The ghostly form floating in a large jar had been the robust reddish-brown of a healthy organ just hours before. Now itB次元官网网址檚 semitranslucent, white tubes like branches on a tree showing through.
This is a pig liver thatB次元官网网址檚 gradually being transformed to look and act like a human one, part of scientistsB次元官网网址� long quest to ease the nationB次元官网网址檚 transplant by bioengineering replacement organs.
The first step for workers in this suburban Minneapolis lab is to shampoo away the pig cells that made the organ do its work, its color gradually fading as the cells dissolve and are flushed out. WhatB次元官网网址檚 left is a rubbery scaffolding, a honeycomb structure of the liver, its blood vessels now empty.
Next human liver cells B次元官网网址� taken from donated organs unable to be transplanted B次元官网网址� will be oozed back inside that shell. Those living cells move into the scaffoldingB次元官网网址檚 nooks and crannies to restart the organB次元官网网址檚 functions.
B次元官网网址淲e essentially regrow the organ,B次元官网网址� said Jeff Ross, CEO of Miromatrix. B次元官网网址淥ur bodies wonB次元官网网址檛 see it as a pig organ anymore.B次元官网网址�
ThatB次元官网网址檚 a bold claim. Sometime in 2023, Miromatrix plans first-of-its-kind human testing of a bioengineered organ to start trying to prove it.
If the Food and Drug Administration agrees, the initial experiment will be outside a patientB次元官网网址檚 body. Researchers would place a pig-turned-humanlike liver next to a hospital bed to temporarily filter the blood of someone whose own liver suddenly failed. And if that novel B次元官网网址渓iver assistB次元官网网址� works, it would be a critical step toward eventually attempting a bioengineered organ transplant B次元官网网址� probably a kidney.
B次元官网网址淚t all sounds science fiction-ey but itB次元官网网址檚 got to start somewhere,B次元官网网址� said Dr. Sander Florman, a transplant chief at New YorkB次元官网网址檚 Mount Sinai Hospital, one of several hospitals already planning to participate in the liver-assist study. B次元官网网址淭his is probably more of the near future than xenotransplantation,B次元官网网址� or directly implanting animal organs into people.
More than 105,000 people are on the U.S. waiting list for an organ transplant. Thousands will die before itB次元官网网址檚 their turn. Thousands more never even get put on the list, considered too much of a long shot.
B次元官网网址淭he number of organs we have available are never going to be able to meet the demand,B次元官网网址� said Dr. Amit Tevar, a transplant surgeon at the University of Pittsburgh Medical Center. B次元官网网址淭his is our frustration.B次元官网网址�
ThatB次元官网网址檚 why scientists are looking to of organs. A Maryland man after receiving the worldB次元官网网址檚 first heart transplant from a pig last January B次元官网网址� an animal genetically modified so its organs didnB次元官网网址檛 trigger an immediate attack from the human immune system. The FDA is considering whether to allow additional xenotransplantation experiments using kidneys or hearts from gene-edited pigs.
Bioengineering organs is markedly different B次元官网网址� no special pigs required, just leftover organs from slaughterhouses.
B次元官网网址淭hat is something that in the long term may very likely contribute to the development of organs we can use in humans,B次元官网网址� said PittsburghB次元官网网址檚 Tevar. HeB次元官网网址檚 not involved with Miromatrix B次元官网网址� and cautioned that the planned outside-the-body testing would be only an early first step.
The Miromatrix approach stems from research in the early 2000s, when regenerative medicine specialist Doris Taylor and Dr. Harald Ott, then at the University of Minnesota, pioneered a way to completely decellularize the heart of a dead rat. The team seeded the resulting scaffolding with immature heart cells from baby rats that eventually made the little organ beat, garnering international headlines.
Fast forward, and now at university spinoff Miromatrix sit rows of large jugs pumping fluids and nutrients into livers and kidneys in various stages of their metamorphosis.
Stripping away the pig cells removes some of the risks of xenotransplantation, such as lurking animal viruses or hyper-rejection, Ross said. The FDA already considers the decellularized pig tissue safe for another purpose, using it to make a type of surgical mesh.
More complex is getting human cells to take over.
B次元官网网址淲e canB次元官网网址檛 take billions of cells and push them into the organ at once,B次元官网网址� Ross said. When slowly infused, B次元官网网址渢he cells crawl around and when they see the right environment, they stick.B次元官网网址�
The source of those human cells: donated livers and kidneys that wonB次元官网网址檛 be transplanted. Nearly a quarter of kidneys donated in the U.S. last year were discarded because hospitals often refuse to transplant less than perfect organs, or because it took too long to find a matching recipient.
As long as enough cells still are functioning when donation groups offer up an organ, Miromatrix biologists isolate usable cells and multiply them in lab dishes. From one rescued human organ the company says it can grow enough cells to repopulate several pig liver or kidney scaffolds, cells responsible for different jobs B次元官网网址� the kind that line blood vessels or filter waste, for example.
In 2021, researchers with Miromatrix and the Mayo Clinic reported successfully transplanting a version of bioengineered livers into pigs.
That set the stage for testing a B次元官网网址渓iver-assistB次元官网网址� treatment similar to dialysis, using bioengineered livers to filter the blood of people in acute liver failure, a life-threatening emergency. Doctors now have little to offer except supportive care unless the person is lucky enough to get a rapid transplant.
B次元官网网址淚f you can just get over the hump, then you might actually recoverB次元官网网址� B次元官网网址� because the liver is the only organ that can repair itself and regrow, said Mount SinaiB次元官网网址檚 Florman. B次元官网网址淚B次元官网网址檒l be excited when they get their first patient enrolled and I hope that itB次元官网网址檚 with us.B次元官网网址�
ItB次元官网网址檚 not clear how soon that testing can begin. The FDA recently told Miromatrix it has some questions about the study application.
If the outside-the-body liver experiment works, whatB次元官网网址檚 next? Still more research aimed at one day attempting to transplant a bioengineered organ B次元官网网址� likely a kidney, because a patient could survive with dialysis if the operation failed.
While regrowing kidneys isnB次元官网网址檛 as far along, B次元官网网址淚 was completely stunnedB次元官网网址� at the progress so far, said Dr. Ron Shapiro, a kidney transplant expert at Mount Sinai.
He treats many older patients on dialysis who B次元官网网址渨ill wait for years and years to get a kidney and likely die waiting on the list who would be perfectB次元官网网址� for such experiments B次元官网网址� if they come in time.
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The Associated Press Health and Science Department receives support from the Howard Hughes Medical InstituteB次元官网网址檚 Science and Educational Media Group. The AP is solely responsible for all content.
Lauran Neergaard, The Associated Press
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