Tissue engineering of injectable soft tissue filler: using adipose stem cells and micronized acellular dermal matrix

In this study of a developed soft tissue filler, adipose tissue equivalents were constructed using adipose stem cells (ASCs) and micronized acellular dermal matrix (Alloderm). After labeling cultured human ASCs with fluorescent green protein and attaching them to micronized Alloderm (5 x 10(5) cells/1 mg), ASC-Alloderm complexes were cultured in adipogenic differentiation media for 14 days and then injected into the dorsal cranial region of nude male mice. The viabilities of ASCs in micronized Alloderm were determined at 1, 4, 7, and 14 days, and complexes, which had been cultured for 14 days and implanted in vivo for 2 months, were histologically evaluated by light, confocal, and scanning electron microscopy. The viabilities represented that ASCs in micronized Alloderm were alive during the culture period. ASC-Alloderm complexes cultured for 14 days contained round cells with large lipid vesicles by light microscopy and many spherical cells by SEM. ASCs in implanted ASC-Alloderm complexes harvested from mice at 2 months postinjection were histologically found to have differentiated into adipocytes which had green fluorescence dye. Micronized Alloderm may be found useful as scaffold for human ASCs when constructing fat tissue for three-dimensional soft tissue filling. The present study suggests that ASC-Alloderm complexes can be used as injectable three-dimensional soft tissue fillers.