Medical researchers have been able to create certain kinds of living cells with 3D printers for more than a decade. Now a few companies are getting closer to mass production of higher-order tissues (bone, cartilage, organs) and other individually tailored items, including implants. From an article: Organovo has successfully transplanted human liver tissue into mice to cure chronic liver failure. Pending the success of human trials, possible applications include the $3 billion market for inherited conditions such as hemophilia. [...] Aspect prints tissue cells to create structures that resemble parts of the human body, such as an airway or meniscus, to spur easier research on treatments for, say, asthma or muscle tears. By taking muscle cells from a lung, for example, the company built respiratory tissue that responded to common asthma inhalers as a person's body should. [...] Materialise designs custom 3D-printable implants, surgical guides, and other medical devices. It's waiting on approval from the U.S. Food and Drug Administration for implants designed to fuse bones.