The process consists of three stages: the target organ is scanned via MRI, it is then printed using patient-specific bioinks, "substances made of sugars and proteins", made of their own cells after which the organ is then matured it in a suitable laboratory or host environment.
The heart, about the size of a rabbit's, marked "the first time anyone anywhere has successfully engineered and printed an entire heart replete with cells, blood vessels, ventricles and chambers".
Describing their work in Advanced Science, the research team started by taking biopsies of fatty tissues from abdominal structures known as the omentum in both humans and pigs. For this goal, the bed of the team's 3D printer houses a small, cubic Value-Added Tax, made to contain a gelatinous support media.
That hydrogel forms the basis of the 3D bioink, which is then mixed with stem cells that have been differentiated into cardiac and endothelial cells. For patients with late stage heart failure, a heart transplant is the only solution. Scientists need to better program the 3D-printed heart and its varied components and cells to coordinate their movements, so the organ doesn't just look like a heart, but acts like one too.
But CT scans can't provide images of the smaller blood vessels crisscrossing heart tissue-there, in order to make sure the entire patch receives enough oxygen, mathematical models were used to create a more-complete vasculature, calculated based on the laws of oxygen consumption and equations for optimal distribution.
"But larger human hearts require the same technology".
The cells are now able to contract, but do not yet have the ability to pump. Admittedly, it is still leagues away from producing a viable, transplantable organ.
Heart disease is the leading cause of death in the USA and Israel, and heart transplants are often only afforded to those with end-stage heart failure, but the lengthy wait (up to six months) for a suitable donor can often prove fatal.
He said that given a dire shortage of heart donors, the need to develop new approaches to regenerate a diseased heart was urgent.
"The biocompatibility of engineered materials is crucial to eliminating the risk of implant rejection, which jeopardizes the success of such treatments", said Dvir. "Here, we can report a simple approach to 3D-print thick, vascularized and perfusable cardiac tissues that completely match the immunological, cellular, biochemical and anatomical properties of the patient". Dvir says. They then plan to transplant the 3D-printed heart in animal models.
Cells from a patient's omentum tissue are separated and processed into a personalized thermoresponsive hydrogel.