No abstract

The failure to eradicate most cancers and in particular melanoma may be as fundamental as a misidentification of the target. The identification of cancer stem/initiating cells within the tumour population with a crucial role for tumour formation may open new pharmacological perspectives. Our data show three main novelties for human melanoma: firstly, melanoma biopsy contains a subset of cells expressing CD133 (CD133+) and the latter is able to develop a Mart-1 positive tumour in NOD-SCID mice. Secondly, the WM115, a human melanoma cell line, has been found to express both CD133 and ABCG2 markers. This cell line grows as floating spheroids, expresses typical progenitors and mature neuronal/oligodendrocyte markers and is able to transdifferentiate into astrocytes or mesenchymal lineages under specific growth conditions. As in xenografts generated with CD133+ biopsy melanoma cells, those produced by the cell line displayed lower levels of CD133 and ABCG2. Thirdly, the WM115 cells express the most important angiogenic and lymphoangiogenic factors such as notch 4, prox1 and podoplanin which can cooperate in the development of the tumourigenic capability of melanoma in vivo. Therefore, in this study, we demonstrate the presence of stem/initiating subsets in melanoma both in biopsy and in an established melanoma cell line grown in vitro and in xenografts. Interestingly, considering that melanoma gives metastasis primarily through lymphatic vessels, herein, we demonstrated that a melanoma cell line expresses typical lymphoangiogenic factors.

BackgroundMesenchymal stromal cells may represent an ideal candidate to deliver anti-cancer drugs. In a previous study, we demonstrated that exposure of mouse bone marrow derived stromal cells to Doxorubicin led them to acquire anti-proliferative potential towards co-cultured haematopoietic stem cells (HSCs). We thus hypothesized whether freshly isolated human bone marrow Mesenchymal stem cells (hMSCs) and mature murine stromal cells (SR4987 line) primed in vitro with anti-cancer drugs and then localized near cancer cells, could inhibit proliferation.Methods and Principal FindingsPaclitaxel (PTX) was used to prime culture of hMSCs and SR4987. Incorporation of PTX into hMSCs was studied by using FICT-labelled-PTX and analyzed by FACS and confocal microscopy. Release of PTX in culture medium by PTX primed hMSCs (hMSCsPTX) was investigated by HPLC. Culture of Endothelial cells (ECs) and aorta ring assay were used to test the anti-angiogenic activity of hMSCsPTX and PTX primed SR4987(SR4987PTX), while anti-tumor activity was tested in vitro on the proliferation of different tumor cell lines and in vivo by co-transplanting hMSCsPTX and SR4987PTX with cancer cells in mice. Nevertheless, despite a loss of cells due to chemo-induced apoptosis, both hMSCs and SR4987 were able to rapidly incorporate PTX and could slowly release PTX in the culture medium in a time dependent manner. PTX primed cells acquired a potent anti-tumor and anti-angiogenic activity in vitro that was dose dependent, and demonstrable by using their conditioned medium or by co-culture assay. Finally, hMSCsPTX and SR4987PTX co-injected with human cancer cells (DU145 and U87MG) and mouse melanoma cells (B16) in immunodeficient and in syngenic mice significantly delayed tumor takes and reduced tumor growth.ConclusionsThese data demonstrate, for the first time, that without any genetic manipulation, mesenchymal stromal cells can uptake and subsequently slowly release PTX. This may lead to potential new tools to increase efficacy of cancer therapy.

Abstract-We evaluated the healing potential of human fetal aorta-derived CD133ϩ progenitor cells and their conditioned medium (CD133 ϩ CCM) in a new model of ischemic diabetic ulcer. Streptozotocin-induced diabetic mice underwent bilateral limb ischemia and wounding. One wound was covered with collagen containing 2ϫ10 4 CD133 ϩ or CD133 Ϫ cells or vehicle. The contralateral wound, covered with only collagen, served as control. Fetal CD133 ϩ cells expressed high levels of wingless (Wnt) genes, which were downregulated following differentiation into CD133Ϫ cells along with upregulation of Wnt antagonists secreted frizzled-related protein (sFRP)-1, -3, and -4. CD133ϩ cells accelerated wound closure as compared with CD133Ϫ or vehicle and promoted angiogenesis through stimulation of endothelial cell proliferation, migration, and survival by paracrine effects. CD133ϩ cells secreted high levels of vascular endothelial growth factor (VEGF)-A and interleukin (IL)-8. Consistently, CD133ϩ CCM accelerated wound closure and reparative angiogenesis, with this action abrogated by coadministering the Wnt antagonist sFRP-1 or neutralizing antibodies against VEGF-A or IL-8. In vitro, these effects were recapitulated following exposure of high-glucose-primed human umbilical vein endothelial cells to CD133 ϩ CCM, resulting in stimulation of migration, angiogenesis-like network formation and induction of Wnt expression. The promigratory and proangiogenic effect of CD133 ϩ CCM was blunted by sFRP-1, as well as antibodies against VEGF-A or IL-8. Key Words: ischemia Ⅲ wound healing Ⅲ diabetes Ⅲ stem cells Ⅲ angiogenesis C hronic wounds represent a relevant clinical and socioeconomic burden, with diabetic foot ulcers alone causing costs of 300 million pounds per annum to the United Kingdom National Health System. 1 Diabetic patients with foot ulcers associated with peripheral vascular disease manifest the worst outcome, with higher amputation and mortality rates than patients carrying nonischemic ulcers. 2,3 Although the efficacy of a topical gel formulation of recombinant human platelet-derived growth factor-BB was recently demonstrated in patients with nonischemic neuropathic ulcers, 4 most ischemic ulcers are refractory to conventional treatment and growth factor (GF) therapy. 5 Therefore, new strategies for the cure of life-threatening ischemic ulcers are urgently awaited.Preliminary evidence supports the potential of adult or fetal stem/progenitor cells for the healing of skin ulcers. 6 -8 However, because of the lack of an appropriate preclinical model, no information is available regarding the effectiveness of cell therapy on ischemic diabetic foot ulcers. The healing activity of stem cells is credited to their ability to transdifferentiate into the vascular and nonvascular components of injured tissue, as well as to secretion of GFs, which may activate endogenous modulators of angiogenesis in the recipient. 9 -11 Notably, fetal stem cells show significant advantages over their adult counterparts in terms of proliferative capa...