Is it feasible to create free-living human cells?

A few days back I saw a news item about an upcoming HBO movie about Henrietta Lacks, and I’ve been thinking again about how aggressively the HeLa cell lines are said to be able to spread in cell cultures and how aggressively careful researchers need to protect against cross-contamination. But HeLa and other human cell lines are still “houthouse flowers”, living in strictly controlled conditions. I’m wondering if it would be feasibly doable within a reasonable time-frame (meaning less than decades) to produce cells that could live freely in “real world” circumstances, such as ocean water, fresh water, or soil? Slowly acclimating the cell lines to the real-world conditions one level of exposure at a time? If you happened to be a mad scientist with that goal?

(Answer not needed soon.)

Possibly, but they would need to be so different from the original cell line that you could scarcely call them “human”. They’d need multiple adaptations for single-celled existence that human cells simply don’t have.

I have a hard time thinking of a cell line which is so hard to protect against contamination from as a “hothouse flower”. Yeah, living in a little tray of agar is easy… but when you put that tray through the autoclave and you still get HeLa cells, that tells me that they’re already managing to live “in the wild”, so to speak.

They can survive being put through an autoclave? Whoa.

Well, I’m guessing that they don’t survive the autoclave itself. Even tardigrades would have difficulty with that. More likely, what’s happening is that there are a few cells clinging to other surfaces outside of the autoclave, and they re-colonize from those. My point is that those few cells clinging to the other surfaces look an awful lot like free-living.

But there are a couple big differences between agressively colonizing agar and truly existing ‘in the wild’.

First, as you noted living in a tray of agar is easy: that’s what agar is designed for. Being able to deal with the varying conditions and range of nutrients (or lack thereof) in a clump of dirt is much much different.

More importantly, to really make it in the wild, an organism not only had to be able to deal with all the stresses and difficulties of living in a clump of dirt, but it has to do it as well or better than all the other creatures that are already evolved to live in a clump of dirt, while avoiding all the creatures that have evolved to eat things living in a clump of dirt.
There’s nothing really (in theory) to prevent someone with huge resources to mix up a bunch of agar that’s missing or has an alternate form of some of the nutrients, and keep throwing HeLa cells into it, until they finally get a mutation that allows the cells to survive there. The could keep repeating the process until they get a line of cells that can survive in a clod of dirt – as long as that’s been sterilized and protected from being colonized by nematodes and soil-dwelling bacteria and so forth. [If the person is allowed to genetically engineer the line of cells to explicitly add particular genes or activators for existing genes, they process might take less time]

With incredible more levels of effort and time, they might be able to gradually evolve a cell line that could at least sort-of compete in an actual wild ecosystem. But that cell line would probably end up looking and acting a lot like something that currently does make a living in the dirt, and I certainly wouldn’t call in ‘human’ at that point.

Sounds more like sloppy cell culture to me. HeLa cells do not survive autoclaving and can not survive outside of culture conditions for long. They are hardy cells and contamination of a cell line with HeLa cells will lead to mostly HeLa cells in short order.