The FDA wishes to remind physicians and clinical investigators that its definition of xenotransplantation includes any procedure that involves the transplantation, implantation, or infusion into a human recipient of human body fluids, cells, tissues, or organs that have had ex vivo contact with live nonhuman animal cells, tissues, or organs. The definition includes human embryos co-cultured with living nonhuman animal cellular material, such as bovine tubal cells or Vero cells, and includes feeder layer cells irradiated to render them nonproliferative.
Crawford, Jr LM. Xenotransplantation Advisory. JAMA. 2002;288(6):688. doi:10.1001/jama.288.6.688