Mary travelled to China to investigate pig-to-human organ transplants (Image: Jen Siska\/Getty)<\/span><\/span><\/div>\n 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 \u2014 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.<\/p>\n 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: \u201cYou 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\u2019s rhythm, there will be snorting and mild panic until you fall into line.\u201d<\/p>\n<\/div>\n Read more:<\/strong> Donald Trump dealt huge blow as UK medicines regulator rejects autism claims <\/a><\/p>\n<\/div>\n Mary lying in an iron lung allowing it to control her breathing (Image: Mary Roach)<\/span><\/span><\/div>\n Speaking now from her San Francisco home, the bestselling science writer admits: \u201cI had this idea that I\u2019d spend a night in the iron lung. But it\u2019s an enclosed box \u2014 it depends on being a sealed space because you\u2019re creating a vacuum to expand the lungs, so it has to be a very tight fit.<\/p>\n \u201cIt 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.\u201d<\/p>\n While this adventure in pulmonology may not have gone to plan, it is a perfect example of Mary\u2019s determination to immerse herself in the topics she writes about.<\/p>\n A self-described \u201cscience goober\u201d, she began her career penning general features for magazines and soon found that scientific assignments were the most interesting ones.<\/p>\n Replaceable You charts Mary\u2019s forays into the field of regenerative medicine, which focuses on replacing or regenerating damaged human cells, tissues or organs.<\/p>\n The seven-time New York Times bestselling author\u2019s previous works have explored diverse topics, from the many uses for human cadavers to space travel. So why regenerative medicine next?<\/p>\n It\u2019s a topic that is rarely out of the headlines, whether it\u2019s US<\/a> tech bros trying to live forever or Russian dictator Vladimir Putin<\/a> boasting to his Chinese<\/a> counterpart on the sidelines of a recent conference: \u201cBiotechnology is continuously developing\u2026 Human organs can be continuously transplanted. The longer you live, the younger you become, and [you can] even achieve immortality.\u201d<\/p>\n Mary says with a smile: \u201cWell, I\u2019m 66 so everything\u2019s starting to fall apart, that\u2019s part of it. Almost all of my books have dealt with the human body in some way so it\u2019s not surprising as a Mary Roach topic \u2014 replacing bits and pieces of the body.<\/p>\n \u201cThere were a couple of things I became interested in after talking to a reader who wrote to me. She\u2019s an elective amputee \u2014 her foot was healthy and had a blood supply but it was twisted. After a dozen operations, it wasn\u2019t serving her the way she wanted, so she wanted it off. But she couldn\u2019t find a surgeon to do that.<\/p>\n \u201cThat got me interested in the idea of bodies as a whole system and a collection of bits and pieces.\u201d Her reader did eventually find a surgeon willing to amputate her foot, Mary adds.<\/p>\n<\/div>\n Mary also investigated advances in prosthetic limbs (Image: Getty)<\/span><\/span><\/div>\n 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.<\/p>\n Researchers across the globe are working on tweaking porcine genes so the animals\u2019 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.<\/p>\n Biotech firm ClonOrgan is cultivating the country’s largest population of genetically modified pigs, so this is where Mary headed.<\/p>\n 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: \u201cIt is dawning on me that I have come a long way to not see pigs.\u201d<\/p>\n Mary adds: “I should have known because it\u2019s called a \u2018designated pathogen-free facility\u2019 and I am just a big pile of pathogens! Obviously I wasn\u2019t 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.\u201d<\/p>\n 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).<\/p>\n 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: \u201cStem cells.\u201d 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.<\/p>\n<\/div>\n The genetically modified pigs live in a super-clean facility (Image: Mary Roach)<\/span><\/span><\/div>\n Mary explains: \u201cFor example, you could take someone\u2019s blood and regress the cells to a state of pluripotency, where you can instruct the cells to become what you want them to be.<\/p>\n \u201cThere\u2019s work going on with creating dopamine-producing neurons that you could use for Parkinson\u2019s<\/a> patients. And there\u2019s really cool work going on with islet cells and diabetes<\/a>.\u201d<\/p>\n Some advances are clear successes \u2014 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.<\/p>\n 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.<\/p>\n \u201cThere have been a lot of great advances in prosthetics for legs with microprocessors that learn one\u2019s gait etc,\u201d she says. \u201cYou see a lot of press about the bionic-looking hands with fingers that move because they\u2019re hooked up to impulses from the brain to the muscle.<\/p>\n \u201cBut I went to the annual conference of the amputee coalition here in the States and I didn\u2019t see anybody with one of those.\u201d<\/p>\n Meanwhile, the chapter that has stayed with Mary the most is set at Massachusetts General Hospital\u2019s Sumner M. Redstone Burn Center. There, she discovered the basics of healing with autografts (grafts using the patient\u2019s own skin), allografts (using skin from another human), and xenografts (using skin from another species such as Icelandic cod).<\/p>\n Pigs get another mention here \u2013 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.<\/p>\n “Surgeons can have a reputation for being a little less personally involved, but when it\u2019s a burn \u2013 a major, third degree burn on the majority of the body \u2013 that\u2019s a relationship that lasts for months or even years of surgeries. That was an amazing couple of days.\u201d<\/p>\n<\/div>\n So, does Mary plan to have part of herself regenerated soon? She laughs: \u201cWithin the next 10 years, I’ll certainly be getting some new lenses for my eyes. Right now, they haven\u2019t quite nailed the ability to move your focus from close to far automatically, the way the human eye does.<\/p>\n \u201cBut it\u2019s come a tremendous distance from the 1960s and 1970s when it was an operation that required a multi-day hospital stay.”<\/p>\n 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.<\/p>\n \u201cMy takeaway was just how hard it is to come up with a replacement that is as good as what someone was born with,\u201d Mary adds. \u201cYou can replace a mangled foot with a prosthetic and it\u2019s better than what they had, but in terms of creating something equal to or better, that\u2019s almost impossible.<\/p>\n “But then, of course it\u2019s impossible. You\u2019re talking about 200 years of medicine and engineering competing with millions of years of evolution, so it\u2019s 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.<\/p>\n “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\u2019s unbelievable.\u201d<\/p>\n<\/div>\n Have you ever wondered whether a human finger could be used to reconstruct a penis? Mary Roach leaves no stone unturned in her quest to explore the limits of regenerative medicine.<\/p>\n The seasoned science writer has mastered the art of explaining complex topics in a way that is digestible for the reader, with a healthy dose of characteristic humour.<\/p>\n There are deeply moving chapters about healing burns and battling the stigma of stomas. There are chapters on hair transplants and cataract replacements \u2014 regenerative procedures many of us will one day consider.<\/p>\n And there is a bizarre but thought-provoking chapter about the doctor who uses a section of the intestine to reconstruct a human vagina.<\/p>\n As Mary immerses herself in science, her descriptive writing means the reader is carried with her on every adventure \u2014 seeing, hearing and feeling as she does.<\/p>\n Her anecdotes are peppered with witty asides, imaginative metaphors and tongue-in-cheek footnotes that bring the most mundane medical processes to life.<\/p>\n In short, this is a book that makes you feel clever while also making you laugh.<\/p>\n![\"Mary](\"https:\/\/cdn.images.express.co.uk\/img\/dynamic\/151\/1200x712\/secondary\/Untitled-2025-09-29T151254-851-6457241.jpg?r=1759236734493\" "\\"Mary")
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<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/p>\nScience with a sense of humour \u2014 HANNA GEISSLER reviews the book<\/h3>\n<\/header>\n