Insulin-like growth factor I accelerates proliferation and differentiation of cartilage progenitor cells in cultures of neonatal mandibular condyles.
The present study examined the effect of exogenous IGF-I on growth and development of neonatal cartilage of the mandible condyle. Condylar cartilage was cultured as organ culture. The explants were cultured on top of collagen sponges in medium containing 2% fetal calf serum and were treated with IGF-I at doses ranging from 3.25 to 26 nmol/l for up to six days. IGF-I was found to increase significantly the uptake of [3H]-thymidine and [35S]-sulfate in a dose-related manner. The enhanced cellular proliferation, along with the increased synthesis of proteoglycans, resulted in a substantially larger mass of tissue in the organ culture system. The nature of the IGF-I stimulative effect was further studied through the use of a tissue culture system whereby a separated chondroprogenitor zone is cultured under conditions which favor its development at first into cartilage and then into bone. Using this culture system, we could show that IGF-I induces merely the de novo chondrogenesis process. This was reflected in the appearance of relatively large amounts of cartilage specific antigens such as type II collagen, cartilage proteoglycans, chondrocalcin and 100 KDa protein. Yet, no bone specific antigens were significantly increased, as is the case with GH effects. These results indicate that IGF-I is a strong chondrogenetic agent. But, unlike growth hormone, it does not seem to stimulate bone formation.
Maor
G
G
Laboratory for Musculoskeletal Research, Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa.
Hochberg
Z
Z
Silbermann
M
M
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D002356:Cartilage / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D003094:Collagen / Q000096:biosynthesis; D046508:Culture Techniques; D004305:Dose-Response Relationship, Drug; D005455:Fluorescent Antibody Technique; D013006:Growth Hormone / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008278:Magnesium Sulfate / Q000378:metabolism; D008335:Mandibular Condyle / Q000166:cytology / Q000187:drug effects*; D051379:Mice; D008813:Mice, Inbred ICR; D009924:Organ Culture Techniques; D011509:Proteoglycans / Q000096:biosynthesis; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects*; D013997:Time Factors
D011509:Proteoglycans; D007334:Insulin-Like Growth Factor I; D008278:Magnesium Sulfate; D013006:Growth Hormone; D003094:Collagen