Wednesday, October 20, 2021

In a First, Surgeons Attached a Pig Kidney to a Human — and It Worked

In a First, Surgeons Attached a Pig Kidney to a Human — and It Worked


A kidney grown in a genetically altered pig seemed to function normally, potentially a new source for desperately needed transplant organs.







By Roni Caryn Rabin NY Times

Surgeons in New York have successfully attached a kidney grown in a genetically altered pig to a human patient and found that the organ worked normally, a scientific breakthrough that one day may yield a vast new supply of organs for severely ill patients.

Although many questions remain to be answered about the long-term consequences of the transplant, which involved a brain-dead patient followed only for 54 hours, experts in the field said the procedure represented a milestone.

“We need to know more about the longevity of the organ,” said Dr. Dorry Segev, professor of transplant surgery at Johns Hopkins School of Medicine who was not involved in the research. Nevertheless, he said: “This is a huge breakthrough. It’s a big, big deal.”

Researchers have long sought to grow organs in pigs suitable for transplantation into humans. A steady stream of organs — which could eventually include hearts, lungs and livers — would offer a lifeline to the more than 100,000 Americans currently on transplant waiting lists, including the 90,240 who need a kidney. Twelve people on the waiting lists die each day.

An even larger number of Americans with kidney failure — more than a half million — depend on grueling dialysis treatments to survive. In large part because of the scarcity of human organs, the vast majority of dialysis patients do not qualify for transplants, which are reserved for those most likely to thrive after the procedure.

The surgery, carried out at N.Y.U. Langone Health, was first reported by USA Today on Tuesday. The research has not yet been peer-reviewed nor published in a medical journal.

The transplanted kidney was obtained from a pig genetically engineered to grow an organ unlikely to be rejected by the human body. In a close approximation of an actual transplant procedure, the kidney was attached to a person who had suffered brain death and was maintained on a ventilator.

The kidney, attached to blood vessels in the upper leg outside the abdomen, started functioning normally, making urine and the waste product creatinine “almost immediately,” according to Dr. Robert Montgomery, the director of the N.Y.U. Langone Transplant Institute, who performed the procedure in September.

Although the organ was not implanted in the body, problems with so-called xenotransplants — from animals like primates and pigs — usually occur at the interface of the human blood supply and the organ, where human blood flows through pig vessels, experts said.

The fact that the organ functioned outside the body is a strong indication that it will work in the body, Dr. Montgomery said.

“It was better than I think we even expected,” he said. “It just looked like any transplant I’ve ever done from a living donor. A lot of kidneys from deceased people don’t work right away, and take days or weeks to start. This worked immediately.”

Last year, 39,717 residents of the United States received an organ transplant, the majority of them — 23,401 — receiving kidneys, according to the United Network for Organ Sharing, a nonprofit that coordinates the nation’s organ procurement efforts.

Genetically engineered pigs “could potentially be a sustainable, renewable source of organs — the solar and wind of organ availability,” Dr. Montgomery said.

Reactions to the news among transplantation experts ranged from cautiously optimistic to wildly effusive, though all acknowledged the procedure represented a sea change. The prospect of raising pigs in order to harvest their organs for humans is bound to raise questions about animal welfare and exploitation, though an estimated 100 million pigs already are killed in the United States each year for food.

While some surgeons speculated that it could be just months before genetically engineered pigs’ kidneys are transplanted into living human beings, others said there was still much work to be done.

“This is really cutting-edge translational surgery and transplantation that is on the brink of being able to do it in living human beings,” said Dr. Amy Friedman, a former transplant surgeon and chief medical officer of LiveOnNY, the organ procurement organization in the greater New York area.

The group was involved in the selection and identification of the brain-dead patient receiving the experimental procedure. The patient was a registered organ donor, and because the organs were not suitable for transplantation, the patient’s family agreed to permit research to test the experimental transplant procedure.

