Despite a funding ban, several research facilities in the U.S. are proceeding with experiments that could produce human-animal chimeras. The possibility emerged as scientists attempt to grow human organs inside animals such as sheeps and pigs. At least 20 animals are now impregnated with human organs and have been under the care and study of researchers from several American universities in the past 12 months, according to MIT Technology Review.

The animal-human hybrid, or chimeras, are produced through the injection of human stem cells into an animal embryo, which - for its part - is then implanted in animals for gestation. Researchers believe that they will be able to harvest human organs by manipulating the stem cells. The process involves the removal of a specific organ in the animal embryo and the scientists then engineer the human stem cells as a replacement.

The process is certainly beneficial, especially to individuals who have difficulty finding organ donors. However, the research is raising ethical questions mainly because it blurs the line between species, MIT Technology Review reported. This position has been affirmed by governmental agencies. For instance, the National Institute of Health (NIH) refused to fund the endeavor and is contemplating the adoption of regulatory policies, according to an official announcement.

Animal rights groups are also opposing the research initiative citing that it is cruel to animals. It could even lead to an animal that has human characteristics such as when brain cells were injected. "The spectre of an intelligent mouse stuck in a laboratory somewhere screaming, 'I want to get out,' would be very troubling to people," David Resnik, a representative from the NIH, told the International Business Times.