Zeina B, Greenman John, Corry D, Purcell W M
Dermatology Department of Teshreen Hospital, Damascus, Syria.
Br J Dermatol. 2002 Apr;146(4):568-73. doi: 10.1046/j.1365-2133.2002.04623.x.
Previous work has shown that cutaneous microbial species associated with skin conditions of microbial aetiology are susceptible to killing by photodynamic therapy (PDT) using visible light and methylene blue. Antimicrobial PDT (APDT) in vivo would require a therapeutic regimen where bacteria could be killed without damaging adjacent tissue.
To study keratinocyte killing in vitro using APDT.
We used a combination of methylene blue (100 microg mL(-1)) and visible light (42 mW cm(-2)), previously used for microbial killing, to study cytotoxic effects on keratinocytes. Kill rates and subsequent D-values were determined against a human keratinocyte cell line (H103) using trypan blue and neutral red dye viability tests.
The kill rates for keratinocytes were exponential over the 90- and 180-min period of the experiment for neutral red and trypan blue, respectively. The corresponding D-values were shown to be 198 and 205 min using trypan blue exclusion and neutral red uptake viability tests, respectively.
The kill rates for keratinocytes were 18-200-fold slower than those previously determined for cutaneous microbial species, suggesting that in vivo, APDT sufficient to reduce microbes by seven log cycles would have little cytotoxic effect on keratinocytes. This approach may offer a safe alternative to conventional antimicrobial treatment.
先前的研究表明，与微生物病因引起的皮肤疾病相关的皮肤微生物种类易被使用可见光和亚甲蓝的光动力疗法（PDT）杀死。体内抗菌光动力疗法（APDT）需要一种能在不损伤相邻组织的情况下杀死细菌的治疗方案。
研究使用APDT在体外对角质形成细胞的杀伤作用。
我们使用先前用于杀灭微生物的亚甲蓝（100μg mL⁻¹）和可见光（42mW cm⁻²）的组合，来研究对角质形成细胞的细胞毒性作用。使用台盼蓝和中性红染料活力测试，针对人角质形成细胞系（H103）测定杀伤率和随后的D值。
在实验的90分钟和180分钟期间，中性红和台盼蓝对角质形成细胞的杀伤率分别呈指数增长。使用台盼蓝排斥法和中性红摄取活力测试，相应的D值分别显示为198分钟和205分钟。
角质形成细胞的杀伤率比先前测定的皮肤微生物种类的杀伤率慢18至200倍，这表明在体内，足以使微生物减少7个对数周期的APDT对角质形成细胞几乎没有细胞毒性作用。这种方法可能为传统抗菌治疗提供一种安全的替代方案。
