Clinical translation of MSC therapies in orthopaedics has been hampered by heterogeneity and a lack of standardised and validated testing protocols for quality assurance. Although minimal criteria have been proposed¹, it is apparent that these do not predict performance in vivo. We used a combinatorial antibody profiling tool to probe the surface immunophenotype of human bone marrow derived MSCs and used this to define new marker panels. Cells were cultured from three marrow donors using specified expansion conditions and probed by high throughput flow cytometry using a panel of 230 antibodies. Analysis of expression of the surface proteins revealed significant variation in response to culture conditions and considerably less variation between donors. Of the panel of 230 markers 107 were negative, 24 had high expression in all samples, 1 had low expression and 98 displayed significant differences between cell preparations. Cluster analyses revealed that marker expression in one culture condition varied considerably from the other two. Phenotypic characterization of the cell preparations, assessed by analysis of differentiation propensity, showed similar patterns of variability between these samples. This suggests that the selected panel may be used as phenotypic MSC markers. Ongoing work involves the generation of novel antibody arrays which will be used as quality tests in a manufacturing environment. These tests will be used for in-process and product release applications for enhanced cell manufacturing and improved clinical outcomes.