And while bioengineers have succeeded in printing embryonic (mouse) cells via similar technology, the ‘holy grail’ of cell printing — the printing of living embryonic stem cells from human cells — has remained unfulfilled….until now.
Researchers at the University of Edinburgh (Faulkner-Jones et al) have for the first time succeeded in developing a 3D printing technology that churns out living, human embryonic stem cells — each a copy of a human stem cell “template. The new 3D printer “spits out” uniform droplets of liquid containing the cells and it does so gently enough to keep them alive long enough to develop into other cell types.
Human embryonic stem cells (hESCs, in general, ES cells) are obtained from a human embryo. This process of extracting hESCs normally results in the destruction of the embryo* — a fact that has led some to oppose the development of stem cell medical technology.
The value in ES cells is that they are undifferentiated and have the potential to differentiate into other cells types; with the right molecular “prompts”, these “pluripotent” ES cells can develop into any other type of cell, whether heart, brain, bone or muscle cell.
The printing technique initiates cell differentiation by prompting the stem cells to form “embryoid bodies” (i.e., embryo-like, “spheroid aggregate”). It accomplishes this by dispensing two layers of “bio ink” (every printer needs ink, right?) — one layer containing the progenitor stem cells along with a growth medium, the other containing just the nutrient medium — through computer-controlled micro valves.
Each bi-layer droplet was printed into a small well on an array of many small wells, and the entire array was then flipped over so that the droplets hung down. This action allows the hESCs to clump together (into “spheroid aggregates”) inside each well droplet. The droplets were programmed to be printed in a precise size and pattern so as to promote optimal cell differentiation.
Microscopic analysis revealed that 95% of the cells remained alive after 24 hours and more than 89% of the cells were still alive after three days. The cells tested positive for a pluripotency bio-marker indicating that each was still a viable ES cell, and, that the printing technology did not harm the cells.
Quoting from the research paper abstract:
“The resulting aggregates have controllable and repeatable sizes, and consequently they can be made to order for specific applications. Spheroids with between 5 and 140 dissociated cells resulted in spheroids of 0.25–0.6 mm diameter. This work demonstrates that the valve-based printing process is gentle enough to maintain stem cell viability, accurate enough to produce spheroids of uniform size, and that printed cells maintain their pluripotency.”
The new technology — if proven reliable — could be a major advance for regenerative medicine (i.e., growing new tissue, even, one day, whole organs) as well as be used to rapidly test new pharmaceuticals.
The current research represents the first time human embryonic stem cells have been printed from human cells (“This study includes the first analysis of the response of human embryonic stem cells to the printing process using this valve-based printing setup”) ; results were published under the title ‘Development of a valve-based cell printer for the formation of human embryonic stem cell spheroid aggregates ‘ in the Feb. 5 issue of the journal Biofabrication.
* In 2007, researchers in Japan succeeded in “reprogramming” skin cells into pluripotent (embryonic-like) stem cells (via the insertion of four key protein-encoding genes), obviating the need to use/destroy actual embryonic ES cells. This newest method presumably requires only a few human ES cells in order to print new ones, thus, perhaps, also preserving the embryo.
Some source material for this post came from the Yahoo News article: ‘3D-Printed Human Embryonic Stem Cells Created for First Time’
Top image: (Embryoid bodies 24 hours after formation); credit – Stemcellscientist ; CC – By – SA 3.0