Mesenchymal stem cells (MSCs) are expected to have a fundamental role in future cell-based therapies because of their high proliferative ability, multilineage potential, and immunomodulatory properties. Autologous transplantations have the "elephant in the room" problem of wide donor variability, reflected by variability in MSC quality and characteristics, leading to uncertain outcomes in the use of these cells. We propose life imaging as a tool to characterize populations of human MSCs. Bone marrow MSCs from various donors and in vitro passages were evaluated for their in vitro motility, and the distances were correlated to the adipogenic, chondrogenic, and osteogenic differentiation potentials and the levels of senescence and cell size. Using life-image measuring of track lengths of 70 cells per population for a period of 24 hours, we observed that slow-moving cells had the higher proportion of senescent cells compared with fast ones. Larger cells moved less than smaller ones, and spindleshaped cells had an average speed. Both fast cells and slow cells were characterized by a low differentiation potential, and average-moving cells were more effective in undergoing all three lineage differentiations. Furthermore, heterogeneity in single cell motility within a population correlated with the average-moving cells, and fast-and slow-moving cells tended toward homogeneity (i.e., a monotonous moving pattern). In conclusion, in vitro cell motility might be a useful tool to quickly characterize and distinguish the MSC population's differentiation potential before additional use. STEM CELLS TRANSLATIONAL MEDICINE 2015;4:84-90

The median tumour cell reductions in log steps were 3.7 (2.9-4.3) (n ‫؍‬ 13) (Isolex-50), 3.5 (2.6-4.3) (n ‫؍‬ 13) (MiniMACS) and 1.5 (0.9-2.9) (n ‫؍‬ 17) (Ceprate-LC). Results were compared statistically by univariate analysis. Purity was significantly (P Ͻ 0.05) better after Mini-MACS selection. Recovery rates were significantly different between all devices tested. Tumour cell purging was superior after immunomagnetic separation (P Ͻ 0.001). Tumour cell purging is a main objective of CD34 + selection in the autologous setting. High-dose chemotherapy supported by autologous stem cell reinfusion for treatment of metastatic and high-risk female breast cancer is currently under investigation in several American and European studies. 1,2,3 Tumour cell contamination of autologous stem cell products has been described using immunocytochemistry, reverse transcriptase PCR and cell culture techniques in approximately one third of harvests with a range from 0% to 100%. [4][5][6][7] The clonogenic and metastatic potential of tumour cells isolated from blood and autografts was demonstrated in cell culture assays and in nude mice. [8][9][10] The metastatic potential of accidentally retransplanted tumour cells could be investigated by gene marking of autografts prior to infusion followed by the detection of marked cells after relapse. 11 However, due to the poor transduction efficacy of epithelial cancer cells by gene transfer, a negative result would not exclude the possibility of relapse induction by accidentally reinfused tumour cells. Different approaches have been described to purge autografts of tumour cells. 12 A major problem of purging procedures using cytotoxic agents is the damage to haemopoietic progenitor cells with subsequent delay of engraftment, an increased incidence of severe infections due to prolonged neutropenia and bleeding complications due to thrombocytopenia. [13][14][15] Haemopoietic cells necessary for recovery after highdose therapy and progenitor support express the CD34 antigen on their surface. 16 These cells can easily be enriched by immunological methods using anti-CD34 antibodies and separation by biotin-streptavidin immunoaffinity or magnetic separation with paramagnetic microbeads. Rapid and safe engraftment after reinfusion of enriched CD34 + cell fractions has been described by several investigators after allogeneic and autologous transplantation. 17,18 The immunologic selection of CD34-positive cells has no toxic side-effects on haemopoietic stem cells and progenitors without prolongation of cytopenia after reinfusion.Furthermore, CD34 positive-cell selection is a promising approach to reducing the incidence or mitigating the severity of graft-versus-host-disease in the allogeneic setting by adjusted or nearly complete T cell depletion. However, the major rationale for CD34-positive cell selection in autologous marrow and stem cell transplantation is a reduction or removal of contaminating tumour cells accidentally coharvested during leukapheresis to avoid their reinfusion after high-d...

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