A specialized 3D printing process, using human stem cells, could pave the way to building custom replacement organs for patients, eliminating the need for organ donation, immune system suppression, and possible transplant rejection. Sound fantastic?

The new valve-based technique, developed by the biomedical microengineering group at Heriot-Watt University, Edinburgh, Scotland, in partnership with Roslin Cellab, a leading stem cell technology company, allowed the researchers to print delicate embryonic cell cultures, which can replicate indefinitely and differentiate into almost any cell type in the human body. The technique relies on an adjustable "microvalve" to build up layers of human embryonic stem cells (hESCs). Altering the nozzle diameter precisely controls the rate at which cells are dispensed.

They say that the technique will allow them to create more accurate human tissue models that are essential to in vitro drug development and toxicity testing. In the long term, they foresee the technology being further developed to create viable 3D organs for medical implantation from a patient’s own cells.

Lead scientist Dr. Will Shu, said: "We found that the valve-based printing is gentle enough to maintain high stem cell viability, accurate enough to produce spheroids of uniform size, and most importantly, the printed hESCs maintained their pluripotency—the ability to differentiate into any other cell type."