It’s been a long running staple of science fiction movies. A biochemical giant finds an amazing new business opportunity. Some compound or plant in an exotic location is able to alter or remove the limits on cell division in the human body. The “scientists” in the R&D department declare that turning whatever this infinite cell divider is into a pill would create a multi-billion dollar market and help extend human lifespan to extremes we could only dream of. But those are movies. In real life what those “scientists” would be doing is creating something like cancer in a can. There’s a good reason to let our cells stop dividing.
Cell division in humans, and all other animals, is regulated by telomeres; regions of redundant hereditary material on the ends of a chromosome. Without them, chromosome ends for a new cell would come unraveled and all the codons it contains would be lost. But as cells divide, their telomeres shorten until they start unraveling. When they do, their home cell stops dividing and might even commit suicide when there’s too much damage to the chromosomes. And that’s a key component in suppressing cancerous tumors. Cancerous cells can regenerate their telomeres and as they grow out of control, they form tumors which invade nearby tissues and metastasize to spread throughout the body.
This isn’t so cut and dry though. We don’t know how humans would respond to a treatment of compounds that lengthen their telomeres. We only know that nematodes with longer telomeres would have longer lifespans and their offspring would inherit the extended telomeres, also with the longer lifespan seen in their parents. But would the same apply to humans? Human aging is rather complex and just having longer telomeres might not do all that much for us. And there would always be a concern that some of our cells would overdose on the treatment to become cancerous and create tumors. Either way, having us take pills to dramatically change how many times our cells could divide or giving these cells immortality is not a good idea. In fact, it may be an effective way of causing cancers on demand.