Introduction to the symposium on Non-Human primate ART to ES cells

First, I want to thank Barry Bavister and Carol Brenner for organising this meeting. Under the circumstances existing in the wake of Hurricane Katrina, it was nothing short of heroic, from my perspective. I will begin by providing a little foundation for the symposium today. Two years ago at the International Embryo Transfer Society meeting held in Portland, Oregon, Richard Stouffer, Mary Zelinski-Wooten and I organised a symposium entitled ‘ARTS in Action in Non-Human Primates’. We had three broad objectives in mind: (1) to review the current state of reproductive research employing the assisted reproductive technologies (ARTs) in non-human primates (NHP); (2) to enhance interactions and collaborative efforts within and between the National Primate Center system and academic institutions concerning these technologies and reproductive research; and (3) to identify and discuss new developments in reproductive physiology, gamete/embryo biology and efforts to exploit the ARTs in non-human primates (Wolf 2004). Individual topics included gametogenesis, gametes and fertilisation, implantation and pregnancy, ART applications – for instance, in the production of animals with desired genotypes, contraception, nuclear transfer, twinning – and finally, at the bottom of the list, was embryonic stem (ES) cells. Given the present focus on ES cells, it is clear that over the last 2 years we have moved ES cells from the bottom of the list to the top. Conclusions drawn by Dr Bavister at the end of the symposium in 2004 were, first of all, that major technical problems associated with routine production of non-human primates using either conventional in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) are largely solved. Research activities in non-human primates that might carry a translational component include developing chemically defined culture media for embryo development, establishing non-invasive markers for oocyte and embryo quality and perhaps oocyte in vitro maturation. Additionally, unique approaches that could and should be applied strictly to non-human primates include strategies to produce identical twins, either by blastomere splitting or blastocyst bisection, production of transgenic animals, and, of course, somatic cell nuclear transfer to produce cloned animals. Finally, the caveat that the ARTs in non-human primates could contribute to stem cell biology and technology was mentioned. The objectives of today’s symposium are: (1) to educate investigators, the speakers as well as the audience, about the challenges and successes associated with non-human primate ES cell biology; and (2) to foster communication relevant to the use of non-human primate ES cells in translational research. By way of a historical perspective, primate ES cells were first isolated in the rhesus monkey by Jamie Thomson’s group in Wisconsin, from embryos that were produced in vivo and recovered from the uterus by flushing. Such cells, isolated from in vivo-produced embryos, should serve as our ‘gold standard’ for assessing primate ES cell lines. At the National Primate Research Center in Oregon, we have established additional rhesus monkey ES cell lines using either ICSI-derived or IVF-produced embryos. The common marmoset was the second non-human primate species from which embryonic stem cells were derived, again by Jamie Thomson’s group. There is, however, a recent report from Sasaki and co-workers (2005) in Japan, describing their efforts to produce marmoset ES cell banks. In the cynomolgus macaque, Suemori and co-workers (2001) have isolated four ES cell lines and Vrana and co-workers (2003) produced a single ES cell line from a parthenote. With regard to the characteristics of non-human primate ES cells, I’m sure most of you are aware of their growth and maintenance properties that resemble human ES cells as opposed to ES cells from the mouse. As an addendum to these introductory remarks, I will provide a brief overview of our studies on rhesus monkey ES cells at the Oregon National Primate Research Center. We have isolated over 20 ES cell lines from embryos produced by application of ARTs. Three of these lines showed stable but abnormal karyotypes and we observed an even distribution between Xand Y-bearing lines. In characterising these lines, of course, we used conventional approaches of detecting pluripotent genes and gene products, and specific markers such as SSEA 3 and SSEA 4 by transcriptional analysis or indirect immunocytochemistry. We are beginning to ask questions about the heterogeneity of ES cells as there is substantial evidence that lines do vary. One of the ways of doing