[show abstract][hide abstract] ABSTRACT: Human placental multipotent mesenchymal stromal cells (hPMSCs) can be isolated from term placenta, but their angiogenic ability and the regulatory pathways involved are not known. hPMSCs were shown to express integrins alpha(v), alpha(4), alpha(5), beta(1), beta(3), and beta(5) and could be induced to differentiate into cells expressing endothelial markers. Increases in cell surface integrins alpha(5) and beta(1), but not alpha(4), alpha(v)beta(3), or alpha(v)beta(5), accompanied endothelial differentiation. Vascular endothelial growth factor-A augmented the effect of fibronectin in enhancing adhesion and migration of differentiated hPMSC through integrin alpha(5)beta(1), but not alpha(v)beta(3) or alpha(v)beta(5). Formation of capillary-like structures in vitro from differentiated cells was inhibited by pre-treatment with function-blocking antibodies to integrins alpha(5) and beta(1). When hPMSCs were seeded onto chick chorioallantoic membranes (CAM), human von Willebrand factor-positive cells were observed to engraft in the chick endothelium. CAMs transplanted with differentiated hPMSCs had a greater number of vessels containing human cells and more incorporated cells per vessel compared to CAMs transplanted with undifferentiated hPMSCs, and overall angiogenesis was enhanced more by the differentiated cells. Function-blocking antibodies to integrins alpha(5) and beta(1) inhibited angiogenesis in the CAM assay. These results suggest that differentiated hPMSCs may contribute to blood vessel formation, and this activity depends on integrin alpha(5)beta(1).
PLoS ONE 01/2009; 4(10):e6913. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Human placental mesenchymal stem cells (hPMCs) are thought to be multipotent, but their fate after in utero transplantation is not known.
hPMCs isolated from term placenta were assessed for their phenotype markers, mutilineage capacity, and immunomodulatory properties. Their engraftment potential was analyzed in a pregnant rat model after in utero transplantation at embryonic day 17. Immunohistochemistry, tracing of labeled cells, fluorescence in situ hybridization and real-time PCR were used to assess post-transplant chimerism.
In vitro, lineage-negative, CD34-negative hPMCs differentiated into osteocytes, adipocytes, hepatocytes and endothelial cells with tube formation, and actively suppressed the rat lymphocyte proliferative response to allogeneic lymphocyte stimulation (P < 0.0001). After in utero transplantation into pregnant rats, a low level of engraftment was achieved in various fetal tissues. Engraftment occurred in more than 60% of the fetal rats. Cells persisted for at least 12 weeks after delivery and evidence was obtained to suggest differentiation into specific lineages, including hepatocytes and hematopoietic cells. However, a greater number of hPMCs migrated to the placenta than to the fetus, thus limiting the degree of cell engraftment in fetal organs.
We conclude that hPMCs are mutipotent cells that can be engrafted long-term in immunocompetent rats after in utero transplantation.
Human Reproduction 10/2008; 24(1):154-65. · 4.67 Impact Factor
[show abstract][hide abstract] ABSTRACT: Maternal cells can become engrafted in various fetal organs during pregnancy. The nature of the cells and the mechanisms of maternofetal cell trafficking are not clear. We demonstrate that human lineage-negative, CD34-negative (Lin(-)CD34(-)) multipotent mesenchymal stromal cells express alpha(2), alpha(4), alpha(5), and beta(1) integrins, which mediate their adhesion to endothelium, and vascular endothelial growth factor receptor-1 (VEGFR-1), which mediates their response to vascular endothelial growth factor A (VEGF-A). A maternal-fetal VEGF-A concentration gradient exists across the placental barrier, and cord blood plasma induces transendothelial and trans-Matrigel migration of stem cells in vitro. Migration is inhibited by a VEGF-A-neutralizing antibody or antibodies against VEGFR-1 or integrin alpha(2), alpha(4), alpha(5), or beta(1). When Lin(-)CD34(-) multipotent mesenchymal stromal cells are transferred to rat maternal venous blood, they traffic through the placenta, engraft in various fetal organs, and persist in offspring for at least 12 weeks. Cell proliferation ability is retained in the xenogeneic placenta. Maternofetal trafficking is significantly reduced by blocking antibodies against integrins alpha(2), alpha(4), alpha(5), and beta(1) or VEGFR-1. These results suggest that maternal microchimerism arises by the trafficking of multipotent mesenchymal stromal cells via VEGF-A- and integrin-dependent pathways across the hemochorial placenta to fetal tissues.