Drexel professor pioneers 3D printing of stem cells

A revolutionary form of 3-D printing has captured the innovative minds of Wei Sun, Ph.D., and his research team at Drexel University in the Biofabrication Lab of the College of Engineering. The team has recently become the first known group to successfully print blocks of Embryonic Stem Cells in a way that viably allows these cells to divide while maintaining their ability to differentiate.

Maintaining this pluripotency—the ability to grow into one of four types of tissue—also means that if fine-tuned, this process may lead to researchers being able to 3-D print groups of cells that can grow into functional organs.

The research involving 3-D printing of cells began for Sun and his group in 2002. In the past few years, Sun has also developed technology that is capable of printing cancerous tumors. The other researchers who contributed to the recently published paper are Liliang Ouyang, Rui Yao, Shuangshuang Mao, Xi Chen and Jie Na from Sun’s lab in Tsinghua University in Beijing. The paper was published in Biofabrication Nov. 4, 2015. Sun, the Albert Soffa chair in the Drexel College of Engineering is also the director of the Biofabrication lab as well as the research lab at Tsinghua where this research took place.

The paper outlines the process by which ESCs were printed in a temperature-controlled hydrogel. The mixture was printed into a 3-D construct to support the cells as they grew and divided. Depending on the size of the printed cell block and the cell density of the printing material, the ESCs demonstrated different behaviors when they began to form Embryoid Bodies. These EBs make up the early stages of embryogenesis, which later leads to differentiation, tissue specialization, and eventually, organ growth. Being able to control which types of EBs were created just by manipulating the way the ESC-hydrogel mixture is extruded from the 3-D printing device is a major development this research has made more feasible. In an article by Drexel Now, Sun said: “There is still a long way to go from a varying sized EB to a regenerated organ, but our work provides a promising tool to facilitate this development.”

A simpler task achieved through the recent research was that of printing the cells in a block like fashion so that they could grow into specific tissue types. These lab-made tissues can be used for drug development and testing. This process using 3-D printing results in tissues that more closely resemble tissues in living organisms, since growth in a petri dish is less natural. However, the block shape achieved through printing creates an environment similar to that in vivo, where cells are surrounded on all sides by other cells.

By optimizing their processes, the researchers were able to obtain a 90 percent survival rate for the printed cells, and were also able to observe that by printing the material into the grid-shaped block of cells, the living ESCs were able to proliferate and grow into EBs while still maintaining differentiability.

In the Drexel Now article, Sun commented that “We are not directly going to printing an organ, but we can print an in vitro 3-D biological model which could lead to growing different size embryoid bodies, different types of cells, and, ultimately, to growing a regenerated organ. This will be a significant advance for stem cell research and for regenerative medicine.”

Sun stated in an email that a future research endeavor will involve 3-D printing a “cell-laden, micro-fluidic device” to be used for advanced drug delivery systems. The research in Sun’s lab is partially sponsored by a grant given by the Drexel-SARI Research Center located in Shanghai.