Interstitium - A new organ?
Recently, a paper was published in Nature, reporting on the discovery of what the authors call a new organ - the interstitium. Before we get into the merits of the paper, let's cover some basics. Most organs are made up of two general tissue types - parenchyma and interstitium. Parenchyma describes the functional cell types of the organ - the cells that do whatever the organ has evolved to do. For example, in the lung, you would describe the alveoli (air sacs) and trachea as part of the parenchyma. Interstitium is made up of a variety of other cells and structures that support the parenchyma. ("Inter" = between, "stitial" = to set, positioned "interstitium" = positioned between) This part is made up of different kinds of collagen and other structures as well as some cells that contribute to things like inflammation and wound healing, like fibroblasts. So parenchyma = the heavy lifters, interstitium = support for the heavy lifters.
Theise, et. al. put forward this idea that in the body, the interstitium in and between various organs is actually a connected system, a kind of a super organ that pervades the entire body. How they concluded this was by using a technique called probe-based confocal laser endomicroscopy (pCLE). Confocal imaging is a way of gathering images with super high resolution, which is great for multiple layers of tissue. And pCLE uses confocal imaging to gather pictures in the course of an endoscopy, in some cases removing the need for a piece of the tissue to be removed for biopsy. In this paper, patients undergoing pancreatic surgery had imaging done by pCLE both during the surgery, and after the surgery, using biopsy sections.
The authors focused on submucosa (sub=under, the spaces under the mucosa, or parenchyma) of the pancreas and found that these spaces were similar to lymph nodes and vessels but distinct from blood vessels, as they contained the mesenchymal marker vimentin, but not the endothelial (blood vessels) markers CD31, ERG, and LYVE-1. The authors also noted a population of flat, undifferentiated cells that line up on the collagen bundles of these interstitial spaces. In sections of other organs, the authors noted that a similar pattern is present in skin, lung, bladder, and intestines.
This is new and interesting because in many organs, the surrounding tissue is thought to simply provide support and structure. But the authors demonstrated that these areas are filled with fluid and are found in a variety of organs. The authors also seem to think that the interstitium is distinct from the lymphatic system, and might work differently. One idea that the authors propose is that the interstitium basically functions as shock absorbers to protect parenchyma in various organs. They also bring up the possibility that metastasizing cancer cells could use this system to spread. Since it seems that this network of interstitial spaces is similar in various tissues, it's possible that the system is connected and this is yet another path that cancer cells can use to spread to new places.
I think that while this paper offers some cool new information, we shouldn't necessarily call the interstitium a new organ. I think that this might change how we understand the interstitium, and it certainly is meaningful because it seems that interstitial spaces might be connected to one another. But I think that calling it a new organ is a stretch. We've known for a long time that the interstitium exists, this is just more information about what it does.
One thing I should also mention here is that the lead author for this paper is involved in the alternative medicine sphere and has since made some claims that maybe the new findings about the interstitium can "explain acupuncture." Acupuncture is not considered a valid treatment option for anything by credible doctors. It's one of those things that is pretty much all placebo effect. If you think about it, why on earth would sticking needles in your body do anything positive? If there isn't sound evidence that something works and no one knows why it would even work, then it probably doesn't work.
For further reading:
1. https://www.nature.com/articles/s41598-018-23062-6
2. https://slate.com/technology/2018/04/the-new-organ-discovery-doesnt-explain-acupuncture.html
Theise, et. al. put forward this idea that in the body, the interstitium in and between various organs is actually a connected system, a kind of a super organ that pervades the entire body. How they concluded this was by using a technique called probe-based confocal laser endomicroscopy (pCLE). Confocal imaging is a way of gathering images with super high resolution, which is great for multiple layers of tissue. And pCLE uses confocal imaging to gather pictures in the course of an endoscopy, in some cases removing the need for a piece of the tissue to be removed for biopsy. In this paper, patients undergoing pancreatic surgery had imaging done by pCLE both during the surgery, and after the surgery, using biopsy sections.
The authors focused on submucosa (sub=under, the spaces under the mucosa, or parenchyma) of the pancreas and found that these spaces were similar to lymph nodes and vessels but distinct from blood vessels, as they contained the mesenchymal marker vimentin, but not the endothelial (blood vessels) markers CD31, ERG, and LYVE-1. The authors also noted a population of flat, undifferentiated cells that line up on the collagen bundles of these interstitial spaces. In sections of other organs, the authors noted that a similar pattern is present in skin, lung, bladder, and intestines.
This is new and interesting because in many organs, the surrounding tissue is thought to simply provide support and structure. But the authors demonstrated that these areas are filled with fluid and are found in a variety of organs. The authors also seem to think that the interstitium is distinct from the lymphatic system, and might work differently. One idea that the authors propose is that the interstitium basically functions as shock absorbers to protect parenchyma in various organs. They also bring up the possibility that metastasizing cancer cells could use this system to spread. Since it seems that this network of interstitial spaces is similar in various tissues, it's possible that the system is connected and this is yet another path that cancer cells can use to spread to new places.
I think that while this paper offers some cool new information, we shouldn't necessarily call the interstitium a new organ. I think that this might change how we understand the interstitium, and it certainly is meaningful because it seems that interstitial spaces might be connected to one another. But I think that calling it a new organ is a stretch. We've known for a long time that the interstitium exists, this is just more information about what it does.
One thing I should also mention here is that the lead author for this paper is involved in the alternative medicine sphere and has since made some claims that maybe the new findings about the interstitium can "explain acupuncture." Acupuncture is not considered a valid treatment option for anything by credible doctors. It's one of those things that is pretty much all placebo effect. If you think about it, why on earth would sticking needles in your body do anything positive? If there isn't sound evidence that something works and no one knows why it would even work, then it probably doesn't work.
For further reading:
1. https://www.nature.com/articles/s41598-018-23062-6
2. https://slate.com/technology/2018/04/the-new-organ-discovery-doesnt-explain-acupuncture.html
You talk about how acupuncture is junk science. What are your thoughts on "alternative medicine" in general? I'd bet you have some interesting things to say about that?
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