Kidneys Team: Wake Forest Institute For Regenerative Medicine How It's Made: A 3-D bioprinter deposits multiple types of kidney cells—cultivated from cells taken by a biopsy—while simultaneously building a scaffold out of biodegradable material. The finished product is then incubated. The scaffold, once transplanted into a patient, would slowly biodegrade as the functional tissue grows. Benefit: An estimated 80 percent of patients on organ-transplant lists in the U.S. await kidneys. Bioprinted kidneys are not yet functional, but once they are, the use of a patient's own cells to grow the tissue means doctors will someday be able to provide every recipient with a perfect match.\n\nBlood Vessels Team: University of Pennsylvania and MIT How it's made: Using an open-source RepRap printer and custom software, researchers print a network of sugar filaments inside a mold and coat the filaments in a polymer derived from corn. They then dispense a gel containing tissue cells into the mold. Once it sets, they wash the structure in water, which dissolves the sugar and leaves empty channels in the tissue. Benefit: Researchers showed that pumping nutrients through the channels increased the survival of surrounding cells. Because blood vessels maintain tissue health, learning how to scale up and print a larger, more robust vascular system is the key to eventually printing entire organs.\n\nSkin Grafts Team: Wake Forest Institute for Regenerative Medicine How it's made: First, a custom bioprinter scans and maps the patient's wound. One inkjet valve ejects the enzyme thrombin, and another ejects cells mixed with collagen and fibrinogen (thrombin and fibrinogen react to create the blood coagulant fibrin). Then, the printer deposits a layer of human fibroblasts, followed by a layer of skin cells called keratinocytes. Benefit: For traditional grafts, surgeons take skin from one area of the body and splice it onto another. The Wake Forest researchers hope to print new skin directly into a wound. Ultimately, they plan to build a portable printer that can be used in war and disaster zones.\n\nBones Team: Washington State University How it's made: Researchers print scaffolds with a ceramic powder (human bone is 70 percent ceramic), using the same 3-D printers that produce metal parts found in electric motors. An inkjet covers the ceramic with a layer of plastic binder. This structure is baked at 2,282˚F for 120 minutes and placed into a culture with human bone cells. After a day, the scaffold supports them. Benefit: Every year, millions of automobile-accident survivors suffer from complex fractures, which are difficult to repair using traditional methods. Using MRIs for reference, doctors could print a custom graft that perfectly matches the fracture.