Growth Factors and Stem Cells to Solve Hair Thinning

By - AMS posted Jan 12, 2022 11:32 AM


Daniel Sister reviews the available literature and recommends a new treatment

Hair loss, hair thinning, platelet rich plasma, growth factors, stem cells

It’s an unfortunate fact of life that we lose hair and/or have thinner hair as we age, both male and female alike. Every day we lose some hair, whether when in the shower, brushing, drying or styling. According to the American Hair Loss Association, two-thirds of men above the age of 35 show signs of hair loss. Although more prominent in men, hair loss is a condition that also affects women generally from their 50s and 60s. However, there are different types of hair loss. 

Alopecia areata (AA) is a common condition that causes inflammation-induced hair loss. It is characterised by well-demarcated patches of hair loss, which can progress to complete loss of hair from the scalp (alopecia totalis) or even from the whole body in the most severe of cases (alopecia universalis). Often, patients are young, so the disease burden is substantial, leading unsurprisingly to overwhelming effects on the patient’s quality of life and self-esteem. 

Alopecia areata is considered an organ-specific autoimmune disease stemming from loss of the hair follicle’s (HF) immune privilege, so therapies are mostly immunosuppressive. Finding new therapies for this condition, and improving the effectiveness of existing conditions, are therefore of utmost importance.


In men, this condition is generally known as male pattern baldness, but it can also affect women and is defined as common, chronic, progressive hair loss. 

Androgenetic alopecia is characterised by miniaturisation of the hair follicles, gradually causing conversion of terminal hairs into vellus hairs, leading to a progressive reduction in the density of hair on the scalp. It affects up to 80% of Caucasian men and 40% of women. Its frequency increases with age, despite the fact that it may start at puberty.

A number of products have been proposed as hair loss therapies. Drug therapies specifically approved by the Food and Drug Administration (FDA) are limited to minoxidil and finasteride. Specific vitamin cocktails (Vivascal) or stem cell extract (Calecim). 

Although testosterone acts directly on many tissues, some of its desirable effects do not occur until it is converted into another androgen, in this case, dihydrotestosterone (DHT). DHT is a specific hormone responsible for male and female pattern baldness.

DHT acts on the skin (sometimes producing acne) and on the hair follicles, putting hair on the chest but often taking it off the scalp. Male-pattern baldness is one thing, prostate disease quite another — but DHT also stimulates the growth of prostate cells, producing normal growth in adolescence but contributing to benign prostatic hyperplasia (BPH) in many older men.


The daily normal loss is less than 100 hairs per day and these are normally replaced by new, thick hair — so the loss does not tend to be noticeable. Normally, this cycle of hair production will continue for the duration of a person’s life.

With age, hair becomes thinner (intermediate or miniaturised hair) and the growth cycle is not as successful at replacing the lost hairs. However, hair loss can be linked to the ageing process as well as other factors, including stress, illness, hormonal changes, side effects of medication, or even excessive hair styling, such as hair extensions. They may influence and inhibit hair production by aberrant hair follicle cycling and changes in the hair follicle morphology, leading in some cases, to the physical destruction of the hair follicle. 

Hair is an extremely complex structure, consisting of several different cells and chemical species. The root lies below the surface of the skin and is enclosed within a hair follicle, which is in turn entirely encased in connective tissue and acts as the hair production unit. 

The core of any hair follicle is the hair fibre, which is composed of different types of epithelial cells.

The primary component of hair fibre is keratin, a long chain of amino acids that forms the cytoskeleton of all epidermal cells. Research has proven that the durability and resistance of hair fibre to degradation under environmental stress stems from the high amount of sulphur that comes from the amino acid — cysteine — in the hair fibre. The sulphur in the cysteine molecules in adjacent keratin proteins binds to form disulphide chemical bonds, which are very strong and very difficult to break.

These cells are in contact with the dermal papilla, situated at the base of the hair follicle. The dermal papilla is fed by the bloodstream, which carries nutrients to produce new hair and plays an essential role in the promotion and maintenance of hair growth.