Dr. Friedman said she envisioned using hearts, livers and other organs grown in pigs, as well. “It’s truly mind-boggling to think of how many transplants we might be able to offer,” she said, adding, “You’d have to breed the pigs, of course.”

Other experts were more reserved, saying they wanted to see whether the results were reproducible and to review data collected by N.Y.U. Langone.

“There’s no question this is a tour de force, in that it’s hard to do and you have to jump through a lot of hoops,” said Dr. Jay A. Fishman, associate director of the transplantation center at Massachusetts General Hospital.

“Whether this particular study advances the field will depend on what data they collected and whether they share it, or whether it is a step just to show they can do it,” Dr. Fishman said. He urged humility “about what we know.”

Many hurdles remain before genetically engineered pigs’ organs can be used in living human beings, said Dr. David Klassen, chief medical officer of the United Network for Organ Sharing.

While he called the surgery “a watershed moment,” he warned that long-term rejection of organs occurs even when the donor kidney is well-matched, and “even when you’re not trying to cross species barriers.”

The kidney has functions in addition to clearing blood of toxins. And there are concerns about pig viruses infecting recipients, Dr. Klassen said: “It’s a complicated field, and to imagine that we know all of the things that are going to happen and all the problems that will arise is naïve.”

Xenotransplantation, the process of grafting or transplanting organs or tissues between different species, has a long history. Efforts to use the blood and skin of animals in humans go back hundreds of years.

In the 1960s, chimpanzee kidneys were transplanted into a small number of human patients. Most died shortly afterward; the longest a patient lived was nine months. In 1983, a baboon heart was transplanted into an infant girl known as Baby Faye. She died 20 days later.

Pigs offered advantages over primates for organ procurement — they are easier to raise, reach maturation faster, and achieve adult human size in six months. Pig heart valves are routinely transplanted into humans, and some patients with diabetes have received pig pancreas cells. Pig skin has also been used as temporary grafts for burn patients.

The combination of two new technologies — gene editing and cloning — has yielded genetically altered pig organs. Pig hearts and kidneys have been transplanted successfully into monkeys and baboons, but safety concerns precluded their use in humans.

“The field up to now has been stuck in the preclinical primate stage, because going from primate to living human is perceived as a big jump,” Dr. Montgomery said.

The kidney used in the new procedure was obtained by knocking out a pig gene that encodes a sugar molecule that elicits an aggressive human rejection response. The pig was genetically engineered by Revivicor and approved by the Food and Drug Administration for use as a source for human therapeutics.

Dr. Montgomery and his team also transplanted the pig’s thymus, a gland that is involved in the immune system, in an effort to ward off immune reactions to the kidney.

After attaching the kidney to blood vessels in the upper leg, the surgeons covered it with a protective shield so they could observe it and take tissue samples over the 54-hour study period. Urine and creatinine levels were normal, Dr. Montgomery and his colleagues found, and no signs of rejection were detected during more than two days of observation.

“There didn’t seem to be any kind of incompatibility between the pig kidney and the human that would make it not work,” Dr. Montgomery said. “There wasn’t immediate rejection of the kidney.”

The long-term prospects are still unknown, he acknowledged. But “this allowed us to answer a really important question: Is there something that’s going to happen when we move this from a primate to a human that is going to be disastrous?”

Thursday, October 14, 2021

What Do Dogs (and Other Animals) Do All Day and All Night?

 

More Fun Than Fun: What Do Dogs (and Other Animals) Do All Day and All Night?

RAGHAVENDRA GADAGKAR The Wire

Free-ranging dogs in Gayeshpur, a township close to the IISER Kolkata campus. Photo: Sourabh Biswas, a PhD student researching stray-dog behaviour and ecology. 

The amount of time an animal spends performing different tasks is called its time-activity budget.

Raghavendra Gadagkar recalls the time he spent figuring out the time-activity budget of wasps in Bangalore’s Cubbon Park, and the research insights that simple exercise led to.

