Lab mice, rejoice! At the University of Haifa’s Institute of Evolution, a new lab animal has been discovered that could free all you mice from the tragic fate that scientists have been imposing on you for decades. No longer will you have to subject your bodies, or parts of them, to terrible diseases, and lay down your lives for the sake of scientific progress in the quest to treat and cure human illnesses.
Over the past decades, hundreds of thousands, possibly millions, of white mice have been robbed of their health and their lives in the prison of research labs big and small − all in the attempt to advance research into diseases that kill humans. Moreover, 95 percent of the studies done on mice have never reached the clinical trial stage, and in the remaining 5 percent, the findings in mice have been found to be inapplicable to human patients suffering from cancer.
Five years ago, renowned cancer researcher Robert Weinberg of MIT’s Whitehead Institute declared that the lab mouse is not the right animal to use in studying human diseases, particularly cancer. In a 2008 Newsweek interview, Weinberg said: “Drug companies have been wasting millions of dollars a year for decades on cancer research using mice, which is of very low predictive value and has little relation to cancer research in humans. Far more than anything else, the lack of good animal models has become the rate-limiting step in cancer research.”
White mice, which are very easy to obtain, also have a short life span even when researchers aren’t trying to make them sick by injecting them with carcinogens: 60 percent die from cancer regardless. White mice are the most convenient research animals to use and have played a part in many scientific achievements, but when it comes to cancer research, healing techniques that proved effective in mice have not been transferable to humans.
Prof. Aaron Avivi, together with his colleagues, senior researchers Dr. Imad Shams and Dr. Irena Manov of the Institute of Evolution, recently published an article in the scientific journal BMC Biology. In it they describe their discovery of the ultimate lab animal for researching cancer as well as other human diseases. The animal is the blind mole-rat, which weighs 100-200 grams and is quite ugly. As per its name, it is blind, and also lacks earlobes (although it does have ears, sunken into its head so that the dust in which it burrows will not get in). The rat is covered with light gray fur and much of its head is comprised of four very sharp teeth: two in the upper jaw and two smaller ones in the lower jaw.
This aggressive little rodent has nothing in common with the friendly rat that sometimes appears in British children’s fairy tales. No one would want to invite it to a tea party, or even hold it in his hand. But if Ayn Rand had ever heard of it, she surely would have touted it for the way its form is perfectly suited to its function in nature. Its impressive muscle mass for its small size; its long life span (up to 20 years); its adaptability to conditions in which there is a severe lack of oxygen; and a host of other survival capabilities − all explain why this creature has become one of the biggest pests in agriculture. It rapidly and efficiently digs long tunnels at a depth of as much as 80 centimeters, and stores the onions and tubers it collects in cleverly designed underground chambers. But now that Prof. Avivi has found it to be the ultimate lab animal for cancer research, the blind mole-rat may have to kiss the good life goodbye.
Avivi, 63, looks younger than his age. He is energetic, impatient, loud and, at scientific conferences, sometimes perceived as a little too colorful. Avivi’s unique personality may help explain the somewhat convoluted path his scientific career has taken. Highly regarded by his peers, he has had difficulty securing research grants because he is incapable of groveling, or even just being very polite. These qualities may also make it hard for him to obtain grants to keep pursuing the revolutionary research he just published. Not to mention that many of his colleagues, having fallen in love with their long-time research subjects, may still try to retroactively justify decades of research with the wrong animals.
The cow whisperer
Aaron Avivi lives in the central Galilee village of Avtalyon, with his wife of 25 years, the well-known writer Gabriela Avigur-Rotem. It was their shared love of literature, particularly for the stories of Argentine writer and physicist Ernesto Sabato, that brought them together. Sabato once said that the scientist discovers what already exists, while the artist creates a new reality. But even if Avivi has discovered something that has existed for tens of millions of years and is known as an agricultural pest − that discovery may create a new reality of scientific research.
Avivi was born and raised in Haifa, where he attended the Hebrew Reali School, and from as far back as he can remember, always wanted to be a biologist. When he was three, he would spend hours observing ants to see how they built their nests. When he was five, the neighbors’ pet took part in his first research experiment: He discovered that he could get a dog that had just had puppies to nurse another newborn puppy that someone had tossed into the trash near his home in Kiryat Eliezer. In high school, Avivi would often hide the teacher’s notebook so his absence couldn’t be recorded, and then set off to explore the lovely nature area around Beit Biram near “Little Switzerland” in the Carmel range, and sometimes − purely for research purposes, of course − he would go as far as the beach or to hear trials in a courtroom.
