Engineering Tissues without the Use of a Synthetic Scaffold: A Twenty-Year History of the Self-Assembly Method

Figure 3

Schema of the production of the “tubular” model by the self-assembly technique. Upper panel: classic tubular self-assembly technique. (1) Mesenchymal cells are seeded in a cell culture plate coated with gelatin. They are cultivated for 28 days in the presence of ascorbate. One plate is seeded with smooth muscle cells (SMC) (in the case of blood vessels) and another with dermal fibroblasts. (2) Then the stromal sheet formed by the SMC is tightly rolled around a cylindrical mandrel followed by (3) the stromal sheet formed by the dermal fibroblasts. (4) The resulting construct is cultivated for a variable time in order to ensure fusion of the rolled sheets. When fusion has been achieved, the mandrel can be removed and the tubular structure could be perfused to be seeded with endothelial cells and allowed to mature. Middle panel: Hybrid tubular self-assembly technique. (1) Instead of using two cell culture plates, each one seeded with a different type of cell population, the plate is separated in two halves with a cell separator. Then each compartment is seeded with one type of cell population: SMC in one part and dermal fibroblasts in the other. (2) After cell adhesion, the separator is removed and cells are cultivated for 28 days in the presence of ascorbate. (3) The stromal sheet is then tightly rolled around the cylindrical mandrel. (4) The resulting construct is cultivated for a variable time in order to ensure fusion of the rolled sheets. When fusion has been achieved, the mandrel can be removed and the tubular structure could be perfused to be seeded with endothelial cells and allowed to mature. Lower panel: tools required to produce tissue by the tubular self-assembly technique. Heavy weights are used to block contraction of the stromal sheets by mesenchymal cells, especially SMC. A cylindrical mandrel is used to create the lumen of the blood vessel. A cell separator divides the cell culture plate in order to create two cellular compartments.