In vitro synthesis of type I collagen: Quantification of carboxyterminal propeptide of procollagen type I versus tritiated proline incorporation

Radioimmunoassay of the carboxyterminal propeptide of human type I procolla gen has been recently introduced to measure in vitro synthesis of type I co llagen by osteoblasts and fibroblasts, However, it has not been assessed wh ether the equivalent results are obtained with this new assay and with trit iated proline incorporation to collagen protein. To this purpose, both meth ods were used to quantify synthesis of type I collagen in normal human oste oblast cultures to which fetal calf serum and human serum were added in ord er to stimulate protein synthesis. A positive correlation in the results ob tained by both methods was obtained (r = 0.95, P = 0.0001). Given the techn ical advantages of detection of levels to carboxyterminal propeptide of typ e I procollagen, we consider that this is the technique of choice for the q uantification of in vitro synthesis of type I collagen by normal human oste oblasts.