You don't apply DNA methylation - it is the basis for measuring epigenetic age. I mentioned HRT as one way of reducing epigenetic age for epithelial cells.
The reference you gave measure blood or urine samples which would probably not be representative of epithelial cells. Also i like non-descriptive but professional looking stock photos of multi-pipettes and the ubiquitus vortex genie 2. Extra points for consecutive photos of the same tip-rack in obviously proffessional use.
