Photobiomodulation with polychromatic light (600-1200 nm) improves fat graft survival by increasing adipocyte viability, neovascularization, and reducing inflammation in a rat model

Abstract

Objectives Unpredictability with the final volume and viability of the graft are the major concerns in fat grafting. An experimental study was conducted to increase graft retention using photobiomodulation (PBM) with polychromatic light in near-infrared region (600-1200 nm) by utilizing its stimulatory effects on angiogenesis, neovascularization, adipocyte viability, and anti-inflammatory properties. Methods A total of 24 rats were divided into four groups (n = 6) according to the applied polychromatic light protocol to the recipient site (none, before fat transfer, after fat transfer, and combined). In all groups, inguinal fat pad was excised, measured for volume and weight, and transferred to the dorsum of the rat. At the end of the experiment, fat grafts were harvested from the recipient site for volume and weight measurements, histological, and immunohistochemical evaluation. Results Intergroup comparison revealed that fat graft retention regarding weight and volume, was significantly superior in Group IV (p = 0.049 and p = 0.043, respectively), which polychromatic light was applied both before and after transfer of the graft. Hematoxylin-eosin and Masson's trichrome stained sections showed absence of necrosis, fibrosis, inflammation, cyst formation, and increased vascularization of both inner and outer zones of the grafts in Group IV. Also, immunohistochemical staining scores for perilipin (indicator for adipocyte viability), CD31 and VEGF (indicators for angiogenesis and neovascularization) were significantly higher (p < 0.001). Ki67 scores were significantly lower in this group because of anti-inflammatory environment (p < 0.001). Conclusions Application of PBM to the recipient site before and after fat transfer improved outcomes in rats at 56 day after fat grafting by means of volume retention, increased neovascularization and adipocyte viability and reduced necrosis, fibrosis and inflammation.