In 2009, Invetech and Organovo developed and marketed the world's first 3D bio-printers to be used for investigating human tissue repair and organ replacement.

Presently, researchers from the University of Edinburgh have developed a cell printer that can be used to print living embryonic stem cells. The printer is able to print uniform-size droplets of cells in a careful enough way such as to keep the cells alive and able to develop into other kinds of cells. These new techniques could potentially be used to make realistic human tissues for testing new drugs and for growing new replacement organs.

Human embryonic stem cells are obtained from human embryos, and are capable of growing into any other kind of human cell. Because of this, stem cells have been of great interest to scientists for research and for their potential to be used for regenerative medicine such as organ replacement, repairing damaged cells, etc.

A computer-controlled machining tool was modified and combined with bio-ink dispensers and a microscope to create this new cell printer. These bio-ink dispensers contained stem cells in a nutrient-rich fluid called "cell medium", and another of the dispensers contained only the medium. The stem cells are dispensed via computer-operated valves. During operation, this printer dispenses cells onto a dish with many small wells. Following this step, the dish is flipped over causing the droplets to hang so stem cells can form clumps in the wells.

In the study, 95% of the cells were found to have survived 24 hours after being printed which indicates that the printing process is relatively safe for the cells. After three days, more than 89% of the cells remained alive, and they tested positive for a marker of their pluripotency (which is their potential to develop into other kinds of cells).

This study was the first to successfully print human embryonic cells, and researchers world-wide have high hopes for the potential implications of these findings.

Sources:
Yahoo! News
Live Science