A leading international expert on embryonic stem cells has voiced his opposition to so-called "therapeutic" cloning. Dr. Alan Trounson, Australian embryonic stem cell expert and a leader in the field worldwide, says that stem cell research has advanced so rapidly in the past few months that therapeutic cloning is now unnecessary.
"This is further evidence that destructive research cloning is unnecessary," Brownback said. "Developments in adult and non-embryonic stem cell research are providing effective and ethically sound methods of medical treatment. "Some maintain that all types of research should continue, but with limited resources, we must invest our money in success. Research proves we can more effectively treat patients through adult and non-embryonic stem cells. Cloning delays cures.
"Dr. Trounson's announcement is a wake-up call for those who still support destructive research cloning," Brownback said.
Professor Trounson spoke out against cloning in numerous articles, including "Stem-cell cloning not needed, says scientist," The Age (Melbourne), pg. 2, July 29, 2002; "Stem-cell research outpaces cloning," The Australian, pg. 3, July 29, 2002; "Therapeutic cloning no longer necessary: expert," AAP Newsfeed, July 29, 2002. "I can't see why, then, you would argue for therapeutic cloning in the long term because it is so difficult to get eggs and you've got this issue of (destroying) embryos as well," Trounson said. Adult stem cells, meanwhile, continue to show that they are more effective, with a greater potential to treat disease.
-Researchers in Sweden, noting that cells "of early embryonic origin, including those derived from differentiated embryonic stem cells, are inefficient in adult recipients upon transplantation," found success growing adult blood stem cells and using the cells to treat models of immune diseases in mice. (Pinto do Ó P et al., "Hematopoietic progenitor/stem cells immortalized by Lhx2 generate functional hematopoietic cells in vivo"; Blood 99, 3939-3946; June 1, 2002)
-Researchers at the University of Florida transformed adult liver stem cells into insulin-secreting pancreas cells, and reversed hyperglycemia in diabetic mice. They noted: "Adult stem cells appear to offer great promise for the production of an almost unlimited supply of insulin-producing cells… The ability to grow insulin-producing cells from liver stem cells shows the remarkable potential of adult stem cells for future cell therapy." (Yang L et al.; "In vitro trans-differentiation of adult hepatic stem cells into pancreatic endocrine hormone-producing cells"; Proceedings of the National Academy of Sciences USA, published online, June 4, 2002)
-Scientists at Massachusetts General Hospital successfully turned adult stem cells into insulin-producing cells that could reverse diabetes, noting that the new cells could be made from a patient's own pancreatic stem cells, to treat their diabetes. (Abraham EJ et al.; "Insulinotropic hormone glucagon-like peptide-1 differentiation of human pancreatic islet-derived progenitor cells into insulin-producing cells"; Endocrinology 143, 3152-3161; Aug 2002)
-Others have used adult stem cells to restore bone growth in children with a severe bone and cartilage disease (Horwitz EM et al.; "Isolated allogeneic bone marrow-derived mesenchymal cells engraft and stimulate growth in children with osteogenesis imperfecta: implications for cell therapy of bone"; Proc Natl Acad Sci USA 99, 8932-8937; June 25, 2002 -While others have used adult bone marrow stem cells to effectively cure severe combined immunodeficiency ("bubble boy" disease). (Hacein-Bey-Abina S et al.; "Sustained correction of X-linked severe combined immunodeficiency by ex vivo gene therapy"; New England Journal of Medicine 346, 1185-1198; April 18, 2002)
-And, scientists at Scripps Research Institute used bone marrow stem cells to grow new blood vessels in the eyes of mice, a development researchers say could lead to treatments for some forms of blindness in humans, including diabetic retinopathy and macular degeneration. (Otani A et al.; "Bone marrow-derived stem cells target retinal astrocytes and can promote or inhibit retinal angiogenesis"; Nature Medicine published online, doi:10.1038/nm744; July 29, 2002)