Embryonic stem cells: new tool to study osteoblast and osteoclast differentiation

¹ INSERM, ERI 7, Nantes, France; Université de Nantes, Nantes atlantique universités, Laboratoire de Physiopathologie de la Résorption Osseuse et Thérapie des Tumeurs Osseuses Primitives, EA3822, Nantes, France
² INSERM U533, Nantes, France

^* To whom correspondence should be addressed. E-mail: laurence.duplomb{at}univ-nantes.fr.

	Abstract

Bone remodeling involves synthesis of organic matrix by osteoblasts and bone resorption by osteoclasts. A tight collaboration between these two cell types is essential to maintain a physiological bone homeostasis. Thus, osteoblasts control bone-resorbing activities and are also involved in osteoclast differentiation. Any disturbance between these effectors leads to the development of skeletal abnormalities and/or bone diseases. In this context, the determination of key genes involved in bone cell differentiation is a new challenge to treat any skeletal disorders. Different models are used to study the differentiation process of these cells, but all of them used pre-engaged progenitor cells, allowing to study only the latest stages of the differentiation. Embryonic Stem (ES) cells come from the inner mass of the blastocyst prior its implantation to the uterine wall. By their capacity to differentiate into all germ layers, and so into all tissues of the body, ES cells represent the best model to study earliest stages of bone cell differentiation. Osteoblasts are generated by two methods including or not the generation of embryoid body. Mineralizing-cells are obtained after two weeks of culture and express all the specific osteoblastic markers (ALP, Coll I, osteocalcin and others). Osteoclasts are generated from a single cell suspension of ES cells seeded on a feeder monolayer and bone-resorbing cells expressing osteoclastic markers such as TRAP or RANK are obtained within 11 days. The aim of this review is to present the recent knowledge and advances in the differentiation of both osteoblasts and osteoclasts from ES cells.