Overcoming Hurdles with Fat Grafting: A novel Nanoifber-hydrogel Composite to Promote Fat Graft Survival
Deepa Bhat, MD, Bart Kachniarz, MD MBA, Michelle Seu, BA, Xiaowei Li, PhD, Russell Martin, PhD, Brian Cho, MD, Sashank Reddy, MD PhD, Justin Sacks, MD MBA, Hai Quan Mao, PhD.
Johns Hopkins University, Baltimore, MD, USA.
BACKGROUND: Autologous fat grafting is an important adjunct to soft-tissue reconstruction in patients after oncologic resection of tumors. However, it is associated with multiple complications such as fat necrosis, oil cyst formation, and poor volume retention. There currently exist no tissue scaffold materials that aid in human fat graft retention. The purpose of this study is to demonstrate that our novel nanofiber-hydrogel composite serves as a tissue scaffold that improves fat graft retention and promotes enhanced vascularization within the graft.
METHODS: The following groups were studied: 100% lipoaspirate, 50% lipoaspirate/50% composite, 50% lipoaspirate/50% hydrogel, 75% lipoaspirate/25% composite, and 100% composite. 500uL of material was subcutaneously injected into both flanks of Foxn1nu NU/J male mice (2 injections per mouse). Fifteen mice were used per group. Mice were imaged using MRI at post-operative day (POD) 2, 28, 56, and 84 to assess graft volume retention. Grafts were explanted on days 7, 28, and 84. 3D reconstruction was performed using MicroFil perfusion and computed tomography (CT) scan. Immunohistochemistry (IHC) was performed on explanted grafts to evaluate graft vascularization and adipocyte morphology.
RESULTS: The 50% lipoaspirate/50% composite and 75% lipoaspirate/25% composite groups had the highest volume retention on MRI volumetric analysis (38%, 41% respectively) on POD84 (Figure 1). The 100% composite only group had the poorest volume retention (14%) on POD 84. Results of microfilament perfusion show superior vascularity of composite-containing grafts. On IHC, groups containing the nanofiber-hydrogel composite demonstrated superior rates of angiogenesis and blood vessel ingrowth into the graft as compared to lipoaspirate and lipoaspirate/hydrogel only groups (Figure 1). Furthermore, adipocyte morphology was better preserved in groups containing the nanofiber-hydrogel composite.
CONCLUSIONS: Both groups containing a combination of lipoaspirate/composite exhibited superior volume retention at POD 84 compared to solely lipoaspirate or lipoaspirate/hydrogel combination. Furthermore, the combination of lipoaspirate and composite results in better volume retention compared to either group alone. As demonstrated through IHC, our nanofiber-hydrogel composite promotes higher degrees of angiogenesis than does 100% lipoaspirate or 50% lipoaspirate/50% hydrogel. The nanofiber-hydrogel composite better preserves adipose cell morphology in fat grafting. This has important clinical implications, as improved fat graft retention would save the patient the additional morbidity of undergoing multiple bouts of anesthesia and multiple surgical procedures.
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