Scientists from the University of Manchester in the U.K. have developed human kidney tissue in a lab capable of producing urine once implanted into a mouse. Findings were published in Stem Cell Reports.

The study, led by  Sue Kimber and Adrian Woolf, outlines the development of the kidney tissue with the aim of advancing kidney disease treatments.

"Worldwide, two million people are being treated with dialysis or transplantation for kidney failure, and sadly another two million die each year, unable to access these treatments,” said Woolf, a Consultant in Paediatric Nephrology at Royal Manchester Children's Hospital, Manchester University NHS Foundation Trust.

Researchers began by generating microscopic parts of a kidney form human stem cells grown in a lab, which were then combined with a gel that acted as connective tissue. This tissue was then implanted in mice. After three months, nephrons making up the kidney structure and functional units had formed. While these nephrons contained small human blood vessels, they lacked a large artery. However, the structures were shown to filtrate, produce and excrete urine.

"We have proved beyond any doubt these structures function as kidney cells by filtering blood and producing urine—though we can't yet say what percentage of function exists," said Kimber. "What is particularly exciting is that the structures are made of human cells which developed an excellent capillary blood supply, becoming linked to the vasculature of the mouse. Though this structure was formed from several hundred glomeruli, and humans have about a million in their kidneys—this is clearly a major advance. It constitutes a proof of principle—but much work is yet to be done."