Scientists are trying to grow human organs inside pigs, suggesting that this will address the problem of donor organ shortage worldwide.

The global donor organ shortage has affected transplant patients. According to U.S. statistics, about 22 people die every day while waiting for organ transplants.

To address this growing problem, researchers have been studying the use of adult stem cells to grow human organs, and these organs are to be grown inside pigs.

Researchers at the University of California Davis Health System have injected human stem cells into pig embryos to produce human-pig hybrid embryos known as chimeras - a name inspired by the part lion, part goat and part snake monster from Greek mythology.

According to a report in CNN, the embryo will need a few weeks to mature in order for scientists to determine whether the procedure worked, and after 28 days, the pregnancies will be terminated and the tissue will be extracted for analysis.

There are two stages in creating the chimera. First is the technique known as CRISPR gene editing where scientists remove a section of the pig's DNA, such as the pancreas, so that the pig embryo will not be able to create that particular organ.

The human stem cells are then injected into the embryo and start growing a pancreas. These foreign cells will not be rejected by the embryo because it hasn't developed its immune system yet.

The UC Davis team hopes that the resulting fetus will grow a human pancreas.

"Our hope is that this pig embryo will develop normally but the pancreas will be made almost exclusively out of human cells and could be compatible with a patient for transplantation," Pablo Ross, reproductive biologist and research leader, told BBC.

According to Walter Low, professor at the University of Minnesota's Department of Neurosurgery, said the scientists has chosen pigs as "biological incubator" for human cells because the animal's organs are almost the same size as human organs.

However, the U.S. National Institutes of Health said that it will not support the research. The main concern is that the chimeras might acquire a cognitive state.

Ross believes that the idea is unlikely, but said that it is the reason they are being cautious with the research. The team believes human-pig chimeras should look and behave like normal pigs, except that one organ will be composed of human cells.

The scientists are pushing forward in their research in the hope of creating life-saving organs and potential treatments for debilitating diseases.