ok, the Frequency TX masterplan should be, that if transdifferention has been done, the newly generated cell from the supporting cell would be on the correct position and would know all the parameters of the damaged, or
dead orginal hair cell? Like on this illustration?
https://www.researchgate.net/figure...pporting-cell-differentiates-into-a-hair-cell
Ideally, it would be B rather than A.
I've been thinking about these issues and re-reading some of the public statements in press releases and then re-reading parts of the paper. The goal is of course to provide a single drug treatment to restart a dormant process that will first lead supporting cells to differentiate (expand) and then for a portion of them to convert to hair cells.
To expand the supporting cells they used "the glycogen synthase kinase 3b (GSK3b) inhibitor CHIR99021 (CHIR or C) and the histone deacetylase (HDAC) inhibitor valproic acid (VPA or V)" as well as a "growth factor cocktail". They refer to this combination as EFICVP6. To differentiate the supporting cells into hair cells they use LY411575 and CHIR.
So the goal is to only have to do the first step: induce the supporting cells to divide/expand. The idea is that this will then start the differentiation process. Thus, it makes sense to look at what was and wasn't in the paper.
In the paper, they performed a number of experiments:
1) For a cell culture (with cells presumably from newborn mice), they did both steps.
2) For a cell culture from adult mice, they did both steps.
3) Cells from an adult rhesus macaques expanded using EFICVP6, but the cells did not differentiate to hair cells (they suggest this was due to contamination).
4) Cells from a human adult inner ear expanded after treatment with EFICVP6 and differentiated into hair cells after treatment with LY411575 and CHIR. Thus, both steps were used and the combined treatment lasted 22 days.
5) Finally, they used cochlear explants from neonatal mice. These were treated with CHIR, VPA, and
"2-phospho-L-ascorbic acid (pVc or P), a stable form of vitamin C" for 3 days. In this case, they only did the first (expansion) step. This is the published evidence for the idea that all that is necessary is to induce cell division in the supporting cells, and the differentiation to hair cells will follow. The caveat to this is that the mice were 2 days old. Thus, there is not yet published evidence that using only the expansion protocol leads to new hair cells in adults.
The fact that they can grow such large numbers of hair cells is a big deal for research broadly speaking (and seems to be underappreciated around here), but experiments 4 and particularly 5 seem to me to be the big deal in terms of a path to a trial. Four because it demonstrates that regeneration is possible with adult tissue and five because it demonstrates that regeneration is possible after only inducing expansion.
What should we be looking for in the next paper(s)?
a.) can/do they overcome the weaker expansion in adult tissue compared to neonatal tissue?
b.) can/do they demonstrate that inducing expansion results in differentiation in adult mice?
c.) can/do they induce expansion and differentiation in living mice? (preferably with a single administration of small molecules rather than a multi-day cell culture)
d.) for newborn mice, can/do they go beyond talking about the properties of hair cells and actually demonstrate the restoration of hearing?
e.) for adult mice, can/do they demonstrate restoration of hearing?
f.) Once those are done, can/do they show that a single administration works (i.e., restores hearing) in a living young or (ideally) adult primate?
I don't expect all of that in 1 paper, and I am assuming that they already know the answers (or have a really good idea of the answers) to a number of these outcomes. However, my guess is that they will need to get to (f) before human trials can begin.
) as uncompressed audio. Our consciousness can not handle the chaos of multiple frequency input and shuts down the unnecessary frequencies. That's why most of us don't hear the T sound while listening to music.
Member
Manager