Under normal circumstances, hair growth in each hair follicle follows a cycle consisting of three main stages: anagen (growing phase), catagen (transition or rapid involution phase) and telogen (resting phase).

Under the influence of the dermal papilla, differentiation of the epidermal cells during the anagen stage produces hair fibre and associated products. Insufficient dermal papilla cell stimulation results in the suspension of growth of the hair fibre and root sheaths. The dermal papilla can become isolated in the dermis and the hair fibre can be pulled out, leading to hair loss. 

New developments in preventing and/or treating both hair loss, hair thinning, and baldness has occurred with the use of growth factors such as platelet-rich plasma (PRP) and stem cell extracts on the scalp.

PRP is derived from autologous blood (patient’s blood) and is therefore inherently safe and free of transmissible diseases. It consists of a high concentration of blood platelets in a small volume of plasma.

Platelets in the plasma are small (2 micrometres) but powerful. They contain the alpha vesicles that store and release the growth factors promoting healing and regeneration (tissue healing and bio-cellular regeneration).

Platelet-rich plasma therapy has established itself as an effective treatment option to treat hair loss. The procedure has been discussed on many patient forums like or and has a high patient review rating on


Stimulate the growth of dermal mesenchyme. PDGF signals are involved in both epidermal follicle interaction and the dermal mesenchyme interaction required for hair canal formation and the growth of dermal mesenchyme. 


In 2001, Yano et al.1, Lashgar et al.2, and Kozlowska et al.identified VEGF as a significant mediator of hair follicle growth and cycling, providing the first direct evidence that improved follicle vascularisation promotes hair growth as well as increases follicle and hair size. It also allows for a significant increase in perifollicular vascularisation during the anagen phase of the hair cycle, followed by regression of angiogenic blood vessels during the catagen and telogen phase.

In 2007, a trial of 104 patients receiving hair transplants by Rinaldi et al.4 showed, by means of confocal microscopy, that the up-stimulation of VEGF through adenosine receptors induces significant changes in the average diameter of the scalp’s perifollicular vessels compared with placebo and an elongation of the transplanted follicles in the anagen phase. 


Stimulates mitosis in epithelial cells and fibroblasts and improves the ratio of anagen. EGF inhibits the entry to the catagen phase by promoting the anagen phase. EGF signals control the orientation and elongation of follicles and are co-stimulating angiogenesis5.


Stimulates the proliferation and differentiation of keratinocytes and endothelial cells, as well as improves the advancement of hair follicles. 


Improves the migration, survival, and proliferation of HF cells. Furthermore, IGF-1 has been suggested to play a crucial role in regulating cellular differentiation and tissue generation during the development of hair follicles.


Greatly stimulates hair growth and slows down apoptosis. 


Stimulate DNA synthesis, the proliferation of several types of cells, and increase type I collagen production. They also stimulate the signalling pathways that manage the hair cycle.


Works with HGF activator (discharged by DPs) to enhance the proliferation of follicular epithelial cells. 


TNF-alpha (Tumor Necrosis Factor) is an inflammatory cytokine responsible for a diverse range of signalling events within cells, leading to apoptosis.


We now know plasma contains more than 300 growth factors, including the keratinocyte growth factor, stem cells (21) (CD44+, CD90+), and signalisation molecules: CD9, CD-W17, CD41, CD42a-d, CD51, CD-W60, CD61, CD62P, CD63. As well as other chemokines and cytokines: fibrin, fibronectin, vitronectin, Epinephrine, SDF-1 (stromal cell-derived factor).  

Uebel et al.6 have shown that storing hair grafts in PRP can enhance graft survival, improve hair density and stimulate the growth of transplanted follicular units.

Figure 2 Patient  (A) before and (B) 3 months after treatment with PRP

Following this, Li ZJ et al.7 published their results on the use of PRP as a potential therapeutic tool for promoting hair growth. Takikawa8 wrote: ‘Activated PRP increased the proliferation of DP (dermal papilla) cells and stimulated extracellular signal-regulated kinase (ERK) and Akt signalling. Fibroblast growth factor 7 (FGF-7) and beta-catenin, which are potent stimuli for hair growth, were up-regulated in DP cells. The injection of mice with activated PRP induced faster telogen-to-anagen transition than was seen on control mice.’

