Cellular responses of embryonic hyaline cartilage to experimental wounding in vitro

Abstract

It is well established that the reparative potential of many tissues is greatest during embryonic development. Despite the extensive literature documenting repair in nonembryonic cartilage models, there is no comparable wealth of experience relating to embryonic cartilage repair. With the embryonic chick sternum as a model of hyaline cartilage, this paper accounts cellular responses and alterations in extracellulat matrix composition in response to experimental wounding in vitro. Creation of an experimental lesion induced a rapid (<20 minutes) apoptotic response in chondrocytes adjacent to the lesion edge; the presence of perichondrium delayed this response. Alterations in the extracellular matrix included immediate mechanical damage to type-II collagen fibrils and an increase in the expression of chondroitin-4 sulphate next to the lesion. Creation of the lesion induced an increased proliferative response in chondrocytes behind the zone of apoptosis and the expression of α5 and α6 integrin subunits.