Younger Regenerative Exosome Serum

Your skin makes glycerin on its own (mostly from sebaceous oil breakdown) and shuttles it to your outermost layer of skin, or your epidermis, via aquaporin-3.

Aquaporin-3 is a transporter that is essential for normal skin hydration, elasticity, and repair. Interestingly, mice lacking in AQP3 have dry and less elastic skin that can be fully corrected with glycerin.

This ingredient is non-irritating, plays well with almost every ingredient, and works across all skin types. Typical use is anywhere between 3-10% but can go up to 79% in some leave-on products.

Just know very high concentrations (>40%) can feel tacky in low humidity.

Glycerin is the name for this ingredient in American English. British English uses Glycerol/Glycerine.

Our skin makes fewer of them as we age. This is a big part of why older skin heals slower and looks less bouncy.

The idea behind putting them in skincare is to "top up" the supply from the outside.

"Conditioned media" sounds mysterious but it's basically just leftover broth.

They're made in a lab where scientists grow human skin cells (fibroblasts) in a nutrient liquid. These cells release a cocktail of helpful proteins into that liquid as they live and grow.

Then, these cells are filtered out and the ingredient is the "conditioned" liquid now full of secreted goodies.

So what does neonatal mean here? It just means the original cells came from newborn tissue (usually donated foreskin), which tend to be younger, more active, and better at pumping out growth factors than adult cells.

Technically, this isn't one single ingredient, it's a mix of dozens of active molecules working together, including:

Studies find growth factor conditioned media can help with:

The evidence behind this ingredient is pretty solid too (and not just marketing).

A 24 week study of a fibroblast conditinoed media serum showed measurable improvements in the look of photodamaged skin, and these results were backed by actual skin biopsies rather than just before/after photoshoots.

And a broader review that pulled together many growth factor studies came to a similar conclusion: they generally help with fine lines, texture, firmness, and are well-tolerated.

It's also worth knowing the caveat that the review pointed out most of these serums also contained peptides, antioxidants, and exosomes.

The honest answer is there isn't a tidy "use at 1-2%" number the way there is for something like niacinamide.

This is because conditioned media isn't a single molecule. Brands add it as a percentage of a finished formula so that number is all over the map.

The serums built around it usually advertise very high levels (~50%) while others just use a splash. And the individual growth factors floating inside are actually present in very tiny amounts (think nano/micrograms per gram).

Here's one regulatory anchor point: the FDA has approved a wound healing gel that uses a pure growth factor at 0.01% (100 micrograms per gram). This shows the active growth factors themselves work at very low concentrations.

So the "50%" numbers you see on labels refer to the diluted broth and not the pure proteins.

The single most important thing to understand growth factors is that they are very fragile.

Dr. Zoe Draelos wrote this about them for Dermatology Times:

Independent lab work backs up the fragility.

Many growth factors lose a big chunk of their activity within a day or two sitting in water at room temperature and this is why smart formulating matters so much. Airless pumps, water-free formulas, and cool storage all help the ingredient survive long enough to do something. It's also a green flag if a brand can show real stability testing.

None of this means growth factor serums don't work; plenty of people get lovely results. It just means the formulation and packaging are doing a lot of the heavy lifting.

You may have heard a worry that growth factors "feed" skin cancer because their whole job is to encourage cells to multiply (this is called mitogenic activity).

It's a fair question to ask so here's the actual picture.

The theoretical concern is real enough that dermatologists take it seriously. There IS a hypothetical worry that they can encourage the wrong cells to grow in skin that already has sun damage or pre-cancerous spots.

Due to this, the cautious advice is to check with your dermatologist before using growth factor products if you have psoriasis, a history of skin cancer, or a lot of pre-cancerous sun damage.

Now the reassuring side:

There has been no documented pattern of growth factor products causing skin cancers despite millions of units sold over many years.

A large safety review of pure PDGF (one of the growth factors in these blends) found it to be non-toxic, non-mutagenic, and non-carcinogenic across decades of medical use. This is including repeated daily application to open wounds.

And a dermatology review specifically looking at topical EGF found no evidence that it stimulates cancer cells to grow (partly because these proteins are large and mostly stay near the surface).

The bottom line for a healthy person with no specific risk factor:

Growth factor conditioned media has a strong track record and is generally considered safe and well tolerated.

But be sure to loop in your dermatologist first if you have psoriasis, active or past skin cancer, or heavy sun damage. This is not because it's proven dangerous but because it's a sensible precaution while the long-term research keeps building.

The US allows human-derived growth factors so Human Neonatal Fibroblast Conditioned Media appears on labels.

In the EU, human-cell-derived ingredients are banned in cosmetics. EU products use plant-derived alternatives (barley is a common one) to get a similar effect.

Propanediol is not likely to cause sensitivity and considered safe to use. It is derived from corn or petroleum with a clear color and no scent.

It's actually inactive on its own and works like a slow-release "storage" form; the enzymes in your skin called esterases gradually convert it into active vitamin E over time.

One in vivo study showed 5% of the acetate in the living layer of the epidermis converted to vitamin E after 5 days of application. This study also found the skin gained protection against UV damage even though the conversion was slow and small.

Once converted, vitamin E acts as a skin's main fat-soluble antioxidant that fights free radicals to protect skin from damage.

Topical vitamin E generally boosts the skin's photoprotection, and it reduced UV-damage in animal models.

This ingredient has some brightening potential but it's more of a prevention ingredient than spot-fader. Cell studies show it can slow down melanin production but it's worth noting that it's not the most powerful brightener out there.

