DHE Uptake and PDT Response in an In-Vitro Tumor Model
Considerable evidence suggests that tumor destruction by Photodynamic Therapy (PDT) results at least in part from primary damage to the tumor vasculature (Henderson and Dougherty, 1984; Star et al, 1986;). Nevertheless, a significant contribution of direct photodynamic tumor cell killing to tumor necrosis cannot be ruled out, the magnitude of which might be expected to be limited by such factors as photosensitizer penetration into tumor tissue, as well as local oxygen concentration. Multicellular tumor spheroids (MTS) are spherical aggregates of cells whose growth is accompanied by the development of heterogeneous subpopulations differing in their proliferation, nutrition, and oxygenation status (Sutherland and Durand, 1976). As such, MTS constitute a useful 3-dimensional tissue culture model intermediate between single cell cultures and poorly-vascularized solid tumors in vivo. We have been using MTS of V-79 Chinese hamster cells in order to study the role of a variety of treatment and biological conditions to determining the response of tumors to the direct photocytotoxic effect of PDT, involving the photosensitizing drug DHE (as Photofrin IITM) in combination with red light.
KeywordsPorphyrin Alan Concession Photofrin Hematoporphyrin
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