Regenerative hair treatments: PRP, exosomes and growth factors — what the science actually says

What does capillary regeneration really mean?

In advertising, the word 'regeneration' can suggest that we are able to manufacture a hair follicle anew where one no longer exists. That is not what we can promise at present.

In hair medicine, when we talk about regenerative strategies we are referring primarily to attempting to modify the follicular microenvironment. We seek to influence the cells of the dermal papilla, vascularisation, inflammation, cellular signals, growth factors and the follicular cycle.

The goal may be to enable certain still-viable follicles to produce higher-quality hair. But reactivating is not recreating.

How does a hair follicle work?

Hair does not grow continuously at the same rate. The follicle passes through different phases. The anagen phase is the phase of active growth. The catagen phase is a brief transitional phase. The telogen phase is a resting phase. Afterwards the hair is shed and a new cycle begins.

In a healthy scalp, thousands of follicles are simultaneously in different phases. The problem arises when certain conditions alter the duration, the synchronisation or the productive capacity of those cycles.

What happens in androgenetic alopecia?

Androgenetic alopecia is the most frequent cause of progressive hair loss in both men and women. In genetically susceptible follicles, androgens — especially signalling related to dihydrotestosterone, or DHT — progressively contribute to a phenomenon known as follicular miniaturisation.

The follicle continues to exist for a long time. But each new hair may become finer, shorter and less pigmented. In other words, a terminal hair is progressively transformed into a miniaturised hair.

This difference is crucial for understanding why certain treatments can work: because we still have a living follicle.

Can a miniaturised follicle recover?

At certain stages, it can improve. If we manage to modify the mechanisms responsible for miniaturisation and once again promote more favourable follicular activity, some hairs may increase their diameter, the duration of the anagen phase and apparent density.

But there is a limit. The more advanced the alopecia and the greater the structural loss, the smaller the margin we have for recovering density through biological stimulation. That is why the timing of diagnosis matters.

What happens if the follicle has disappeared?

Here we must draw a particular distinction with scarring alopecias. In these conditions, inflammation can irreversibly destroy the follicular unit and replace it with fibrosis.

Once a follicle has been completely destroyed, PRP does not create a new one, exosomes do not create a new one, and growth factors do not create a new one. And delaying the diagnosis of cicatricial alopecia while undergoing cosmetic treatments can allow irreversible hair loss to continue. That is why, before regenerating, we must diagnose.

What is scalp PRP?

PRP stands for platelet-rich plasma. It is obtained from the patient's own blood. We draw a certain amount of blood and, through centrifugation, separate its different components. The goal is to obtain a plasma fraction with a platelet concentration higher than that of baseline blood, although the exact composition depends enormously on the system and protocol used.

The preparation is then administered into the scalp. PRP is therefore an autologous treatment — meaning it comes from the patient themselves.

What do platelets do besides clot?

We normally associate platelets with coagulation, and that is indeed one of their fundamental functions. But platelets also contain granules with numerous bioactive molecules. Among these we find various growth factors, such as PDGF, VEGF, TGF-β, EGF, and IGF-1, among others.

When platelets are activated, they can release these signals into the surrounding environment. The therapeutic hypothesis is that certain signals can favourably modify dermal papilla cells, vascularisation, inflammation, the follicular cycle, and the tissue microenvironment.

What are growth factors?

They are signalling molecules. We can think of them as chemical messages between cells. One cell releases a signal, another cell has the corresponding receptor, and when the two interact, a specific biological response is triggered.

Growth factors can participate in processes such as proliferation, migration, angiogenesis, repair, differentiation, and cell survival.

But here we must avoid a common oversimplification: more growth factors does not automatically mean more hair. Follicular biology depends on extraordinarily complex networks. Some signals stimulate certain processes while others inhibit them. And the same molecule can have different effects depending on the concentration, timing, receptor, tissue, and biological context.

Does PRP really work for hair loss?

There is reasonable evidence, particularly for androgenetic alopecia. A systematic review and meta-analysis published in 2025 brought together 43 randomised clinical trials involving 1,877 participants. The overall results support the idea that certain PRP preparations can improve parameters such as hair density, although there is considerable heterogeneity between protocols.

This means that evidence does exist. But it does not mean it works the same way in every patient.

Does PRP work better than minoxidil?

We should not automatically turn them into competitors. A 2025 systematic review and meta-analysis directly compared PRP and topical minoxidil for androgenetic alopecia. The literature shows favorable results for both treatments, but the differences depend on the parameter analyzed, and the studies continue to show heterogeneity.

