Epithelial to mesenchymal transition (EMT)1 occurs naturally during embryogenesis, tissue repair, cancer progression, and metastasis. EMT induces cellular and microenvironmental changes resulting in loss of epithelial and acquisition of mesenchymal phenotypes, which promotes cellular invasive and migratory capabilities. EMT can be triggered by extracellular factors, including TGF-␤, HGF, and EGF. Overexpression of transcription factors, such as SNAIL, SLUG, ZEB1/2, and TWIST1, also induces EMT and is correlated to cancer aggressiveness. Here, the breast adenocarcinoma cell line MCF7 was transduced with SNAIL to identify specific mechanisms controlled by this transcription factor during EMT. Overexpression of SNAIL led to EMT, which was thoroughly validated by molecular, morphological, and functional experiments.

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Considerable progress has been made on the development of adipose-derived stem/stromal cells (ASCs) as pro-angiogenic therapeutic tools. However, variable clinical results highlight the need for devising strategies to enhance their therapeutic efficacy. Since ASCs proliferate and stabilize newly formed vessels during the angiogenic phase of adipose tissue formation, we hypothesized that mimicking an angiogenic milieu during culture of ASCs would enhance their capacity to support endothelial cell survival and angiogenesis. To test this, we compared the effect of an endothelial growth medium (EGM-2) and conventional media (αMEM) on the progenitor and angiogenic properties of ASCs. ASCs cultured in EGM-2 (ASC-EGM) displayed the highest clonogenic efficiency, proliferative potential and multilineage potential. After co-culture under growth factor starvation, only ASC-EGM attenuated luciferase-expressing human umbilical vein endothelial cells (HUVEC) apoptosis and supported the formation of endothelial cords in a dose-dependent manner. These effects were recapitulated by the conditioned medium of ASC-EGM, which displayed a 100-fold higher expression of hepatocyte growth factor in comparison with ASC-αMEM. Next, HUVEC and ASCs were co-transplanted subcutaneously into immunodeficient mice, and the survival of HUVEC was monitored by bioluminescent imaging. After 60 days, the survival of HUVEC transplanted alone was equivalent to that of HUVEC co-transplanted with ASC-αMEM (15.0 ± 0.7 vs. 13.0 ± 0.5%). Strikingly, co-transplantation with ASC-EGM increased HUVEC survival to 105.0 ± 3.5%, and the resulting organoids displayed functional vasculature with the highest human-derived vascular area. These findings demonstrate that pre-conditioning of ASCs in endothelial growth medium augment their pro-angiogenic properties and could enhance their therapeutic efficacy against ischemic diseases.

Adipose-derived stromal/stem cells (ASCs) are promising candidates for cell-based therapies. However, the lack of markers able to unequivocally identify these cells, the differential expression of cell surface molecules among stromal progenitors from different tissues and cellular alterations caused by culture are phenomena that need to be comprehensively addressed in order to improve ASC purification and consequently refine our knowledge about their function and therapeutic efficiency. In this study, we investigated the potential of CD271, a marker used for purification of bone marrow-derived mesenchymal stem cells, on enriching ASCs from CD34 stromal cells of human adipose tissue. Putative ASC populations were sorted based on CD271 expression (CD45 CD31 CD34 CD271 and CD45 CD31 CD34 CD271 cells) and compared regarding their clonogenic efficiency, proliferation, immunophenotypic profile, and multilineage potential. To shed light on their native identity, we also interrogated the expression of key perivascular cell markers in freshly isolated cells. CD271 cells displayed twofold higher clonogenic efficiency than CD271 cells. Upon culture, the progeny of both populations displayed similar immunophenotypic profile and in vitro adipogenic and chondrogenic potentials, while CD271 cells produced more calcified extracellular matrix. Interestingly, uncultured freshly isolated CD271 cells displayed higher expression of pericyte-associated markers than CD271 cells and localized in the inner region of the perivascular wall. Our results demonstrate that cells with in vitro ASC traits can be obtained from both CD271 and CD271 stromal populations of human adipose tissue. In addition, gene expression profiling and in situ localization analyses indicate that the CD271 population displays a pericytic phenotype.