title: Strontium can increase some osteoblasts without increasing hematopoietic stem cells.
abstract: Osteoblasts are a key component in the regulation of the hematopoietic stem cell (HSC) niche. Manipulating osteoblast numbers results in a parallel change in HSC numbers. We tested the activity of strontium (Sr), a bone anabolic agent that enhances osteoblast function and inhibits osteoclast activity, on hematopoiesis. In vitro treatment of primary murine osteoblasts with Sr increased their ability to form bone nodules, and in vivo it increased osteoblast number, bone volume, and trabecular thickness and decreased trabecular pattern factor. However, the administration of Sr had no influence on primitive HSCs, although the number of hematopoietic progenitors was higher than in control cells. When Sr-treated mice were used as donors for HSC transplantation, no difference in the engraftment ability was observed, whereas hematopoietic recovery was delayed when they were used as recipients. Despite the changes in osteoblast numbers, no increment in the number of N-cadherin(+) osteoblasts and N-cadherin transcripts could be detected in Sr-treated mice. Therefore, increasing the overall number and function of osteoblasts without increasing N-cadherin(+) cells is not sufficient to enhance HSC quantity and function. Our study further supports the notion that N-cadherin(+) osteoblasts are fundamental in the hematopoietic niche.
authors.affiliation: Stem Cell Biology Section, Kennedy Institute of Rheumatology and Division of Investigative Sciences, Hammersmith Hospital, Imperial College, London, United Kingdom.
authors.forename: Stefania
authors.initials: S
authors.lastname: Lymperi
authors.forename: Nicole
authors.initials: N
authors.lastname: Horwood
authors.forename: Stephen
authors.initials: S
authors.lastname: Marley
authors.forename: Myrtle Y
authors.initials: MY
authors.lastname: Gordon
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Cope
authors.forename: Francesco
authors.initials: F
authors.lastname: Dazzi
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects*; D048430:Cell Shape / Q000187:drug effects; D002478:Cells, Cultured; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects*; D051379:Mice; D008807:Mice, Inbred BALB C; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects*; D010012:Osteogenesis / Q000187:drug effects; D010281:Parathyroid Hormone / Q000494:pharmacology; D013324:Strontium / Q000494:pharmacology*
chemical_list: D010281:Parathyroid Hormone; D013324:Strontium