The use of synchrotron infrared microspectroscopy to demonstrate the effect of intense pulsed light on dermal fibroblasts.

Abstract Intense pulsed light (IPL) has been used extensively to treat striae distensae (SD). Twenty-four patients (21 females and 3 males) with age ranging between 15-42 years with a mean of 24.2 ± 5.89 years were included in this study. All patients were treated with IPL for five sessions and were given 4-week interval between the sessions. Formalin-fixed, paraffin- embedded skin biopsies were cut into 5-μm-thick sections from patients before and after treatments. They were stained with hematoxylin and eosin (H&E) and collagen with Masson trichrome stain. Histological examination of SD revealed epidermal thinning, flattened rete ridges, and fragmentation with degeneration of the collagen and elastic fibers. After IPL treatments, collagen expression was found also to be increased in a highly significant manner and P values were < 0.001 after IPL treatments. The use of synchrotron infrared (IR) microspectroscopy also revealed that amide 1 and beta sheets were expressed in a significant manner after IPL treatment. In conclusion, it was demonstrated that IPL can treat striae through fibroblast stimulation which led to protein expression especially collagen stimulation, and it seems that it is a promising therapeutic modality for striae with minimal side effects.