The four-hour operation was carried out on Saturday on a 62-year-old man suffering from end-stage kidney disease, Massachusetts General Hospital (MGH) said.“The procedure marks a major milestone in the quest to provide more readily available organs to patients,” the hospital said in a statement.Organ shortages are a chronic problem around the world and the Boston hospital said there are more than 1,400 patients on the waiting list for a kidney transplant at MGH alone.“Our hope is that this transplant approach will offer a lifeline to millions of patients worldwide who are suffering from kidney failure,” said Dr Tatsuo Kawai, a member of the team which carried out the operation.The hospital said the pig kidney used for the transplant had been genetically-edited to remove harmful pig genes and add certain human genes.The hospital said the patient, Richard Slayman of Weymouth, Massachusetts, “is recovering well at MGH and is expected to be discharged soon.”Slayman, who suffers from Type 2 diabetes and hypertension, had received a transplant of a human kidney in 2018 but it began to fail five years later and he has been on dialysis.