Pig transplants and bionic limbs — new book explores breakthroughs | Science | News

When science writer Mary Roach lay down inside an iron lung, she hoped to spend a night allowing the mechanical respirator to expand and deflate her lungs — as thousands of polio sufferers did during epidemics in the mid-1900s. The patient lies inside a large, airtight metal cylinder, leaving only their head exposed. The machine then uses negative pressure to control the lungs like a bellows, mimicking natural breathing.

It’s pretty simple, in theory. However, once in position and listening to its chugging motor, Mary discovered that the sensation of having a machine breathe for you is an uncomfortable one. She writes in her new book, Replaceable You: Adventures in Human Anatomy: “You most decidedly are not in charge of your breathing. You will inhale when the machine makes you inhale, and ditto on the exhales. Should you try to defy the machine’s rhythm, there will be snorting and mild panic until you fall into line.”

Speaking now from her San Francisco home, the bestselling science writer admits: “I had this idea that I’d spend a night in the iron lung. But it’s an enclosed box — it depends on being a sealed space because you’re creating a vacuum to expand the lungs, so it has to be a very tight fit.

“It was this weird feeling of, on the one hand, taking deep, luxuriant breaths, and on the other hand feeling like someone is choking you! So it was not really conducive to sleep. I lasted seven or eight minutes! It was fascinating, though not quite what I expected.”

While this adventure in pulmonology may not have gone to plan, it is a perfect example of Mary’s determination to immerse herself in the topics she writes about.

A self-described “science goober”, she began her career penning general features for magazines and soon found that scientific assignments were the most interesting ones.

Replaceable You charts Mary’s forays into the field of regenerative medicine, which focuses on replacing or regenerating damaged human cells, tissues or organs.

The seven-time New York Times’ bestselling author’s previous works have explored diverse topics, from the many uses for human cadavers to space travel. So why regenerative medicine next?

It’s a topic that is rarely out of the headlines, whether it’s US tech bros trying to live forever or Russian dictator Vladimir Putin boasting to his Chinese counterpart on the sidelines of a recent conference: “Biotechnology is continuously developing… Human organs can be continuously transplanted. The longer you live, the younger you become, and [you can] even achieve immortality.”

Mary says with a smile: “Well, I’m 66 so everything’s starting to fall apart, that’s part of it. Almost all of my books have dealt with the human body in some way so it’s not surprising as a Mary Roach topic — replacing bits and pieces of the body.

“There were a couple of things I became interested in after talking to a reader who wrote to me. She’s an elective amputee — her foot was healthy and had a blood supply but it was twisted. After a dozen operations, it wasn’t serving her the way she wanted, so she wanted it off. But she couldn’t find a surgeon to do that.

“That got me interested in the idea of bodies as a whole system and a collection of bits and pieces.” Her reader did eventually find a surgeon willing to amputate her foot, Mary adds.

An early chapter sees the writer fly 6,000 miles to investigate the latest advances in animal-to-human transplantation. The process of transferring tissue or organs from one species to another is known as xenotransplantation. For organs, pigs are the most promising donors.

Researchers across the globe are working on tweaking porcine genes so the animals’ organs appear less foreign to the human immune system, reducing the risk of rejection. The stakes are particularly high in China, where cultural beliefs mean donation rates lag behind other nations.

Biotech firm ClonOrgan is cultivating the country’s largest population of genetically modified pigs, so this is where Mary headed.

But when her hosts stopped their car across the river from the high-tech facility that houses their donors, it suddenly became clear she was not going to get up close and personal with them. She writes: “It is dawning on me that I have come a long way to not see pigs.”

Mary adds: « I should have known because it’s called a ‘designated pathogen-free facility’ and I am just a big pile of pathogens! Obviously I wasn’t going to get to go and pet them, but I had this idea I would be inside the facility, not across the river looking at the place.”

The trip was nonetheless filled with fascinating conversations with experts pushing the frontier of xenotransplantation, including one who optimistically predicted that pig-to-human organ transplants could become routine within five to ten years. (Trials of pig organs in living people are just beginning in the US).

Replaceable You explores the history and future of many corners of regenerative medicine. Asked what might have the most potential to be transformative, Mary replies instantly: “Stem cells.” Stem cells are undifferentiated cells that can turn into many different types of cell such as muscle, nerve, blood or cartilage. Early embryos are essentially a ball of stem cells, and scientists are working on techniques to reprogramme adult cells to this state so they can be guided to become whatever type is needed to repair the body.

Mary explains: “For example, you could take someone’s blood and regress the cells to a state of pluripotency, where you can instruct the cells to become what you want them to be.

“There’s work going on with creating dopamine-producing neurons that you could use for Parkinson’s patients. And there’s really cool work going on with islet cells and diabetes.”

Some advances are clear successes — like the life-saving iron lung and perfusion systems to keep donor hearts alive for longer outside the body, buying time for transportation to a recipient. The benefits of others are more nuanced.

There is a vast array of high-tech prosthetic limbs on offer these days but at the Amputee Coalition National Conference in California, Mary learned that, for some amputees, simpler is better.

“There have been a lot of great advances in prosthetics for legs with microprocessors that learn one’s gait etc,” she says. “You see a lot of press about the bionic-looking hands with fingers that move because they’re hooked up to impulses from the brain to the muscle.

“But I went to the annual conference of the amputee coalition here in the States and I didn’t see anybody with one of those.”

Meanwhile, the chapter that has stayed with Mary the most is set at Massachusetts General Hospital’s Sumner M. Redstone Burn Center. There, she discovered the basics of healing with autografts (grafts using the patient’s own skin), allografts (using skin from another human), and xenografts (using skin from another species such as Icelandic cod).

Pigs get another mention here – scientists are working on modifying pig skin to be more like human skin. While shadowing top plastic surgeon Dr Jeremy Goverman, Mary met a 54-year-old woman who suffered devastating burns to 90% of her body after catching light while trying to ignite tree clippings. Witnessing the relationship between Dr Goverman and his long-term patients was deeply moving, she recalls.

« Surgeons can have a reputation for being a little less personally involved, but when it’s a burn – a major, third degree burn on the majority of the body – that’s a relationship that lasts for months or even years of surgeries. That was an amazing couple of days.”

So, does Mary plan to have part of herself regenerated soon? She laughs: “Within the next 10 years, I’ll certainly be getting some new lenses for my eyes. Right now, they haven’t quite nailed the ability to move your focus from close to far automatically, the way the human eye does.

“But it’s come a tremendous distance from the 1960s and 1970s when it was an operation that required a multi-day hospital stay. »

Her globe-trotting tour of regenerative medicine leaves the reader with a greater appreciation for the scientists striving to rebuild our bodies, but it also lays bare just how difficult a task that is.

“My takeaway was just how hard it is to come up with a replacement that is as good as what someone was born with,” Mary adds. “You can replace a mangled foot with a prosthetic and it’s better than what they had, but in terms of creating something equal to or better, that’s almost impossible.

« But then, of course it’s impossible. You’re talking about 200 years of medicine and engineering competing with millions of years of evolution, so it’s a pretty tough competition. So much of the body we take for granted, like the fact that when you read and then you look up, your eye is automatically adjusting focus like the best focus-puller on a movie set.

« So much of this is happening automatically without us even being aware of it. If you take one facet of the body and really start to look at it, it’s unbelievable.”