Yes, we do.
I'd be thankful if you actually paid attention.
We can't.
No you don't.
I have not seen.
It could be quite horible, if we are compromising or weakening our stem cell system. Delayed wound healing and compromised healing in older, chronically sick people or prefered lifestyle & prefered interventions related can be due to lesser/decreasing stem cell activity. Probably it become a reason to naturally extinguishing of species. Probably, it can be due to not following the mother nature, lesser direct exposure to mother earth. In zoo, caged & stressed animals do bear less child. Alike in big & polluted cities, fruit trees bear lesser fruits.