Enhancement of cell and tissue destruction in cryosurgery by use of eutectic freezing

An in vitro study was performed to investigate a more effective method of destroying malignant tissue during cryosurgery, which is based on eutectic crystallization. Eutectic formation is a solidification process through which water and solutes form a hydrate and can be recognized by a secondary heat release in differential scanning calorimetry (DSC). We investigated whether it is possible to induce eutectic crystallization by infusing concentrated salt solutions into cell suspension and tissue systems. These systems included AT-1 rat prostate tumor (cell suspensions/tissues) and normal rat liver tissues. In cell suspensions, the post-thaw viability significantly drops at or below the temperatures where eutectic crystallization occurred. When eutectic crystallization is induced in tissues, histological analysis shows significantly enhanced freezing injury. These results imply that this method may be of benefit in cryosurgical applications particularly at the edge of the iceball where tumor cell survival is in question. The possible advantages of inducing eutectic crystallization are i) enhancement of direct cell injury; ii) enlargement of effective cryosurgical cell/tissue destruction zone by selecting a salt with a high eutectic temperature; and iii) improvement of the efficacy of monitoring during cryosurgery (i.e. iceball and cryolesion size will match more closely).