Revere is thinking about how to grow meat without the animal. It’s a cool idea that’s been floating around in science fiction for a while now, but, well, of course it has problems, and Revere notes a couple.
The two biggest, as far as I can see from a quick perusal of the burgeoning literature, are finding a suitable nutrient to grow the cells in; and then growing tissue that has the proper texture for being a meat substitute. Animal meat is not just muscle cells but a complicated structure also containing connective tissue, blood and blood vessels, nerves and fat. Just growing up masses of identical cells isn’t sufficient. You have to reproduce an architecture.
I see those two problems as aspects of one much bigger problem. Muscle doesn’t grow in isolation: it’s always in a solid environmental context. It’s made up of cells that respond to activity in a way that enhances performance for the organism, and incidentally promotes flavor and texture and bulk for the delectation of the carnivore. So what do you need to make edible muscle mass, beyond a sheet of myocytes in a culture dish (which, I suspect, would have the texture of slime and would not sell well in test markets)?
An architecture is right. You need connective tissue to form a framework and you need a rigid but motile structure to do work and exercise the growing muscle. Then, because you want a piece of muscle larger than a drop, you need a delivery system for nutrients: a circulatory system, with a pump. This muscle in a vat is going to need a skeleton and a heart.
When I teach physiology, one of the organs I emphasize is the liver. It’s amazing how important a liver is to just about everything: growth, digestion, physical performance, reproduction, the whole shebang. Our cultured muscle will need a liver equivalent to support it. Even if we get rid of the digestive system entirely and feed this muscle mass on delivered supplies of pure glucose, amino acids, and various cofactors and enzymes, the liver is a primary regulatory agent for those substances.
Then we need an immune system. A huge lump of cells growing in a bath of sugar and amino acids is bacterial heaven — it’s going to need major antibacterial/antiviral support.
The more I think about it, the more I think people are going at it backwards. We shouldn’t be thinking about building muscle from the cells up, to create a purified system to produce meat for the market, we should be going the other way, starting with self-sustaining meat producers and genetically paring away the less commercially viable bits, like the brain. Instead of test-tube meat, we should be working on more efficient organisms that generate muscle tissue with the properties we want.
Guess what? Farmers have already been doing this! Look at the domestic cow and chicken and turkey: they’re far more brainless than their wild relatives, and have been reduced to as much stupidity and helplessness as possible, without compromising their ability to survive semi-autonomously and harvest nutrients from naturally occurring food sources. I don’t see all that much difference in the consequences between building up a functional meat producer from cells in a dish, and stripping down a functional meat producer from a line of domesticated animals. Both starting points are aiming at the same final result; I suspect that the top down procedure is more likely to achieve success in my lifetime.