Fabrication of scaffold-free mesenchyme tissue bands by cell self-aggregation technique for potential use in tissue regeneration

Three-dimensional cell constructs comprising only tissue-specific cells and extracellular matrix secreted by them would be ideal transplants, but their fabrication in a cell aggregation manner without cell scaffolds relies on random cell self-aggregation, making the control of their size and shape difficult. In this study, we propose a method to fabricate band-shaped tissues by inducing the self-aggregation of cell sheets using the developed cell self-aggregation technique (CAT). Acting as cell aggregation stoppers, silicone semicircular pillars were attached to two positions equidistant from both short ends of the rounded rectangular culture groove and coated with a specifically charged biomimetic polymer as a CAT-inducing surface. Mesenchymal stem cells, chondrocytes, and skeletal myoblast cells seeded on the surface of the culture grooves formed band-shaped aggregates between the two aggregation stoppers following spontaneous detachment with aggregation of the cell sheet from the outer edge of the grooves during day one of culture. The aggregated chondrocyte band matured into a cartilage-like plate with an abundant cartilage matrix while retaining its band shape after two weeks of chondrogenic cultivation. Additionally, the aggregates of mesenchymal stem cells and myoblast cell bands could patch the induced collagen membrane derived from rat subcutaneous tissue like a bandage immediately after their formation and successfully mature into fat and muscle tissues, respectively. These results indicate that, depending on the cell type, scaffold-free band-shaped cell aggregates produced by CAT have the potential to achieve tissue regeneration that follows the shape of the defect via in vitro maturation culture or in vivo organization.