Novel internal ultraviolet light phototherapy for the treatment of inflammatory bowel disease.

In this study, we discovered the efficacy and safety of the specific wavelength and bandwidth of ultraviolet-A (UVA) light as an antimicrobial modality. In vitro safety studies using a fiber optic UVA delivery system supported by the Kenneth Rainin Foundation showed that, under specific and monitored conditions, UVA can be safely applied even at close distance to various human cell types, with no evidence of DNA damage, cell growth inhibition, or histologic inflammation. In vivo, single and repeated intracolonic UVA exposure in mice did not show harm on endoscopic evaluation and full-thickness pathologic assessment when compared to unexposed control animals. These experiments led to discovery of a safe and effective therapeutic window of UVA which is a complex function of UVA peak wavelength, bandwidth, intensity, time of exposure and distance to target tissue.