The most interesting clinical question is often not 'PRP or minoxidil?' but rather 'what therapeutic combination makes sense for this patient?' Because they work through different mechanisms.

Does PRP replace minoxidil or anti-androgenic treatment?

Generally, we should not frame it that way. If androgenetic alopecia is present, we need to treat the disease. PRP can be part of a therapeutic strategy, but we must not lose sight of the fundamental mechanisms driving miniaturization.

Depending on the patient, treatments such as minoxidil, finasteride, dutasteride, other anti-androgenic strategies, and complementary treatments may be considered. The choice depends on sex, age, diagnosis, degree of alopecia, medical history, contraindications, reproductive goals, tolerability, and preferences. Treatment must be individualized.

Why do results with PRP vary so widely?

Because there is no single PRP. Two clinics can use the phrase 'hair PRP' and be administering biologically different products. The blood volume, centrifugation system, number of centrifugation cycles, platelet concentration, leukocyte content, activation method, volume administered, depth, number of infiltrations, and interval between sessions can all vary.

This lack of standardization is one of the major limitations of the literature on PRP and explains part of the heterogeneity found in meta-analyses. That is why asking 'Does PRP work?' is almost too simple: we must also ask 'Which PRP?'

How many PRP sessions are needed?

There is no universally established scientific protocol for all patients. Many studies use several initial sessions separated by weeks, followed in some protocols by a maintenance phase. However, the guidelines vary considerably.

This is why we should be wary of claims such as 'exactly three sessions regenerate 80% of hair.' The evidence does not allow for the establishment of a universal formula of that kind.

When do results start to become visible?

Hair grows slowly, and modifying the follicular cycle takes time. This is why we should not seriously evaluate a hair treatment after ten days. PRP studies typically assess changes over several months.

Furthermore, a single photograph can be misleading due to lighting, angle, length, hairstyle, or whether the hair is wet or dry. The evaluation should be as standardized as possible.

How do we objectively know whether it is working?

We can assess hair density, hair shaft diameter, the proportion of miniaturised hairs, standardised photographs, trichoscopy and digital measurements. This is far more useful than simply asking, 'Do you feel like you have more hair?'.

Because the patient sees their hair every day, and progressive changes can be difficult to perceive subjectively.

What are exosomes?

Exosomes are small extracellular vesicles released by cells. We can think of them, in simplified terms, as tiny cellular communication packages. They carry various molecules: proteins, lipids, RNA, microRNA and other bioactive signals.

These vesicles can interact with other cells and modify their behaviour. This communication capacity has generated enormous interest in regenerative medicine, oncology, immunology, neurology, dermatology and hair restoration.

Are exosomes stem cells?

No. This is one of the most common commercial misconceptions. An exosome is not a stem cell. It has no nucleus, no autonomous capacity for division, and no ability to transform itself into another tissue.

It may originate from mesenchymal stem cells or other cells, but what we administer are extracellular vesicles produced by those cells. Therefore, stem cell does not equal exosome.

What might exosomes do in the hair follicle?

Preclinical studies suggest they may influence several pathways related to growth, survival, inflammation, angiogenesis and dermal papilla activity. Among the pathways under investigation are Wnt/β-catenin, Sonic Hedgehog and TGF-β/SMAD, along with various microRNAs and VEGF-related signals.

A systematic review published in 2026 describes these mechanisms as biologically promising, but emphasises that clinical evidence remains limited and that significant issues around standardisation, production and regulation still exist.

Do exosomes make hair grow?

Here we must distinguish between biological potential and consolidated clinical evidence. The 2025 systematic review on exosomes and hair restoration identified 11 clinical studies. These included 2 randomised trials, prospective studies, retrospective studies, case series and clinical case reports.

The studies reported improvements in at least some hair parameter, but there was enormous heterogeneity in exosome origin, preparation, dose, method of administration, type of alopecia, follow-up duration and outcome measurement.

Therefore, the results are promising. However, we do not yet have the same level of evidence as for more established treatments.

By how much did density increase in the exosome studies?

The 2025 systematic review found reported increases of approximately 9.5 to 35 hairs/cm² across different studies, and increases in shaft thickness of up to approximately 13 μm. But these numbers should not be used as a promise to a patient.

Why? Because the studies used different products, different populations, different protocols, different follow-up periods, and different methods. Furthermore, the sample sizes were generally small. The review itself concludes that we need larger randomized trials and standardized protocols before drawing firm conclusions.

Why is it so difficult to study exosomes?

Because 'exosome' does not define a single drug. Exosomes can originate from adipose tissue, bone marrow, the umbilical cord, the placenta, follicles, or other cellular sources.

