More than 460,000 Americans have end stage renal disease. While transplant of a human kidney is the best treatment for kidney failure, there simply aren’t enough donor kidneys to go around, leaving the vast majority of these patients tied to dialysis machines for the rest of their lives.Every day 13 people die waiting for a kidney. Vanderbilt University Medical Center nephrologist and associate professor of medicine Dr. William H. Fissell IV and his colleague Dr. Shuvo Roy at the University of California, San Francisco have spent the better part of two decades working on a technology solution to this problem of supply and demand. And now, in 2016, they are closing in on what he calls the “Holy Grail” for people with kidney disease: An implantable artificial kidney.