Three-Dimensional Culture Promotes Secretion of Extracellular Matrix Structure Fat Flap with Lipoaspirates <i>in Vitro</i>.

Abstract

Adipose tissue engineering represents a possible solution for large-volume soft-tissue reconstruction. Although there have been several reports on the construction of tissue-engineered fat (TEF) flaps <i>in vivo</i> and <i>in vitro</i>, each condition has various limitations. Thus, we developed a novel approach for engineering fat tissue using a three-dimensional culture system. We used different volumes of lipoaspirates to fill the same tissue engineering chamber (30%, 50%, 80%, and 100% volume/space ratio) for different periods (3, 5, 7, and 14 days) to determine whether lipoaspirates can form structural fat tissue <i>in vitro</i>. We then studied the histological structure and extracellular matrix (ECM) of the tissue formed <i>in vitro</i>. We selected engineering tissue-like fat of the 80% volume/space ratio group cultured for 7 days to be subcutaneously implanted into mice for up to 3 months, and lipoaspirates without structure <i>in vitro</i> were used as a control. The lipoaspirates from the 80% volume/space ratio group cultured <i>in vitro</i> formed TEF-like tissue, which increased in small adipocytes and ECM with time until becoming stable on day 7. The live/dead test showed that the tissue cultured <i>in vitro</i> remained viable until day 7. Immunofluorescence staining results revealed that the collagen I and IV content increased over time. Moreover, after grafting, "self-assembly" fat had higher volume retention, better vascularization, fewer oil droplets, and less fibrosis than the lipoaspirates without structure <i>in vitro</i>. Therefore, our results demonstrate that lipoaspirates filled in tissue engineering chamber can be cultured <i>in vitro</i> and can "self-assemble" into TEF-like tissue. Furthermore, the "self-assembly" fat tissue produced better grafting results than those of lipoaspirates without structure <i>in vitro</i>.