A clarification related to the term “biologist” or “cancer researcher”: Many people, this writer included, long conjured images of such scientists as intrepid explorers embarking on exciting missions − trailing animals in the bush, say, or deliberately giving themselves an illness in order to see how to cure it, and in their leisure time, also becoming “microbe hunters.” But there is no glamour in the daily grind of the microbiologist whose world, as the title implies, is so very tiny. To become a microbiologist, it doesn’t hurt to possess a hefty degree of obsessive-compulsive personality disorder, which may not be such a boon for one’s coworkers, but certainly helps the research continue. Most such work requires hours upon hours in a fluorescent-lit lab, and mainly involves the counting of microscopic cells in Petri dishes, creating precise microscopic sections, and obsessively maintaining hygiene.
Avivi readily describes himself as having “advanced OCD,” and it’s not hard to see this. He cannot abide being interrupted with questions in the midst of the three-and-a-half-hour lecture he gives me − quite a fascinating and well-structured lecture, I must admit. In his rare moments of silence, he arranges the cups, bottles and ashtray on the table in a perfect row. And he has even less patience for people who try to make jokes at the blind mole-rat’s expense, for not everything is a laughing matter.
During his military service in the Nahal Brigade (which combines military service with work in outlying settlements) he worked in a cattle shed. “I fell in love with cows,” he candidly confesses. It takes some guts to admit that you love cows; although, then again, he was never a Tel Aviv type or a fashion plate. Avivi decided he wanted to study genetics and applied to Tel Aviv University and Hebrew University, as well as to medical school at Hadassah. He didn’t get into med school; he got into Tel Aviv but decided not to go because he wanted the experience of student and campus life the way it was in Jerusalem back in the 1970s.
Avivi’s application somehow got lost between the medical school and the Faculty of Life Sciences in Jerusalem, and after being repeatedly rebuffed by the faculty secretary, one day he showed up in her office with a backpack and a sleeping bag, and informed her that he was going to camp out there until she let him meet with the dean of the faculty.
The dean, who was passing by and overheard Avivi’s loud argument with the secretary, immediately offered him admission to the department. Aviv earned a bachelor’s degree in biology and a master’s in genetics, doing research on his beloved cows. Around that time he was offered the chance to go to Denmark to learn how to make an “ID for cows” (i.e., a system that could be used to record the genetic information of cows), so he could start a lab in Israel for analyzing genetic information relating to cows from blood tests, which until then were being sent to Copenhagen.
“Since I loved cows so much, they sent me. As far as I know, this lab still hasn’t been started. I was in Copenhagen, and I enjoyed it there, thought I didn’t manage to learn a word of Danish. But I still feel at home when I’m in Denmark. I came back to Israel. I went to work in the Veterinary Institute associated with the Israeli Agriculture Research Center as a cow researcher.”
By that point Avivi was married for the first time and also the father of two. He began working on his doctorate at the Veterinary Institute, with an affiliation to the Weizmann Institute of Science as well. After a year, he saw he wouldn’t be able to get anywhere with his attempt to start a cattle research lab at the Veterinary Institute, and meanwhile, the Weizmann Institute was insisting that he do Ph.D studies there. At the time, Avivi was studying thyroid development in cattle fetuses. Prof. Yossi Schlesinger, a scientist at Weizmann, was researching the communication between hormones and their receptors. Schlesinger offered to be his doctoral adviser.
Avivi completed his doctoral studies and was offered post-doctoral positions at several prestigious universities in the United States, including Harvard − but just then was at the start of a protracted divorce process, after which he received joint custody of his children. He decided to remain in Israel so he could be fully involved in their upbringing.
Avivi did his post-doctorate at Weizmann, though this time he abandoned his beloved cows and started studying growth factors in humans. He stayed on at the institute as a researcher until 1996. “I had two job offers, one at Hadassah Ein Kerem and one at the Institute of Evolution in Haifa. I saw that I couldn’t afford to buy an apartment near Jerusalem,” he recalls, adding that he was by then the partner of Avigur-Rotem. Apparently her impression of him on their first date was that he was “a very handsome guy but just a kid,” because he looked surprisingly young for his age (and they are exactly the same age).
