Preparation and characterization of directed, one-day-self-assembled millimeter-size spheroids of adipose-derived mesenchymal stem cells.

Three-dimensional cell spheroids prepared without using any artificial scaffold materials are desirable for cell-based transplants. However, conventional cell culture systems are inefficient for rapid, large-scale and non-cytotoxic generation of size-controlled spheroids (>1 mm diameter) that are required for tissue regenerative therapy application. In this study, we prepared millimeter-order spheroids of adipose-derived mesenchymal stem cells (ADSCs) by controlling the spheroid size (diameter range: 0.4-2.5 mm). Notably, spheroid generation required only one day of culture on charged culture dishes. Almost all spheroid-derived ADSCs were viable and produced adhesion molecules and growth factors, which play an important role in tissue regeneration. Moreover, spheroid-derived ADSCs could infiltrate and recellularize collagenous tissue membranes in vitro. The ADSC spheroids developed in this study could be directly (without additional processing) used for cell-based tissue regeneration therapy. Furthermore, the rapid scale-up process and noncytotoxic generation of spheroids would also enable other applications such as use as screening models for drug discovery.