O084 Adipose-derived stem cells attenuate the induction of tissue destructive and inflammatory fibroblasts by ionising radiation

Abstract Introduction Radiation-Induced Fibrosis (RIF) is a common complication of radiotherapy with no effective treatment, causing permanent, progressive disability and disfigurement of cancer patients. Autologous lipotransfer has promise as a treatment for RIF, with adipose-derived stem cells (ADSCs) proposed as the key effector mechanism. This study investigates the effects of ADSCs on irradiated human dermal fibroblasts (HDFs). Methods HDFs (n = 3), control or irradiated (10Gy), were grown in monoculture, co-culture with ADSCs or in the presence of ADSC-conditioned media (ADSC-CM) over a 2-week period. RT-PCR was used to determine the mRNA expression of 84 inflammatory and fibrotic genes. ELISA was used to measure the levels of MMP1, MMP3 and CCL2 secreted. Immunocytochemistry was used to stain HDFs for type 1 collagen and αSMA. Results Compared to control HDFs, irradiated HDFs demonstrated reduced proliferation and upregulated the mRNA expression and protein secretion of multiple fibrotic and inflammatory genes, including MMP-1, MMP-3, IL-4 and CCL2. Accompanying upregulation of these genes was increased expression of fibroblast activation markers FAPA and PDPN and decreased expression of THY1. Coculture with ADSCs or ADSC-CM attenuated many of these effects. Conclusion Ionising radiation promotes the generation of FAPα+THY1- tissue-destructive fibroblasts that secrete high levels of MMPs, degrading and restructuring the extracellular matrix of the skin. Elevated secretion of pro-inflammatory mediators CCL2 and IL-4, create a microenvironment permissive for the recruitment of monocytes and pro-fibrotic macrophages. ADSCs reverse many of the changes driven by ionising radiation, including the generation of tissue-destructive fibroblasts, through paracrine signalling. Take-home message Ionising radiation promotes the generation of FAPα+THY1- tissue-destructive fibroblasts that secrete high levels of MMPs, degrading and restructuring the extracellular matrix of the skin. ADSCs can reverse many of the changes driven by ionising radiation, including the generation of tissue-destructive fibroblasts, through paracrine signalling.