Matrix Metalloproteinase 1 Is Necessary for the Migration of Human Bone Marrow-Derived Mesenchymal Stem Cells Toward Human Glioma

Human mesenchymal stem cells (MSCs) have increasingly been used as cellular vectors for the delivery of therapeutic genes to tumors. However, the precise mechanism of mobilization remains poorly defined. In this study, MSCs that expressed similar cell surface markers and exhibited multilineage differentiation potentials were isolated from various donors. Interestingly, different MSC isolates displayed differential migration ability toward human glioma cells. We hypothesized that distinct molecular signals may be involved in the varied tumor tropisms exhibited by different MSC isolates. To test this hypothesis, gene expression profiles of tumor-trophic MSCs were compared with those of non–tumor-trophic MSCs. Among the various differentially regulated genes, matrix metalloproteinase one (MMP1) gene expression and its protein activities were enhanced by 27-fold and 21-fold, respectively, in highly migrating MSCs compared with poorly migrating MSCs. By contrast, there was no change in the transcriptional levels of other MMPs. Functional inactivation of MMP1 abrogated the migratory potential of MSCs toward glioma-conditioned medium. Conversely, the nonmigratory phenotype of poorly migrating MSC could be rescued in the presence of either recombinant MMP1 or conditioned medium from the highly migrating MSCs. Ectopic expression of MMP1 in these poorly migrating cells also rendered the cells responsive to the signaling cues from the glioma cells in vivo. However, blocking the interaction of MMP1 and its cognate receptor PAR1 effectively diminished the migratory ability of MSCs. Taken together, this study provides, for the first time, supporting evidence that MMP1 is critically involved in the migration capacity of MSCs, acting through the MMP1/PAR1 axis. Stem Cells 2009;27:1366–137

CD34+/M-cadherin+ Bone Marrow Progenitor Cells Promote Arteriogenesis in Ischemic Hindlimbs of ApoE−/− Mice

BACKGROUND: Cell-based therapy shows promise in treating peripheral arterial disease (PAD); however, the optimal cell type and long-term efficacy are unknown. In this study, we identified a novel subpopulation of adult progenitor cells positive for CD34 and M-cadherin (CD34⁺/M-cad⁺ BMCs) in mouse and human bone marrow. We also examined the long-lasting therapeutic efficacy of mouse CD34⁺/M-cad⁺ BMCs in restoring blood flow and promoting vascularization in an atherosclerotic mouse model of PAD. METHODS AND FINDINGS: Colony-forming cell assays and flow cytometry analysis showed that CD34⁺/M-cad⁺ BMCs have hematopoietic progenitor properties. When delivered intra-arterially into the ischemic hindlimbs of ApoE⁻/⁻ mice, CD34⁺/M-cad⁺ BMCs alleviated ischemia and significantly improved blood flow compared with CD34⁺/M-cad⁻ BMCs, CD34⁻/M-cad⁺ BMCs, or unselected BMCs. Significantly more arterioles were seen in CD34⁺/M-cad⁺ cell-treated limbs than in any other treatment group 60 days after cell therapy. Furthermore, histologic assessment and morphometric analyses of hindlimbs treated with GFP⁺ CD34⁺/M-cad⁺ cells showed that injected cells incorporated into solid tissue structures at 21 days. Confocal microscopic examination of GFP⁺ CD34⁺/M-cad⁺ cell-treated ischemic legs followed by immunostaining indicated the vascular differentiation of CD34⁺/M-cad⁺ progenitor cells. A cytokine antibody array revealed that CD34⁺/M-cad⁺ cell-conditioned medium contained higher levels of cytokines in a unique pattern, including bFGF, CRG-2, EGF, Flt-3 ligand, IGF-1, SDF-1, and VEGFR-3, than did CD34⁺/M-cad⁻ cell-conditioned medium. The proangiogenic cytokines secreted by CD34⁺/M-cad⁺ cells induced oxygen- and nutrient-depleted endothelial cell sprouting significantly better than CD34⁺/M-cad⁻ cells during hypoxia. CONCLUSION: CD34⁺/M-cad⁺ BMCs represent a new progenitor cell type that effectively alleviates hindlimb ischemia in ApoE⁻/⁻ mice by consistently improving blood flow and promoting arteriogenesis. Additionally, CD34⁺/M-cad⁺ BMCs contribute to microvascular remodeling by differentiating into vascular cells and releasing proangiogenic cytokines and growth factors

Study on chemotaxis and chemokinesis of bone marrow-derived mesenchymal stem cells in hydrogel-based 3D microfluidic devices

BACKGROUND: Controlling the fate of mesenchymal stems cells (MSCs) including proliferation, migration and differentiation has recently been studied by many researchers in the tissue engineering field. Especially, recruitment of stem cells to injury sites is the first and crucial step in tissue regeneration. Although significant progress has been made in the chemotactic migration of MSCs, MSC migration in three dimensional environments remains largely unknown. We developed a 3D hydrogel-based microfluidic-device to study the migration behavior of human MSCs in the presence of stromal-cell derived factor-1α (SDF-1α), interleukin 8 (IL-8) and Substance P (SP) which have been utilized as chemoattractant candidates of human mesenchymal stem cells (hMSCs). RESULTS: We systematically investigated the chemotactic migration behaviors of hMSCs and their responses to SDF-1α, IL-8, and SP. SDF-1α was shown to be the most fascinating chemoattractant candidate among those factors at a certain time point. We also found that each chemokine showed different chemoattractant abilities according to their concentration. In the case of SP, this factor showed chemokinesis not chemotaxis. Especially at a 7–8 × 10(−8) M concentration range, the chemokinesis ability driven by SP was further increased. The data suggest that some factors at the optimal concentration exhibit chemokinesis or chemotaxis in a 3D hydrogel-based microfluidic device. CONCLUSION: In this study on chemotaxis and chemokinesis of hMSCs, the system parameters such as chemokine concentration, system stability, and 2D or 3D microenvironment are critically important to obtain meaningful results