Long-Term Severe In Vitro Hypoxia Exposure Enhances the Vascularization Potential of Human Adipose Tissue-Derived Stromal Vascular Fraction Cell Engineered Tissues

The therapeutic potential of mesenchymal stromal/stem cells (MSC) for treating cardiac ischemia strongly depends on their paracrine-mediated effects and their engraftment capacity in a hostile environment such as the infarcted myocardium. Adipose tissue-derived stromal vascular fraction (SVF) cells are a mixed population composed mainly of MSC and vascular cells, well known for their high angiogenic potential. A previous study showed that the angiogenic potential of SVF cells was further increased following their in vitro organization in an engineered tissue (patch) after perfusion-based bioreactor culture. This study aimed to investigate the possible changes in the cellular SVF composition, in vivo angiogenic potential, as well as engraftment capability upon in vitro culture in harsh hypoxia conditions. This mimics the possible delayed vascularization of the patch upon implantation in a low perfused myocardium. To this purpose, human SVF cells were seeded on a collagen sponge, cultured for 5 days in a perfusion-based bioreactor under normoxia or hypoxia (21% and <1% of oxygen tension, respectively) and subcutaneously implanted in nude rats for 3 and 28 days. Compared to ambient condition culture, hypoxic tension did not alter the SVF composition in vitro, showing similar numbers of MSC as well as endothelial and mural cells. Nevertheless, in vitro hypoxic culture significantly increased the release of vascular endothelial growth factor (p < 0.001) and the number of proliferating cells (p < 0.00001). Moreover, compared to ambient oxygen culture, exposure to hypoxia significantly enhanced the vessel length density in the engineered tissues following 28 days of implantation. The number of human cells and human proliferating cells in hypoxia-cultured constructs was also significantly increased after 3 and 28 days in vivo, compared to normoxia. These findings show that a possible in vivo delay in oxygen supply might not impair the vascularization potential of SVF- patches, which qualifies them for evaluation in a myocardial ischemia model.

Lectin from Laetiporus sulphureus effectively inhibits angiogenesis and tumor development in the zebrafish xenograft models of colorectal carcinoma and melanoma

In spite of extensive usage of Laetiporus sulphureus (sulphur polypore) in traditional European and Asian ethno-medicine for centuries, its anticancer therapeutic potential and toxicity profile remained explored in animal models. Herein, using zebrafish (Danio rerio), as a preclinical animal model, we demonstrated that L. sulphureus lectin (LSL) and ethanol extract (LSE) are non-toxic at high doses up to 400-500 μg/mL, while they effectively inhibited angiogenesis and cancer development at much lower doses. Lectin showed 74-fold higher anti-angiogenic potency than the extract, and even 378-fold higher therapeutic potential than sunitinib-malate, cardiotoxic and myelosupressive anti-angiogenic drug of clinical relevance. Using wound healing and MTT assays, we proved LSL's strong antimigratory effect and selective endothelial cytotoxicity in relation to lung fibroblasts. In addition, employing the zebrafish xenograft models, we demonstrated that LSL almost completely reduced growth, neovascularization and metastasis of human colorectal carcinoma and mouse melanoma. Even more, LSL exerted 8-fold higher potency towards colorectal carcinoma than melanoma, showing markedly higher activity than cisplatin, while LSE failed to express any anticancer activity. Accompanied with non-toxic response, including neutropenia and inflammation, the results of this study strongly imply that LSL could be used as safe adjuvant in chemotherapy against colorectal carcinoma and melanoma.

In Vivo Angiogenic Capacity of Stem Cells from Human Exfoliated Deciduous Teeth with Human Umbilical Vein Endothelial Cells

Dental pulp is a highly vascularized tissue requiring adequate blood supply for successful regeneration. In this study, we investigated the functional role of stem cells from human exfoliated deciduous teeth (SHEDs) as a perivascular source for in vivo formation of vessel-like structures. Primarily isolated SHEDs showed mesenchymal stem cell (MSC)-like characteristics including the expression of surface antigens and in vitro osteogenic and adipogenic differentiation potentials. Moreover, SHEDs were positive for NG2, α-smooth muscle actin (SMA), platelet-derived growth factor receptor beta (PDGFRβ), and CD146 as pericyte markers. To prove feasibility of SHEDs as perivascular source, SHEDs were transplanted into immunodeficient mouse using Matrigel with or without human umbilical vein endothelial cells (HUVECs). Transplantation of SHEDs alone or HUVECs alone resulted in no formation of vessel-like structures with enough red blood cells. However, when SHEDs and HUVECs were transplanted together, extensive vessel-like structures were formed. The presence of murine erythrocytes within lumens suggested the formation of anastomoses between newly formed vessel-like structures in Matrigel plug and the host circulatory system. To understand underlying mechanisms of in vivo angiogenesis, the expression of angiogenic cytokine and chemokine, their receptors, and MMPs was compared between SHEDs and HUVECs. SHEDs showed higher expression of VEGF, SDF-1α, and PDGFRβ than HUVECs. On the contrary, HUVECs showed higher expression of VEGF receptors, CXCR4, and PDGF-BB than SHEDs. This differential expression pattern suggested reciprocal interactions between SHEDs and HUVECs and their involvement during in vivo angiogenesis. In conclusion, SHEDs could be a feasible source of perivascular cells for in vivo angiogenesis.