Naoki Morimoto

Adipose tissue engineering requires effective strategies for regenerating adipose tissue, with adipose-derived stem cells (ASCs) being favored due to their robust self-renewal capacity and multipotent differentiation potential. In this study, the efficacy of poly-L-lactic acid (PLLA) mesh containing collagen sponge (CS), seeded with ASCs to promote adipose tissue formation, was investigated. PLLA-CS implants seeded with GFP-positive ASCs were inserted at high concentration (1 × 10 ⁶ cells/implant, H-ASC) and low concentration (1 × 10 ⁵ cells/implant, L-ASC), as were unseeded controls. Adipogenesis was evaluated at 3, 6, and 12 months using a rat inguinal model. At 3 months, the weight and volume of newly formed tissues in the H-ASC group were significantly higher than those in the control group. Histological assessment revealed that the area of all newly formed tissue, including the adipose tissue inside the implants in the H-ASC group, was larger at 6 and 12 months compared with that of the control and L-ASC groups, with the adipose percentage at 12 months being higher in the H-ASC group than in the control group. GFP-positive ASCs in both the L-ASC and H-ASC groups adhered to the CS scaffolds and survived for up to 12 months postimplantation, with spontaneous differentiation into adipocytes observed exclusively in the H-ASC group. Double immunofluorescence confirmed the presence of GFP-positive adipocytes. In summary, this study demonstrated that ASCs coimplanted with PLLA-CS implants could enhance adipose tissue formation within the implants. Uninduced ASCs were capable of spontaneously differentiating into adipocytes within the PLLA-CS implants, with differentiation correlating with the number of implanted cells.