Photodynamic therapy (PDT) is a treatment
modality that has advanced rapidly in recent years. It causes tissue and
vascular damage with the interaction of a photosensitizing agent (PS), light of
a proper wavelength, and molecular oxygen. Evaluation of vessel damage usually
relies on histopathology evaluation. Results are often qualitative or at best
semi-quantitative based on a subjective system. The aim of this study was to
evaluate, using CD31 immunohistochemistry and image analysis software, the
vascular damage after PDT in a well-established rodent model of chemically
induced mammary tumor. Fourteen Sprague-Dawley rats received a single dose of
7,12-dimethylbenz(a)anthraxcene (80 mg/kg by gavage), treatment efficacy was
evaluated by comparing the vascular density of tumors after treatment with
Photogem® as a PS, intraperitoneally, followed by interstitial fiber
optic lighting, from a diode laser, at 200 mW/cm and light dose of 100 J/cm
directed against his tumor (7 animals), with a control group (6 animals, no PDT). The
animals were euthanized 30 hours after the lighting and mammary tumors were
removed and samples from each lesion were formalin-fixed. Immunostained blood
vessels were quantified by Image Pro-Plus version 7.0. The control group had an
average of 3368.6 ± 4027.1 pixels per picture and the treated group had an
average of 779 ± 1242.6 pixels per area (P < 0.01),
indicating that PDT caused a significant decrease in vascular density of
mammary tumors. The combined immunohistochemistry using CD31, with selection of
representative areas by a trained pathology, followed by quantification of
staining using Image Pro-Plus version 7.0 system was a practical and robust
methodology for vessel damage evaluation, which probably could
be used to assess other antiangiogenic treatments.