In vitro effects of glucose and growth factors on limb bud and mandibular arch chondrocytes maintained at various serum concentrations

Abstract

In human and experimental diabetic pregnancy there is an increased risk of congenital malformation in the offspring. Some malformations involve growth retardation and altered chondrocyte differentiation, suggesting that a diabetic milieu may modify embryonic cell replication and the development of (pre)chondrocytes. The aim of the present work was to study the effects of a diabetes-like environment in vitro on the growth and differentiation of rat chondrocytes in the presence of specific growth factors and different concentrations of serum. This was performed with a modified micromass culture system of embryonic (pre)chondrocytes from the limb bud and mandibular arch areas using medium supplemented with different glucose concentrations and with serum from diabetic rats. An elevated ambient glucose concentration inhibited the growth of mature chondrocytes in vitro, and this effect was diminished in a serum-rich culture milieu. The (pre)chondrocytes exhibited a marked dependence on the serum level in the culture medium for optimal in vitro development. Diabetic rat serum had the lowest stimulatory capacity of the three different types tested (at similar glucose concentrations), suggesting a deficiency of growth-stimulating factor(s) rather than the presence of inhibiting factor(s) in this type of serum. One of the deficient factor(s) in diabetic rat serum may be similar to IGF-II, but a combined deficiency of several growth-stimulating agents is likely to be present. Chondrocytes originating from the mandibular arch in general appeared more sensitive to MSA and IGF-II than those from the limb buds. The present observations support the notion that while diabetes-induced hyperglycemia in the conceptus contributes to severe growth retardation of the mandibular arch, additional factors also play a role.