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Spare parts: the human quest for unlimited mileage and what science is doing to keep you on the road longer.

by Shawn Blore

Subjects: 

Longevity--Research; Transplantation of organs, tissues, etc.--Innovations; Artificial organs--Innovations


We're
at a curious moment in human history. The generation that invented youth culture, the demographic mob that overthrew a centuries-old convention favoring age and wisdom over youth and hormones - the baby boomers - are finally reaching, well, that age. That age of creaking knees, and aching backs and eyes that can't quite make things out anymore. That age when a life of hard driving begins to show up on the chassis. With cars it hits around year five. The ball joints go, the tad starts dripping, you have to pump the clutch a little harder to rev up into the high gears. You realize you're going to have to either spend a pile of money on new parts, or junk the aging heap altogether.

Now, it's possible that having reached that age the boomers will renounce their youthful indiscretions, restore the gerontocracy (which they will, anyway, soon be joining) and accept the natural fate of all mankind with a certain quiet dignity. Possible, but what are the odds? This is after all the generation that brought Leave it to Beaver back to life, the bunch that refuses to believe Elvis ever died. Having pledged their troth to the worship of youth, it's unlikely they'll turn apostate now.

So where does that leave us? There are in fact two other forces at work. The boomers are the richest generation in all of recorded history and the last to truly share the Victorians' faith in Better Living Through Science. In this case that faith is being amply rewarded, for while the free market can't do everything, it is astonishingly efficient at fulfilling the needs of large, rich demographic groups. Forget about going softly into that sweet good night. Loud or soft, the boomers just ain't going. As junking the heap altogether is completely out of the question, the market is working frantically to develop a full warehouse of spare body parts. What follows is an update from the research front.

Prolonging Engine Life

While no one is exactly sure what causes human organs to deteriorate with age, one school of thought holds that it's the result of years of corrosion by so-called free radicals - highly reactive molecules that are produced as a normal byproduct of cell metabolism. According to this theory, the best way to reduce cell tissue damage is to minimize the production of free radicals by keeping the metabolic rate as low as possible. Sort of like staying off the highways and keeping the speed below five kph.

When put into practice this theory does yield dramatic results. In one study at Case-Western Reserve University, in Cleveland, Ohio, scientists found that giving mice approximately half their normal caloric intake extended their lifespan by nearly 30 per cent. The bad news is that severely restricting one's diet is the only known way of reducing free radical production. Investigations into the efficacy of semi-starvation on human beings have so far been hampered by a lack of volunteers.

Raiding the Wrecks

It was only 30 years ago that an ambitious South African surgeon teamed up with a 51-year-old bus driver to make medical history with the world's first human heart transplant. Dr. Christiaan Barnard went on to fame and fortune. Unfortunately, the patient parked himself permanently 18 days after the first press conference.

By the mid-'70s doctors had pretty much worked out the mechanics of chopping out an old heart and slapping in a new one. What hampered progress in the field - and indeed in all organ transplants was the immune system's unfortunate habit of attacking and destroying the donor organ. Even when the tissue type of donor and recipient were carefully matched the risk of chronic rejection was high.

That all changed in the early '80s with the introduction of Cyclosporin, a new drug that suppressed the immune system response of the organ recipient. Tissue typing became a thing of the past (except for kidneys) and the number of transplants skyrocketed. In 1980 there were about 20 organ transplants (counting the heart, kidney, liver, lungs and pancreas) in B.C. By 1993 there were close to 200. In the first eight months of 1997, 75 British Columbians received a new kidney, six received a kidney/pancreas matched set, 20 received a new liver, 13 a new heart, and eight received either one or two new lungs.

The progress in survival rates was equally impressive. Doctors typically use the survival rate at one year to measure the success of a transplant operation because after that period you're as likely to die of some other cause as you are of organ failure. By 1996 the one-year survival rate for kidney transplant patients in B.C. had reached approximately 95 per cent, for liver patients it was 84 per cent and for heart recipients 73 per cent. The lowest one-year survival rate, for double lung recipients, was still a healthy 70 per cent.

"Transplantation is no longer an experimental procedure," according to Dr. Stephen Chung, research director for the BC Transplant Society, the agency that oversees organ donation in British Columbia. "More and more people are being indicated for transplantation," says Dr. Chung, "and the age limit is being widened to reach younger and older patients." According to Dr. Chung there is no longer a hard and fast age limit. "If you're 75 and your overall health is good except for a bad heart, we would likely put you on the list for a transplant."