More recently, two scientists who determined the time-activity budgets of free-ranging dogs in West Bengal made a surprising discovery as well. 

My inspiration for this essay comes from reading a paper entitled ‘Time-activity budget of urban-adapted free-ranging dogs’, by Arunita Banerjee and Anindita Bhadra, published in the journal acta ethologica on September 8. This study provides a rigorous quantitative answer to the question raised in the title of my essay, at least for stray dogs in India.

People often ask me why I like some papers more than others. One of my answers is that a paper should make me jealous that I did not write it. This feeling can only come if I could easily have conducted that study and written the paper, at least in principle. Arunita and Anindita’s paper has the potential of making every citizen of India jealous because any one of us could have done their study and could have done it anytime in the last 100 years, if not earlier.

But there is also another reason why this paper moved me so much. It brought back fond memories of my own research in the late 1970s and early 1980s, when I was studying the Indian paper wasp Ropalidia marginata as a hobby. At that time, I was a doctoral student at the Microbiology and Cell Biology Laboratory at the Indian Institute of Science (IISc), Bangalore, studying the interaction between bacteria and their viruses. But my heart was split between the molecular biological research that I loved very much and the exciting goings-on at the Centre for Theoretical Studies (CTS) at IISc. In CTS, I often hung around the famous ecologist Madhav Gadgil and his students. Madhav Gadgil had established a field research station in the nearby Bandipur Tiger Reserve and National Park.

Chital and other animals in Bandipur

Gadgil’s aim was to initiate long-term ecological studies at Bandipur. His student H.C. Sharatchandra camped full-time in the park, and Gadgil regularly visited from Bangalore. At the end of the first year of their study, they published an inspiring account entitled ‘A year of Bandipur’ in the Journal of Bombay Natural History Society in December 1975. They summarised their preliminary findings thus:

“Bandipur is a dry deciduous forest dominated by Anogeissus latifolia and Tectona grandis. The study area of 23 sq km supported a population of 800 chital (Axis axis), 90 elephants (Elephas maximus), 20 sambar (Cervus unicolor), 40 wild dogs (Cuon alpinus), over 10 panthers (Panthera pardus) and 10 or fewer tigers (Panthera tigris) and a small number of gaur (Bos gaurus), barking deer (Muntiacus muntjack), wild pig (Sus scrofa), and sloth bear (Melursus ursinus).”

As a city-dweller, I found this kind of science mesmerising. But one of Sharatchandra’s projects captivated me even more. He was especially watching chital, to understand how they spent their time. What could be a more common-sense approach to science, I thought to myself.

A few years later, Sharatchandra and Gadgil reported that they had observed randomly chosen chital and recorded their behaviours until they went out of sight. From 6,500 such observations during daylight hours, they determined how much time chital spent performing different tasks.

Such apportionment of time is called a time-activity budget or, simply, a time-budget. To make a time-budget, they first categorised chital activity into eight categories: locomotion, anti-predator behaviour, grooming, trophic behaviour, fighting, play, displays and sexual behaviour.

They found that chital, in general, spent 80-90% of their time in trophic behaviours, 4-8% in antipredator behaviours, less than 6% fighting, less than 5% in display, just about 1% or less in locomotion, a similar amount in grooming, about 2% in play and about 0.5% in sexual behaviour.

Next, they separately calculated time-budgets for juveniles, adult females, adult males in velvet and adult males with hard antlers – and found interesting differences between the different life stages. For example, males with hard antlers spent relatively less time on trophic behaviours and relatively more time in display, fighting and locomotion. Adult females spent relatively more time in anti-predatory behaviours, and the juveniles spent more time in play.

Clearly, chital in different life-stages apportioned their time to different behaviours in an adaptive manner. I looked for but found few such data for other animal species. The lack of data was surprising because it seemed so easy and so much fun to do this kind of research. I could not help feeling that knowing the time-budgets of different animals under different conditions could tell us so much about how and why animals do what they do.

I resolved that I would calculate the time-activity budgets for my wasps at the earliest opportunity.

