Every week, two million people across the world will sit for hours, hooked up to a whirring, blinking, blood-cleaning dialysis machine. Their alternatives: Find a kidney transplant or die.

In the US, dialysis is a roughly 40-billion-dollar business keeping 468,000 people with end-stage renal disease alive. The process is far from perfect, but that hasn't hindered the industry's growth. That's thanks to a federally mandated Medicare entitlement that guarantees any American who needs dialysis—regardless of age or financial status—can get it, and get it paid for.

The legally enshrined coverage of dialysis has doubtlessly saved thousands of lives since its enactment 45 years ago, but the procedure’s history of special treatment has also stymied innovation. Today, the US government spends about 50 times more on private dialysis companies than it does on kidney disease research to improve treatments and find new cures. In this funding atmosphere, scientists have made slow progress to come up with something better than the dialysis machine-filled storefronts and strip malls that provide a vital service to so many of the country's sickest people.

We thought, if people are growing ears on the backs of mice, why can’t we grow a kidney? Shuvo Roy, UC San Francisco

Now, after more than 20 years of work, one team of doctors and researchers is close to offering patients an implantable artificial kidney, a bionic device that uses the same technology that makes the chips that power your laptop and smartphone. Stacks of carefully designed silicon nanopore filters combine with live kidney cells grown in a bioreactor. The bundle is enclosed in a body-friendly box and connected to a patient’s circulatory system and bladder—no external tubing required.

The device would do more than detach dialysis patients—who experience much higher rates of fatigue, chronic pain, and depression than the average American—from a grueling treatment schedule. It would also address a critical shortfall of organs for transplant that continues despite a recent uptick in donations. For every person who received a kidney last year, 5 more on the waiting list didn’t. And 4,000 of them died.

There are still plenty of regulatory hurdles ahead—human testing is scheduled to begin early next year1—but this bioartificial kidney is already bringing hope to patients desperate to unhook for good.

Innovation, Interrupted

Kidneys are the body’s bookkeepers. They sort the good from the bad—a process crucial to maintaining a stable balance of bodily chemicals. But sometimes they stop working. Diabetes, high blood pressure, and some forms of cancers can all cause kidney damage and impair the organs' ability to function. Which is why doctors have long been on the lookout for ways to mimic their operations outside the body.

The first successful attempt at a human artificial kidney was a feat of Rube Goldberg-ian ingenuity, necessitated in large part by wartime austerity measures. In the spring of 1940, a young Dutch doctor named Willem Kolff decamped from his university post to wait out the Nazi occupation of the Netherlands in a rural hospital on the IJssel river. There he constructed an unwieldy contraption for treating people dying from kidney failure using some 50 yards of sausage casing, a rotating wooden drum, and a bath of saltwater. The semi-permeable casing filtered out small molecules of toxic kidney waste while keeping larger blood cells and other molecules intact. Kolff's apparatus enabled him to draw blood from his patients, push it through the 150 feet of submerged casings, and return it to them cleansed of deadly impurities.

In some ways, dialysis has advanced quite a bit since 1943. (Vaarwel, sausage casing, hello mass-produced cellulose tubing.) But its basic function has remained unchanged for more than 70 years.

Not because there aren’t plenty of things to improve on. Design and manufacturing flaws make dialysis much less efficient than a real kidney at taking bad stuff out of the body and keeping the good stuff in. Other biological functions it can’t duplicate at all. But any efforts to substantially upgrade (or, heaven forbid, supplant) the technology has been undercut by a political promise made four and a half decades ago with unforeseen economic repercussions.