Rita Levi-Montalcini: A Legacy of Scientific Innovation and Advocacy
Introduction: Professor Rita Levi-Montalcini, born on April 22, 1909, in Turin, Italy, left an indelible mark on the field of neuroscience through her groundbreaking discoveries and unwavering dedication to scientific inquiry, despite being forced at one point to conduct her research from the confinements of her bedroom in Turin. From her pioneering research on nerve growth factor (NGF) to her advocacy for gender equality in academia, Rtia’s contributions continue to inspire generations of scientists worldwide.
Main: Before we begin, I would like to encourage you to give a listen to the other episodes on the scientists I found inspirational. I am making this podcast as a hobby alongside my PhD studies, which lately have been oh so delightful, I definitely need some motivation myself. I would love to hear from you on any feedback you have, don’t hesitate to drop an email or comment. In other news, I am starting a new series on the model organisms that made all the scientific advancements possible, because I think their lives are also worth remembering and cherishing. Thank you for being a listener, I appreciate it! Now back to our story.
Rita Levi-Montalcini was born into a distinguished Italian Jewish family and grew up with her twin sister, Paola. Her parents instilled in them a deep appreciation for education and intellectual pursuit. Despite the traditional roles her father tried to impose on her, Levi-Montalcini was determined to break these barriers. Her interest in science and her commitment to helping others led her to a career in medicine. Like many scientists featured on this podcast, it seems to me that being told “no” correlates to a Nobel Prize, so maybe ask your parents or a good friend to play the opposition with the promise of sharing the prize with them and let me know how that goes. I think we might be onto something.
At the age of 20, Levi-Montalcini chose to deviate from the path her father, Adamo Levi, had imagined for her. She was acutely aware of the marginalized position women held in a predominantly male society and was resolved to challenge these gender biases. After gaining the support of her mother, she successfully persuaded her father to let her study medicine, overcoming his initial reluctance. Facing the academic challenges head-on, she completed her required studies in just eight months and began attending the University of Turin's School of Medicine in 1930. I found it funny how her act of rebellion was to choose science when many parents nowadays would kill to have their kid as a doctor. Initially, she considered becoming a writer and admired Swedish writer Selma Lagerlöf, but after seeing a close family friend die of stomach cancer, she decided to attend the University of Turin Medical School.
Levi-Montalcini's academic pursuits were marked by resilience in the face of adversity. Under the tutelage of renowned Italian histologist Giuseppe Levi, she delved into the intricacies of neurogenesis, exploring the mechanisms underlying nerve cell development and migration. Her fascination with the developing nervous system fuelled her research endeavours, laying the groundwork for her groundbreaking discoveries in the years to come.
As Mussolini's fascist regime tightened its grip on Italy and enacted discriminatory racial laws targeting Jewish citizens, Levi-Montalcini faced mounting challenges as a Jewish scientist. In 1939, amidst rising persecution, she made the difficult decision to end her work at the University of Turin, seeking refuge in Belgium to continue her research at a neurological institute. However, the looming threat of Hitler's influence compelled her to return to Turin in 1940, where she established a makeshift laboratory in her bedroom to continue her pioneering studies on neurogenesis in the chick embryo, while aiding fleeing Jews from wrath of the war.
Despite the tumultuous backdrop of World War II, Levi-Montalcini's unwavering commitment to scientific inquiry remained steadfast. Her groundbreaking experiments on chick embryos, conducted under extraordinary circumstances, yielded remarkable insights into the role of limb buds in neuronal development. The limb buds are the incipient structure in the embryo from where the limb will later arise. At that time not much was known about the process. Inspired by Viktor Hamburger's seminal work, Levi-Montalcini meticulously dissected and stained chick embryos, unravelling the intricate processes governing neuronal proliferation, differentiation, and survival.
Shortly after the war's conclusion, Viktor Hamburger, a prominent German researcher whose earlier work had inspired Rita Levi-Montalcini to delve into nerve cell development, reached out to her. Having resided in the United States since before the conflict, Hamburger was intrigued by Levi-Montalcini's research, which she had ingeniously managed to disseminate in Belgium and the Vatican during wartime to circumvent bans in Italy. Impressed by her innovative results, he extended an invitation for her to join his laboratory at Washington University in St. Louis as a post-doctoral fellow.
Science time!