An opportunity presented itself when I found some naturally occurring nests of R. marginata right in the middle of Cubbon Park, in Bangalore. The park was a frequent haunt of mine both because it was close to Central College and because it then had an excellent public library. I spent many hours sitting in front of the wasp nests with a notebook and pencil (often surrounded by a bunch of curious children) and observed the insects.

As a first step, I made a list of all that the wasps did, in plain English, as a layman would. My list read as follows: sit with folded legs and lowered antennae; sit with raised antennae; sit with raised antennae and wings; groom oneself; walk; inspect the cells; feed the larvae; attack, peck or chase another wasp; absent from the nest; return with food; building material; water or nothing; and so on. My list grew to a little more than 100 items.

Such a list is called an ethogram and is the first step towards conducting an observational study of the behaviour of any animal species.

But I still lacked two crucial ingredients for my research. For one, I did not know how to mark the wasps for individual identification.

The Mahabaleshwar seminar

It was my great fortune that the world’s most famous wasp researcher, Mary Jane West-Eberhard, came to India to participate in a seminar on ‘Evolution of Social Behaviour’ that Madhav Gadgil had organised, in October 1979. Being one of the annual seminars on modern biology sponsored by the Tata Institute of Fundamental Research, Ahmednagar College and the University Grants Commission, it was held at the picturesque hill station of Mahabaleshwar, near Pune in Maharashtra.

A galaxy of the world’s greatest experts on social behaviour, including John Maynard Smith, William G. Eberhard, John Hurrell Crook, Robert L. Trivers and John. F. Eisenberg participated in the seminar, apart from Mary Jane herself. We had the unique opportunity of taking long walks with these experts in the afternoons, which were deliberately free of formal lectures. Every one of these experts made an indelible impression on me, and I stayed in touch with them for a long time after that.

But Mary Jane West-Eberhard was very special. For one thing, she was a wasp expert (some of us call her the ‘wasp queen’!). She is also one of the kindest and most altruistic scientists I have had the privilege of knowing. She came to Bangalore and stayed on for a few weeks and, among many other things, she taught me how to mark the wasps.

She also left behind her box of Testors enamel paints that she always carried with her when she travelled. She also left behind several thousand rupees that she had saved from her per-diem, as a start-up grant for my research on wasp behaviour. I set that aside, calling it the ‘Mary Jane Fund’, and it was more than sufficient to finance my low-cost research for some years. It even afforded me the luxury of travelling daily in an auto-rickshaw to Cubbon Park and back.

Making unbiased observations

The second missing ingredient was a knowledge of how to observe the wasps without introducing human bias. Subconscious human bias is not something that can be avoided merely with good intentions and willpower. I needed a better way, and I found it in the now-famous paper ‘Observational Study of Behavior: Sampling Methods’ (1974) by Jeanne Altmann. Like thousands of other researchers (the paper has been cited over 17,384 times), I carefully studied Altmann’s paper and standardised a package of unbiased sampling methods to observe the wasps.

My observation package included three methods of observation designed to reduce bias towards the more conspicuous animals and behaviours. One involves making a rapid scan of all the wasps on the nest and noting whatever they are doing at that instant, much like taking a still photograph. This is called an “instantaneous scan” or scan sampling. I made my random choices by drawing lots: I began with small pieces of cardboard with the wasps’ names written on them in my left pocket, and moved them one by one to my right pocket, and started all over again.

The second method involved randomly choosing one wasp at a time for observation and observing only that wasp, no matter what it did. This method is called focal animal sampling.

In the third method, I chose a small set of very rare behaviours (which were not adequately sampled by the other two methods) and recorded every occurrence of each of those behaviours by any wasp in a predetermined period of time. We simply call this method ‘all occurrences’.

