Effect of photodynamic therapy on normal fibroblasts and colon anastomotichealing in mice

Photodynamic therapy as an adjuvant modality to surgical resection of colon cancer is feasible provided that it does not affect healing of the anastom osis. The aim of this study was to evaluate the effects of photodynamic the rapy on the viability of normal fibroblasts and on the healing process of c olonic anastomosis in mice. Both in vitro and in vivo methods were employed . For in vitro study, 2 x 10(5) human fibroblasts were incubated in triplic ate with S-aminolevulinic acid (2.5 mu g/well) for 48 hours. Cells then und erwent photoradiation at light doses of 50, 100, and 200 joules/cm(2) using a nonlaser light source. Viability was assessed by methylene blue dye excl usion. For in vivo studies, 60 mice were randomized into study and control groups and underwent laparotomy involving colonic anastomosis. The anastomo sis underwent photodynamic therapy using 5-aminorevulinic acid (60 mg/kg) a s a photosensitizer and a nonlaser light (40 joules/cm(2)). On postoperativ e days 1, 4, 7, 14, and 21, six mice were killed and subjected to bursting pressure and histologic examinations. Results of in vitro study showed pret reatment cell viability to be 96% to 99% in both groups. Photodynamic thera py caused no significant change in fibroblast; viability at all light doses . Results of in vivo studies showed that the mean bursting pressure of both groups dropped to a low peak on day 4. Subsequently there was a gradual in crease in bursting pressure along the examined time points (P < 0.001). The re was no difference in bursting pressure between the two groups for all ti me points examined. It was concluded that photodynamic therapy has no effec t on viability of normal human fibroblasts and no adverse effects on healin g of colonic anastomosis.