An in vitro model fails to demonstrate aerosolization of tumor cells

Abstract

Background: We investigated the ability of pressurized CO₂ gas to aerosolize B16 melanoma (B16) tumor cells in an in vitro model.

Methods: The experimental apparatus consisted of an 18.9-L plastic cylindrical vessel and a compliant latex pouch was attached to the top. Two 5-mm ports penetrated the vessel; insufflation and desufflation were carried out through them. A culture dish containing 20 million B16 cells in liquid culture media was placed at the base within the container. In the first experiment, the vessel was insufflated with CO₂ gas to a static pressure of 15 or 30 mm Hg with the outflow port closed. After 10 min, the outflow port was opened and the gas was desufflated through a collecting device containing sterile culture medium. In a second experiment, a continuous flow of CO₂ through the vessel was maintained after a pressure of 15 or 30 mm Hg was established. A total of 10 L CO₂ was cycled through the vessel. In both experiments, 24 determinations were carried out at each pressure. Each experimental culture dish was microscopically scanned for 2 weeks for the presence of tumor cells. The third and fourth experiments tested for the presence of aerosolized nonviable tumor cells in the expelled gas. Using the model described above, after 10 mins of 30 mm Hg static pressure, the CO₂ gas was expelled directly onto a glass slide and cytofixed. Alternately, after 10 mins at 30 mm Hg static pressure, the gas was expelled through a saline-filled Soluset (Abbott Laboratories), centrifuged, and the residue cytofixed onto a glass slide. Each of the five slides per experiment were examined microscopically for the presence of cells.

Results: In the first and second experiments, no cells or growth were observed in any of the 96 experimental dishes. In experiments three and four, no cells were detected on any of the slides.

Conclusions: It was not possible with this model to aerosolize tumor cells in a pressurized CO₂ environment. Our results suggest that aerosolization of tumor cells is not the mechanism of port site recurrences after laparoscopic surgery for malignant disease.