Collagenous microbeads as a scaffold for tissue engineering with adipose-derived stem cells

Background: Standard approaches to soft-tissue reconstruction include autologous tissue flaps and alloplastic implants. Both of these approaches have disadvantages, including donor-site morbidity, implant migration, and foreign body reaction. Autologous fat transplantation, with a minimally invasive cannula harvest, has lower donor-site morbidity than tissue flaps do, but there is an unpredictable degree of resorption of the transplanted fat over time. Adipose-derived stem cells isolated from harvested fat are better able to withstand the mechanical trauma from the suction cannula and may allow for improved cell survival and generation of new fat tissue after transfer to another anatomic site. The authors hypothesized that porous collagenous microbeads (CultiSphers; Sigma, St. Louis, Mo.) could be useful as injectable cell delivery vehicles for adipose-derived stem cells. This strategy would allow induction of differentiation ex vivo and precise placement of cells and scaffold in a tissue bed. The objective of this study was to assess the ability of the stem cells to proliferate and differentiate on these microbeads. Methods: Adipose-derived stem cells were isolated from discarded human adipose tissue and cultured on porous collagenous microbeads in a stirred bio-reactor (spinner flask). The cells attached and proliferated on the microbeads and maintained high viability over several weeks of culture. Results: When exposed to adipogenic or osteogenic medium, the cells differentiated into adipocytes and osteoblasts, respectively, while attached to the microbeads. Conclusion: Collagenous microbeads are a favorable scaffold for adipose-derived stem cells, allowing ex vivo proliferation and differentiation on particles that are small enough to be injected.