The Chicago Sun-Times reports that advances in tissue engineering and artificial organs are making xenotransplantation - use of animal organs to replace failing human organs - less interesting. "Ten years ago, everybody thought it would come about. Enthusiasm has waned." Overcoming immune system rejection and other barriers has - like more or less everything to do with medical research - proven to be more difficult than first thought. Meanwhile, stem cell research and materials science advances seem likely to lead to the first artificial organs grown from patient tissue in a decade or so. This is a brute force method of extending healthy life span - in the long run we should eliminate the root causes of age-related damage.