Overall, it has a pretty solid safety profile and has been found to be non-irritating and non-comedogenic. Allergic reactions may happen but stay rare due to how widely the ingredient gets used.

The concentration will vary depending on the formula; industry data shows 0.1% in baby lotions, 3% in lipsticks, and 5% in foot powders. You can also find this ingredient at 100% in a pure vitamin E oil.

Most leave-on skincare keeps it at the lower end, often between 0.5-1%.

You might have heard of "niacin flush", or the reddening of skin that causes itchiness. Niacinamide has not been found to cause this.

In very rare cases, some individuals may not be able to tolerate niacinamide at all or experience an allergic reaction to it.

If you are experiencing flaking, irritation, and dryness with this ingredient, be sure to double check all your products as this ingredient can be found in all categories of skincare.

When incorporating niacinamide into your routine, look out for concentration amounts. Typically, 5% niacinamide provides benefits such as fading dark spots. However, if you have sensitive skin, it is better to begin with a smaller concentration.

When you apply niacinamide to your skin, your body converts it into nicotinamide adenine dinucleotide (NAD). NAD is an essential coenzyme that is already found in your cells as "fuel" and powers countless biological processes.

In your skin, NAD helps repair cell damage, produce new healthy cells, support collagen production, strengthen the skin barrier, and fight environmental stressors (like UV and pollution).

Our natural NAD levels start to decline with age, leading to slower skin repair, visible aging, and a weaker skin barrier. By providing your skin niacinamide, you're recharging your skin's NAD levels. This leads to stronger, healthier, and younger looking skin.

Another name for vitamin B3 is nicotinamide. This vitamin is water-soluble and our bodies don't store it. We obtain Vitamin B3 from either food or skincare. Meat, fish, wheat, yeast, and leafy greens contain vitamin B3.

The type of niacinamide used in skincare is synthetically created.

Copper has wound healing properties due to its role in creating new blood vessels and tissue repair.

This ingredient offers promising benefits, but it is relatively new and more evidence is needed to prove its efficacy. The manufacturer claims this ingredient:

A study from 2022 found this ingredient helped protect skin against damaged from UV exposure (though this should not replace your sunscreen!).

The lysate in the ingredient name refers to a fluid that forms from breaking down the cell membrane.

Because hydrolyzed hyaluronic acid is smaller in size, it can slip past your outermost layer of skin more easily than full-sized HA.

Most formulations will combine all sizes to get the best of both worlds.

Typical usage levels range from 0.01-1%. Any percentage higher than 2% might become goopy and tacky.

This ceramide works by slotting into gaps within the stratum corneum's lipid matrix to limit trans-epidermal water loss (TEWL) and shield the skin against external irritants.

A study with 312 patients found that using a ceramide-containing routine for 4 weeks reduced the severity of atopic dermatitis by over 61%.

Another clinical study in subjects aged 60 and older found that a ceramide body wash and moisturizer improved skin dryness and itchy skin in 15 days.

Overall, ceramides are considered non-irritating and safety tests have found little to no observable adverse effects from using this ingredient.

Ceramide NP is usually sourced from plants (like soybean or rice bran), or produced synthetically.

The skin's ability to produce ceramides gets disrupted in skin conditions like eczema. This in turn weakens the skin barrier and applying ceramides topically has been shown to replenish what's been lost to restore barrier function.

Most of the studies with Ceramide AP test it as part of a multi-ceramide complex; studies reinforce ceramide AP's role in rebalancing ceramides in skin and improving skin hydration.

EOP stands for a linked Ester fatty acid, a linked Omega hydroxy fatty acid, and the Phytosphingosine base.

What makes Ceramide EOP special is its ultra-long fatty acid chain; this unique structure allows it to bridge the lipid layers in your skin barrier to prevent water loss (something no other ceramide can do).

Low levels of Ceramide EOP have been found in people with eczema and psoriasis.

Using it together with other ceramides, cholesterol, and linoleic acid have been shown to meaningfully improve hydration and reduce water loss.

In one clinical study, a regimen using Ceramide EOP, NP, and AP led to significant symptom improvements in patients with eczema, psoriasis, and dry skin in just 4 weeks.

You'll usually see concentrations between 0.1-0.5% in formulations. Overall, this is a well-tolerated and safe ingredient for cosmetic use.

Because it is not a free-fatty acid, this ingredient is fungal acne safe (there's nothing for Malassezia to feed on).

On a cellular level, it disrupts the cell membranes of microbes by poking holes that make the cell leak. This shuts down the chemical reactions the microbe needs to make energy so it can no longer survive.

Another perk of this ingredient is that it stays functional across a wide pH range (3-10).

You'll often see it paired with boosters like Ethylhexylglycerin; one study showed that a 1:9 ratio of Ethylhexylglycerin to Phenoxyethanol damages bacterial membranes as effectively as doubling the Phenoxyethanol concentration on its own.

Typical use concentrations range from 0.3-1% depending on the formula, and this ingredient is capped at 1% int the EU.

Safety-wise, the fear mongering does not hold up to the evidence. The EU's Scientific Committee on Consumer Safety and FDA consider it safe as a preservative at up to 1%, including for children of all ages.

Adverse systemic effects only showed up in animal studies at exposures roughly 200x higher than what people get from cosmetics. And despite its very widespread use, this ingredient is a rare sensitizer and allergic reactions are uncommon.

Caprylhydroxamic Acid is often used with natural antimicrobial products as an alternative to preservatives.

Industry-reported use ranges from 8% in rinse-off products and 2% in leave-on formulations.