Properties of osteoblast-like cells isolated from the cortical endosteal bone surface of adult rabbits.

Abstract

The purpose of the present study was to isolate cells from the cortical endosteal bone surface of adult rabbits and characterize some properties of these cells in vitro. Following removal of the marrow from the medullary cavity of long bones, the cells lining the cortical endosteal bone surface were obtained by enzymatic digestion using 0.1% crude collagenase. These cells were examined immediately after isolation or following their growth for 8–10 days in primary culture. Freshly isolated cells contained 7–10 times more alkaline phosphatase (AP) than acid phosphatase activity. This AP activity was extremely heat labile (incubation at 58°C caused >90% loss of enzyme activity within 15 min) and significantly more sensitive to inhibition by levamisole and L-homoarginine than L-phenylalanine. Synthetic bPTH-(1–34) [1–100 ng/ml], native bPTH-(1–84) [1 U/ml] and prostaglandin E2 [1–10 µg/ml] all caused a significant accumulation of cAMP in cultured endosteal bone cells. In contrast, neither salmon calcitonin (1 U/ml) nor porcine insulin (10–1000 ng/ml) stimulated an increase in cAMP. These results suggest that cells isolated from the cortical endosteal bone surface of adult rabbits are osteoblasts or osteoblast-like. These cells retain their ability to respond in a specific manner to bone-seeking hormones following their growth in culture. Cortical endosteal bone cells isolated from rabbits of different ages, physiologic or pathologic conditions can be used to assess the changes in bone cell function and responsiveness which may accompany senescence or development of adult metabolic bone disease.