Photodynamics Therapy Associated Skin Necrosis In Port-Wine Stains:Angioarchitecture And Its Role In Mechanism

Background and Objective Port-wine Stain(PWS), also called aka nevus flammeus, is one of congenital capillary deformities. The incidence of neonatal is about 0.3-0.5%, and its stability of large crowds.In the 1990 s,China, for the first time, used photodynamic therapy(PDT) for the treatment of PWS, and it obtained the remarkable curative effect. Along with the development of the photosensitizer, combined with the second generation photosensitizer: mooring Finn(HMME) PDT, become the new mainstream choice for the treatment of PWS.Skin necrosis in the lesion after PDT treatment as one of its serious complications,increased the popularity of patients with PWS for HMME-PDT. At the same time, because of the poor efficacy of PDT, we needs to explore new light source and the corresponding parameters, subject to the same limit to skin necrosis after treatment. Therefore, exploring HMME-PDT’s mechanism and the reason why skin necrosed after treatment, exploring how to avoid the serious complications, has very important significance.At the same time, in the mechanism research of skin necrosis after HMME-PDT for PWS,there is no literature reported both at our country or abroad. According to the patients who accepted HMME-PDT closely follow-up in the long term, and after treatment by HMME-PDT with patients with skin necrosis and scar healing course of the disease and clinical manifestation, presumably the complications may be due to the radical therapeutic PDT in parameter adjustment or any other personal factors. It leads to the excessive destruction of dermal vascular network, and occurs skin necrosis.Needing of the experimental data to support the theory, this research used the skin young pigs as animal model to explore the damage under different excitation wavelength light source and different energy of microscopic construction subcutaneous blood vessels. And try to understand the pathological basis of complications such as skin necrosis and regularity. It will provide experimental evidence to illustrate the mechanism of serious complications.On this basis, the original research jointed two common excitation light source, to adjust its energy compatibility, in order to achieve the safety and efficacy of preliminary exploration. Because HMME-PDT is widely used in PWS treatment today, this study can also provide excitation light source for clinical HMME-PDT treatment with PWS patients,and a new energy to provide a new thought and theoretical basis.Materials and Methods:Material:This study including 2 months Chinese miniature pig(white) X10, including 5 male /5female(including experimental site for abdominal skin young pigs, the skin after use).Shanghai fudan zhangjiang biomedical co., LTD. Offers of mooring Anaheim photosensitizer HMME(Fu Mei Da ?) X12(100 mg). Semiconductor laser(630 nm wavelength) X1, frequency doubling Nd: YAG laser(532 nm wavelength) X1. Related specimen processing tools and several animal anesthetic tools, CD31 immunohistochemical study tools, TUNEL method to detect apoptosis kit and pathological Image processing and statistical software(Image-Pro Plus 6.0).Methods:Building skin young pigs animal model, to simulate normal human skin. Experimenter used 532 nm, 630 nm excitation light source and different energy density(80 ~ 160mw/cm2), using photosensitizer haim mooring Finn HMME(high dose of 5 mg/Kg).(1) Record at different times skin reaction after treatment(2) Use different excitation light source and different energy treatment for pathological respectively, and the specimens aire processed by immunohistochemical staining to observe target vessel area microscopic building damage relations with skin necrosis(3) Lesions at the same instant, 2 days, 4 days, 7 days, 15 days, 20 days after treatment are cutted for pathological slices, by immunohistochemical and special staining to observe blood vessels to construct damage change over time(4) 630 nm and 532 nm light source cover each other in order to observe the skin safety,and to observe pathological changed of microscopic damage of blood vesselsResults1 in 10 different animals died of lung infection in the experimental stage only.2 experimental animals(a, b) medium energy density of 100 mw/cm2 irradiation(40minutes) photodynamic therapy. 630 nm light spot in 3 days after slight scabby, 532 nm light has no obvious skin reactions. Termination of 20 days of observation, both animals do not appear the skin damage. 4 different animals(c, d, e, f) were accepted a high energy density of 120-130 mw/cm2(630 nm light irradiation for 40 minutes, 532 nm light irradiation for 60 minutes) photodynamic therapy. Two groups of 4 animals flare after 3days is scabby. Termination of 20 days of observation, three of the 630 nm light spot place appeared necrosis after scarring(75%) and 532 nm light spot place no necrosis and scar(0%). 1 experimental animals(g) only accept high energy density of 140-150 mw/cm2irradiation(40 minutes) photodynamic therapy. 630 nm and 532 nm all appear thicker scab skin flare in three days. Termination of 20 days of observation, the skin damage is still unhealed ulcer. 1 only experimental animals(h) accept high energy 160 mw/cm2(15minutes of exposure) photodynamic therapy. In 630 nm to 532 nm light spots all lesiond appear thicker scabs in 3 days. Termination of 20 days of observation, the trend of ulcer healing, soften the thick callus, no obvious scar formation. 1 experimental animals(I)accept a lower energy density of 80 mw/cm2 irradiation(40 minutes) photodynamic therapy, part of the flare overlapping coverage. 630 nm light spot and 532 nm light overlapping coverage in 3 days is not scabby, overlap area has no obvious skin reactions.Termination of 20 days of observation, both does not appear the skin damage.Related immunohistochemistry and TUNEL test showed that the damage of blood vessels to build by 630 nm excitation light source for the depth of 1144.0 um(1067.495 to1067.495 um) of subcutaneous vascular network. 532 nm excitation light source vascular damage by the construction of depth of 921.9 um(850.47 to 850.47 um) of subcutaneous vascular network. The microscopic observation showed that damage of blood vessels construction in photodynamic therapy without apparent depth change over time, the skin was observed 3 days after treatment of nutrition. In 15 to 20 days, vascular remodeling or scarring appear in epidermis and the dermis.Conclusion The safety of the 532 nm light always satisfactory(especially in the 120-130 mw/cm2, the treatment of 60 minutes, perform well). In 630 nm light source under the relatively high energy density, skin necrosis complications may occur. By reducing the irradiation time,we can solve the problem of skin lesions. The depth of 921.9 to 1144.0um dermal vascular network damage is closely related to complications such as occurrence skin necrosis.Skin microscopic vascular construction(dermal vascular network) destruction has nothing to do with the follow-up time after treatment. HMME photodynamic treatment for port-wine stains may no follow-up action. Low energy under 630 nm to 532 nm light sources joint cover radiation safety in dispute, and the curative effect of combining both for port-wine stains is worth looking forward to.