Immortality by cell regeneration has a biological limit – 09/02/2023 – Science

The possibility of creating a radical form of regenerative medicine, rebuilding any part of our body cell by cell, has excited certain billionaires who dream of immortality. But the dream is likely to run up against some fundamental limits of biology, says Indian-American physician Siddhartha Mukherjee.

Mukherjee, 53, professor and researcher at Columbia University (USA), is the author of “The Song of the Cell”, a book in which he examines how science’s understanding of these fundamental units of life has advanced dramatically since the mid-19th century .

After all, while a mere 150 years ago it still wasn’t clear that all living things, from microbes to blue whales, are made up of cells that multiply and sometimes specialize, the last few decades have made it increasingly possible to design cellular units. under Measure. Some barriers, however, remain.

“Some organs, with regard to their cell biology, are dependent on their history, on their trajectory. The brain is an excellent example of this”, he argued in conversation with the Sheet.

“The fact that you can remember your mother’s face, or your grandmother’s face, depends on when you encountered that face in your life history, and the architecture of your brain was altered because of that memory. So, there’s no use hoping that, after a neuron replacement in your brain happens, you’ll still be you”, explains Mukherjee.

“The situation of the bone marrow, for example, is different. Its cells, which give rise to all blood cells, regenerate every 12 or 14 days, depending on the cell type —for this reason, a person can receive a bone marrow transplant, and it will continue to behave like that person’s marrow, regenerating most of his blood.”

However, even in this case, he recalls, there is a component of cells derived from the bone marrow that depends intrinsically on the history of each organism: the T and B memory cells of the immune (defense) system, which function as a library of invaders that a certain body has managed to win throughout its life.

Important sections of the book, by the way, are dedicated to the cells of the immune system and those that form the brain and the rest of the nervous system. There are also sections that explore the mysteries of cancer — an enemy that, according to the author, is the equivalent of “cell biology seen in a pathological mirror,” and which won Mukherjee a Pulitzer Prize for nonfiction for his book on the subject, called “The Emperor of All Evils”.

Filled with inventive metaphors, personal impressions of his work as a researcher and literary references, the text of the book also makes several dives into the history of cell biology. This includes the trajectory of characters such as the Dutch Antonie van Leeuwenhoek (1632-1723), creator of the first microscope that allowed the observation of unicellular organisms, and the German Rudolf Virchow (1821-1902), who coined the Latin expression “Omnis cellula e cellula” — all cells derive from other cells.

For him, retelling the personal and scientific biography of these figures is not just an artifice to “humanize” the more arid aspects of his research.

“I mean, we’re talking about intellectual stories. So for me the key is trying to understand the intellectual lineage of each scientist, understanding the thought process that led to a discovery,” he explains. “It is very significant, for example, that Mendel, who was a major character in my previous book [‘O Gene: Uma História Íntima’]was a monk – but a very special kind of monk,” he says, referring to the 19th-century Czech priest who played a central role in understanding how genes work.

“He was in a monastery where, for example, there was a wide availability of books on science, on natural history. And it’s also significant that the order to which he belonged had a long history of working with agricultural crops. So none of this is accidental. .”

The book also tackles the mysteries behind the origin of multicellular organisms—a relative novelty of evolution (perhaps around 1 billion years old) compared to the 4 billion age of single-celled organisms. The most surprising thing is that it seems possible, in the laboratory, to transform today’s unicellular beings into protomulticellular creatures. It is yet another indication in favor of the hypothesis that, in fact, the process would have happened naturally, multiple times, in different lineages of organisms.

According to the researcher, it is possible that situations such as increased predation among unicellular organisms, or advantages linked to specialization and division of tasks, pushed some lineages of living beings towards life with many cells.

The side effect of this process, however, was precisely the appearance of cancer, a multiform problem derived from the fact that, sometimes, certain cells leave aside the cooperative pact and begin to multiply in an uncontrolled and irregular way. Given that, isn’t it a miracle that cancer isn’t much more common?

“It depends on what you mean by the word ‘cancer'”, ponders the author. “Certainly mutations that cause cancer in cells are much more common than we imagine. This is the case with eyelid cells, for example, which are very exposed to sunlight. Therefore, there are mechanisms in the organism as a whole that prevent this from going forward. —a constant game of cat and mouse between the two trends.” There are multitudes within every living being with more than one cell.

Work: “The Song of the Cell”
Author: Siddhartha Mukherjee
Translation: Berilo Vargas
Publishing company: Companhia das Letras
How much: BRL 104.90; 552 pages.