title: Intense pulsed light protects fibroblasts against the senescence induced by 8-methoxypsoralen plus ultraviolet-A irradiation.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the influence of intense pulsed light (IPL) irradiation on 8-methoxypsoralen plus ultraviolet-A irradiation (PUVA)-induced senescence of fibroblasts in vitro.
  
  
  BACKGROUND
  Exposure to PUVA may result in stress-induced senescence in fibroblasts. IPL has been widely used to treat photo-aged skin, but the mechanism is not clear.
  
  
  METHODS
  The expression of senescence-associated β-galactosidase (SA-β-gal) was determined by histochemical staining, cell viability was assessed via an MTT assay, telomere length was determined by real-time polymerase chain reaction (PCR), and changes in the generation of reactive oxygen species (ROS) were determined by flow cytometry (FCM).
  
  
  RESULTS
  In comparison with the control cells, cells irradiated with PUVA and PUVA+IPL showed a general elevation in SA-β-gal activity (p<0.05). The number of SA-β-gal-positive fibroblasts in the PUVA+IPL group was clearly lower than that in the PUVA group (p<0.05). Cell viability showed a time-dependent decrease in both the PUVA and PUVA+IPL groups, in comparison with the viability in the control group, and there was no difference in viability between the PUVA and PUVA+IPL groups. PUVA treatment shortened telomere length and increased the level of ROS, in comparison with the corresponding findings for the control cells (p<0.05), whereas irradiation with IPL after PUVA exposure prevented telomere shortening and decreased the ROS level, in comparison with PUVA treatment only (p<0.05).
  
  
  CONCLUSIONS
  PUVA treatment induced fibroblast senescence, and irradiation with IPL after PUVA exposure partially rejuvenated the cells, demonstrating a protective effect against PUVA-induced fibroblast senescence.
authors: Department of Dermatology, Xijing Hospital, the Fourth Military Medical University, Xi'an, China.
authors: Ruiyan
authors: R
authors: Wang
authors: Wei
authors: W
authors: Liu
authors: Weijie
authors: W
authors: Gu
authors: Ping
authors: P
authors: Zhang