In addition, they can vary depending on how the cells are cultured, how the vesicles are isolated, how they are purified, how they are stored, what concentration they contain, and what molecules they carry. Therefore, two products commercially labeled as 'exosomes' can be biologically very different.

What is the difference between exosomes and growth factors?

A growth factor is a signaling molecule. An exosome is a vesicle that can carry multiple molecules. Inside an exosome we can find proteins, RNA, microRNA, lipids, and regulatory signals.

So, to simplify: a growth factor is a message, while an exosome is a vehicle that can carry many messages. It is not a perfect definition from a molecular standpoint, but it helps to understand the difference.

What is the secretome?

Another increasingly used term is 'secretome.' The secretome is the collection of substances that a cell releases into its environment. It can include growth factors, cytokines, proteins, chemokines, extracellular vesicles, exosomes, and other molecules.

Therefore, secretome is not the same as exosomes. Exosomes may be part of the secretome, but the secretome contains much more.

And what about conditioned medium?

Conditioned medium is the medium in which certain cells have been cultured and into which they have released substances. It can contain components of the secretome. But, again, conditioned medium is not the same as purified exosomes.

This distinction is extremely important because commercially we encounter terms such as 'stem cell serum,' 'growth factors,' 'exosomes,' 'secretome,' or 'conditioned media' used almost as if they were interchangeable. They are not.

What does 'hair growth factors' mean?

It can mean many things. It may refer to factors contained in PRP, to recombinant proteins, to secretomes, to conditioned media, to products derived from cell cultures, or to cosmetic combinations.

That is why, if someone offers 'growth factors,' the correct medical questions are: what product exactly? What is its origin? How is it manufactured? What does it contain? What concentration? What clinical evidence supports it? How is it regulated? How is it administered? Without these answers, the expression 'growth factors' tells us very little.

Is scalp mesotherapy a treatment?

The word mesotherapy primarily describes an administration technique. It consists of performing multiple superficial microinjections. But saying 'we do scalp mesotherapy' does not tell us what we are administering: it could be a medication, PRP, a combination of substances, or another preparation.

Therefore, mesotherapy is not the active ingredient — it is the route or technique through which we administer something. What truly matters is what we are injecting.

Can microneedling help?

Microneedling creates microchannels and a controlled injury. This can activate repair mechanisms and also facilitate the delivery of certain substances. There is interesting evidence in androgenetic alopecia, especially in combination with other treatments.

Furthermore, some exosome studies have used microneedling as a delivery system, which adds another variable to the interpretation: does the result come from the exosome, the microneedling, or both? That is precisely why controlled comparative studies are so important.

Can PRP and exosomes be combined?

Biologically, combined strategies are conceivable. But combining two promising treatments does not automatically prove that the combination is superior. To make that claim, we need comparative studies.

In aesthetic and regenerative medicine there is a tendency to think: A works, B might work, therefore A + B must work far better. That is not necessarily true. We need evidence.

Who is most likely to benefit from a regenerative hair treatment?

In general, these strategies make the most sense when viable follicles still exist — for example, in certain patients with androgenetic alopecia, miniaturisation, or early to moderate density loss.

But even within androgenetic alopecia, not everyone responds in the same way. Age, disease duration, degree of miniaturisation, genetics, concomitant treatments, scalp condition, and adherence all play a role.

What about telogen effluvium?

Telogen effluvium has a completely different biology. It can appear after an illness, fever, surgery, physiological stress, nutritional deficiency, thyroid dysfunction, medications, rapid weight loss, or other triggers.

Before injecting any product, we must ask: why is the hair falling out? If there is, for example, an iron deficiency, a thyroid disorder, a responsible medication, a nutritional restriction, or a systemic disease, the fundamental treatment is to identify and correct the underlying cause — not to try to replace the diagnosis with an injection.

And what about alopecia areata?

Alopecia areata is an autoimmune disease. There are studies on PRP and other strategies, but we must not treat it as though it were simply 'a tired follicle that needs growth factors.' Its pathophysiology is completely different.

In extensive cases, we now even have targeted immunological treatments that have significantly changed the therapeutic landscape. So — same symptom, hair loss, but completely different diseases.

And what about cicatricial alopecias?

Here we must be especially careful. In diseases such as certain forms of lichen planopilaris, frontal fibrosing alopecia, cutaneous lupus, or folliculitis decalvans, irreversible destruction of the follicle can occur.

The priority is to stop the inflammation, not to sell regeneration. Because while we debate exosomes, we may be losing follicles forever.

Can we restore a completely bald area that has been that way for years with PRP?

