Surgeons in Boston have transplanted a kidney from a genetically engineered pig into an ailing 62-year-old man, the first procedure of its kind. If successful, the breakthrough offers hope to hundreds of thousands of Americans whose kidneys have failed.

So far, the signs are promising.

Kidneys remove waste products and excess fluid from the blood. The new kidney began producing urine shortly after the surgery last weekend and the patient’s condition continues to improve, according to physicians at Massachusetts General Hospital, known as Mass General. He is already walking the halls of the hospital and may be discharged soon.

The patient is a Black man, and the procedure may have special significance for Black patients, who suffer high rates of end-stage kidney disease.

A new source of kidneys “could solve an intractable problem in the field — the inadequate access of minority patients to kidney transplants,” said Dr. Winfred Williams, associate chief of the nephrology division at Mass General and the patient’s primary kidney doctor.

If kidneys from genetically modified animals can be transplanted on a large scale, dialysis “will become obsolete,” said Dr. Leonardo V. Riella, medical director for kidney transplantation at Mass General. The hospital’s parent organization, Mass General Brigham, developed the transplant program.

Over 800,000 Americans have kidney failure and require dialysis, a procedure that filters toxins from the blood. Over 100,000 are on a waiting list to receive a transplanted kidney from a living or dead human donor. End-stage kidney disease is three times more common among Black Americans than among white people.