8550 Processing Technique Affects Aromatase Expression in Fat Grafts for Breast Reconstruction

Abstract Disclosure: S. Arbuiso: None. Y. Chen: None. N.A. Vernice: None. A. Zhang: None. I.J. Rhodes: None. C.C. Alston: None. S. Hanif: None. S. Liu: None. P. Bhardwaj: None. D. Janhofer: None. G.G. Black: None. D.M. Otterburn: None. K.A. Brown: None. Introduction: Autologous fat grafting is commonly used in breast reconstruction as it is associated with good cosmetic outcomes, high patient satisfaction, and minimal risks. Adipose tissue is known to support cancer growth via the secretion of adipokines and the modulation of estrogen levels due to aromatase expressed in adipose stromal cells. A higher body mass index (BMI) and postmenopausal status are associated with higher levels of aromatase. With novel processing techniques being developed to increase fat graft retention, there is a need to better understand how these will affect the biology of lipoaspirates for women who have previously had breast cancer. This study aims to assess how different processing techniques used in fat grafting (1) impact aromatase gene expression, (2) affect breast cancer cell proliferation, and (3) affect the cellular composition of the engrafted lipoaspirate. Methods: Patients who underwent breast reconstruction for breast cancer treatment or for prophylactic measures, and were receiving autologous fat grafting, were enrolled in a prospective randomized controlled trial (NCT04891510). Patients were randomized to one of three processing techniques: standard decantation, active filtration, and low-pressure decantation. Conditioned media (CM) was created from each sample. Aromatase mRNA was measured in the lipoaspirate using qRT-PCR for aromatase (CYP19A1) and related to patient BMI or menopausal status. The effect of CM on the proliferation of MCF7 cells (estrogen receptor positive (ER+) breast cancer cell line) was measured using CyQUANT. Formalin-fixed lipoaspirate samples were embedded in HistoGel and paraffin. Adipocyte diameter was measured in hematoxylin and eosin (H&E) stained sections using ImageJ. Results: Aromatase mRNA levels were correlated with BMI and were higher in postmenopausal women (p≤0.05), with the standard decantation group demonstrating a stronger correlation with BMI. Samples processed via active filtration were associated with weaker correlations between aromatase gene expression and BMI and menopausal status. CM induced MCF7 cell proliferation to a similar extent to cells plated in fetal bovine serum-containing media. There was no difference in proliferation patterns between treatment groups. Upon histological assessment, adipocytes were intact, and adipocyte diameter was significantly correlated with patient BMI. Conclusion: Lipoaspirate may contain factors that promote breast cancer cell proliferation, unaffected by processing technique. Caution should be used to ensure local control of the cancer has been achieved prior to reconstruction. Our data suggest that active filtration selects for a lower percentage of adipose stromal cells, which may be beneficial for patients who previously had ER+ breast cancer. Presentation: 6/1/2024