Sacrificial Ink Writing Technique for 3D Printed Organs

Researchers at Harvard have developed a way to 3D print vascular channels in large matrices composed of stem cell-derived organ building blocks. The technique could pave the way for 3D-printed organs.

Living embryoid bodies surround a hollow vascular channel printed using the SWIFT method.

human organs using 3D printing would help to address the current shortfall in
available transplants. However, to date, this has proved to be pretty tricky. One
of the major stumbling blocks is the lack of functional vasculature in 3D-printed
biological constructs.

To address this, these researchers developed a new technique called sacrificial writing into functional tissue (SWIFT), in which they focus on printing vessels within a pre-existing live cell matrix. This matrix consists of cultured clusters of stem cells, called stem-cell-derived organ building blocks, which have been packed together.

“This is an
entirely new paradigm for tissue fabrication,” explained Mark Skylar-Scott, a
researcher involved in the study. “Rather than trying to 3D print an entire
organ’s worth of cells, SWIFT focuses on only printing the vessels necessary to
support a living tissue construct that contains large quantities of organ
building blocks, which may ultimately be used therapeutically to repair and
replace human organs with lab-grown versions containing patients’ own cells.”

The technique begins when the researchers create thousands of adult induced pluripotent stem cell aggregates, and pack them closely together. At cold temperatures, this matrix of cell clusters has a thick consistency, allowing a thin nozzle to travel through the matrix and deposit a gelatin “ink”. This deposited gelatin is sacrificial, and when the researchers heat it back up to body temperature, the gelatin melts and can be washed away, leaving a network of branching tunnels through the cell matrix.

Tissues created without SWIFT-printed channels display cell death (red) in their cores after 12 hours of culture (left), while tissues with channels (right) have healthy cells.

By perfusing these tunnels with oxygenated medium, the researchers can nourish cells deep within the matrix, and by seeding the channels with endothelial cells, can mimic a vascular network.

“Our SWIFT biomanufacturing method is highly effective at creating organ-specific tissues at scale from organ building blocks ranging from aggregates of primary cells to stem-cell-derived organoids,” said Jennifer Lewis, another researcher involved in the study. “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.”

See a video
about the technique below.

Study in Science Advances: Biomanufacturing of
organ-specific tissues with high cellular density and embedded vascular

Via: Harvard’s Wyss Institute