Vitamin C Boosts Epidermal Growth via DNA Demethylation

In cell cultures. So nothing about topical, or digestive pathways. Just, expose cells to vitamin c rich medium.

How would topical application work, and what kind of homeostasis effect, from ingestion.

If you are low on vitamin c in your diet, sure. If not, you may not get much benefit from having more.

Topical vitamin C (L-ascorbic acid) at concentrations of 10-20% with pH <3.5 can penetrate the stratum corneum, though stability and formulation significantly impact bioavailability.

You can just freshly mix cheap vitamin C powder and water to the desired concentration, adjust pH to be less irritating. The solution can last for a few days, if cooled and protected from light. For it to be effective (according to studies), it needs to be applied daily/frequently. However, DIY is so cheap, you can use it all over your body. Wash/wipe off excess (see below).

The problem is commercialization. Vitamin C is very, very reactive, so formulating it for shelf storage and production is challenging. I think you either have to add expensive/exotic antioxidant systems, or rely on ascorbate derivatives which may be less/not effective.

Fair warning: Vitamin C degrades to dehydroascorbic acid: After some delay, vitamin C solution may stain skin and everything in contact yellow. DHA may also further break down into erythrulose, a self-tanning agent browning the skin semi-permanently (likely not very healthy). Vitamin C may also react with other things (eg. skin care products) in unpredictable ways and can actually form radicals under some conditions. Eg. It can react with benzoic acid to form benzene. On the modern skin, with UV exposure, a primordial soup of "actives", complex hydrocarbons and all natural metal catalysts, vitamin C may facilitate genesis…

The science is promising, but the chemistry of vitamin C is hard to control, or even reason about.