title: Microgravity during spaceflight directly affects in vitro osteoclastogenesis and bone resorption.
abstract: During space flight, severe losses of bone mass are observed. Both bone formation and resorption are probably involved, but their relative importance remains unclear. The purpose of this research is to understand the role of osteoclasts and their precursors in microgravity-induced bone loss. Three experiments on isolated osteoclasts (OCs) and on their precursors, OSTEO, OCLAST, and PITS, were launched in the FOTON-M3 mission. The OSTEO experiment was conducted for 10 d in microgravity within bioreactors with a perfusion system, where the differentiation of precursors, cultured on a synthetic 3-dimensional bonelike biomaterial, skelite, toward mature OCs was assessed. In OCLAST and in PITS experiments, differentiated OCs were cultured on devitalized bovine bone slices for 4 d in microgravity. All of the experiments were replicated on ground in the same bioreactors, and OCLAST also had an inflight centrifuge as a control. Gene expression in microgravity, compared with ground controls, demonstrated a severalfold increase in genes involved in osteoclast maturation and activity. Increased bone resorption, proved by an increased amount of collagen telopeptides released VS ground and centrifuge control, was also found. These results indicate for the first time osteoclasts and their precursors as direct targets for microgravity and mechanical forces.
authors.affiliation: Department of Human Anatomy and Histology, University of Bari Medical School, Policlinico, Piazza G. Cesare 11, I-70124 Bari, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Tamma
authors.forename: Graziana
authors.initials: G
authors.lastname: Colaianni
authors.forename: Claudia
authors.initials: C
authors.lastname: Camerino
authors.forename: Adriana
authors.initials: A
authors.lastname: Di Benedetto
authors.forename: Giovanni
authors.initials: G
authors.lastname: Greco
authors.forename: Maurizio
authors.initials: M
authors.lastname: Strippoli
authors.forename: Rosaria
authors.initials: R
authors.lastname: Vergari
authors.forename: Antonella
authors.initials: A
authors.lastname: Grano
authors.forename: Lucia
authors.initials: L
authors.lastname: Mancini
authors.forename: Giorgio
authors.initials: G
authors.lastname: Mori
authors.forename: Silvia
authors.initials: S
authors.lastname: Colucci
authors.forename: Maria
authors.initials: M
authors.lastname: Grano
authors.forename: Alberta
authors.initials: A
authors.lastname: Zallone