSC) could offer new possibilities in the treatment of cartilage defects. Our aim was to evaluate whether anisotropic scaffolds are capable to support a cellular cartilaginous phenotype in vitro.

Electrostatically flocked matrices consisted of a collagen substrate, gelatine as adhesive and polyamide flock fibres. Chondrogenic cells and MSC were embedded in the scaffolds. Adherence, vitality and proliferation was assessed using confocal laser-scan microscopy (cLSM). Chondrogenic induction was performed in the presence of TGF-beta 3. Accumulation of proteoglycans was quantified by alcian-blue stain and collagen type II synthesis after extraction of the newly synthesized matrix.

cLSM showed proliferation of embedded MSC as evidenced by DAPI/Phalloidin stain. Vitality of embedded cells remained high over time. Articular chondrocytes and nucleus pulposus cells synthesized proteoglycans and collagen type II in the scaffolds. Also MSC embedded in the flock scaffolds differentiated and increased their chondrogenic phenotype over time.

Using cLSM and biochemical analyses we demonstrated that cells adhered and proliferated well in the new scaffolds. Furthermore we showed that the scaffolds are capable to support induction and maintenance of the chondrogenic phenotype. We conclude that flocking technology is suitable for fabrication of scaffolds for cell cultivation and cartilage tissue engineering.