Formation of a human-derived fat tissue layer in P_DLLGA 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) (P_DLLGA) hollow fibres in facilitating the development of HBMSC-derived adipocytes for advancement of an associated adipocyte layer. The large surface area of 75:25 P_DLLGA 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 (TM) Deep Red neutral lipid staining in an ^FLP_DLGA 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 P_DLLGA-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.