Growth Plate, Bone and Calcium

Studies of bone biology have been complicated by the highly organized structures and complex cellular biology. Thanks to new models and technologies, our view and understanding of the biological importance of the skeleton has expanded dramatically in the last years. We first take the opportunity to highlight a few papers discussed in this chapter. The possibility of using C-type natriuretic peptide as a novel therapeutic strategy for skeletal dysplasias gives new hope for the treatment of achondroplasia. Two papers demonstrating that oxytocin is a bone-anabolic hormone represent a new paradigm. The recent discovery of the extracellular calcium-sensing receptor as a critical modulator of skeletal development was chosen as the mechanism of the year. Other new mechanisms include the demonstration of prolactin as a regulator of bone metabolism and the discovery of a new estrogen receptor involved in the regulation of bone growth. An important observation for clinical practice is the finding that late menarcheal age can be considered as a risk factor for osteoporosis. We also included a preclinical study indicating that osteocytes are target cells to increase bone mass, a finding which may lead to new treatment options in patients with osteoporosis. Clinical trials are represented by 2 papers that potentially could open up a new therapy of hypoparathyroidism in children and another paper demonstrating that the effectiveness of vitamin D supplementation is independent of the dosing regimen. A concept revised is represented by a paper showing a new player involved in hypophosphatemic rickets. New anti-cancer and anti-inflammatory drugs are reported to interfere with bone growth representing new concerns. Giving some food for thought is a paper suggesting that aspirin might have the capacity to prevent osteoporosis. Finally we chose two reviews: one nicely summarizing the experiences of the use of bisphosphonates in the treatment of osteogenesis imperfecta, and another proposing a new way of classifying rickets based on the etiology of the underlying hypophosphatemia. New hope: one step further towards an effective treatment of achondroplasia