Authors: A L Boskey L Spevak S B Doty L Rosenberg
Publish Date: 2014/01/27
Volume: 61, Issue: 4, Pages: 298-305
Abstract
The small leucinerich bone proteoglycans biglycan and decorin can be purified by chromatography on hydroxyapatite columns demonstrating their potential affinities for bone apatite To determine their effects on in vitro apatite formation and growth a mixture of the chondroitinsulfate CS bone proteoglycans or purified fractions of the dermatan sulfate DS containing proteoglycans DSdecorin and DSbiglycan obtained from skin and articular cartilage respectively were analyzed in a gelatin gel diffusion system in which apatite formation occurs in the absence of proteins in a 35 day period Low concentrations of the bone CSproteoglycan mixture and low DSbiglycan concentrations 5–25 μg/ml increased apatite formation relative to proteoglycanfree controls at 35 days The CSproteoglycan mixture was less effective at 50 μg/ml than at 10 μg/ml DSbiglycan was similarly most effective at 5–25 μg/ml At 5 days when apatite growth and proliferation were assessed 10 and 50 μg/ml of both CSbone proteoglycan and DSbiglycan increased mineral yields DSdecorin in contrast had no significant effect on mineral accumulation at any of these concentrations In seeded growth experiments 1 and 10 μg/ml CSproteoglycan and 10 and 50 μg/ml DSbiglycan were significant effective inhibitors of mineral accretion whereas DSdecorin showed no tendency to inhibit seeded growth Using molar extinction coefficients to determine concentrations the binding of DSbiglycan and DSdecorin to apatite specific surface 54 m2/g was determined using a Langmuir adsorption isotherm model DSbiglycan had a greater affinity for apatite than DSdecorin 0285 ml/μmol versus 00098 ml/μmol DSbiglycan binding was more specific with fewer binding sites 35 μmol/m2 compared with 182 μmol/m2 for DSdecorin Data suggest that of the small proteoglycans biglycan may play a more significant role than decorin in the regulation of mineralization
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