If donor organs were more readily available, says Dr. Chung, transplantation would become even more commonplace, as a treatment for diseases like liver cancer and possibly other cancers, and as a possible treatment for diabetes. Unfortunately, they aren't.

Transplantation is really a victim of its own success," says Dr. Chung. "The number of people who need one has begun to grow exponentially, whereas the supply of organs seems to have plateaued out." Patients in B.C. are now waiting an average of about six months for a lung, and up to 28 months for a kidney. Simply put, there are just not enough folks biting the biscuit, at least in the right way.

Though nearly 250,000 people die in British Columbia each year, only about one per cent suffer brain death while in a hospital hooked up to a respirator, which is the sine qua non of organ donation. Of those, a distressing number don't donate their organs. The BC Transplant Society is focusing on ensuring that as many people as possible donate, both by raising awareness about organ donation and by creating a provincial organ donor registry in a centralized computer database. In other parts of the country, and particularly south of the border, researchers are developing other means of increasing the spare parts inventory, from judicious borrowing from other species, to making up parts from scratch.

Looking to Foreign Models

Though convincing people to donate their organs can be tricky, animals can be much more amenable. The most famous recent animal-to-human transplant - called a xenotransplant - involved 15-day-old Baby Fae, a California girl who in 1984 received a heart from a baboon. Less glamorous but perhaps more useful in the long run is the research being done with pig-to-people transplantation at Duke University in North Carolina. Pigs hold out the promise of an unlimited organ supply because, unlike baboons, they are born in litters of eight, reach maturity in six months, and look neither cute nor cuddly nor even vaguely human.

The big problem is the severe reaction of the immune system to animal organs. Duke researchers have been able to mitigate the worst of those problems by genetically engineering a kind of pig with a tolerance for certain human immune system proteins. The team is now working on a technique for masking the animal organs to fool a recipient's immune system. Results are promising, but then solving the technical challenges is just one of the hurdles to a permanent piggy organ bank.

There remains the question of ethics. Animal rights groups are dead set against xenotransplantation. BC Transplant Society officials are quick to point out that no research on animal organ transplantation is being done in British Columbia, though not, they say, because of any potential controversy. Research director Stephen Chung believes animal organs have a very. promising future, if we can overcome the medical and ethical hurdles.

If.

British author Douglas Adams once postulated that the only way to solve the ethical dilemma of using animals for meat would be to develop a breed of cow that wanted to be eaten and could say so in fluent English. In the case of organ donors, however, it may be better if we just don't ask.

Growing Your Own

If talking the kids into giving up their innards seems a trifle chancey, and borrowing bits from Babe leaves you queasy, growing your own organs may be the way to go. It may sound like a concept straight out of science fiction, but tissue engineering has advanced to the point where companies with viable products now exist in the marketplace. The basic technique is not unlike growing grass.

The first step is to isolate the 'seeds' - unspecialized human tissue cells with an ability for unlimited growth. These are then seeded across a scaffold of the appropriate shape and size and kept well supplied with growth-promoting nutrients. In the case of Advanced Tissue Sciences Inc. of La Jolla, California, the tissue being grown is skin. Fibroblasts (skin 'seed cells') are obtained from a discarded penis foreskin, seeded across a flat nylon mesh and encouraged to grow. The resulting sheets of skin are being used in place of skin grafts for burn victims.

There's nothing that says the scaffolds have to be fiat, however. Dr. Joseph Vacanti at Boston Children's Hospital recently molded a scaffold of ultra pure biodegradable plastic into the shape of a human ear. The mold was then seeded with cartilage cells and the novel ears that resulted were grafted on to a number of willing mice. The ears remained healthy and in place for the lifetime of the mice. Although there isn't much of a market for spare ears (Evander Holyfield notwithstanding), the same technique can also be used to create 'grow-your-own' breasts for mastectomy patients. Human trials are expected to begin within the next year.

Internal organs like the liver are a more difficult problem, both because the three-dimensional topography is a lot more complex and because an organ comprises a number of different tissue types. Researchers at MIT are taking a shot at the problem by growing one layer of tissue at a time, then sandwiching the slices together to form a complete organ. A working prototype may be as little as five years away. Within another 15 years, according to ear-grower Joseph Vacanti, it will be possible to grow an entire arm or leg in the laboratory and then simply stitch it on to a needy patient.

