Retinoic acid enhances the displacement of newly synthesized hyaluronate from cell layer to culture medium during early phases of chondrogenesis

Abstract Chondrogenic differentiation in mouse limb bud mesenchymal cells cultured at high density was suppressed by supplementation of the medium with retinoic acid (1 μg/ml or 3.3 × 10 −6 M). Since in control medium overt chondrogenesis begins on day 3, retinoic acid was introduced on day 2 so that the relationship between initial biosynthetic changes and inhibition of chondrogenesis could be studied. During the first 24 h of exposure the treated cells remained viable but suffered 10% inhibition in growth and synthesized [ 3 H]glucosamine-labeled glycosaminoglycan at a level 24% below untreated cells. The amount of labeled hyaluronic acid released into the culture medium by the treated cells was, however, 2-fold greater, on a per cell basis, than that in the untreated cultures. It is suggested that the displacement of hyaluronate may play a role in the disruption of mesenchymal cell differentiation and of limb morphogenesis as observed in other systems.