In Vivo Quantification of the Effectiveness of Topical Low-Dose Photodynamic Therapy in Wound Healing Using Two-Photon Microscopy

Abstract

The effect of low-dose photodynamic therapy on in vivo wound healing with topical application of 5-aminolevulinic acid and methylene blue was investigated using an animal model for two laser radiation doses (1 and 4 J/cm2). A second-harmonic-generation-to-auto-fluorescence aging index of the dermis (SAAID) was analyzed by two-photon microscopy. SAAID measured at 60–80 μm depths was shown to be a suitable quantitative parameter to monitor wound healing. A comparison of SAAID in healthy and wound tissues during phototherapy showed that both light doses were effective for wound healing; however, healing was better at a dose of 4 J/cm2.

The In Vivo Quantitative Assessment of the Effectiveness of Low-Dose Photodynamic Therapy on Wound Healing Using Optical Coherence Tomography

“…Previously, our group analyzed the two-photon microscopy images of the wound healing process and succeeded in quantitatively assessing the state of the wound and studying the effect of low-dose photodynamic therapy using the techniques of two-photon microscopy. The results of this study are completely consistent with the results obtained earlier [50].…”

Quantitative Assessment of Low-Dose Photodynamic Therapy Effects on Diabetic Wound Healing Using Raman Spectroscopy

“…The wounds were irradiated by a CW AlGalnP laser (λ = 630 nm, p = 5 mW) with two doses: 1 J/cm 2 or 4 J/cm 2 for 3 min 45 s and 15 min, respectively. These doses were chosen, according to the Arndt–Schultz’s pattern of biological response [ 31 ], and they were used in the authors’ previous studies [ 7 , 21 ]. The diabetic mice were randomly divided into five groups; each group included 5 mice: the control group, LDPDT-5-ALA/1 J/cm 2 , LDPDT-MB/1 J/cm 2 , LDPDT-5-ALA/4 J/cm 2 , and LDPDT-MB/4 J/cm 2 groups.…”

“…DM is one of the challenges of the wound healing process [ 5 ]. Normal wound healing is a dynamic and complex physiological process involving the following overlapping phases: hemostasis, inflammation, proliferation, and remodeling [ 6 , 7 ]. The wound healing begins with hemostasis achieved through vasoconstriction and platelet-mediated activation of the intrinsic clotting cascade, ending in formation of a fibrin clot [ 6 , 8 ].…”

Positive effects of low‐dose photodynamic therapy with aminolevulinic acid or its methyl ester in skin rejuvenation and wound healing: An update

“…However, it has recently been found that low-dose ALA/MAL-PDT can also stimulate wound healing (Table 2). Low-dose ALA-PDT with topical application of 20% ALA and two low-dose light energy (1 J/cm 2 and 4 J/cm 2 ) was proven to allow the wound healing process to accelerate in mice with better effect at a laser radiation dose of 4 J/cm 2 , and quantitative assessments were carried out by two-photon microscopy and optical coherence tomography [21,63]. Nevertheless, the specific mechanism of wound healing induced by low-dose ALA/MAL-PDT is still poorly understood.…”

“…In the past, low-dose PDT was considered as PDT with sublethal PS and/or light, which had immunomodulatory effects and kept the cell viability intact [20]. Recently, low-dose PDT is defined as PDT using low doses of radiation (similar to the dose of low-level light therapy that can stimulate wound healing) and exogenous PS with an optimal (relatively low) concentration [21]. Some scholars have established different PDT protocols for skin keratinocytes including lethal, sublethal and proliferation conditions [22].…”