A new study led by the University of Edinburgh has found that the bacteria that causes leprosy (also known as Hansen’s disease) – one of the world’s oldest and most persistent diseases that can affect the nerves, skin, eyes, and nasal mucosa in humans – can reprogram cells to increase the size of the liver in adult animals without causing damage, scarring, or tumors. These findings suggest the possibility of adapting this natural process to renew aging or damaged livers in humans and thus expand our lifespans.
In previous research, scientists promoted the regrowth of mouse livers by generating stem cells and progenitor cells – the next step after a stem cell which can become any type of cell for a specific organ – through an invasive technique that often led to scarring and tumor growth. In order to overcome such unwanted side-effects, the researchers built upon their previous discovery of the partial cellular reprogramming ability of Mycrobacterium leprae (the microorganism causing leprosy), by infecting with it 57 armadillos, which are natural hosts for this bacterium.
By comparing their livers to those of uninfected armadillos and those that were found to be resistant to infection, the experts discovered that the infected animals developed enlarged, yet healthy livers, with the same vital components as the uninfected or disease-resistant animals. The bacteria appeared to have “hijacked” the inherent regenerative ability of the liver to increase its size and to reach a “rejuvenated” state. Moreover, the livers of infected armadillos contained gene expression patterns – which have a fundamental role in building cells – similar to those in younger animals and human fetuses. Finally, genes connected to metabolism, growth, and cell proliferation were activated, while those related to aging were suppressed.
According to the scientists, these amazing phenomena were caused by M. leprae’s ability to reprogram the liver cells by returning them to the earlier stage of progenitor cells, which in turn became new hepatocytes that developed into fresh liver tissue.
These findings could help develop interventions for rejuvenating aging or damaged livers in humans. “If we can identify how bacteria grow the liver as a functional organ without causing adverse effects in living animals, we may be able to translate that knowledge to develop safer therapeutic interventions to rejuvenate aging livers and to regenerate damaged tissues,” concluded senior author Anura Rambukkana, an expert in Regenerative Medicine at the University of Edinburgh.
The study is published in the journal Cell Reports Medicine.
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