So before I proceed with the science section of this episode as always I’ll give you the question of the episode. For people new here, I ask the audience a science related question close to the topic of the episode so we can all keep our curiosity sharp and why not, learn some more things today! So here it goes: What is the animal that can regenerate limbs, nerves and even brains when amputated, making them the cutest freak of nature? Hint: they look like they always have a smile on their face which from some angles is bordering the creepy smiley emoji that refuses to disappear from the messaging apps.
Back to the subject. This time compared to other episodes I will focus less on the hard science and rather read an excerpt from her autobiographical book called “In praise of imperfection: my life and work”, which I highly recommend, it is a raw but elegant account of her long and fruitful life. The excerpt I chose is about the moment she made her great discovery while being in the USA where she lived the last part of her life after the war, and I chose it because it perfectly illustrates the grand moments every scientist seeks which keeps them going in the face of failure and hardship. This builds up grit, which I think all of us have to develop, as life for most of us doesn’t leave us unf... unbothered, that’s the word I was seeking.
She said the following about these crucial, but challenging times: “My doubts about the future of my research, which had led me to seek Luria and Dulbecco's advice and been the cause of many sleepless nights, were not to last long. From one day to the next and in an entirely unforeseeable way, I regained the faith in and the enthusiasm for the possibilities of experimental neuroembryology that I thought irretrievably lost.
It happened in the course of one afternoon in late autumn of 1947, while I was somewhat haphazardly examining, under the microscope, the latest series of silver-salt-impregnated chick-embryo sections. Their coloring had come out perfectly: the nerve cells that had begun to differentiate in the cerebral vesicles and spinal cord-the embryos had been fixed between the third and the seventh days of incubation-stood out in their every detail with a deep brown-blackish hue on the golden yellow background of the nonimpregnated cord tissue formed of satellite cells and as yet undifferentiated nerve cells. My attention was drawn to the spinal cord which revealed, even at first glance, a surprising variety of scenarios not only in its different segments but-in embryos at the same stage of development and fixed just a day or a few hours apart-also within the same segment. The thoracic and sacral segments offered a spectacle not unlike that of the maneuvers of large armies on a battlefield. Thousands of cells ...were proceeding in long columns from ... of the spinal cord. The migration began on the fourth day of incubation and ended on the sixth, when the cells reached their destination at the sides of the central canal. The identical modalities with which, in all of the cases I examined, the various phases of the process took place, revealed the genetic programming at work and, at the same time, the striking similarity between these processes and those that-in respect to the migration of birds, insects, locusts, termites, and ants-we view as revealing the workings of "instinct."
In the case of the migrations of living organisms, one can fall back on this vague term which explains everything, and therefore explains nothing. In the case of cells, unable as we are to use the term instinct since we do not attribute to them even hypothetical powers of decision, one speaks of the activation of a genetic program, not essen- tially different from programs that programmers draw up for computers. The thin dividing line between the realization of an instinct and of a program lies merely in the assumption that the former is a prop- erty of multicellular organisms in which we recognize the presence of a grouping, rudimentary as it may be, of nerve cells in charge of an individual's behavior; whereas the latter is common to living entities such as unicellular organisms or cells, and to inanimate objects such as computers as well. That day, however, as I peered through the microscope, nerve cells were acquiring a personality not usually attributed to them.
At the cervical level, I was witness to the disappearance of the membrane marking the boundaries of the nucleus, the retraction of the nerve fiber, and a decrease in the volume of the cell bodies. In immediately successive stages, the same cells acquired an appearance known, in histological terminology as "picnotic," or indicating the establishment of a process of irreversible degeneration. The im- pression was that of a battlefield covered with corpses. In embryos fixed at the stage immediately afterward-that is, ten to twenty-four hours later-the ventro-medial sector was invaded by macrophages, or cells able to ingest and destroy bacteria and the detritus of other, degenerated cells. The image that suggested itself to me was of corpses being removed from a battlefield by special crews trained and equipped for the purpose. A few hours later, all traces of cellular detritus had vanished; the column of cells still differentiating was vastly reduced in diameter, and an inspection of the fibers of the cells that comprised it revealed that they were innervating the muscles of the same segment of the trunk.
