Photodynamic therapy (PDT) has been investigated in clinical studies as a treatment method for breast cancer chest wall recurrences. Complete response percentage in these studies is not 100% in most patients, indicating the presence of a remaining tumor after PDT. Some in vitro studies show that tumor cells present distinct threshold dose, suggesting that the remaining tumor in vivo could require higher doses or different PDT strategies. There is still a lot of controversy of the multiple PDT sessions effect on bulky tumors. The purpose of this study is to investigate low-dose PDT parameters in 3D cultures of breast cancer cells grown by the magnetic levitation method. PDT was performed with Photodithazine® (PDZ) and LED irradiation at 660 nm. Two concentrations of PDZ were investigated and the 50 μg/mL concentration, which showed a superficial distribution, was used in the PDT. Partial damage was observed in the tumors and the viability test showed a small percentage of cell death. This outcome is favorable for the investigation of PDT effects in the remaining tumor. Multiple PDT sections could provide more noticeable alterations in cell morphology and metabolism.
pathology. The optical properties of these intrinsic fluorophores respond to the microenvironment and the metabolic status, thus making fluorescence spectroscopy a valuable tool to study the conditions of biological tissues. The purpose of this study is to investigate the hairless mice skin metabolic changes during the photoaging process through lifetime and fluorescence measurements targeting NADH and FAD. Two lasers centered at 378 nm and 445 nm, respectively, perform excitation of NADH and FAD. The fluorescence acquisition is carried out at mice dorsal and ventral regions throughout the photoaging protocol and aging process. Differences in fluorescence and lifetime data between young and photoaged mice measurements were observed. The endogenous fluorescence spectrum of photoaged dorsal skin showed an increase compared to young and aged skin. Lifetime of bound NADH and free FAD presented an increase in the first week that continued until the end of the protocol. Aging process is being investigated to complement the information obtained from fluorescence data and lifetime of photoaging process.
Photodynamic therapy (PDT) promotes skin improvement according to many practitioners, however the immediately in
vivo assessment of its response remains clinically inaccessible. As a non-invasive modality, optical coherence
tomography (OCT) has been shown a feasible optical diagnostic technique that provides images in real time, avoiding
tissue biopsies. For this reason, our investigation focused on evaluates the PDT effect on a rodent model by means of
OCT. Therefore, a normal hairless mouse skin has undergone a single-session PDT, which was performed with topical 5-
aminolevulinic acid (ALA) cream using a red (630 nm) light emitting diode (LED) which reached the light dose of 75
J/cm<sup>2</sup>. As the optical imaging tool, an OCT (930 nm) with axial resolution of 6.0 microns in air was used, generating
images with contact to the mouse skin before, immediately after, 24 hours, and 2 weeks after the correspondent
procedure. Our result demonstrates that, within 24 hours after ALA-PDT, the mouse skin from the PDT group has shown
epidermal thickness (ET), which has substantially increased after 2 weeks from the treatment day. Moreover, the skin
surface has become evener after ALA-PDT. Concluding, this investigation demonstrates that the OCT is a feasible and
reliable technique that allows real-time cross-sectional imaging of skin, which can quantify an outcome and predict
whether the PDT reaches its goal.