Cryomedical Sciences Inc. (CMSI) teamed with the University of Texas Medical Center and Johns Hopkins Medical Center proposes to develop cryosurgical procedures for the treatment of gastrointestinal (GI) cancers. This Phase 1 study will focus on molecular biological studies and development of prototype cryosurgical devices; whereas the Phase II work will focus on the application of these endoscopic cryosurgical devices in a canine model. CMSI recognizes a need to explore the molecular biological mechanisms of cell death that occur as a consequence of hypothermic(15 to 4C) and freezing (0C to -196C) episodes. CMSI is using molecular biological research to develop improved cryosurgical protocols through an understanding freeze-related cell death and survival. Data from cryosurgeons in the past few years have indicated that cancer cells in the middle of a tissue iceball created during cryosurgical procedures die immediately due to necrosis; whereas many of the cells that die in the iceball periphery where temperatures approach 0C die several days subsequent to cryoablation. While some of the peripheral cells survive the freezing insult. In vitro and molecular genetic studies performed at CMSI show that cells frozen at -70C die by necrosis; whereas at least 25 percent of the cells that die at -15C succumb via apoptosis. These observations lead to CMSI's in vitro cryochemo adjunct therapy studies showing that the addition of non-toxic levels of the apoptosis initiator 5-fluorouracil (5-FU) to kidney, liver, prostate and most notably colon cancer cells enhances the efficacy of cryoablation. This Phase I grant will determine if (1) sub-lethal freezing of HT-29 and/or Caco-2 colon carcinoma cells results in the increase in synthesis of the cell death regulators, bcl-2, bax, Apaf 1, FADD, Fas and PARP; (2) sublethal freezing causes an up-regulation of caspase mRNA levels; (3) cell death due to freezing injury is cell cycle phase dependent and (4) modifications can be made to two prototype cryosurgical devices that are currently being designed for treating Barrett's esophagus and colon cancer to make them more useful and efficacious in the cryosurgical suite.
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| Gage, Andrew A; Baust, John G (2002) Cryosurgery - a review of recent advances and current issues. Cryo Letters 23:69-78 |