... The reconstruction of these many processes-which took place in my mind in the span of an hour-filled me with joy. It struck me that the discovery of great migratory and degenerative processes affecting nerve cell populations at the early stages of their development might offer a tenuous yet valid path to follow into the fascinating and uncharted labyrinth of the nervous system. The doubts about the future of experimental neuroembryology, which had prompted me to seek Luria's advice, had been based on the conviction that it would have been impossible to unveil the mechanisms underlying neurogenesis with the theoretical and technical means then at our disposal. The absence of valid criteria to follow in such a venture was even more evident in the light of comparisons between this field of study and those of genetics and virology in which-thanks to excellent models and sound, verified principles-always newer and greater heights were being reached. Not only did the nervous system not lend itself to experimental analysis, but its enormous complexity seemed to discourage all attempts to espy whatever might be taking place in it, "behind the scenes" as it were. The startling realization that nerve cell populations were subject to quotas and to the elimination of excess numbers in their ranks, as well as to migrations that went hand in hand with functional differentiation, showed that there were ontogenetic processes at work in the nervous system which were not as inaccessible to investigation as I had previously imagined.
In that intoxicated state, I knocked on Viktor's office door and asked him to follow me back to my lab bench. Scattered next to the microscope were the hundreds of slides containing the sections I had just examined. I rapidly sketched the images I had observed on a piece of paper, and told him my interpretation of the processes as I had mentally reconstructed them. Viktor listened attentively, amused by my enthusiasm, and agreed that they were observations of ex- treme interest, which provided the key for the study of differentiative processes in the nervous system up till then practically ignored. His enthusiasm, rising to the same pitch as my own and making me all the happier in light of his habitually more calm and cautious attitude, was confirmation of what since the start had struck me as a sort of revelation. When Viktor left the room. I put one of my favorite records on the record player I had installed in the laboratory: a Bach cantata.”
I hope you felt like me the deep sense of victory which emanates from between the scientific jargon and reserved vocabulary. Making sense of life is one of the most satisfying feelings one can have. We should all celebrate and cherish these kinds of moments in our lives, and I would say that this was the definition of fortuitousness. And yes, if that last word was at a spelling bee contest, I would’ve lost, sometimes the English language is not kind to the non-native speakers.
After wrapping up his own experiments, Hamburger found himself in receipt of a letter and manuscript from his former student, Elmer Bueker, who had been conducting limb transplantation experiments of his own. Bueker's hypothesis centered around the idea that rapidly growing tissue might attract nerve fibers akin to a developing limb. He had transplanted small sections of proliferating tumors onto chicken embryos and observed intriguing results. Among these, the mouse sarcoma 180 tumor showed remarkable proliferation and nerve infiltration, leading to enlargement of nearby spinal ganglia in the embryo. Intrigued by Bueker's findings, Levi-Montalcini promptly replicated the experiment using Cajal's silver stain technique. Her observations not only confirmed Bueker's results but also discerned that the nerves infiltrating the tumor did not establish direct connections with its cells, unlike in normal tissue innervation. Moreover, she noted a significant increase in nerve presence in tissues distant from the tumor long before such innervation occurred in control embryos. Levi-Montalcini's suspicions were further aroused when she observed nerve penetration into blood vessels draining the tumor, hinting at the tumor's secretion of a diffusible growth-promoting factor. To confirm this, she transplanted tumors onto the external membranous layer enveloping chicken embryos, ensuring no direct contact with internal embryonic tissues but sharing the same blood supply. Remarkably, the tumor still induced dramatic nerve growth, providing conclusive evidence that it released a soluble nerve growth-promoting factor and initiating a determined quest to identify this enigmatic substance. Collaborating with the biochemist Stanley Cohen, they embarked on experiments to unravel the mechanisms underlying nerve cell growth and their attraction to the tumor core. Together, they uncovered the macromolecule responsible for this phenomenon, which they dubbed nerve growth factor (NGF). They managed to extract this factor from the mouse salivary glands and realized that it was the same one involved in the development of the nerves. In short why this discovery was such a big deal is because it explained essentially how the nerve growth was promoted on a molecular level. With this one molecule, NGF, one could promote nerve growth in a developing and adult tissue. This opened the door in our current days to the discovery of a whole class of macromolecules, as well as regenerative therapies which use this NGF to aid to the regeneration of the damaged nerves. Maybe unsurprisingly, their groundbreaking discovery of NGF earned them the Nobel Prize in recognition of their pioneering research. She later said "It was a great honor. Still, there is no great a thrill as the moment of discovery." - Rita Levi-Montalcini
Bill Mobley, Chair of the Department of Neurosciences at the University of California, San Diego School of Medicine reflects: “The discovery of NGF really changed the world in which we live, because now we knew that cells talk to other cells, and that they use soluble factors. It was hugely important”. As it became clear that NGF only acted on a few specific types of nerve cells, many researchers became engaged in the search for additional factors that might influence the growth and survival of other types of nerves. However, the hunt for additional factors proved to be long and arduous, and it was not until the 1980s that Yves Barde, Hans Thoenen, and colleagues isolated a factor from the brain, which they called brain-derived neurotrophic factor. Soon, NGF was also found to act in the brain, and two additional neurotrophins were later discovered.
