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Thomas Harding

Publications and source records attributed to Thomas Harding.

5 recordsLinked to original sources
PubMed2005

Vascular endothelial cell growth factor receptor 3-mediated activation of lymphatic endothelium is crucial for tumor cell entry and spread via lymphatic vessels.

Lymphangiogenic growth factors vascular endothelial growth factor (VEGF)-C and VEGF-D have been shown to promote lymphatic metastasis by inducing tumor-associated lymphangiogenesis. In this study, we have investigated how tumor cells gain access into lymphatic vessels and at what stage tumor cells initiate metastasis. We show that VEGF-C produced by tumor cells induced extensive lymphatic sprouting towards the tumor cells as well as dilation of the draining lymphatic vessels, suggesting an active role of lymphatic endothelial cells in lymphatic metastasis. A significant increase in lymphatic vessel growth occurred between 2 and 3 weeks after tumor xenotransplantation, and lymph node metastasis occurred at the same stage. These processes were blocked dose-dependently by inhibition of VEGF receptor 3 (VEGFR-3) signaling by systemic delivery of a soluble VEGFR-3-immunoglobulin (Ig) fusion protein via adenoviral or adeno-associated viral vectors. However, VEGFR-3-Ig did not suppress lymph node metastasis when the treatment was started at a later stage after the tumor cells had already spread out, suggesting that tumor cell entry into lymphatic vessels is a key step during tumor dissemination via the lymphatics. Whereas lymphangiogenesis and lymph node metastasis were significantly inhibited by VEGFR-3-Ig, some tumor cells were still detected in the lymph nodes in some of the treated mice. This indicates that complete blockade of lymphatic metastasis may require the targeting of both tumor lymphangiogenesis and tumor cell invasion.

Adenoviridae↗
PubMed2003

Third-generation lentivirus vectors efficiently transduce and phenotypically modify vascular cells: implications for gene therapy.

Grafting of saphenous vein (SV) conduits into the arterial circulation triggers a number of adaptive pathological changes characterized by progressive medial thickening, neointima formation and accelerated atheroma. Previous studies have shown that modification of vein graft biology is possible by adenovirus (Ad)-mediated gene transfer, although gene expression is transient. Advancement of vascular gene therapy to the clinic is compromised by the lack of safe and efficient vector systems that provide sustained therapeutic gene delivery to the vasculature. Due to inadequacies of both Ad and adeno-associated virus (AAV) serotype-2 (AAV-2) systems, we have evaluated gene delivery to endothelial cells (ECs) and smooth muscle cells (SMCs) using alternate AAV serotypes and a third-generation vesicular stomatis virus glycoprotein-pseudotyped lentiviral system. Transduction of both primary human SV EC and SMC was lower using all alternate AAV serotypes compared to AAV-2. However, transduction of both cell types by lentivirus was efficient even at clinically relevant exposure times (15 min), was without toxicity and was promoter sensitive. Transduction levels at lower doses were further enhanced with the addition of the surfactant Poloxamer-407 (P-407). Direct comparison with Ad and AAV-2 confirmed the unique potential for this system. Moreover, we constructed and overexpressed the therapeutic gene tissue inhibitor of metalloproteinase-3 (TIMP-3) using lentivirus and demonstrated transgene production comparable to Ad with concomitant blockade of SMC migration and induction of cell death. We have demonstrated for the first time the potential for third-generation lentiviral vectors, but not alternate AAV serotypes, as efficient vascular gene delivery vectors.

Cardiovascular System↗