“I also knew that there was no way Gabi would agree to move to Jerusalem,” he says. “So Gabi and I decided to look for somewhere we could buy near Haifa. We started exploring the Misgav area near Carmiel, and we kept getting further and further away from Haifa. We were looking for a nonspiritual place. Someone at work suggested we check out Avtalyon. I said, ‘But that’s the end of the world.’ But we went there anyway, and within a day we bought a house there where you can see the whole amazing ‘quilt’ of the Netofa Valley from the windows and the yard.”
The head of the evolution institute in Haifa was Prof. Abie Nevo, who founded it in the early 1970s. Nevo was a member of Kibbutz Sa’ar where the soil was very dense and full of moisture so that the female blind mole-rat made its breeding nests for giving birth above ground.
“A female that weighs just 100-200 grams builds a nest that’s a meter in diameter and 80 centimeters high,” says Avivi. “Nevo came across one of these structures and peeked inside to see what was happening there and he found mole-rat pups.”
Nevo, who had written a book and several articles about the blind mole-rat, suggested that Avivi study it, too.
“My first reaction was aversion,” says Avivi. “Why should anyone tell me what to study? But I managed to stay polite this time. I bit my lip and he gave me the book he’d written about the blind mole-rat.”
In the scientific literature the animal is called the Subterranean Blind Mole-Rat (Spalax), although, he notes, “in this part of the world it is called the Israeli blind mole-rat, or the Palestinian blind-mole rat.” This little animal is inhabiting the Middle East from Egypt through Israel, Syria, Lebanon and Turkey, and has reached the Balkans. Certain aspects of its nature vary from one breeding area to another.
Cows are an unusual fetish, though familiar at least. But what’s so attractive about the blind mole-rat?
“The mole-rat is a soloist, an individualist, it’s not a social animal, it’s very aggressive. But in Egypt, because of the desert climate, where it’s hot and hard to find food, you find mole-rats that live in a family unit so as to cooperate in the quest for food. In the Balkans, the mole-rat is larger − some as large as small cats even. In Israel, they are very aggressive and individualistic. This animal is an agricultural pest. It eats onions, tubers, roots. You can be walking in a potato field and suddenly see a straight line 100 meters long of wilted plants, alongside fresh soil mounds, that the mole-rat cut and from which it collected the young, small potatoes. A tiny animal of just 100-200 grams creates mounds that weigh two to three kilos; in other words, it can push 10 times its weight.
“Aside from the burrows it also has a home that’s built in a fantastic architecture, especially those of females that are about to give birth: There’s a children’s room and a bathroom and a pantry. And this pantry isn’t just piles of this and that, it’s all neatly organized. Near Haifa, in the near Acre, you see lots of daffodils [in these homes]. The children’s room is built of all kinds of twigs. The nursing female mole-rats make a ‘pergola’ roof and cover it with earth and put all kinds of grass in there. The mole-rat lives underground nearly all the time, but when the pups are weaned, the mother chases them out. Because unlike us she won’t recognize her offspring and could end up mating with them, and then the odds of birth defects are greater. Nevertheless, once chased out the young ones start to dig their own territory underground.
“Gestation lasts a month and there are from three to five pups per litter. What’s interesting is that when it’s mating season you can see for a 100 meters in every direction straight burrows leading directly to the den, to the female’s territory. It’s a sign for the males that come to look for her. And she bites and chases away the ones she doesn’t want. There’s a debate as to when the mole-rate became blind: 60 million years ago or 25 million years ago. But it’s certain that at one time its evolutionary ancestor was a seeing animal because the mole-rate has a remnant of eyes underneath the skin, the size of a poppy seed. But even though the animal lives 40-80 centimeters underground, she has a biological clock. She knows when it’s light and when it’s dark.”
How do we know that the mole-rate can distinguish between light and dark?
“You can easily test it by housing the animal in small cage, with tubes on its sides and sensors on the tubes, connected to a computer program that records all of the rat’s movements. After a few days, you see it sleeps at night and is active during the day. Some are the opposite, nocturnal. Active at night and asleep during the day. We could call them the Tel Avivians.”
