INFRARED IMAGING AND FLUORESCENCE MEASUREMENTS IN PHOTODYNAMIC THERAPY OF A FIBROSARCOME ANIMAL MODEL

ETCHEVERRY, MARIA EUGENIA; PASQUALE, MIGUEL; CORTI AGUSTINA; MARIO, GARAVAGLIA

Buenos Aires (CABA)

Congreso; Reunión Conjunta de sociedades de biociencias; 2017

Infrared imaging and In vivo spectrofluorometric analysisare non-invasive procedure that can be used to follow photodynamictherapy (PDT) of tumors. Infrared imaging detects radiation emittedby the tissue as a result of its temperature and produces a tempera-ture field. The second technique analyzes the light emitted by thetissue containing a fluorescent photoactive drug.Using a thermal imaging camera (Agema 550) and portable spec-trofluorometer with an excitation source emitting at 400 nm wave-length and a spectral analyzer ranging from 500 nm to 800 nm, theevolution of the m-tetrahydroxyphenyl chlorin (m-THPC) photosen-sitizer at the tumoral tissue of BALB/c murines with fibrosarcoma lo-cated at their flank was followed up. Thermal images were registered during the illumination while fluorescence was measured before, im-mediately after illumination and at interval of 24 h for 48 ? 256 h. Weinvestigated the usefulness of both techniques for monitoring theextent of the photodynamic reaction in the tumor tissue illuminatedwith a light dose of 20 J/cm2 from a 637 nm LED lamp with an outputof 1,06 W. The average fluorescence intensity in the tumor reacheda maximum after 24 - 72 h. Subsequently, illuminations 24, 48, 72and 96 h post-injection were performed, and the fluorescence wasmeasured immediately before and after each illumination, observingin average a decrease in the intensity. Eventually, 24 h post-illumi-nation, the fluorescence at certain parts of the tumor increased incomparison with that measured immediately after illumination. Tem-perature monitoring revealed non-uniform temperature distributionin the illuminated areas. The temperature gradually increased in thepresence of photosensitizer in comparison with control mice. Duringthe PDT temperature increase from 28,7°C to 35,2 °C. The use ofboth techniques allows a more confident evaluation of the PDT treat-ment and are expected to contribute to improve protocols for PDTapplication.