Freely available online OPEN ACCESS BJR VOL. 7, NO. 4, APRIL 2018 289 Follow us @BoneJointRes Article focus  The aim of this study was to isolate stem cells from osteopenic rats, and to investi- gate and compare their cluster of differ- entiation marker expression, proliferation, migration, osteogenic, and adipogenic differentiation potential.  The hypothesis of this study is that these characteristics will differ between mesen- chymal stem cells (MSCs) harvested from young, adult, and ovariectomized rats. Key messages  The poor bone formation in postmeno- pausal women could be due to poor retention and function of mesenchymal stem cells resulting into delayed unions.  Our study found significant differences in both the osteogenic and adipogenic potential of stem cells derived from young and osteopenic animals. Similarly, cells derived from osteopenic rats also demon- strated reduced migrative capacity to stromal cell-derived factor 1 (SDF-1). Strengths and limitations  This study examines the effect of age and osteopenia on cell characteristics, using both quantitative and qualitative analysis. The influence of age and osteoporosis on bone marrow stem cells from rats Objectives This study aimed to assess the effect of age and osteoporosis on the proliferative and differ- entiating capacity of bone-marrow-derived mesenchymal stem cells (MSCs) in female rats. We also discuss the role of these factors on expression and migration of cells along the C-X-C chemokine receptor type 4 (CXCR-4) / stromal derived factor 1 (SDF-1) axis. Methods Mesenchymal stem cells were harvested from the femora of young, adult, and osteopenic Wistar rats. Cluster of differentiation (CD) marker and CXCR-4 expression was measured using flow cytometry. Cellular proliferation was measured using Alamar Blue, osteogenic differentiation was measured using alkaline phosphatase expression and alizarin red pro- duction, and adipogenic differentiation was measured using Oil red O. Cells were incubated in Boyden chambers to quantify their migration towards SDF-1. Data was analyzed using a Student’s t-test, where p-values < 0.05 were considered significant. Results CD marker expression and proliferation of the MSCs from the three groups was not signifi- cantly different. The young MSCs demonstrated significantly increased differentiation into bone and fat and superior migration towards SDF-1. The migration of SDF-1 doubled with young rats compared with the adult rats (p = 0.023) and it was four times higher when com- pared with cells isolated from ovariectomized (OVX) osteopenic rats (p = 0.013). Conclusion Young rat MSCs are significantly more responsive to osteogenic differentiation, and, con- trary to other studies, also demonstrated increased adipogenic differentiation compared with cells from adult and ostopenic rats. Young-rat-derived cells also showed superior migra- tion towards SDF-1 compared with MSCs from OVX and adult control rats. Cite this article: Bone Joint Res 2018;7:289–297. Keywords: Osteoporosis, Mesenchymal stem cells, Bone formation, Differentiation, Migration, Stem cells 74.BJRBJR 0 0 10.1302/2046-3758.74.BJR-2017-0302.R1 bone-biology 2018  BONE BIOLOGY doi: 10.1302/2046-3758.74.BJR- 2017-0302.R1 Bone Joint Res 2018;7:289–297. A. Sanghani-Kerai, L. Osagie-Clouard, G. Blunn, M. Coathup University College London, London, United Kingdom  A. Sanghani-Kerai, PhD, PhD Student,  L. Osagie-Clouard, MBBS, Academic Orthopaedic Registrar,  G. Blunn, PhD, Professor of Biomedical Engineering,  M. Coathup, PhD, Head of Centre, Division of Surgery and Interventional Sciences, Institute of Orthopaedics and Musculoskeletal Science, University College London, Royal National Orthopaedic Hospital, Stanmore, Middlesex, UK. Correspondence should be sent to L. Osagie-Clouard; email: l.osagie@ucl.ac.uk