Life with little oxygen
Although the book about the mole-rat was basically forced upon him, Avivi says as he began to read it, he thought: “Wow, what an interesting animal. There were two things that immediately grabbed me: the biological clock with the completely degenerated eye, and the fact that this animal lives underground and therefore survives with a shortage of oxygen. Moreover, it can withstand major changes in the oxygen supply. Why does this matter? The amount of rainfall in London is similar to that of northern Israel. However, in London it drizzles like Chinese [water] torture all the time. Here we have about 14 rainy days that can reach 80 millimeters of rain; hence, the mole-rat’s tunnels are flooded. We measured 6 percent oxygen in their tunnels after a rain session. But the mole-rat can survive in 3 percent oxygen. That’s one-seventh of the normal oxygen above ground at sea level and one-third of the oxygen level on the top of Mount Everest.”
The fact that the mole-rat, a mammal, needs so little oxygen to survive, is what really excited Avivi, who’d now found a new love. Two senior researchers at the Institute for Evolution, Dr. Shams and Dr. Manov, joined him.
“The mole-rat can withstand hypoxia, a lack of oxygen. Why was this a big deal? I knew that hypoxia was connected to the most lethal diseases in the Western world: brain strokes, heart attack, lung diseases and all kinds of cancer,” Avivi explains.
Without getting into explanations that require a master’s degree in biology to understand, Avivi offers a relatively simple account of the connection between oxygen, cancer and the blind mole-rat:
“The hypoxia-inducible factor HIF1, master gene, activates an entire family of genes that are all related to the response to oxygen supply. One of them, which is very famous and because of which the Tour de France has become so unsporting, is called erythropoietin, or in short EPO. The competitors in the Tour de France take EPO and it causes a progenitor cell that has the potential to develop into an erythrocyte (red blood cell) to differentiate and actually become one. As a result, the cyclists have more red blood cells [whose] entire function is to be an oxygen carrier. The red is because of the iron that binds oxygen molecules.
“But EPO is just one of these factors. There’s also VEGF. It’s responsible for the sprouting of new blood vessels. This is actually the first gene that made us realize that something interesting is happening here. Why? Because the VEGF of a mole-rat and a cancerous tumor behave similarly. What does the tumor do? Because its cells divide faster than blood vessels grow ... it experiences waves of hypoxia. To survive, the tumor bypasses the HIF1 control system so VEGF is working constitutively at maximum capacity and sending the message: ‘Grow blood vessels, grow blood vessels.’
“In a cancerous growth there are lots of blood vessels [and it looks] almost like a filet mignon. We examined this in the blind mole-rat, and we found that like in cancer also in the mole-rats, VEGF is also working at maximum capacity, by bypassing HIF and the hypoxic-stress control system. [By contrast,] in the rat that lives above ground, after 6 hours at 6 percent oxygen − which is the maximal stress the rat can survive − there is an increase in HIF expression followed by an increase in VEGF expression.
“At the minimal oxygen level the mole-rats survive, 3 percent, they start dying after more than eight hours, but we cannot compare the two [animals] under such [conditions] as the rats will die in just a one-and-a-half to two hours. So we work at 6 percent because then we know rats will also survive for enough time to follow the impact of the lack of oxygen. A similar pattern to the rats’ expression happens with all above-ground mammals. When one calculates the ratio between the amount of VEGF the blind mole-rat has relative to the rat − you find that the blind mole-rat has twice as much.
“Why do I point this out? Because when someone has a tumor and they do a biopsy, among other tests, also VEGF is measured. When there’s a ratio of 1.4 between a suspicious cell to a normal cell, the growth is suspected to be malignant. The blind mole-rat has twice as much VEGF and twice as many blood vessels compared to a rat. We generally test the trapezius neck muscle. Because when the blind mole-rat digs, it works with its head and it has twice as much muscle mass in its neck than the rat has. Its color is also like a filet mignon, while in the rat it’s light pink, as in humans. White, yellow, black or red − under the skin we’re all light pink.”