Applying a combination of these sampling methods to observe uniquely marked wasps on two colonies in Cubbon Park, I fulfilled my dream of computing the time-activity budget of R. marginata. The result was most surprising. Most wasps spent about 95% of their waking hours in just six of the 100-odd behaviours I observed. And at first sight, these six – sit and groom, sit with raised antennae, sit with raised wings, walk, inspect cells and be absent from the nest – seemed to be rather inconsequential to the lives of the wasps. They were not quite in the same class as feeding, fighting and mating

But I said to myself: if I am not to be biased towards conspicuous behaviours during observation, why should I be biased towards seemingly important behaviours during interpretation? So I decided to see what sense I could make of the life of the wasps by studying the six behaviours in which the wasps found it worthwhile to spend 95% of their time.

Indeed, there was a most interesting pattern. While nearly every wasp devoted about 95% of its time to these six behaviours, they varied enormously in the manner in which they distributed their time between the behaviours. Some wasps spent 50% or more of their time sitting and grooming themselves and 10% or less time away from the nest. Some others did the opposite, spending 70% or more of their time away from the nest and 10% or less sitting and grooming themselves. Yet others spent more time sitting with raised antennae than they did sitting with folded antennae and wings or being away from the nest.

Why do the wasps’ time-budget activities vary so much? Was there a method in their madness – a hidden pattern in their behaviour that might tell us something profound about the organisation of their society?

Behavioural castes

Science is a collective activity, and I spent countless hours discussing these matters with my friend and colleague Niranjan V. Joshi. It always helps to discuss your science with someone who is not working in the same field.

When I joined IISc for my PhD, it was my great fortune that I was allotted a room in the hostel that had also been allotted to Joshi. We made great roommates. I told him all about my observations and experiments, my results and interests, especially during long walks back from the city after watching late-night movies.

It turned out that quite fortuitously, Joshi was grappling with a similar problem in a totally different context. While pursuing his PhD on the molecular structure of polysaccharides, he was also helping another colleague, Sulochana Gadgil, make sense of the pattern of rainfall distribution over different parts of India. To do so, he was using a statistical technique called principal components analysis. It became obvious to us that we could use the same technique to make sense of the variation in the time-activity budgets of the wasps.

Well, it worked like a charm.

This technique takes information on the time spent by different wasps in the six behaviours as input and returns two new variables as output – such that most of the information (or variation) is contained in the two new variables. For all practical purposes, we could now focus just on the two variables, called the principal components. When we plotted the positions of the wasps on a graph, with principal component 1 on the X-axis and principal component 2 on the Y-axis, we had a eureka moment. The wasps arranged themselves in three distinct clusters.

Our data revealed that wasps in the first cluster spent most of their time sitting and grooming, so we called them ‘Sitters’. Wasps in the second cluster were very active in fighting with each other, so we called them ‘Fighters’. And wasps in the third cluster spent a lot of time away from the nest, so we called them ‘Foragers’.

When workers in a colony specialise in different tasks, they are called castes. In advanced societies, such as those of ants, the different castes are also morphologically different. In our case, the Sitters, Fighters and Foragers were morphologically indistinguishable, so we called them behavioural castes. (Morphology refers to the forms and features of an individual body.)

The construction of time-activity budgets and the consequent discovery of behavioural castes in the Indian paper wasp was an early success that laid the foundation for nearly everything my students and I have discovered about this fascinating species in the nearly 40 years of subsequent research. During data analysis, I had deliberately not treated the queens of the wasp colonies any differently than I had treated the workers. So after the analysis, we could ask: where was the queen in this pattern? Was she a Sitter, a Fighter or a Forager?

Because queens in similar species were known to be aggressive individuals that suppressed their workers through physical intimidation, we naturally expected the queens of R. marginata to be Fighters. But we were most surprised to see that our queens belong to the Sitters. A counter-intuitive result like this is a powerful catalyst for rapid progress, as it served in our case.

Over the years, my students and I discovered that queens could afford to be meek and docile Sitters because they rub their non-volatile pheromones onto the nest’s surface to signal their presence to their workers. The workers regulate their own foraging and other activities through a process of decentralised self-organisation. Pre-designated potential queens periodically replace queens in a remarkably conflict-free process.

