A team at the Wyss Institute for Biologically Inspired Engineering at Harvard University and the Harvard John A. Paulson School for Engineering and Applied Sciences (SEAS) has recently invented a method for 3D bioprinting thick vascularized tissue constructs composed of human stem cells, extracellular matrix, and circulatory channels lined with endothelial blood vessel cells. The resulting network of vasculature contained within these deep tissues enables fluids, nutrients and cell growth factors to be controllably perfused uniformly throughout the tissue.
Building on their earlier work, Lewis and her team have now increased the tissue thickness threshold by nearly tenfold, setting the stage for future advances in tissue engineering and repair. The method combines vascular plumbing with living cells and an extracellular matrix, enabling the structures to function as living tissues. Lewis’ novel 3D bioprinting method uses a customizable, printed silicone mold to house and plumb the printed tissue structure. Inside this mold, a grid of vascular channels is printed first, over which ink containing living stem cells is then printed. The resulting soft tissue structure is replete with blood vessels, and via a single inlet and outlet on opposite ends of the chip, can be immediately perfused with nutrients to ensure survival of the cells. To achieve a variety of tissue shapes, thicknesses, and compositions, the shape of the printed silicone chip can be customized and the cell inks can be tuned to include a wide variety of cell types. The work was supported by the National Science Foundation and the Wyss Institute for Biologically Inspired Engineering at Harvard University.