Epitalon and telomere length
Longer chromosome ends invite another question: in which cells, and by which route?
The fetal-fibroblast result
In the human fetal fibroblast experiment, Epithalon was added to cultures that initially lacked telomerase activity. The study reported expression of the catalytic telomerase subunit, enzyme activity and telomere elongation. Epithalon is the spelling used in that paper's title.
I appreciate the linked measurements. The account moves from expression of a component to activity of the enzyme and then to the length of the chromosome ends. Each measurement gives the next one a little more context.
The population matters just as much: these were human fetal fibroblasts in culture. A finding in human cells can be biologically interesting while the question of a benefit to a person remains unanswered.
Normal and breast-cancer cell lines
A later study reported telomere extension through hTERT upregulation and telomerase activation in normal human cells. In breast-cancer cell lines, extension occurred largely through Alternative Lengthening of Telomeres, abbreviated ALT. The study reported only minor ALT activity in the normal cells.
This is the result that makes a simple rejuvenation story awkward. I regard that awkwardness as useful: the same broad lengthening outcome came with a different dominant mechanism in cancer cells. A longer telomere cannot carry an uncomplicated judgement of benefit on its own.
The finding also stops short of a prediction about a person's cancer risk. The experiment concerns human cell lines, including breast-cancer lines. It offers a reason for more careful mechanistic and safety work.
Function after telomere extension
I would give priority to a study that connects telomere maintenance with durable, appropriate cell function. Length is an attractive measurement because it sounds like a restored resource. The normal-cell and cancer-cell comparison makes the cell's identity and the route of maintenance just as interesting.
A review of Epitalon also notes limited physical, chemical and structural characterisation and uncertainty about whether the proposed mechanisms are the whole account. That is a useful reminder that even the underlying description of the peptide still has open questions.
The gingival stem-cell experiment has its own change-of-identity question. It concerns nerve-related markers rather than telomere length, so its result needs a separate place in the gallery.