Ok well then you are basically saying that all work that being done by hearing restoration project is nothing ? their project is so far up-to schedule.
A number of people seem to have some misunderstanding about stem cells. What HRP is doing and what this clinic (or any of these clinics) is doing are two very different things.
There seems to be this notion that you can take "stem cells" and inject them into a part of the body and that they will know what is damaged and become whatever tissue is needed. That's not how it works. First off, there are many different stem cells so you would need to be specific about what stem cells. For example, with leukemia, hematopoietic stem cells are harvested from the bone marrow. These cells naturally become blood cells so they can in fact be injected and create new blood cells with little or no additional intervention. Injecting mesenchymal stem cells (MSC) taken from fat would not help because they naturally become bone, cartilage, etc.
There is no analog for the ear. You can't just take stem cells from bone marrow or fat or any place else and inject them into the ear and expect them to develop into hair cells or auditory neurons . (I believe this is
@HomeoHebbian's point.)
In contrast to adult stem cells, embryonic stem cells can become many different types of cells - they are pluripotent. And yet, injecting them into the inner ear will not automatically regenerate hair cells. There's a fundamental difference between generation (development) and regeneration. Even during development, stem cells don't innately "know" what to turn into. There are numerous signalling pathways that serve to guide a cell to its specific fate. This signalling happens endogenously during development, but if you were to inject embryonic stem cells into the ear, there is no automatic signalling to guide the cell to become a hair cell.
With respect to hearing, what HRP, Stanford, Harvard, and others are working on is understanding and attempting to replicate the signalling necessary to guide a stem cell, either an embryonic or induced pluripotent SC, to a particular fate, e.g., a hair cell. An example of this on a large scale is the "ear in a dish" developed by folks at Indiana University (
http://www.nature.com/nature/journal/v500/n7461/full/nature12298.html).
This is obviously very different than what any of these stem cell clinic are doing. I encourage anyone with an interest in the differences between development and regeneration to read this paper:
http://dev.biologists.org/content/142/9/1561.abstract
So if stem cells aren't regenerating hair cells, is there any MOA by which they could improve anything ear related? My understanding is that there is some evidence (not sure how good it is) that MSCs can have anti-inflammatory effects (e.g.,
http://www.nature.com/mt/journal/v20/n1/full/mt2011211a.html) which could be beneficial depending on the underlying damage. Again, I'm not sure how settled this is, but this has nothing to do with regeneration.
An aside regarding joints/cartilage: many/most/all of these clinics use adipose derived stem cells which are mesenchymal stem cells (MSC). MSCs can naturally become cartilage. Thus we are more in the leukemia case than the ear case in terms of plausible MOA, and there are clinical trials underway to understand the effect of MSCs on arthritis and similar conditions. Additionally, in the US, at least one reputable institution (i.e., not a for profit stem cell clinic) performs stem cell injections for arthritis (
https://www.emoryhealthcare.org/sports-medicine/stem-cell-treatment.html). However, they are not claiming regeneration of cartilage: "There is some limited data suggesting an ability to regenerate a portion of the cartilage that may be worn down in the patient's joint. Whether or not the cartilage regenerates has little correlation with relief of pain. In cases of more advanced arthritis, we are less likely to see any cartilage regeneration." Thus even in that case, the actual MOA isn't clear.
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