@article{KleinMeissnerKleffetal.2014,
  author    = {Klein, Diana and Meissner, Nicole and Kleff, Veronika and Jastrow, Holger and Yamaguchi, Masahiro and Erg{\"u}n, S{\"u}leyman and Jendrossek, Verena},
  title     = {Nestin(+) Tissue-Resident Multipotent Stem Cells Contribute to Tumor Progression by Differentiating into Pericytes and Smooth Muscle Cells Resulting in Blood Vessel Remodeling},
  series = {Frontiers in Oncology},
  volume    = {4},
  journal   = {Frontiers in Oncology},
  number    = {169},
  issn      = {2234-943X},
  doi       = {10.3389/fonc.2014.00169},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-120973},
  year      = {2014},
  abstract  = {Tumor vessels with resistance to anti-angiogenic therapy are characterized by the normalization of the vascular structures through integration of mature pericytes and smooth muscle cells (SMC) into the vessel wall, a process termed vessel stabilization. Unfortunately, stabilization-associated vascular remodeling can result in reduced sensitivity to subsequent anti-angiogenic therapy. We show here that blockade of VEGF by bevacizumab induces stabilization of angiogenic tumor blood vessels in human tumor specimen by recruiting Nestin-positive cells, whereas mature vessels down-regulated Nestin-expression. Using xenograft tumors growing on bone-marrow (BM) chimera of C57Bl/6 wildtype and Nestin-GFP transgenic mice, we show for first time that Nestin(+) cells inducing the maturation of tumor vessels do not originate from the BM but presumably reside within the adventitia of adult blood vessels. Complementary ex vivo experiments using explants of murine aortas revealed that Nestin(+) multipotent stem cells (MPSCs) are mobilized from their niche and differentiated into pericytes and SMC through the influence of tumor-cell-secreted factors. We conclude that tissue-resident Nestin(+) cells are more relevant than BM-derived cells for vessel stabilization and therefore have to be considered in future strategies for anti-angiogenic therapy. The identification of proteins mediating recruitment or differentiation of local Nestin(+) cells with potential stem cell character to angiogenic blood vessels may allow the definition of new therapeutic targets to reduce tumor resistance against anti-angiogenic drugs.},
  language  = {en}
}
@article{KleinBenchellalKleffetal.2013,
  author    = {Klein, Diana and Benchellal, Mohamed and Kleff, Veronika and Jakob, Heinz G{\"u}nther and Erg{\"u}n, S{\"u}leyman},
  title     = {Hox genes are involved in vascular wall-resident multipotent stem cell differentiation into smooth muscle cells},
  series = {Scientific Reports},
  volume    = {3},
  journal   = {Scientific Reports},
  number    = {2178},
  doi       = {10.1038/srep02178},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-131496},
  year      = {2013},
  abstract  = {Human vascular wall-resident CD44+ multipotent stem cells (VW-MPSCs) within the vascular adventitia are capable to differentiate into pericytes and smooth muscle cells (SMC). This study demonstrates HOX-dependent differentiation of CD44(+) VW-MPSCs into SMC that involves epigenetic modification of transgelin as a down-stream regulated gene. First, HOXB7, HOXC6 and HOXC8 were identified to be differentially expressed in VW-MPSCs as compared to terminal differentiated human aortic SMC, endothelial cells and undifferentiated pluripotent embryonic stem cells. Silencing these HOX genes in VW-MPSCs significantly reduced their sprouting capacity and increased expression of the SMC markers transgelin and calponin and the histone gene histone H1. Furthermore, the methylation pattern of the TAGLN promoter was altered. In summary, our findings suggest a role for certain HOX genes in regulating differentiation of human VW-MPSC into SMCs that involves epigenetic mechanisms. This is critical for understanding VW-MPSC-dependent vascular disease processes such as neointima formation and tumor vascularization.},
  language  = {en}
}