Stem cell-derived growth factors: the future of skin rejuvenation?

Let's start with the most important question: are we injecting stem cells?

In the vast majority of the products we discuss in aesthetic medicine, no. And this is the first major source of confusion. When we hear 'stem cell-derived,' many people imagine that we are going to introduce living stem cells into the skin. But many current strategies are based on something different.

Researchers observed that stem cells — particularly certain mesenchymal stem cells — do not act solely by converting into other cell types. They also release an enormous number of molecules into their surrounding environment. Those molecules can communicate with other cells, and this communication appears to be a very important part of their biological effect.

Cells do not simply exist: they talk to one another

This is probably the simplest way to understand it. Imagine a cell as a small factory: it is not isolated — it receives messages and sends messages. Those messages might say 'grow,' 'repair,' 'produce collagen,' 'reduce inflammation,' 'form new vessels,' or 'migrate to this area.' Among these signalling molecules we find growth factors.

What exactly is a growth factor?

A growth factor is a protein or signalling molecule capable of binding to receptors present on certain cells. When it binds to its receptor, it activates a series of messages inside the cell: it is like a key that triggers specific instructions. It does not physically add collagen to the skin, it does not fill a wrinkle, it does not provide volume the way a filler does. It sends a signal, and the cell responds.

What growth factors can be found in these products?

Depending on the cellular source and the production method, we can find different molecules. Among the most studied are VEGF (Vascular Endothelial Growth Factor), related to vascular formation and function; FGF (Fibroblast Growth Factor), involved in the proliferation and activity of fibroblasts; EGF (Epidermal Growth Factor), which participates in epidermal proliferation and repair processes; PDGF (Platelet-Derived Growth Factor), related to tissue repair and fibroblasts; and TGF-beta, a particularly important family in the regulation of remodelling, the extracellular matrix, and collagen production.

But a real biological product does not simply contain 'one growth factor.' It may contain a complex combination of proteins, cytokines, chemokines, extracellular vesicles, and other signalling molecules.

So, what is the secretome?

This word is appearing more and more frequently, and it is quite straightforward to understand: the secretome is the complete set of substances that a cell releases into its surrounding environment. Imagine that we culture cells in a laboratory; during that culture, the cells release growth factors, cytokines, proteins, lipids, extracellular vesicles, and other molecules into the medium. That entire collection constitutes the secretome.

And what is 'conditioned medium'?

When we culture cells in a nutritive liquid, after a certain period that liquid contains the substances the cells have secreted. This liquid is called conditioned medium and may contain a combination of growth factors and other molecules produced by the cells. It has been studied in dermatology, particularly in association with procedures such as microneedling, fractional laser, and other resurfacing treatments.

A systematic review and meta-analysis of randomized trials found that adding stem cell conditioned medium to resurfacing techniques could improve certain photoaging parameters compared to the procedure alone, although the studies were small and heterogeneous.

And what about exosomes?

Here we arrive at what is probably the most fashionable term of the moment. An exosome is not a growth factor, nor is it a stem cell. Exosomes are small extracellular vesicles; we can think of them as tiny packages that one cell sends to another. Inside, they can carry proteins, lipids, RNA, microRNA, and various signaling molecules. That is what makes them so interesting: they do not simply send a message — they can transport an entire set of molecular instructions.

So we have four distinct concepts

Putting it simply: the stem cell is the original living cell; the secretome is everything that cell releases; growth factors are some of the signaling molecules contained within that secretome; and exosomes are small vesicles released by cells that carry different molecules.

They are not synonyms. A product that contains growth factors does not necessarily contain exosomes, and one that claims to contain exosomes does not mean it contains living stem cells.

Why might they rejuvenate the skin?

To understand this, we first need to talk about aging. With age, and especially with accumulated sun damage, fibroblasts reduce part of their activity, the extracellular matrix is altered, collagen breaks down and becomes disorganized, elastic fibers change, the capacity for repair diminishes, the skin loses thickness and elasticity, and wrinkles, irregular pigmentation, and changes in texture appear. The idea behind regenerative medicine is not simply to fill in what is missing, but to try to modify the behavior of the tissue itself.

The fibroblast is one of the key players

Fibroblasts are fundamental cells of the dermis: they produce collagen, elastin, endogenous hyaluronic acid, and other components of the extracellular matrix. Certain growth factors can act on these fibroblasts and modify their proliferation, their activity, and matrix synthesis. This is why there is such interest in using them to improve skin quality, promote repair, and stimulate dermal remodeling.

Will applying a serum with growth factors give me brand-new skin?

No. And this is where one of the great differences between biology and marketing begins. The skin has an extremely effective barrier: the stratum corneum, whose very function is to prevent large molecules from easily entering our body. Many growth factors are relatively large proteins, so their ability to penetrate completely intact skin is limited. This raises a fundamental question: how do we get them to reach the place where we want them to act?

