Progress Made in Quest of 3D-Printed Organs for Transplant

(CN) – Currently more than 113,000 people in America are on waiting lists for organ transplants that could save their lives. The procedures are increasingly successful, in many cases extending people’s lives for decades while transforming their quality of life.

The problem is a shortage in the supply of available organs.

Every day, 20 people die while waiting for an organ necessary to their survival.

A team of researchers at Harvard have made significant technological progress toward solving this critical problem by developing a new technique that could render the 3D printing of internal organs viable at long last.

Called SWIFT – sacrificial writing into functional tissue – the technique introduces a vascular network into artificially generated organs capable of keeping cells regenerating and alive.

While artificial organs grown in a lab have long been regarded as the “holy grail” for solving the transplant shortage issue, the problem is that without an infrastructure capable of facilitating circulation the organs dry out and die, typically within 12 hours.

Another problem dogging artificial organ growth is the lack of cell density, which prevents artificial organs from functioning properly and precludes their use in organ replacement and repair.

But the two-step process developed by the Harvard scientists overcomes at least two major hurdles and puts the medical profession closer to being able to use 3D-printed organs in procedures.

“By integrating recent advances from stem-cell researchers with the bioprinting methods developed by my lab, we believe SWIFT will greatly advance the field of organ engineering around the world,” said Jennifer Lewis, a scientist and teacher at Harvard’s Wyss Institute.

A cross-section image shows living cells (green) surrounding a hollow channel that has been 3D printed and evacuated using the SWIFT method. (Photo credit: Wyss Institute at Harvard University)

The team began by taking stem cells and compacting them into dense aggregates and then further joining them together until they had a tissue with about a 200 million cell-per-millimeter density.

Next the team built a vascular network through the dense tissue whereby oxygen and other nutrients could be distributed throughout the organ. The construction uses sacrificial ink, which is embedded in the tissue while its formed and then later removed to create the vascular channels.

“Forming a dense matrix from these OBBs kills two birds with one stone: not only does it achieve a high cellular density akin to that of human organs, but the matrix’s viscosity also enables printing of a pervasive network of perfusable channels within it to mimic the blood vessels that support human organs,” said co-first author Sébastien Uzel, a research associate at the institute.

OBB, or organ building blocks, is a technical term for the stem-cell derived aggregates the scientists use to construct the organ tissue. The scientists use centrifugal force to compact the stem cells, then place the aggregated matter in a chamber with cold temperatures.

At this point, the sacrificial writing or 3D printing begins to form the vascular chambers. Using a thin nozzle, the ink is distributed throughout the tissue without harming the cells.

Once the tissue is returned to room temperature, the ink can be washed away – leaving the channels in place.

“This is an entirely new paradigm for tissue fabrication,” said co-first author Mark Skylar-Scott, a research associate at the Wyss Institute.

The next step is to put the fabricated organs into animal models to test their viability.

“The ability to support living human tissues with vascular channels is a huge step toward the goal of creating functional human organs outside of the body,” said Wyss Institute founding director Donald Ingber.


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