Our early knowledge of the time-activity budgets of the wasps continues to steer our research in newer and unexpected directions four decades on.

What do dogs do with their time?

Let us now return to Arunita Banerjee and Anindita Bhadra’s study of the time-budgets of dogs. Their study surpasses those of the chital and paper wasps I have just described on several counts.

First, let us spare a thought for young Arunita, who collected the data. The ethogram came from the combined observations of all the members of Anindita’s ‘Dog Lab’ for 12 years. Anindita tells me that their latest count for the total number of unique dog behaviours is 177 – and counting. But the time-activity budgets were made by Arunita by the method of instantaneous scanning. Her data constitutes 5,669 sightings over one year.

To make these sightings, Arunita walked day and night, in predetermined routes and at randomly chosen spots, in several suburban regions of West Bengal, including the campus of IISER Kolkata, Gayeshpur, Haringhata, Kanchrapara, Kalyani, Halisahar, Naihati, Barrackpore, Balindi, Jaguli and Mohanpur. Whenever she saw a dog, she noted, initially in her pocket notebook and later on her phone, the age, sex and behaviour of the dog as well as the date, time and location of the sighting.

Arunita told me in an email:

“On weekends, I would purchase a to and fro ticket from Kalyani station with the destination being Barrackpore, which was nine stations away. Train stations in the pre-pandemic times were centres of bustling human activity, with multiple eateries, rickshaw stands and major bus stands nearby. This ensured that there was no dearth of dogs in the area; in fact, many lived in the stations because it served as a good source for both food and shelter. So now I would board the train at Kalyani, and depending on the halts in the particular train’s route, I would deboard randomly at one of these ten stations.

Once I was done scanning the station premises and the adjoining areas for dogs, I would take the next train, in whichever direction it might be and deboard again at a different station.”

With these sightings and applying clever statistical techniques that I will not go into, Arunita and Anindita calculated the time-budgets of the Indian stray or free-ranging dog, or at least of those that live in West Bengal.

The dog’s time-activity budget averaged over males and females, at different times of the day and different age classes.

Notice that the most common behaviour is that of being inactive while those of showing various active postures and gaits, foraging and feeding, vocalisation and play occupy decreasing amounts of the dogs’ time.

What I have presented here is only an average time budget that hides much interesting variation across the time of day and seasons of the year – not to mention the age, sex and the physical and social environment of the dogs. As it did for the wasps, the dog time-budget will raise many questions and is sure to guide Anindita Bhadra and her students on a path of discovery, to yield many surprising facts about these all too familiar animals.

One big surprise is already evident in their research paper. It is our common perception that dogs are primarily nocturnal. But their research has shown that stray dogs are just as active during the day as they are at night. The canines appear to be highly adaptive and manage to survive under most conditions created by humans. How did they become so adaptive? Is it a by-product of domestication, or could it be that the ability to adapt was a prerequisite for domestication?

Clearly, a scientific understanding of dogs will tell us much – not only about dogs and how we should adapt to them but also about evolution in general and domestication in particular. Being found everywhere and easy to observe and experiment with, dogs are well-suited for both basic research in ethology and behavioural ecology and to produce knowledge relevant to society, especially in the context of human-animal conflict. And yet, so few scientists in India study dogs. Part of the reason seems to be that we have a very narrow definition of what is respectable science and even of science itself.

But luckily, that is changing. It is a matter of great satisfaction that Anindita Bhadra has chosen to devote her career to the study of stray dogs in India. My optimism grows at the sight of the large number of bright and passionate young researchers being trained in her Dog Lab in IISER Kolkata. May their tribe flourish!

Raghavendra Gadagkar is a Department of Science and Technology (DST) Year of Science Chair Professor at the Centre for Ecological Sciences at the Indian Institute of Science, Bengaluru.

 

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