Adipogenic Potential of Adipose-Derived Stromal Cell Subpopulations Enriched For Bone Morphogenetic Protein Receptor IA+

Background: Due to significant resorption rates (20-80%) with autologous fat grafting, there is a need to develop techniques that increase the retention of graft volume over time. Yoshimura previously investigated the efficacy of supplementing fat grafts with ASCs, a strategy known as cell-assisted lipotransfer (CAL).[1] As one of the believed roles ASCs play in fat grafts is to differentiate into fat cells themselves,[2]the present study took a more targeted look at the CAL strategy by investigating the potential benefit of enriching ASCs for Bone Morphogenetic Protein Receptor IA (BMPR-IA), a marker associated with adipocyte differentiation. 

Methods: BMPR-IA⁺ and BMPR-IA^- ASCs were sorted using magnetic activated cell sorting (MACS). After treatment with adipogenic differentiation media in vitro for seven days, Oil Red-O staining and quantification were conducted on both subpopulations, as was qRT-PCR for adipogenic gene expression (AP2, LPL, and PPAR-ɣ). The proliferative capacity of mature adipocytes, co-cultured with BMPR-IA⁺ and BMPR-IA^-cells, was measured by an XTT assay.

Results: BMPR-IA⁺ cells showed significantly higher adipogenic gene expression in qRT-PCR. Oil Red-O staining and quantification showed more lipid droplet formation in BMPR-IA⁺ cells. XTT assay revealed that mature adipocytes experienced greater cell proliferation when co-cultured with BMPR-IA⁺ cells than with BMPR-IA^- cells or alone.

Conclusions: Our data demonstrate that subpopulations of ASCs may be identified with enhanced adipogenic capacity and suggest potential clinical benefit in performing cell-assisted lipotransfer with BMPR-IA⁺ cells for soft tissue augmentation. Further in vivo studies will be required to validate these findings.