creation of a chimera might involve both an Institutional Review Board (IRB), if cells are to be obtained from human donors for research, and an Institutional Animal Care and Use Committee (IACUC), if animals are to be used in the research. In some instances, Institutional Biosafety Committees (IBCs) and radiation safety committees might also have roles to play in research review. If hES cell research involves potential clinical applications (such as development of products to be tested in humans), FDA regulations will apply. However, care should be taken that the ESCRO committee does not duplicate or interfere with the proper functions of an IRB or other existing institutional committee. The functions of IRBs and ESCRO committees are distinct and should not be confused.

One particularly important aspect of regulatory compliance for hES cell research deals with protection of donors of blastocysts and gametes. Laboratory research that uses hES cells is generally not subject to federal regulations governing research with human subjects unless it involves personally identifiable information about the cell line’s progenitors. In general, research institutions are likely already to have rules in place for research involving other biological tissues, and hES cell research, like any other form of biological or biomedical research, would be covered by these rules and in many cases will not require further review. In the case of hES cell research, however, it will be critically important for investigators and institutions to know the provenance of hES cell lines, particularly if the cell lines are imported from another institution. That would include obtaining an assurance that the process by which the cells were obtained was approved by an IRB to ensure that donors provided voluntary informed consent and that risks were minimized.

The second role of ESCRO committees is to review research proposals that involve particularly sensitive kinds of research, including all proposals to generate additional hES cell lines by any means. The vast majority of in vitro experiments using already derived hES cell lines are unlikely to raise serious ethical issues, and will require minimal review. Some research with hES cells, such as the creation of human/nonhuman chimeras, will need more extensive review.

Other types of studies should not be permitted at this time (such as implantation of embryos or cells into a human uterus or breeding of any interspecies chimera). Still others warrant careful consideration, including research in which identifying information about the donors is available or becomes known to the investigator and experiments involving implantation of hES cells or human neural progenitor cells into nonhuman animals. Because of the sensitive nature of some aspects of hES cell research, it is critical that the scientific community propose and