S2104 THE CASE FOR PERIOSTEUM AS A LONG-TERM GUARANTEE OF SUCCESS IN ACT

Abstract

Autologous chondrocytes transplantation (ACT) was first used in humans in 1987 and is based on a surgical technique where cells are injected under a periosteal flap. Due to the sometimes tricky surgical isolation and suture of the periosteum and complications with hypertrophy of periosteal tissue (5 – 10% of the cases) that in some cases requires a second arthroscopic trimming ‘easier’ transplantation techniques based on cells cultured on scaffolds and membranes have been suggested. However, the standard ACT technique creates a unique in vivo bioreactor where chondrocytes and periosteum form a unique local environment. If live periosteum and chondrocytes are transplanted to a defect in the rabbit patellae a cartilage repair tissue is formed in contrast to treatment with ‘dead’ periosteum and live chondrocytes were no repair tissue is demonstrated. The unique environment formed by the periosteum and chondrocytes might be responsible for the unique in vivo induction of early embryological development patterns seen in limb formation in the foetus: We have found that the transplanted chondrocytes are expressing early developmental genes e.g Sox 9 and wnt14 and fibroblast growth factor 3 receptors (FGFR3), a marker of chondrocytes progenitor cells. Furthermore, we have found that the articular chondrocytes are able to demonstrate a phenotypic expressivity with an additional ability of bone and adipose tissue formation. Changes to the transplantation procedure must address these unique features of the ACT technology in order to maintain the long term clinical outcome.