Findings highlightpromise of chimeric organismsfor science and medicine

The word “chimera” originally described mythological creatures or deities in polytheistic religions. In science, an interspecies chimera is an organism containing cells from different species. Rapid advances in the ability to grow cells, tissues and organs of one species within an organism of another species (forming “chimeric” organisms) offer an unprecedented opportunity for tackling longstanding scientific mysteries and addressing pressing human health problems, particularly the need for transplantable organs and tissues. The lab of Juan Carlos Izpisua Belmonte combined cutting-edge gene-editing and stem cell technologies to grow a rat pancreas, heart and eyes in a developing mouse, providing proof-of-concept that functional organs from one species can be grown in another. The work marks the first steps toward the generation of transplantable human organs using large animals.