The discovery of growth factors in the brain ushered in a second wave of excitement for growth factor biology and spurred research to determine their role in neurodegenerative diseases and psychiatric disorders, Mobley says. Recent studies have shown that NGF plays a role in learning and memory, and experiments conducted by Cattaneo’s and Calissano’s research groups demonstrate that removal of NGF in either in vivo or in vitro experimental models results in the onset of an Alzheimer-like molecular syndrome, which leaves many hopeful that NGF and other neurotrophins may be useful for treating Alzheimer’s disease. Furthermore, anti-NGF antibody-based therapeutics have shown promise in recent clinical trials for the prevention of pain, further proof that Levi-Montalcini’s pioneering techniques and experimental findings are just as relevant today as they were half a century ago. However, perhaps the most recent evidence of NGF’s many-faceted role can be found in a 2012 PNAS article that reported that this protein factor is present in semen and modulates ovulation, linking NGF to reproductive function and suggesting that it may one day be useful for treating infertility.
Like NGF, Levi-Montalcini never ceased to surprise and amaze. Her most recent experiments were published in January 2012, which made her the oldest member of the National Academy of Sciences to publish.
Later on, winning the prize opened many unexpected doors for her. She said: "I can do things that are very, very important, which I would never have been able to do if I did not receive it [the Nobel Prize]. It has given me the possibility of helping a lot of people
Beyond the confines of the laboratory, Levi-Montalcini's humanitarian spirit and advocacy for scientific funding and gender equality left an indelible mark on society. Despite facing entrenched sexism and anti-Semitism, she emerged as a vocal champion for scientific education and mentorship, founding foundations to support underprivileged children and African women in pursuing higher education. Her appointment as a Senator for life in Italy and her victorious battle against proposed budget cuts for research underscored her unwavering commitment to advancing scientific progress and social justice. She was the first Nobel prize winner to live up to a hundred years old. She lived up to a 103, never having had a husband or children, but nevertheless being missed by many around the world.
Conclusion: So, what is the conclusion of this episode? Live up to a hundred to spite all of your enemies, maybe. But on a serious note, my take is to never give up. Work on that project, push through that challenge, if you are kicked out the door come back through the window, and grow together with the people around you. Rita Levi-Montalcini's remarkable journey serves as a testament to the transformative power of scientific inquiry and the human spirit's capacity to transcend adversity. Her pioneering discoveries and unwavering advocacy leave an indelible imprint on the annals of scientific history, inspiring future generations to dare, to discover, and to make a difference in the world.
I will end with the poem written by William Butler Yeats called “The choice” found at the beginning of her autobiography which encapsulates the essence of this episode.
From the book “In praise of imperfection : my life and work.”
Entry poem
The choice
The intellect of man is forced to choose
Perfection of the life, or of the work,
And if it take the second must refuse
A heavenly mansion, raging in the dark.
When all that story’s finished, what’s the news?
In luck or out the toil has left its mark:
That old perplexity an empty purse,
Or the day’s vanity, the night’s remorse.
-William Butler Yeats
References
https://www.pnas.org/doi/10.1073/pnas.1302413110
https://dilemaveche.ro/sectiune/la-fata-timpului/rita-levi-montalcini-o-artista-a-stiintei-2311088.html
“Rita Levi-Montalcini and the discovery of NGf, the first nerve cell growth factor” - Luigi ALOE, Archives Italiennes de Biologie, 149: 175-181, 2011. DOI: 10.4449/aib.v149i2.1377 http://www.architalbiol.org/index.php/aib/article/view/149175/21701989
In praise of imperfection : my life and work. Levi-Montalcini, Rita. 1988
https://www.nobelprize.org/prizes/medicine/1986/levi-montalcini/lecture/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3612637/