Building from Scratch

In the quest for unlimited mileage through replacement parts, some physicians believe mass production of artificial organs may be the route to take. The first great milestone in this quest came in 1982, when the Jarvik-7 artificial heart was placed in the chest of patient Barney Clark in Salt Lake City, Utah. Ironically, however, Clark's poor survival (he died after 115 days) and the unwieldiness of the heart itself, has overshadowed the progress that has been made in the past few years.

Artificial lungs made their debut in animal tests in 1996. That same year, six different biotech companies put artificial blood products on the market. The products ranged from a Teflon-like liquid to a protein solution produced by genetically engineered bacteria. The first artificial pancreas- a plastic implant designed to take over the pancreas's function of controlling blood sugar levels-underwent animal testing last year in Toronto.

The development of external artificial organs, notably kidneys and livers, is particularly well advanced, to the point where they will soon become, if not mainstream, at least an accepted part of medical practice. Most experts believe that soon artificial organs will likely play the role of a bridge, a temporary stop-gap to keep you alive until a donor is found, or your replacement organ grows out.

The most exciting advances in the artificial field have actually occurred not under the hood, but in the suspension. Hip replacements, for example, have been commonplace for years. But in the bad old days having an artificial hip meant limping your way painfully through life. With the advent of cemented hip joint replacements in the '90s, artificial hip recipients - including football star Bo Jackson - are now fully capable of playing in the best leagues.

The advances are even more apparent with knee replacements. Previously surgeons could only relieve some of the pain of damaged knees, removing any bits of damaged cartilage floating about in the joint. Replacing the joint was difficult because the underlying bone was often severely worn away. With the latest artificial knees, the Teflon and stainless steel joint can be attached to ceramic bone material. During surgery the doctor carves down until the damaged cartilage and bone tissue has all been removed, then grafts the ceramic bone onto the remaining natural bone tissue.

That the knees are fully functional was dramatically illustrated by 46-year-old former tennis mediocrity Eddie Dibbs, who returned to the seniors circuit after getting a pair of new knees in 1994. By all accounts he's playing as well as he never did.

RELATED ARTICLE: Replacement Culture

Every new advance carries its own set of complications. The various liberation movements of the past 40 years - women's, sexual, homo, sexual - have certainly made society a fairer place, but they have also given rise to vastly more complex family structures. The replacement revolution promises to jangle things even further. Advances in immunosuppression drugs have made un-matched organ donation standard procedure, but though that new heart may be from a perfect stranger, it doesn't always come without strings.

The families of organ donors often feel a need to meet and even establish a relationship with the organ recipient. The practice is actively discouraged in British Columbia (organ donation is completely anonymous), but in the U.S. many hospitals are helping to foster this new kind of community. A New Orleans woman who in 1992 received a heart/lung transplant from a teenager killed in a traffic accident has gone on to create an organization that helps bring organ recipients together with their 'replacement relations'.

Replacement culture is also beginning to generate its own literature. As early as 1974, replacement culture's first bestseller, Michael Crichton's Coma, was turned into r-culture's first blockbuster movie. Lately the canon has expanded to include testimonials and how-to books. In the United States, the United Network for Organ Sharing's (UNOS) 1994 Report of Centre Specific Graft and Patient Survival Rates (US$115) details patient survival rates for all organs at all U.S. hospitals. UNOS's Analysis of Waiting List Registrations and Median Waiting Times will tell you how long you're likely to wait for an organ in each U.S. state. In New York, for example, the average wait for a new heart is 363 days, whereas residents of the state of Mississippi wait only 27 days. In British Columbia the average waiting time for a new heart is about 90 days. For New Yorkers in a hurry (there's another kind?) it pays to leave town.

Any new community also needs its own heroes and icons. R-culture got its first big boost in the early '90s when famed football star Bo Jackson underwent an innovative new type of hip replacement surgery, one that allowed him to continue his career. The process was taken even further by broadcaster Hugh Downs, who had both knees replaced in February 1996. Downs subsequently devoted an entire episode of his TV show 20/20 to highlighting the existence of r-people like himself. And in Sydney, Australia the World Transplant Games - who'd have thought there'd be enough athletes to even put together a relay race worth watching? - were held in late September.

Nor have the courts remained unaffected. In 1996 Washington State death-row inmates initiated legal action to ensure they were not denied the benefits of organ replacement therapy. Given the current climate of identity politics, it's only a matter of time before other r-people band together in social and political action groups - government-funded, of course - to demand their right to, well, to be r-people, and to have their various parts replaced. After all, why rail against the dying of the light, when you can put in a spare bulb?

Shawn Blore is a Vancouver freelance writer.

COPYRIGHT 1997 Shawn Blore