“One of the first ideas for treating cancerous tumors was to introduce an antagonist in to the body, like a key that can enter a keyhole but cannot open the lock. If we take an ‘antagonist’ key, it can compete with VEGF in the keyhole to start the system working and lead to the growth of blood vessels. Judah Folkman, from Boston, one of the world’s most renowned cancer researchers, was the first to think of this idea and work on this. It turned out that it’s a smart and elegant idea, but not a solution that will cure cancer.
“Every two years there’s a conference on hypoxia and angiogenesis (the mechanism of blood vessel growth) held in the Colorado mountains, at a ski resort, where ... there is high altitude and hence lower available oxygen. There are lectures until noon, and then from 4 to 8 P.M. What do you do in the afternoon break? You go skiing. Folkman was invited to give the keynote lecture ... [but] because he had heart trouble they moved the conference to Vancouver, which is at sea level. Folkman took a plane from Boston, which is also at sea level, to Chicago, which is also at sea level − all to avoid burdening his heart and putting him into a state of hypoxia. But at the airport in Chicago he died of a heart attack. What’s a heart attack? A lack of oxygen.”
And the blind mole-rat doesn’t reach a state of hypoxia?
“No, it doesn’t. One of the criteria of physiological hypoxia is the accumulation of lactic acid resulting from anaerobic metabolism ... When one measures the levels of lactic acid in mole-rat’s muscle after hypoxia stress, there is no change compared to its levels in a normal atmosphere. Under similar conditions it is significantly elevated in the rat. We keep the blind mole-rats in an animal house under normal oxygen conditions, and the hypoxia tolerance is maintained in all of them. Evidently it’s a genetically, inborn mechanism. You can take a blind mole-rat that has been in the animal house for five years, put it in 3 percent oxygen, and it won’t die. There’s no difference between the mole-rat in the burrow and the mole-rat in the lab in terms of its ability to withstand hypoxia.”
Wiping out cancer cells
What’s the conclusion to be drawn from all of this? How does this relate to the study of cancer in humans?
“Take all these findings and add to them the results found by the state-of-the-art methodology of genomics that can reveal the pattern of expression of the whole repertoire of genes in a given tissue. What we demonstrated is that there are differences in expression between mole-rat and rat, with or without exposure to hypoxia, in molecular and biochemical pathways related to cancer, and the conclusion is that the mole rat should be carefully examined as a model for human cancer.”
So blind mole-rats are completely cancer-resistant?
“There is no mammal that is completely, absolutely resistant to cancer, and none of its individuals will never develop malignant tumors. Whoever tells you that there is such a mammal is, politely put, highly exaggerating. However, it’s not possible to breed blind mole-rats in captivity, so every winter we go hunting for animals to renew our stock of animals. This is being done in our institute for the last 40 years. We’ve had thousands of the animals here. I asked Abie Nevo, the person who founded the Institute for Evolution, if a cancerous tumor had ever been observed in a blind mole-rat. He said no. In 40 years no spontaneous cancerous growth has ever been diagnosed.
“I was thinking: Let’s see if it’s possible to induce cancer in these animals. Mole-rats can live over 20 years compared to [other] rats’ life span, which is 4-5 years. They show know aging symptoms and no ailments. They do not lose any muscle mass. They are as strong and vivacious at 20 years old as at 2 years old. So, I took mice and rats − both young ones, about 2 years of age, and old ones, over 10 − and mole-rats and treated them carcinogenic substances. I took the old guys because the older all of us are, the more susceptible to diseases we are. One carcinogen induced soft-tissues sarcoma. After two months, as expected, all the mice had cancer. After four months, all the rats did too. But nothing was observed in the blind mole-rats! But we decided to follow them and see if something happened ... After a year and a half, lumps were found in two of them − but it wasn’t cancerous. It was an abscess, which is an unresolved inflammatory reaction. After 22 months we found one more treated old mole-rat with a lump. This time a cancerous one.
