SENSITIVITY OF OSTEOCYTES TO BIOMECHANICAL STRESS IN-VITRO

It has been known for more than a century that bone tissue adapts to f unctional stress by changes in structure and mass, However, the mechan ism by which stress is translated into cellular activities of bone for mation and resorption is unknown, We studied the response of isolated osteocytes derived from embryonic chicken calvariae to intermittent hy drostatic compression as well as pulsating fluid flow, and compared th eir response to osteoblasts and periosteal fibroblasts. Osteocytes, bu t not osteoblasts or periosteal fibroblasts, reacted to 1 h pulsating fluid flow with a sustained release of prostaglandin E(2). Intermitten t hydrostatic compression stimulated prostaglandin production to a les ser extent: after 6 and 24 h in osteocytes and after 6 h in osteoblast s. These data provide evidence that osteocytes are the most mechanosen sitive cells in bone involved in the transduction of mechanical stress into a biological response. The results support the hypothesis that s tress on bone causes fluid flow in the lacunar-canalicular system, whi ch stimulates the osteocytes to produce factors that regulate bone met abolism.