Friday, 29 December 2017

EXPERIMENT SHOWS SELECTIVE TUMOR DESTRUCTION POTENTIAL OF PHOTODYNAMIC THERAPY.


Photodynamic therapy (PDT) with two chlorin sensitisers was assessed on nude mice bearing human mesothelioma xenografts, and on inner chest tissues of minipigs with the same drug-light conditions to optimize the antitumor activity of PDT while preventing photosensitising injury to normal tissues. Laser light was delivered to the xenografts after administration of m-tetrahydroxyphenyl-chlorin (mTHPC) or an equal dose of polyethylene glycol-derived mTHPC (pegylated mTHPC), respectively. The extent of tumour necrosis was assessed on the basis of microscopic anatomy. Intraoperative PDT was then performed to the chest cavity of minipigs by a sternotomy with the same drug-light conditions at drug-light intervals ranging from twelve hours to six days after i.v. administration of mTHPC and pegylated mTHPC, respectively. RESULTS: Both mTHPC and pegylated mTHPC resulted in photosensitised necrosis of mesothelioma xenografts at drug-light intervals from one to four days, but the extent of necrosis was significantly larger by use of pegylated mTHPC instead of mTHPC at a drug-light interval of three and four days.

The optimal tumorcidal effect was achieved with pegylated mTHPC at a drug-light interval of four days. The photosensitising effect of mTHPC on intrathoracic tissues of minipigs revealed severe damage of virtually all tissues except nerves at short drug-light intervals. Tissue damage gradually became less at longer drug-light intervals and was absent at intervals of three days and longer. In contrast, pegylated mTHPC resulted in no obvious change to any structure at any drug-light interval assessed. CONCLUSIONS: PDT with pegylated mTHPC reveals the potential of selective tumour destruction in this experimental setting and deserves further evaluation for intraoperative application in patients with malignant mesothelioma. Ris, et al., European Journal of Cardio-Thoracic Surgery, 12(4):542-8, October 1997. Photodynamic therapy (PDT) with two chlorin sensitisers was assessed on nude mice bearing human mesothelioma xenografts, and on inner chest tissues of minipigs with the same drug-light conditions to optimize the antitumor activity of PDT while preventing photosensitising injury to normal tissues.

Laser light was delivered to the xenografts after administration of m-tetrahydroxyphenyl-chlorin (mTHPC) or an equal dose of polyethylene glycol-derived mTHPC (pegylated mTHPC), respectively. The extent of tumour necrosis was assessed on the basis of microscopic anatomy. Intraoperative PDT was then performed to the chest cavity of minipigs by a sternotomy with the same drug-light conditions at drug-light intervals ranging from twelve hours to six days after i.v. administration of mTHPC and pegylated mTHPC, respectively. RESULTS: Both mTHPC and pegylated mTHPC resulted in photosensitised necrosis of mesothelioma xenografts at drug-light intervals from one to four days, but the extent of necrosis was significantly larger by use of pegylated mTHPC instead of mTHPC at a drug-light interval of three and four days. The optimal tumorcidal effect was achieved with pegylated mTHPC at a drug-light interval of four days. The photosensitising effect of mTHPC on intrathoracic tissues of minipigs revealed severe damage of virtually all tissues except nerves at short drug-light intervals. Tissue damage gradually became less at longer drug-light intervals and was absent at intervals of three days and longer. In contrast, pegylated mTHPC resulted in no obvious change to any structure at any drug-light interval assessed. CONCLUSIONS: PDT with pegylated mTHPC reveals the potential of selective tumour destruction in this experimental setting and deserves further evaluation for intraoperative application in patients with malignant mesothelioma. Ris, et al., European Journal of Cardio-Thoracic Surgery, 12(4):542-8, October 1997.

EXPERIMENT SHOWS SELECTIVE TUMOR DESTRUCTION POTENTIAL OF PHOTODYNAMIC THERAPY. Rating: 4.5 Diposkan Oleh: ABD KADIR Rusdi

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