This is where microneedling and fractional laser come in

Microneedling creates microchannels; fractional laser creates microscopic treatment columns. Temporarily, the skin barrier becomes more permeable. That is why many studies have investigated growth factors, conditioned media, or extracellular vesicles immediately after these procedures. The logic is straightforward: first we create a controlled injury, and then we take advantage of that window to facilitate the product's interaction with the tissue.

What do studies show about topical growth factors?

We have more literature than many people imagine. A systematic review published in 2023 analyzed 33 studies with a total of 1,180 participants, including nine randomized trials. Topical treatments with growth factors showed, on average, modest improvements in texture, fine lines, wrinkles, and overall appearance. However, the authors found very significant heterogeneity across products, formulations, and evaluation methods, and several comparative trials found no statistically significant differences compared to controls.

This is important. We cannot say 'growth factors don't work,' but neither can we say 'they all spectacularly rejuvenate the skin.' The truth lies somewhere in between.

And specifically, what about products derived from stem cells?

This is where recent research becomes very interesting. A systematic review published in September 2026 specifically analyzed stem cell-based therapies and derivatives for skin rejuvenation, and found only nine primary clinical studies that met the established quality criteria: five randomized trials, two prospective cohorts, and two case series, with 847 participants in total. Studies involving products derived from human cells showed improvements in parameters such as elasticity, collagen synthesis, hydration, and wrinkles, but the authors were unable to conduct a true meta-analysis due to the substantial heterogeneity across treatments and protocols.

Is it promising? Yes, clearly. Does it mean we already have a perfectly standardized therapy? No. And this distinction is fundamental.

Why are the studies so difficult to compare?

Because saying 'stem cell-derived product' can mean completely different things. The cells may come from adipose tissue, bone marrow, umbilical cord, perinatal tissues, or other sources. Furthermore, the culture method, donor age, cellular conditions, extraction method, concentration, preservation, vehicle, dose, and form of application all vary. That is why two bottles labeled 'stem cell growth factors' can be biologically completely different.

This is probably the biggest problem at present

It is not simply a matter of showing that 'growth factors can work.' The question is: which factors? At what concentration? Derived from which cells? Manufactured how? Preserved how? Administered by what procedure? And none of this has yet been fully standardized.

And now we come to exosomes

Exosomes are probably the area where research — and marketing — is growing fastest. A systematic review of human studies published in 2026 identified 19 studies on exosome-based treatments for skin rejuvenation. Taken together, favorable short-term signals were observed regarding hydration, elasticity, wrinkles, pores, pigmentation, and overall appearance; however, most of the studies were not randomized, and there was considerable heterogeneity in products, methods, and follow-up. Another systematic review and meta-analysis from 2026 also found encouraging results in aesthetic medicine, once again underscoring the need for standardized protocols and better clinical trials.

So, do exosomes work?

My answer would be: they appear promising. That is not the same as saying 'it has been proven that any bottle sold as exosomes rejuvenates the skin.' Those are two completely different statements.

And here we need to talk about regulation

I find this point particularly important. In the United States, the FDA has repeatedly warned about products marketed as stem cells, exosomes, or regenerative medicine without proper approval. The FDA notes that there are currently no approved exosome products for the treatment of diseases, and it has received reports of serious adverse events associated with certain unauthorized products. This does not mean that exosomes are dangerous; it means we need to know exactly which product we are using.

'Exosomes' written on a box does not prove that they actually are exosomes

Correctly characterizing extracellular vesicles requires complex laboratory techniques: size, concentration, markers, purity, origin, sterility, and biological content must all be established. A product may use terms such as 'exosome-like,' 'extracellular vesicle technology,' or 'stem cell secretome' without being equivalent to another. This is something a patient simply cannot determine by looking at the packaging.

What about plant-derived growth factors?

Another very common source of confusion. We find cosmetics advertised as 'plant stem cells.' This does not normally mean that living plant stem cells are regenerating human cells; most of the time we are talking about plant extracts, antioxidant molecules, plant-derived vesicles, or products obtained from plant cell cultures. These may have interesting properties, but a plant stem cell does not become a cell in your skin.

What is the difference with PRP?

Very important. PRP (platelet-rich plasma) also contains growth factors, but those factors come from your own platelets. When we activate the platelets, they release molecules such as PDGF, TGF-beta, VEGF, and others. This is why PRP can also be considered a biological signalling strategy, but it is not the same thing as a stem cell secretome.

And what is the difference with polynucleotides?

Polynucleotides are another distinct group: they are not stem cells, they are not growth factors, and they are not exosomes. They are chains of purified nucleotides used with the aim of modifying the tissue microenvironment and promoting repair and biorevitalisation processes. This is why we must be careful when everything is lumped into the same category called 'regenerative.'

Regenerative medicine does not mean a single technology

Under that label we can find PRP, polynucleotides, growth factors, secretome, exosomes, stem cells, and biological matrices. Each one has different mechanisms, different levels of evidence, and different regulations.

What happens after a laser treatment?

