Scientists grow kidneys containing human cells in pig embryos

Pigs are kept in a pen in My Duc district, Hanoi, Vietnam, May 30, 2019. [AP Photo]

Chinese scientists have succeeded in growing kidneys containing human cells in pig embryos, a world first that could one day help address organ donation shortages.

But the finding, published Thursday in a study in the journal Cell Stem Cell, raises ethical issues - especially since some human cells also were found in the pigs' brains, experts said.

The researchers from the Guangzhou Institutes of Biomedicine and Health focused on kidneys since they are the most commonly transplanted in human medicine.

"Rat organs have been produced in mice, and mouse organs have been produced in rats, but previous attempts to grow human organs in pigs have not succeeded," senior author Liangxue Lai said in a statement.

"Our approach improves the integration of human cells into recipient tissues and allows us to grow human organs in pigs."

This is a different approach to the recent high-profile breakthroughs in the United States, where genetically modified pig kidneys and even a heart have been placed inside humans.

The new research paper "describes pioneering steps in a new approach to organ bioengineering using pigs as incubators for growing and cultivating human organs," said Dusko Ilic, a professor of stem cell sciences at King's College London who was not involved in the research.

Ilic cautioned there would be many challenges to turning the experiment into a viable solution, but "nevertheless, this captivating strategy warrants further exploration."

Gene editing

A major challenge in creating such hybrids has been that pig cells outcompete human cells.

To overcome the obstacles, the team used CRISPR gene editing to delete two genes essential for kidneys to form inside a pig embryo, creating what's called a "niche."