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.
Creating 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.
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 channels