Formation of a human-derived fat tissue layer in PdlLGA hollow fibre scaffolds for adipocyte tissue engineering

Development of adipose tissue-engineering strategies, where human bone marrow stromal cells (HBMSC) are combined with three-dimensional scaffolds, is likely to prove valuable for soft tissue restoration. In this study, we assessed the function of poly(dl-lactide-co-glycolide) (PdlLGA) hollow fibres in facilitating the development of HBMSC-derived adipocytes for advancement of an associated adipocyte layer. The large surface area of 75:25 PdlLGA fibres facilitated the rapid generation of extensive adipocyte aggregates from an undifferentiated HBMSC monolayer, where the fat-laden cells stained positive with Oil Red O and expressed the adipocyte marker, fatty acid binding protein 3 (FABP3). Following implantation subcutaneously in severely compromised immunodeficient mice, the adipogenic phenotype of the PLGA–adipocyte graft was maintained for up to 56 days. Confocal microscopy showed associated LipidTOX™ Deep Red neutral lipid staining in an FLPdlLGA fibre–adipocyte graft after 56 days, critical evidence demonstrating maintenance of the adipocyte phenotype in the subcutaneous graft. To support adipose tissue advancement in a defined volume, the PdlLGA–adipocyte scaffold was encapsulated within alginate/chitosan hydrogel capsules (typical diameters, 4.0 mm). In a 28-day in vivo trial in immunodeficient mice, clusters of the capsules were maintained at the subcutaneous site. An adipocyte tissue layer advancing within the surrounding hydrogel was demonstrated.