Surgeons at Duke University Medical Center used pig livers tosustain the life of a critically ill man for five days until theyfound a human liver for transplanting.
During those five days, the patient's blood was filtered andcirculated through five different pig livers via a process knownas ex vivo xenoperfusion.
The human liver transplant was performed on Nov. 30, and thepatient is now out of critical care and doing as well as can beexpected for someone who has gone through such a majortrauma, according to clinician Robert Harland, who directed thexenoperfusion. (When the donor and recipient are of differentspecies, the procedure is called xenoperfusion. It has beenperformed elsewhere, especially in Europe, and organs fromvarious species, including cows and baboons, have been usedHarland told BioWorld.)
Duke University announced that the livers came from non-transgenic pigs provided by DNX Corp., which is collaboratingwith Duke to develop novel technologies and specially bred andtested animals to use as a source of permanent transplantation.
DNX expects to disclose the details of that collaboration early in1993, Steve Holtzman, the Princeton, N.J., company's executivevice president, told BioWorld.
But the goal of the program, according to John Logan, DNX's vicepresident of research, is "to get xenotransplants to work. Astransgenics become available, they can play into the clinicalscenario." Ultimately, that should result in permanentlytransplantable xenografts. First, however, there are lessons tobe learned from human reactions to non-transgenic xenografts.
It's become increasingly important to identify other animalspecies as organ donors because human organs are typically inshort supply. And even these precious few can be rejected by arecipient. "The considerable shortage of human organs is themajor limiting factor in transplantation today," said JeffreyPlatt, a xenograft researcher at Duke.
This has prompted researchers to consider other species,including primates and pigs. But using primates has itsdrawbacks. "You have to take into consideration ethical issues,the expense of maintaining them, the size of the organs andavailability," Platt told BioWorld. Pigs, on the other hand, are"very plentiful, the size and the way in which the organsfunction are similar enough to humans that one could havesome confidence that they can serve as replacements, andthere are certain immune compatabilities between pigs andhumans," Platt explained.
The five pig livers that were used in the xenoperfusionprocedure are now undergoing extensive study to determinewhat occurs at the cellular level when human blood is filteredthrough a pig liver.
"Looking at what happened to these organs in a perfusionsetting might give an idea of what might happen in atransplant setting," said DNX's Logan. And researchers in Duke'sxenograft program are beginning to gather data on humanimmune responses to pig proteins. "We're studying thisparticular patient (who underwent the ex vivo xenoperfusion)in that context," Platt told BioWorld.
-- Jennifer Van Brunt Senior Editor
(c) 1997 American Health Consultants. All rights reserved.