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If you're going to look for cures for diseases in humans, you should be using human genetic and cellular models. Since running experiments on human beings is f

If you're going to look for cures for diseases in humans, you should be using human genetic and cellular models. Since running experiments on human beings is frowned upon, what with control groups and the post-experimental 'sacrifice' of the test subjects for tissue analysis and so on, what to do? Happily, modern technology allows for development of human stem cells into a variety of cell types - even lately into complex tissues consisting of multiple cell types (2021): https://www.frontiersin.org/articles/10.3389/fimmu.2021.798552/full https://www.frontiersin.org/articles/10.3389/fimmu.2021.7985... > "In this review, we will emphasize the transitions from immortalized cell lines to stem cells and describe their use in combination with gut-on-chip models. These “on-chip” models are defined as three-dimensional (3D) cell cultures arranged as multiple cell layers actively perfused by microfluidics for medium exchange to enable an improved tissue formation with increased lifespan. We will highlight selected applications of these gut-on-chip models to understand gastrointestinal diseases and forthcoming strategies to investigate human gut physiology." This looks to be superior to animal testing on multiple grounds - first, animal models don't respond to drugs and don't develop identical disease states to humans, second it's needlessly cruel to animals, particularly when there are now better approaches utilizing technology that should be capable of producing muscle, lung, heart, even brain tissue models based on human stem cells.

tsol 4y ago
Tissue in a lab is not equivalent to a whole organism in drug testing, and what works in one may not work at all in the other. It's a step forward but it still has limited use
refurb 4y ago
Testing isolated human tissue is in no way comparable to a whole organism. Even if you tested all different human tissue types separately, you haven't accounted all for interactions between tissues. Say liver metabolism to a molecule that is toxic to bone marrow.
- photochemsyn 4y ago
  Ideally one could construct a whole model of the human circulatory system in this manner, with a digestive tract module, a liver module, a kidney module, etc. Probably still a bit sci-fi at this point.
  - refurb 4y ago
    Thats pretty much a human then. For example livers arent made up just liver cells (hepatocytes) there are 3 other major cell types. In vitro heptacytes are commonly used today to measure metabolism and toxicity and you get a lot of good info, but they dont substitute an actual liver.
lofatdairy 4y ago
Yeah these have been the hot thing for a minute. Nina Tandons TED talk came out 10 years ago and minus a few more detailed developments, I think it holds up really well as an introduction. The main challenges are related to the fact that cell cultures and tissue cultures are also not easy to standardize (passaging and media variations) and also introducing mechanical stimuli to more accurately model living systems. Serum free media is one area where there's been a bit of development, and recreating function mechanically has been a really interesting field. Dongeun Huh's paper I think he did while a postdoc in Donald Ingbers lab is pretty canonical and still is incredibly impressive but stretching is only part of the deformations these tissues undergo.
Dalewyn 4y ago
>it's needlessly cruel to animals, particularly when there are now better approaches utilizing technology that should be capable of producing muscle, lung, heart, even brain tissue models based on human stem cells. What is the difference between "animals" and "cells"? No, seriously. Answer me. I'll wait. If you're actually serious and sincere about "cruelty", it shouldn't make any difference whether it's a whole animal or a cell: They're both living entities.
- photochemsyn 4y ago
  Consciousness.
  - Dalewyn 4y ago
    What is your reasoning that cells do not possess conciousness? Why is conciousness even the deciding factor?
    - GreenWatermelon 4y ago
      Cells are just biological automata, they are dead thing, just a bunch of robots exchanging messages, no more alive than a chair. However, when many types of cells come together, they form a living being. Consciousness, or life, is an emrgent property that appeared due a collection of cells working together, it's more than the sum of its parts. Where is the boundary? When do these automata become alive? We don't know, but we can be sure that monkeys and mice are alive, and they feel things. They feel pain, which is a property of the neural system. To use another analogy, let's imagine a conscious robot. It's made of various metallic things, of nuts, bolts, alloys, wires, sensors, and let's assume it feels pain. Performing stress testing on the individual bolts that make up its body (just bolts, like spare parts, from a toolbox) would not cause anything to feel pain. I really recommend watching this kurzgesagt video [1] about cells, proteins, and how they interact. [1] https://youtu.be/TYPFenJQciw https://youtu.be/TYPFenJQciw
      - mandmandam 4y ago

tsol 4y ago

Tissue in a lab is not equivalent to a whole organism in drug testing, and what works in one may not work at all in the other. It's a step forward but it still has limited use

refurb 4y ago

Testing isolated human tissue is in no way comparable to a whole organism. Even if you tested all different human tissue types separately, you haven't accounted all for interactions between tissues. Say liver metabolism to a molecule that is toxic to bone marrow.

photochemsyn 4y ago
Ideally one could construct a whole model of the human circulatory system in this manner, with a digestive tract module, a liver module, a kidney module, etc. Probably still a bit sci-fi at this point.
- refurb 4y ago
  Thats pretty much a human then. For example livers arent made up just liver cells (hepatocytes) there are 3 other major cell types. In vitro heptacytes are commonly used today to measure metabolism and toxicity and you get a lot of good info, but they dont substitute an actual liver.

lofatdairy 4y ago

Yeah these have been the hot thing for a minute. Nina Tandons TED talk came out 10 years ago and minus a few more detailed developments, I think it holds up really well as an introduction. The main challenges are related to the fact that cell cultures and tissue cultures are also not easy to standardize (passaging and media variations) and also introducing mechanical stimuli to more accurately model living systems. Serum free media is one area where there's been a bit of development, and recreating function mechanically has been a really interesting field. Dongeun Huh's paper I think he did while a postdoc in Donald Ingbers lab is pretty canonical and still is incredibly impressive but stretching is only part of the deformations these tissues undergo.

Dalewyn 4y ago

>it's needlessly cruel to animals, particularly when there are now better approaches utilizing technology that should be capable of producing muscle, lung, heart, even brain tissue models based on human stem cells. What is the difference between "animals" and "cells"? No, seriously. Answer me. I'll wait. If you're actually serious and sincere about "cruelty", it shouldn't make any difference whether it's a whole animal or a cell: They're both living entities.

photochemsyn 4y ago
Consciousness.
- Dalewyn 4y ago
  What is your reasoning that cells do not possess conciousness? Why is conciousness even the deciding factor?
  - GreenWatermelon 4y ago
    Cells are just biological automata, they are dead thing, just a bunch of robots exchanging messages, no more alive than a chair. However, when many types of cells come together, they form a living being. Consciousness, or life, is an emrgent property that appeared due a collection of cells working together, it's more than the sum of its parts. Where is the boundary? When do these automata become alive? We don't know, but we can be sure that monkeys and mice are alive, and they feel things. They feel pain, which is a property of the neural system. To use another analogy, let's imagine a conscious robot. It's made of various metallic things, of nuts, bolts, alloys, wires, sensors, and let's assume it feels pain. Performing stress testing on the individual bolts that make up its body (just bolts, like spare parts, from a toolbox) would not cause anything to feel pain. I really recommend watching this kurzgesagt video [1] about cells, proteins, and how they interact. [1] https://youtu.be/TYPFenJQciw https://youtu.be/TYPFenJQciw
    - mandmandam 4y ago