To the Editor: Rosenthal (July 17 issue)1 begins her articleby considering the myth of Prometheus. She says that a vulturepreyed daily on his self-renewing liver. Indeed, Greek mythologytells us that a bird ate Prometheus's liver, but older sourcesallude to an eagle instead of a vulture2,3 (Figure 1). Thisis not a trivial point, because vultures are scavengers, whereaseagles are birds of prey. Vultures would never eat living animals.This cultural imprecision might seem unimportant, but terminologyis key with respect to the issue of the "stem-cell promise."Semantic differences between terms such as "nuclear transfer"and "therapeutic cloning"are very important.
Attributed to the Arkesilas Painter, circa 555 B.C.
Reprinted with the permission of the Vatican Museum.
To continue the theme of Greek mythology, we suggest the mythof Phaethon. Helios (the Sun) drove his scalding carriage throughthe skies every day. Having made insistent requests, Phaethon,Helios's young and inexpert son, managed to drive the chariotfor a day, but he could not stop the runaway horses, whose paththreatened to burn the Earth. Annoyed, Zeus struck Phaethonwith a lightning bolt. Since adult stem cells appear to showclinical safety and feasibility,4,5 it should be noted thatother sources of cell therapy could be dangerous,6 at leastuntil we have wider knowledge about how to control them.
Damian Garcia-Olmo, M.D., Ph.D. Universidad Autonoma de Madrid 28046 Madrid, Spain damian.garcia{at}uam.es
Miguel-Angel Garcia-Olmo, M.A. San Antonio University–UCAM 30107 Murcia, Spain
References
Rosenthal N. Prometheus's vulture and the stem-cell promise. N Engl J Med 2003;349:267-274. [Free Full Text]
Prometheus bound [lines 1020-1025]. In: Aeschylus. Vol. 1. Suppliant maidens: Persians: Prometheus: Seven against Thebes. Loeb classical library. Series no. 145. Smyth HW, trans. Cambridge, Mass.: Harvard University Press, 1969.
Orlic D. Adult bone marrow stem cells regenerate myocardium in ischemic heart disease. Ann N Y Acad Sci 2003;996:152-157. [Web of Science][Medline]
Garcia-Olmo D, Garcia-Arranz M, Garcia LG, et al. Autologous stem cell transplantation for treatment of rectovaginal fistula in perianal Crohn's disease: a new cell-based therapy. Int J Colorectal Dis 2003;18:451-454. [CrossRef][Medline]
Hochedlinger K, Jaenisch R. Nuclear transplantation, embryonic stem cells, and the potential for cell therapy. N Engl J Med 2003;349:275-286. [Free Full Text]
Dr. Rosenthal replies: I commend my colleagues for their careful perusal of the ancient literature, having correctly identifiedtwo sources of the Greek legend where an eagle, probably a symbolof Zeus himself, was sent to torture the Titan Prometheus. Asnoted by other scholars,1 the Promethean tale resembles onedescribed in Homer's Odyssey, in which Tityos is tormented bytwo vultures and may have been the original victim of this punishment.
An earlier legend holds precedence in the Caucasus, where earthquakeswere allegedly caused by the struggles of a fierce giant, fetteredin a mountain cave for his various impieties while a vulturepecked intermittently at his bowels.2 Perhaps it was this ancientversion to which Bulfinch's The Age of Fable alludes in describingPrometheus "chained to a rock on Mount Caucasus, where a vulturepreyed on his liver."3 Other literary figures, including Byron,have also described the vulture of Promethean legend.4
As for the argument that vultures never eat live flesh, thisis not strictly true. They are omnivorous, feeding chiefly oncarrion because they have relatively weak beaks and lack thestrength of other birds of prey. They rarely attack live preyunless it is rendered helpless. One might argue that Prometheuswas defenseless against the attacks of emboldened raptors, butthe true ornithologic identity of his devourer remains enshroudedin the mists of myth. Let us hope that as scientists we leaveless indeterminate the documentation of the illusive stem cell'strue identity.
(I am indebted to Professor Brian Bothwick, Department of Classicsand Ancient History, University of Western Australia, for hisinvaluable tutelage and for the use of his excellent library.)
Nadia Rosenthal, Ph.D. European Molecular Biology Laboratory 00016 Monterotondo, Italy
References
Hesiod. Theogony. West ML, trans. Oxford, England: Clarendon Press, 1966.
Olrik A. Ragnarök. Ranisch W, trans. Berlin, Germany: W. de Gruyter, 1922.
Bulfinch T. The age of fable: or stories of gods and heroes. Boston: Charles E. Brown, 1855.
Prometheus. In: Byron GG. Works. London: John Murray, 1832.
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