Noor N and colleagues from Tel Aviv University have successfully produced thick vascularised patches and cellularized human hearts with a natural architecture as proof of concept by 3D printing of reprogrammed omental tissue .
Cells collected by omental biopsy were reprogrammed to become pluripotent stem cells. They were then differentiated into heart muscle cells and endothelial cells. Extracellular matrix was processed into a personalized hydrogel. The cells were combined with hydrogels to form bioinks for parenchymal cardiac tissue and blood vessels. 3D printing of functional vascularized patches were done using this bioink. Blood vessels which were too small to be imaged by computerized tomography were made as per mathematical modeling of oxygen transfer. The functioning of the patches in vitro were assessed and contracting cardiomyocytes demonstrated. As a final proof of concept, cellularized human hearts with natural architecture were also printed.
The thick vascularized and perfusable patches fully match the immunological, biochemical and anatomical properties of the individual from whom the omental cells are taken.
Although miniaturized 3D hearts with own tissue could be printed, we are still a long way off from a functional heart which can pump blood on its own. All the same tissue patches with contractile potential has been developed, which will match that of the person. Much more work has to be done to reach the ultimate goal of 3D printing of a personalized heart which can be used for transplantation instead of a donor heart. At present we can only dream of it!