Layer by layer 3D tissue epitaxy by cell laden hydrogel droplets

We created 3D tissue constructs epitaxially by printing cell-laden hydrogel droplets. The ability to bioengineer 3D tissues is a powerful new approach to treat diverse diseases such as cancer, loss of tissue function, or organ failure. Inspired by the molecular beam epitaxy technique, a common semiconductor manufacturing technology, we present a platform that prints the first example of a 3D smooth muscle (SMC) patch (5 mm times 5 mm times 81 m) consisting of multiple cell-laden hydrogel layers. The bioprinting platform that we developed allows (i) high throughput patterning of SMCs encapsulated in collagen hydrogel droplets (3 seconds/patch), (ii) microscale spatial and temporal droplet placement control (proximal axis: 18 plusmn 15 m, distal axis:0 plusmn 10 m), (iii) printing of 3D cell-laden hydrogel structures (16.2 m thick per layer), (iv) cell seeding uniformity (85 plusmn 13 cells/mm² at 1 million cells/ml; 186 plusmn 77 cells/mm² at 10 million cells/ml). This new platform to print 3D tissue constructs has potential for future therapeutic value in regenerative medicine and tissue engineering leading to printed replacement organs.