Author Description

Stem cell Antigen-1 (Sca-1/Ly-6A) is a glycosylphosphatidylinositol-anchored cell surface protein expressed by a variety of stem cell populations. Previous studies indicate that mice null mutant for Sca-1 display an age-dependent osteoporotic phenotype mediated at least in part by mesenchymal progenitor defects. In this longitudinal study we compared the bone quality of Sca-1 null mice to wild type controls at 3, 5, 7 and 9 months of age. Our results revealed a cell intrinsic osteoclast defect with age in Sca-1 null mice. We also observed a tight temporal correlation within Sca-1 null mice between the onset of the previously characterized mesenchymal progenitor deficiencies at 7 months and the exacerbation of most defects in bone formation, mass, mineralization, microarchitecture and mechanical competence, Thus, we have characterized the initiation and progression of Sca-1 null osteoporotic phenotype and indentified time points important for further investigations aimed at designed therapeutic strategies against this disease condition.