Many research groups are working on building blood vessels. Here is one: scientists "have developed [an] artificial functioning blood vessel outside of the body, made from reprogrammed stem cells from human skin. The team also saw the cells develop into a blood vessel inside the body for the first time. The new technique could have real potential to treat patients with heart disease [by] either injecting the reprogrammed cells into the leg or heart to restore blood flow or grafting an artificially developed vessel into the body to replace blocked or damaged vessels. ... this new study demonstrates that a new type of partial stem cell developed from fibroblasts (skin cells) can be reprogrammed into vascular cells before going into the body, which have no risk turning into tumours. The [team] introduced four genes to human fibroblasts in the laboratory to reprogramme them into partial stem cells so they could become vascular cells. When these newly created cells were injected into an ischemic leg (a leg with restricted blood flow) in an animal model, the function of the leg was improved. The process of developing vascular cells from skin cells took two weeks, which makes a personalised approach of turning a patient's own skin cells into vascular cells feasible for treatment of vessel-blocking related diseases. The researchers say the next step is to test this approach in cells from patients with vascular disease."