Acellular Adipose Tissue (AAT) for Soft Tissue Reconstruction

Overview

Although other methods (e.g., autologous fat transfer, dermal-/collagen-based fillers) for soft tissue reconstruction exist, each has distinct disadvantages leaving room for improvement in this treatment area. Investigators in the Elisseeff Laboratory (Johns Hopkins University Department of Biomedical Engineering) have recently generated a novel tissue-derived material to create instructive matrices for soft tissue reconstruction called Acellular Adipose Tissue (AAT). This material takes advantage of the inherent bioactivity and unique mechanical properties of subcutaneous adipose tissue. Investigators' preclinical data suggest that AAT is safe for use in small and large animals; investigators' clinical (Phase I) data suggest that AAT is safe for use in humans. These data indicate that a Phase II, dose-escalation study of AAT's safety and efficacy in human subjects is warranted.

Soft tissue volume loss acquired through trauma, congenital malformation or comorbid conditions (i.e., HIV/AIDS) is a common and sometimes devastating problem. Traditional therapies include local tissue transfer, allograft placement, and complex scar revision techniques. Recently, autologous fat transfer has become one of the most commonly employed techniques for improving soft tissue contour deformity particularly for the correction of breast and body defects. While the results from this procedure continue to improve, it requires an additional procedure to harvest fat tissue from the abdomen, thigh or flank leading to donor site morbidity. Clinically, volume loss following autologous fat transfer has been reported to be between 40-60% and usually occurs within the first 4-6 months. Regrafting is often needed and implanted adipose tissue frequently leads to post-operative calcifications. For these reasons, a predictable, "off-the-shelf" material that retains the mechanical and biological properties of adipose tissue would be ideal for the reconstruction of smaller soft tissue defects and soft tissue augmentation. Investigators in the Elisseeff Laboratory (Johns Hopkins University Department of Biomedical Engineering) generated a novel tissue-derived material to create instructive matrices for soft tissue reconstruction \[Acellular Adipose Tissue (AAT)\]. In 2016, investigators conducted a Phase 1, open-label, clinical trial of AAT in healthy volunteers who planned to have elective surgery for the removal of redundant tissue (n=8). Overall, AAT demonstrated satisfactory safety results. No participants experienced serious adverse events (SAEs) or unanticipated adverse events (AEs) related to the study, or exited the study due to AEs. All AEs noted were expected and mild, including redness, bruising, textural changes, hyperpigmentation and tenderness at the injection site. Many other adverse events commonly associated with injections were not observed in any participant throughout the study (i.e., scarring, ulceration, scabbing, purpura, oozing, crusting, blanching, blistering, edema or abrasions). These data indicate that conducting a phase II, dose-escalation, safety and efficacy study in humans is warranted. Based on investigators' experience, investigators hypothesize that AAT will be safe and maintain its volume up to 6 months when injected subcutaneously to restore 5-20cc defects in human soft tissue.