“Why is this good? We can now compare between the expected tumors from mice and rats, and the extremely delayed tumor from the mole-rat. It might reflect a difference in the development of cancerous cells in mole-rat compared to mouse and rat, from which we can learn about the mechanism of the extremely high cancer resistance of mole-rats. Another carcinogen we tried should induce skin cancer. Both mice and mole-rats developed a wound after about 10 days. The wound in the mole-rats seemed to be so serious ... I was sure that they were going to die. However, in a couple of weeks the blind mole-rat developed a scar, and then their skin completely healed. It took 3-4 months and all the mice developed the expected skin cancer. “
“We moved from the whole animal to cells. We propagated healthy cells from blind mole-rats, rats and mice, and added another wild rodent, the spiny mouse, so people couldn’t say we were only testing animals in lab conditions. We took the healthy cells of the blind mole-rat and grew them together, in a co-culture, with the cancerous cells of the blind mole-rat. Cells grow on a medium in a Petri dish and are given liquid nutrition. We took the medium in which the healthy mole-rat cells grew, and fed the cancerous blind mole-rat cells with this medium. In both cases the cancerous cells died. No death of the cancerous cells happened when we co-cultured them with mice, or rat or spiny mice normal cells, or fed the cancerous cells with the medium these normal cells grew in. There was no effect of normal cells of all these species on normal cells. So there is something here which is unique to mole-rats interacting with cancer cells.”
What does this mean for cancerous cells in humans? Can healthy blind mole-rat cells be used to kill cancer cells in humans?
“This what is really important. Can we declare that we can use the mole-rats for the sake of human cancer patients? So we took various kinds of cell lines originated from human liver and breast cancers. One of the cell lines of human breast cancer was especially aggressive and metastasizes very quickly. When put all these human-cancer cell lines with the healthy blind mole-rat cells, they were all killed. Again, we tried the same thing with healthy cells from the spiny mouse, the mouse and the rat, and nothing happened.”
So what do you conclude from all this research?
“From the start of cancer research, scientists have always worked on lab mice. Why mice? Because it’s easy to induce tumors in them. And even if we don’t experiment on them, six of 10 will die of spontaneous cancer anyway. It will be wrong and boastful to undervalue the progress in understanding mechanisms of cancer induction, progression and inhibition due to decades of studying mice. But we haven’t managed to transfer this knowledge from mice to humans. Hundreds of millions of dollars have been invested for decades in studies on mice; 90 percent never managed to reach the clinical stage. So the conclusion is that you can’t make a prediction from mice and apply it to humans. In fact, the leading scientists of cancer research claim that sticking to the conservative paradigm of using mice is the major obstacle to progress in human cancer research. With all modesty, I dare to declare that our results indicate that we might have found the missing animal [that will help] progress in the efforts to cure humans from cancer. An animal that kills human cancer cells with no harm to healthy cells. The ‘built-in’ mechanism that defends mole-rats from cancer, a mechanism that was developed and fine-tuned along tens of millions of years of evolution, seems be the key for helping human cancer patients.”
You’re saying that even though 90 percent of mice studies didn’t reach the clinical stage, mice are still considered the research animal of choice.
“It is not me who is saying it. As I said, leading scientists of cancer research that contributed tremendously to cancer research using mice as a model, declare so with no reservations. What I do is sharing with you and the readers, among them hopefully philanthropists with a vision, my unfortunate experience with grant foundations that reject our proposals, even when we score excellent grades, on grounds that they do not support studies with wild, unknown nonclassical animals, because any worthwhile question should be accessible in a well-established model − that is, mice.”
What do you want to study now? What’s next?
“Now we need to take the medium where blind mole-rats’ cells were grown and start cleaning it until we discover what the substance or substances are that are only secreted by blind mole-rat cells, and which undergo an interaction with something that exists only in cancer cells, primarily human cancer cells, because people keep on dying of cancer. What’s our problem? That we are broke, financially. We can see the Promised Land but we won’t get to enter it.”
You mean you can’t get funding for your research? You’d think that everyone would jump at the chance to fund research that could bring about such a turning point in the treatment of cancer and other diseases.
“I think our findings are pioneering and original, and hold the potential for a breakthrough that would help people who are sick with cancer, and I really hope that generous, open-minded donors will consider funding us so we can keep making progress. For a year now we’ve been trying unsuccessfully to interest philanthropists. We have our own ‘Israeli’ animal, we have promising results. If we don’t obtain the financial support that we need like we need air to breathe, we’ll lose the race to scientists who get ample research funding from rich and generous Uncle Sam − funds that aren’t available to researchers who aren’t American.”
In the meantime, lab mice will continue to die by the millions and millions of people will continue to get cancer, heart disease and strokes, the three biggest killers. The blind mole-rat, however, will keep on quietly thriving. Cancer-free.