Researchers can develop hESC lines from donated spare embryos that have not been used for in vitro fertilisation (IVF) treatment. Under the right conditions, hESCs can multiply indefinitely while retaining the ability to develop into more than one type of mature cell. The different cells generated from hESC are a promising source for transplantation to replace diseased or damaged tissue in a wide range of conditions such as diabetes, neurodegenerative disorders, or cardiovascular disease. However, cells developed in this way will express specific blood group antigens and human leukocyte antigens (HLAs), which can cause graft rejection. If scientists can create a stem cell bank with varying types of HLA hESC the best match could be selected for patients and the likelihood of graft rejection reduced.
Researchers from Addenbrooke's Hospital, Cambridge, UK, investigated how many hESC lines would be needed to make matching possible in most cases. In order to estimate the number needed, the team analysed the blood group and HLA types of 10,000 organ donors for their compatibility to 6577 patients registered on the UK kidney-transplant waiting list. They assumed that the blood groups and the HLA types of the organ donors would be representative of potential donated spare embryos from IVF and that the patients on the waiting list would be indicative of potential hESC recipients. By analysing the degree of mismatch between the two groups they were able to estimate the number of hESC lines that would be needed to provide sufficient HLA diversity for the UK population. They found that 150 blood group compatible donors, 100 blood group O donors, or ten highly selected donors that have the genetic make-up for HLA types common in the recipient population could provide maximum benefit for HLA matching.
Study author Professor Bradley concludes: "The findings from this investigation have practical, political, and ethical implications for the establishment of hES-cell banks." Co-author Professor Pedersen adds: "The identification of such potentially valuable donor HLA identities within the UK population points the way for generating hESC lines with broad clinical utility. Our findings thus emphasise the value of the UK Stem Cell Bank and the importance of the wider UK Stem Cell Initiative." (Quote by e-mail; does not appear in published paper)
In an accompanying Comment, Justin St. John (University of Birmingham, UK) states: "The study, although a simulation of the projected requirements, provides the UK Stem Cell Bank with initial targets for the population of a bank that could meet long term therapeutic objectives through the use of IVF-derived hESCs." Dr. St. John notes that the donor and recipient UK populations studied in the Lancet article are under-representative of Asian and African-Caribbean populations. The study therefore provides an example whereby the clinically most valuable identities could be determined in regions or countries in which those ethnic populations comprise the majority.
Contact: To reach the Cambridge researchers, please contact Corina Hadjiodysseos, Press and Publications Office, The Old Schools, Trinity Lane, Cambridge, CB2 1TN. T) 122-333-9670/ 777-401-7600, corina.hadjiodysseos@admin.cam.ac.uk
Comment: Jus St. John, PhD, Lecturer in Mitochondrial and Reproductive Genetics, The Medical School, The University of Birmingham, Birmingham, B15 2TT, UK. T): 44-121-414-8122, j.stjohn.1@bham.ac.uk
Journal
The Lancet