That’s a tough question to answer; there’s an awful lot of stem-cell types and telomerase activity is not necessarily binary. I wouldn’t be shocked if some of the more-differentiated and/or slower-dividing types don’t express it.
We can do a back-of-the-envelope estimate: wikipedia quotes typical telomere length of 11k bp (base pairs) at birth, and one replication eats up 20 bp. That’s a limit of ~500 divisions, so any human stem cell which divides much faster than every ~(80 yrs)/500 = 60 days needs to express telomerase just to keep dividing throughout our lives. In practice, I’d expect that to be an extreme underestimate, since my understanding is that oxidative damage eats up telomeres considerably faster than replication does, especially for infrequently-dividing cells.
Is telomerasa active in all stem cells?
That’s a tough question to answer; there’s an awful lot of stem-cell types and telomerase activity is not necessarily binary. I wouldn’t be shocked if some of the more-differentiated and/or slower-dividing types don’t express it.
We can do a back-of-the-envelope estimate: wikipedia quotes typical telomere length of 11k bp (base pairs) at birth, and one replication eats up 20 bp. That’s a limit of ~500 divisions, so any human stem cell which divides much faster than every ~(80 yrs)/500 = 60 days needs to express telomerase just to keep dividing throughout our lives. In practice, I’d expect that to be an extreme underestimate, since my understanding is that oxidative damage eats up telomeres considerably faster than replication does, especially for infrequently-dividing cells.