Abstracts
2000 Digestive Disease Week

# 2233 Environmental Factors of Temperature, Humidity, Serum Accumulation, and Cell Seeding Regulate Colon Cancer Cell Adhesion in Vitro.
Stephen M. Kavic, Marc D. Basson, New Haven, CT

Physical characteristics of surgical wounds, including temperature, humidity, and serum accumulation, differ between open and laparoscopic procedures, as may the number of viable tumor cells shed during the procedure. To investigate tumor implantation into surgical wounds, we studied the effects of varying these conditions in a model of colon cancer cell adhesion. Human SW620 colon cancer cells were allowed to adhere to matrixprecoated dishes for 30 minutes at seeding concentrations of 90,000-540,000 cells/well at 25oC, 31oC, and 37oC, in the native state of the matrix proteins and after allowing them to dry for 60 minutes, and in the presence of 0-5% serum. Cells were counted in at least 20 random fields per well of at least three wells/experiment for at least three experiments, and data were pooled for analysis. Cell adhesion varied substantially with all variables studied (n>3, p<0.001 for each comparison below). Adhesion was temperature- dependent, with increases over adhesion at 25oC of 67±7.1% at 31oC and 187±5% at 37oC. Adhesion to collagen I, laminin, and fibronectin also proved dependent on the native hydrophilic conformation of these molecules. When these matrix proteins were allowed to dry, as may occur in open surgical wounds, visible changes in hydrophilicity and substantial decreases in adhesion were observed. Adhesion was decreased by 46±7% on collagen I, 25±7% on laminin, and 54±11% on fibronectin. Serum substantially potentiated adhesion. Although 1% serum did not significantly stimulate adhesion, the addition of 5% serum increased adhesion 69±22%. The number of adherent cells also varied linearly with the number of cells seeded from 90,000 cells per well to 540,000 cells per well, with a 650±8% increase over this range. These results do not indicate that laparoscopic port site recurrence is more common than wound implantation after open surgery. Many factors other than cell adhesion are likely to contribute to clinical wound implantation, including tumor biology, surgical technique, wound growth factors, and the host immune response. These results do suggest that physical factors characteristic of the laparoscopic environment such as warm wound temperature, moisture, and serum accumulation in the port site may all contribute to increased colon cancer cell adhesion. However, the single most important determinant of malignant colonocyte adhesion to surgical wounds, laparoscopic or open, is likely to be the size of the tumor cell inoculum.