Wollensak G, Spoerl E, Reber F, Seiler T
Department of Ophthalmology, Technical University of Dresden, Dresden, Germany.
Eye (Lond). 2004 Jul;18(7):718-22. doi: 10.1038/sj.eye.6700751.
Collagen crosslinking using ultraviolet- A (UVA) -irradiation combined with the photosensitizer riboflavin is a new technique for treating progressive keratoconus. It has been shown to increase effectively the biomechanical strength of the cornea and to stop or even reverse the progression of keratoconus. As part of a safety evaluation, the present study was undertaken to investigate in vitro the possible cytotoxic effect of combined riboflavin/UVA-treatment on corneal keratocytes and to compare it to UVA-irradiation alone.
Cell cultures established from porcine keratocytes were treated with 0.025% riboflavin solution and various UVA (370 nm)-irradiances ranging from 0.4 to 1.0 mW/cm2 and with UVA alone between 2 and 9 mW/cm2 for 30 min. The cell cultures were evaluated for cell death 24 h after irradiation using trypan-blue and Yopro-fluorescence staining.
An abrupt cytotoxic irradiance level was found at 0.5 mW/cm2 for keratocytes after UVA-irradiation combined with the photosensitizer riboflavin, which is 10-fold lower than the cytotoxic irradiance of 5 mW/cm2 after UVA-irradiation alone.
A cytotoxic effect of combined riboflavin/UVA-treatment on keratocytes is to be expected at 0.5 mW/cm2, which is reached in the clinical setting in human corneas down to a depth of 300 microm using the standard surface UVA-irradiance of 3 mW/cm2.
使用紫外线A（UVA）照射联合光敏剂核黄素进行胶原交联是一种治疗进行性圆锥角膜的新技术。已证明它能有效提高角膜的生物力学强度，并阻止甚至逆转圆锥角膜的进展。作为安全性评估的一部分，本研究旨在体外研究核黄素/UVA联合治疗对角膜基质细胞可能的细胞毒性作用，并将其与单独的UVA照射进行比较。
用0.025%的核黄素溶液和0.4至1.0 mW/cm²范围内的各种UVA（370 nm）辐照度处理从猪角膜基质细胞建立的细胞培养物，并在2至9 mW/cm²之间单独用UVA处理30分钟。照射后24小时，使用台盼蓝和Yopro荧光染色评估细胞培养物的细胞死亡情况。
在UVA照射联合光敏剂核黄素后，角膜基质细胞在0.5 mW/cm²时发现突然的细胞毒性辐照度水平，这比单独UVA照射后5 mW/cm²的细胞毒性辐照度低10倍。
在0.5 mW/cm²时，核黄素/UVA联合治疗对角膜基质细胞有望产生细胞毒性作用，在临床环境中，使用3 mW/cm²的标准表面UVA辐照度，人角膜中可达300微米深度处会达到该辐照度。
