Next Steps on Research Using Animal Embryos Containing Human Cells
Biomedical researchers have created and used animal models containing human cells for decades to gain valuable insights into human biology and disease development. For example, human tumor cells are routinely grown in mice to study cancer disease processes and to evaluate potential treatment strategies. To advance regenerative medicine, it is common practice to validate the potency of pluripotent human cells – which can become any tissue in the body – through introducing them into rodents.
With recent advances in stem cell and gene editing technologies, an increasing number of researchers are interested in growing human tissues and organs in animals by introducing pluripotent human cells into early animal embryos. Formation of these types of human-animal organism, referred to as “chimeras”, holds tremendous potential for disease modeling, drug testing, and perhaps eventual organ transplant. However, uncertainty about the effects of human cells on off-target organs and tissues in the chimeric animals, particularly in the nervous system, raises ethical and animal welfare concerns.
Currently, the 2009 NIH Guidelines for Human Stem Cell Research specifically prohibit introducing human pluripotent cells into nonhuman primate blastocysts and the breeding of animals into which human pluripotent cells may have contributed to the germ line (egg or sperm cells). Given the direction of the science, however, NIH felt that it was an appropriate time to consider whether further policy provisions regarding other chimera models were needed before making funding decisions. Therefore, as I wrote about last fall, NIH instituted a funding moratorium in September 2015 (NOT-OD-15-158) for research proposing to introduce human pluripotent cells into animal embryos prior to gastrulation stage—the beginning of development of the three germ layers.
Continue reading at osp.od.nih.gov.