What device will allow doctors to 3-D print new human tissue for patients?

A study published in Biofabrication in March detailed how a handheld 3-D printing device called the BioPen could change how medical professionals treat common ailments. The BioPen, which has been under development for three years, extrudes compounds sometimes laced with human stem cells to assist in the regrowth of tissue, such as cartilage in a damaged joint.