Long-term explant culture of rabbit flexor tendon: effects of recombinant human insulin-like growth factor-I and serum on matrix metabolism.
The effects of human recombinant insulin-like growth factor-I (rhIGF-I, 50 ng/ml) on matrix metabolism in the deep flexor tendon from the tendon sheath region of the rabbit were studied in explants cultured for 3 weeks. Tendon segments cultured in medium supplemented with fetal calf serum (FCS) exhibited proliferation of the superficial cell layers. Synthesis of proteoglycan and non-collagen protein (NCP) increased threefold during the first week and remained elevated during the next 2 weeks of culture in medium supplemented with rhIGF-I or FCS, but not in medium without supplements (bovine serum albumin, BSA). The estimated halflife (t1/2) for elimination of newly labeled proteoglycans from the tendon explants ranged from 5.1 to 8.5 days and from 4.9 to 6.8 days for NCP in supplemented medium. Presence of rhIGF-I or FCS did not affect degradation of matrix as compared with BSA. The total hexosamine content per tendon segment was stable during the culture period, but the non-collagen protein content decreased by 25%. Collagen synthesis decreased to 10% of the initial level after 3 weeks in supplemented medium, but to 3% in unsupplemented medium. There was no measurable turnover of collagen in explants cultured in either medium, and the collagen content remained unchanged. Our results suggest that rhIGF-I, as well as FCS, stimulates matrix synthesis but does not influence matrix turnover in rabbit flexor tendon explants in long-term culture as compared with medium without supplements. We conclude that rhIGF-I may be used as a defined growth-promoting factor in serum-free media and may be of importance in tendon healing.
Abrahamsson
S O
SO
Department of Hand Surgery, Malmö General Hospital, Sweden.
Lundborg
G
G
Lohmander
L S
LS
D000818:Animals; D001790:Blood Physiological Phenomena; D003094:Collagen / Q000378:metabolism*; D005688:Galactosamine / Q000032:analysis; D005944:Glucosamine / Q000032:analysis; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D009924:Organ Culture Techniques; D009929:Organ Size; D011509:Proteoglycans / Q000378:metabolism*; D011817:Rabbits; D011994:Recombinant Proteins / Q000494:pharmacology; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D013710:Tendons / Q000187:drug effects* / Q000378:metabolism
D011509:Proteoglycans; D011994:Recombinant Proteins; D012710:Serum Albumin, Bovine; D007334:Insulin-Like Growth Factor I; D005688:Galactosamine; D003094:Collagen; D005944:Glucosamine