This is one of the scenarios I personally find most interesting. After a fractional laser we have controlled inflammation, repair signals, fibroblasts becoming activated, temporary microchannels, and matrix remodelling. Conceptually, introducing certain biological signals at that moment could modulate inflammation, accelerate recovery, and enhance certain repair pathways. Indeed, many studies are currently exploring this combination.

But we must avoid a very tempting phrase

'It accelerates healing, therefore it rejuvenates more.' Not necessarily. Healing and rejuvenation are not exactly the same thing. We need to demonstrate improved texture, better elasticity, increased collagen, fewer wrinkles, or a clinically relevant outcome. It is not enough for the skin to be less red for two days.

And what about inflammation?

This field is particularly interesting because certain molecules derived from stem cells appear to have immunomodulatory effects. This does not mean they 'eliminate inflammation': inflammation is necessary for repair. However, they may shift the balance between certain pro-inflammatory and repair signals, favouring a more organised repair process.

Could they improve collagen?

This is probably one of the best experimentally supported hypotheses. Factors released by mesenchymal cells can influence fibroblasts and pathways related to collagen synthesis, matrix remodeling, metalloproteinases, angiogenesis, and oxidative stress. Recent clinical studies have also found increases in certain parameters related to collagen synthesis, although the protocols remain highly heterogeneous.

Will they replace the laser, the retinoid, or the sunscreen?

No. And I think this point is essential. The treatments with the strongest evidence against photoaging continue to include far better-known strategies: photoprotection, retinoids, lasers and selected technologies, peels in certain patients, and a sound dermatological strategy. Cell-derived products may become a complementary tool; we must not prematurely turn them into substitutes for treatments backed by decades of evidence.

The problem with the term 'rejuvenation'

We also need to define what it means: fewer wrinkles? better hydration? greater elasticity? improved texture? more collagen under the microscope? a better photographic score? These are not exactly the same thing. A study may demonstrate greater hydration, and marketing can turn that into 'deep cellular regeneration.' This happens all the time.

And this brings me to a very simple rule

When someone offers you a regenerative medicine product, ask what it contains exactly. Not 'is it regenerative?'—because that means practically nothing. Ask: are these growth factors? is it conditioned medium? are these exosomes? are these extracellular vesicles? what cells do they come from? are there clinical studies on this specific product? how is it regulated? is it topical or injectable? These questions completely change the conversation.

Is applying it to the skin the same as injecting it?

No, and this difference is fundamental. Applying a product topically after a procedure that temporarily disrupts the skin barrier has a completely different profile from injecting it into the tissue. The injectable route raises far more important questions about sterility, purity, contaminants, immune response, and regulation. That is why we must be especially cautious with biological products used by injection without clear authorization; the FDA has even reported serious adverse events with unapproved exosome products.

What do we know about long-term safety?

Still less than we would like. Topical studies generally show a reasonably good short-term safety profile, but we have relatively short follow-up periods, very different products, and small populations. And in regenerative medicine, long-term safety matters too.

So, do I find this an interesting technology?

Yes, enormously so. Because for the first time we are trying to move from an aesthetic medicine based solely on filling, paralyzing, or removing tissue to one also grounded in cellular communication, repair, remodeling, and biological signaling. That is fascinating.

But precisely because it is fascinating, we must be more demanding

A sophisticated scientific word can sell a great deal: 'stem cells', 'exosomes', 'growth factors', 'regenerative'. But none of those words replaces a clinical trial, product characterisation, controlled manufacturing, and a correct indication.

The future will probably not be a miracle molecule

It will be more interesting than that. We will probably learn to combine energy, repair, signalling, matrices, and cellular factors in an increasingly precise way: for example, creating a controlled microinjury with a laser, then modulating the inflammatory response, promoting better repair, and perhaps optimising collagen remodelling. That is where this technology can make a great deal of sense.

What I want you to remember

When you hear 'growth factors derived from stem cells', it does not mean that stem cells are being injected into you: we are generally talking about signals produced by cultured cells. These signals can include growth factors, cytokines, proteins, and, depending on the product, extracellular vesicles.

The studies conducted to date suggest a real potential for improving certain parameters of elasticity, texture, hydration, wrinkles, and collagen remodelling. But science is still trying to answer fundamental questions about dosage, origin, concentration, manufacturing, route of administration, and duration of effect. The most recent systematic review available in 2026 finds promising results, but only nine major clinical studies sufficiently adequate to be included, and heterogeneity too significant to combine the results through meta-analysis.

I am Dr Florian Vallecillo, and if I want to leave you with a single idea today, it is this: the future of skin rejuvenation will probably not consist solely of adding volume or removing a wrinkle, but increasingly of learning to communicate with the cells of the skin. Growth factors, the secretome, and extracellular vesicles are part of that new way of thinking. But a promising technology does not need exaggeration to be interesting: it needs good products, good science, reproducible protocols, and physicians capable of distinguishing between real biology and regenerative marketing. That, for me, is the true challenge of regenerative aesthetic medicine in the years ahead.