Sakamoto Fernanda H, Tannous Zeina, Doukas Apostolos G, Farinelli William A, Smith Nicholas A, Zurakowski David, Anderson R Rox
Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.
Lasers Surg Med. 2009 Feb;41(2):154-60. doi: 10.1002/lsm.20734.
Aminolevulinic acid photodynamic therapy (ALA-PDT) depends on drug metabolism into porphyrins. Clinically, ALA-PDT has been used with a wide range of protocols for treating both epidermal and dermal targets, despite limited understanding of porphyrin biodistribution over time. We studied porphyrin accumulation after topical application of ALA in vivo, and also describe the porcine ear as a new animal model to study adnexal glands.
STUDY DESIGN/MATERIALS AND METHODS: The microanatomy of anterior ear skin of swine was measured. Topical 20% ALA in water/ethanol was applied under occlusion. Biopsies taken after 5, 10, 15, and then every 15 minutes for a total of 3 hours were examined by fluorescence microscopy of frozen sections to assess accumulation and distribution of porphyrins.
Porphyrin fluorescence of digital photomicrograph images was not visually apparent until 30-45 minutes after application, although quantitative pixel analysis showed a statistically significant increase in epidermal fluorescence only 15 minutes after ALA application. From 30 to 120 minutes, epidermis, hair follicles (HF), and sebaceous glands (SG) became progressively more fluorescent. Eccrine gland fluorescence began to be detected after 30 minutes; SG showed fluorescence starting at 45-75 minutes. Fluorescence in all sites reached maximum intensity from 75 to 180 minutes of incubation. There was a trend for HF and SG to express stronger fluorescence compared with epidermis and eccrine glands.
Anterior pig ear skin is microanatomically similar to human sebaceous skin. The time-dependent accumulation of porphyrins in pilosebaceous units and eccrine glands in this model suggests other routes of uptake of topical ALA in addition to the trans-epidermal route. Apparently, time interval between ALA application and light exposure could be optimized for different uses of ALA-PDT.
氨基乙酰丙酸光动力疗法（ALA-PDT）依赖于药物代谢生成卟啉。临床上，尽管对卟啉随时间的生物分布了解有限，但ALA-PDT已被广泛应用于治疗表皮和真皮靶点的多种方案中。我们研究了局部应用ALA后体内卟啉的蓄积情况，并将猪耳描述为一种研究附属腺的新动物模型。
研究设计/材料与方法：测量猪耳前部皮肤的微观解剖结构。将20%的ALA水溶液/乙醇在封闭条件下局部应用。在5、10、15分钟后取材，然后每隔15分钟取材一次，共取材3小时，对冰冻切片进行荧光显微镜检查，以评估卟啉的蓄积和分布情况。
数字显微照片图像的卟啉荧光在应用后30-45分钟之前肉眼不可见，尽管定量像素分析显示在ALA应用后仅15分钟表皮荧光就有统计学显著增加。在30至120分钟内，表皮、毛囊（HF）和皮脂腺（SG）的荧光逐渐增强。30分钟后开始检测到汗腺荧光；SG在45-75分钟开始显示荧光。所有部位的荧光在孵育75至180分钟时达到最大强度。与表皮和汗腺相比，HF和SG有表达更强荧光的趋势。
猪耳前部皮肤在微观解剖结构上与人的皮脂腺皮肤相似。该模型中卟啉在毛囊皮脂腺单位和汗腺中的时间依赖性蓄积表明，除了经表皮途径外，局部应用ALA还有其他摄取途径。显然，对于ALA-PDT的不同用途，可以优化ALA应用与光照之间的时间间隔。