Generally, we should not promise that. If there is an area where the follicles have been extremely miniaturized or absent for a long time, the capacity for response is limited.

In certain patients with advanced androgenetic alopecia, the strategy capable of physically restoring follicles to an area devoid of them may be hair transplantation. Even then, we must treat the underlying condition in an attempt to preserve the non-transplanted hair.

Does PRP carry risks?

Although it is derived from one's own blood, that does not mean zero risk. It can cause pain, inflammation, sensitivity, small bruises, bleeding, headaches, and local reactions.

Furthermore, there are clinical situations in which we must carefully evaluate blood disorders, platelet abnormalities, anticoagulation therapy, active infections, certain medical conditions, and medication use. The indication must be medical and individualized.

Are exosomes necessarily safe because they contain no cells?

We cannot make that claim. The absence of living cells eliminates certain problems, but introduces others related to biological origin, purification, sterility, characterization, content, storage, contamination, and batch-to-batch variability.

A clinical review found few adverse effects in published hair studies, but noted that across the broader range of dermatological applications, serious adverse events had been reported, and it underscored the need for manufacturing standards and regulatory oversight. Therefore, 'cell-free' does not mean 'risk-free.'

Why is regulation so important when it comes to exosomes?

Because we are talking about complex biological products. We need to know what the vial contains, where it comes from, how it was obtained, how it was purified, whether it is sterile, how it was stored, what quality controls exist, and whether different batches are equivalent.

The 2026 systematic review identifies precisely the lack of manufacturing standardization, scalability, uniform regulatory frameworks, and robust long-term safety and efficacy data as significant obstacles to incorporating these therapies on a widespread basis.

So are exosomes just smoke and mirrors?

Not at all. That would be the opposite mistake. There is an interesting biological basis, considerable preclinical evidence, promising clinical signals, and early controlled trials. Research is advancing rapidly.

What is scientifically correct today is to say 'promising,' not 'definitively proven,' and not 'fraud' either. Science rarely needs extremes.

Which currently has more evidence: PRP or exosomes?

Here the difference is quite clear. PRP has numerous randomized clinical trials and several meta-analyses; the 2025 review we cited included 43 randomized trials and 1,877 participants.

Exosomes, on the other hand: the 2025 clinical systematic review found 11 studies, of which only 2 were randomized trials. Therefore, PRP currently has a far more mature clinical foundation and exosomes are an emerging technology. That may change in the coming years, but that is the state of the evidence today.

Does more modern mean better?

No. In aesthetic and hair medicine there is an enormous fascination with words like 'regenerative,' 'biological,' 'stem cells,' 'exosomes,' 'nanovesicles,' or 'growth factors.' But novelty does not equal efficacy, and technology does not equal evidence.

A treatment backed by twenty years of studies may have far more evidence than one presented six months ago as 'the definitive revolution against baldness.'

What questions should I ask before a hair regeneration treatment?

First: what is my diagnosis? Then: what treatment exactly are they proposing? What evidence exists for my type of alopecia? What product will they use? What is its origin? How many sessions do I need and why? How will they measure whether it works? What other treatments should I continue? What are the risks?

And an extraordinarily important question: what result is realistic in my case?

What should happen before any PRP, exosome, or mesotherapy treatment?

A genuine hair evaluation. This may include clinical history, the hair loss pattern, scalp examination, trichoscopy, family history, medication, nutrition, associated conditions, and blood work when indicated.

Because a woman with low ferritin, hypothyroidism, heavy periods, or telogen effluvium does not necessarily need the same strategy as a man with Norwood III androgenetic alopecia. And neither of them needs the same strategy as a patient with frontal fibrosing alopecia.

So what does the future of hair regeneration look like?

It will probably become increasingly biological, personalised, and combined. We are progressively developing a better understanding of dermal papilla cells, follicular stem cells, microRNAs, extracellular vesicles, Wnt/β-catenin signalling, the immune microenvironment, vascularisation, and cellular senescence.

Research on exosomes shows precisely how far we can try to modify several of these pathways simultaneously. But the future of hair medicine should not be about injecting more things — it should be about better understanding what each follicle needs.

What do I want you to remember about PRP, exosomes, and growth factors?

That there is an enormous difference between regenerative science and regenerative marketing. PRP currently has reasonable clinical evidence for certain patients, particularly in androgenetic alopecia.

Exosomes hold tremendous scientific interest, but we still need more randomised trials, more patients, longer follow-ups, standardised products, comparable protocols, and better regulation.

And no regenerative treatment should make us forget the fundamental question: why is the hair falling out? Because in trichology, diagnosis comes before the syringe.