Maintenance of viability and proliferation of 3T3 cell aggregates incorporating fibroin microspheres into cultures.

This study investigated whether micron-sized microspheres can be used as dispersed scaffolds where anchorage-dependent cells can proliferate and survive in suspension culture. Aggregates of murine 3T3 cells in a non-adherent plate cultured remained viable for more than 2 weeks by the presence of 0.5 mg/ml fibroin microspheres. A nucleoside incorporation assay confirmed the proliferation of 3T3 cells in the aggregates only when cultured with microspheres. Under these conditions, the glucose consumption rate of 3T3 cells increased to 66.5 nmol day-1 cell-1. Histological analysis demonstrated that the intercellular space of cell aggregates was larger in cultures supplemented with 0.5 mg/ml microspheres than in non-supplemented cultures. The cell aggregates with microspheres also exhibited a reduced arrest in G1 phase. Transmission electron microscopy verified the presence of microspheres in the space between cells in aggregates. Fibroin microspheres maintained the viability and proliferability of 3T3 cells cultured under non-adherent conditions and thus can be used to develop viable suspensions of anchorage-dependent cells.