Bioprinting of living human cells has gotten a boost with new work out of Sweden that’s generated cartilage tissue by printing stem cells using a 3D bioprinter.
A team of researchers at Sahlgrenska Academy has not only managed to print surviving stem cells, but their research also went one step further—they were able to influence the cells to multiply and differentiate to form what are called chondrocytes, or cartilage cells, in the printed structure, said Stina Simonsson, associate professor of cell biology at the academy.
“In nature, the differentiation of stem cells into cartilage is a simple process, but it’s much more complicated to accomplish in a test tube,” said Simonsson, who led the research. “We’re the first to succeed with it, and we did so without any animal testing whatsoever.”
A team of biological-materials 3D printing experts at the Chalmers University of Technology and orthopedic researchers from Kungsbacka took part in the research project—the findings of which have been published in a paper in the magazine Nature’s Scientific Reports.
Researchers used cartilage cells taken from knee-surgery patients and then manipulated them in a laboratory, which caused them to rejuvenate and revert into what are called “pluripotent” stem cells—or cells that potentially can develop into many different types of cells.
They then expanded these stem cells, encapsulated them in a composition of nanofibrillated cellulose, and printed them into a structure using a 3D bioprinter. After being printed, researchers treated the stem cells with growth factors that caused them to differentiate correctly so that they formed cartilage tissue, according to the team.
A team of researchers at Sahlgrenska Academy has managed to generate cartilage tissue by printing stem cells using a 3D bioprinter. The work is a major step forward for using cells from live patients to generate new cartilage for medical applications in this way. (Source: Sahlgrenska Academy)
Key to the work was to find a method that would allow the cells to survive printing and multiply, as well as a protocol that would cause the cells to differentiate to form cartilage, Simonsson said.
"We investigated various methods and combined different growth factors,” she explained. “Each individual stem cell is encased in nanocellulose, which allows it to survive the process of being printed into a 3D structure. We also harvested mediums from other cells that contain the signals that stem cells use to communicate with each other. … In layman’s terms, our theory is that we managed to trick the cells into thinking that they aren’t alone.”
What the team found in their work is that it’s necessary to use large amounts of live stem cells to form tissue that can accomplish this type of behavior for printing, Simonsson added.
The results of the study formed cartilage that is very much like human cartilage, with Type II collagen and cells that have structures similar to what’s been observed in samples of human-harvested cartilage, researchers noted.
The work, then, represents a major step forward for using cells from a human patient to generate new cartilage tissue in medical applications through 3D bioprinting, according to researchers.
There is one obstacle to using the method in actual patients, however, Simonsson said. That is, the structure of the cellulose the team used might not be optimal for use in the human body, she said.
“Before we begin to explore the possibility of incorporating the use of 3D-bioprinted cartilage into the surgical treatment of patients, we need to find another material that can be broken down and absorbed by the body so that only the endogenous cartilage remains,” Simonsson said. “The most important thing for use in a clinical setting is safety.”
Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 15 years.