title: The role of circulating bone cell precursors in fracture healing.
abstract: Fracture healing is a complex process that involves several cell types; as a previous report suggested an increase in osteoblast (OB) precursors in peripheral blood during this process, this paper examines the role of circulating bone cell precursors in this process in the light of a prior suggestion that OB precursors are increased. Nine healthy men less than 60 years old with traumatic fractures were enrolled. The parameters circulating OB precursors (osteocalcin+/alkaline phosphatase+/CD15- cells) and osteoclast precursors (CD14+/CD11b+/vitronectin receptor + cells) were measured by flow cytometry; bone formation markers and TGFbeta1, by ELISA; and PTH, by RIA in serum on arrival at the emergency department (baseline) and 15 days after fracture. Bone cell precursors behaved differently during healing. TGFbeta1 was inversely correlated with OB number, but increased their degree of maturation at baseline. Bone formation markers and TGFbeta1 were increased after fracture, whereas PTH was decreased. The TGFbeta1 increase was directly correlated with age, whereas age was not correlated with the precursors. In conclusion, we confirm the role of TGFbeta1 in fracture healing; and its possible role in the control of pre-OB homeostasis. There was no variation in circulating precursor cells during healing, though the increase in TGFbeta1 may suggest increased pre-OB maturation and homing to the injured site.
authors.affiliation: Section of Gerontology, Department of Surgical and Medical Disciplines, University of Torino, Corso Bramante 88/90, Turin, Italy. patrizia.damelio@unito.it
authors.forename: Patrizia
authors.initials: P
authors.lastname: D'Amelio
authors.forename: Maria Angela
authors.initials: MA
authors.lastname: Cristofaro
authors.forename: Anastasia
authors.initials: A
authors.lastname: Grimaldi
authors.forename: Marco
authors.initials: M
authors.lastname: Ravazzoli
authors.forename: Fernanda
authors.initials: F
authors.lastname: Pluviano
authors.forename: Elena
authors.initials: E
authors.lastname: Grosso
authors.forename: Gian Piero
authors.initials: GP
authors.lastname: Pescarmona
authors.forename: Giovanni Carlo
authors.initials: GC
authors.lastname: Isaia
mesh_terms: D000293:Adolescent; D000328:Adult; D002469:Cell Separation; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D017102:Fracture Healing / Q000502:physiology*; D050723:Fractures, Bone; D006801:Humans; D008297:Male; D008875:Middle Aged; D010006:Osteoblasts / Q000166:cytology*; D010010:Osteoclasts / Q000166:cytology*; D010281:Parathyroid Hormone / Q000097:blood; D011863:Radioimmunoassay; D013234:Stem Cells / Q000166:cytology*; D053773:Transforming Growth Factor beta1 / Q000097:blood; D055815:Young Adult
chemical_list: D010281:Parathyroid Hormone; D053773:Transforming Growth Factor beta1