Osteoblasts in osteoporosis: past, emerging, and future anabolic targets.

OBJECTIVE Age-related bone loss is associated with significant changes in bone remodeling characterized by decreased trabecular and periosteal bone formation relative to bone resorption, resulting in bone fragility and increased risk of fractures. Prevention or reversal of age-related decrease in bone mass and increase in bone fragility has been based on inhibition of bone resorption using anticatabolic drugs. The current challenge is to promote osteoblastogenesis and bone formation to prevent age-related bone deterioration. METHODS A limited number of approved therapeutic molecules are available to activate bone formation. Therefore, there is a need for anabolic drugs that promote bone matrix apposition at the endosteal, endocortical, and periosteal envelopes by increasing the number of osteoblast precursor cells and/or the function of mature osteoblasts. In this study, we review current therapeutics promoting bone formation and anabolic molecules targeting signaling pathways involved in osteoblastogenesis, based on selected full-text articles searched on Medline search from 1990 to 2010. RESULTS AND DISCUSSION We present current therapeutic approaches focused on intermittent parathyroid hormone and Wnt signaling agonists/antagonists. We also discuss novel approaches for prevention and treatment of defective bone formation and bone loss associated with aging and osteoporosis. These strategies targeting osteoblastic cell functions may prove to be useful in promoting bone formation and improving bone strength in the aging population.