In their 2009 study, Greco and Brandt9 observed at 3 months an increase in hair density of 18.8% and 29% at 9 months. 

In 2013, Trink et al.10 conducted a very in-depth and the first-ever pilot study to evaluate the efficacy and safety of PRP for the treatment of alopecia areata (AA) in a randomised, double-blinded, placebo and active-controlled, half-head, parallel-group.

A total of 45 AA patients (males and females) were randomised to receive intralesional injections of PRP, triamcinolone acetonide (TrA) or placebo on one half of their scalp. The other half was not treated.

A total of three treatments were given to each patient, with an interval of one month between treatments. The endpoints were hair regrowth, hair dystrophy (as measured by dermoscopy), burning/itching sensation, and cell proliferation (measured by Ki-67). The monoclonal antibody was used to determine the numbers of cycling cells in hair follicles both in alopecia areata and in normal scalp skin.

Patients were evaluated at four points in time: T0 = beginning of study, T1 = 2 months, T2 = 6 months, T3 = 12 months. 

Each patch was digitally macro-photographed, measured, and evaluated by three independent evaluators who were unaware of the treatment modalities. The SALT score was used, which represents hair regrowth as a percentage of change from baseline.

The percentage of dystrophic hairs was evaluated on a four point scale: 

  • 0 = no dystrophic hairs 
  • 1 = 1-29% dystrophic hairs 
  • 2 = 30-50% dystrophic hairs 
  • 3 = >50% dystrophic hairs.

The conclusions cannot be challenged. The treatment with both TrA and PRP led to significant hair regrowth in AA lesions when compared to placebo. Both treatments also led to increased hair regrowth when compared to the untreated side of the scalp. However, patients treated with PRP had significantly increased hair regrowth when compared with those treated with TrA. 

The other interesting factors were that while 96% of the patients in the PRP group experienced regrowth of fully pigmented hair from the beginning of hair growth, in the TrA group, only 25% achieved pigmented hair at the beginning stages of hair regrowth.

This randomised group study proved that PRP injections contribute to major improvements in AA lesions, with 60% of patients achieving complete remission at the end of the study. 

The growth factors from the injected PRP are released and locally activated. They stimulate angiogenesis near the hair root so that the supply of oxygen and nutrients through the blood is re-enabled. The growth factors also shorten the rest period of the follicle, so the growth phase is extended. 

Figure 3 Patient (A) before and (B) 3 months after Calecim hair microneedling

Donners S and de Bruijn11 used PRP during a hair transplant procedure in order to maintain the viability of the graft. Studies have also shown that PRP injected into the scalp during a hair transplant procedure has beneficial results for the patients. Uebel4 studied a small series of patients comparing two areas of hair transplant with or without PRP in the root of the grafts. Two areas (2.5 cm2) were marked on the scalp and each planted with 20 grafts/cm2. After 1 year, the area implanted with the PRP-enriched grafts demonstrated a higher follicle unit survival rate and density.

PRP has multiple uses when used in conjunction with hair transplants. It can be used to strengthen a poor donor area, improve graft survival and minimise the post-operative side-effects. Furthermore, injecting PRP into the patient’s scalp increases vascularisation to the transplanted follicular units, thus increasing yield and the density of non-transplanted hair.

Recently Sukhbir Singh12 published his experience of over 20 patients with chronic biopsy proved AA disease. Each patient would have had two unsuccessful years of various forms of therapy. They were then treated with PRP alone, without any side effects, and with good preliminary results.


Stephens13 treated ten male patients (age range, 25–72 years) suffering from AGA at stage II to III according to the Norwood-Hamilton scale and were treated with a single injection of autologous PRS (combination of PRP and SVF) in the upper scalp. Hair density was significantly increased after 6 weeks and 12 weeks post-injection (P = 0.013 and P < 0.001). In hair-to-hair matching analyses, new hair grew from active follicles. Furthermore, non-functioning hair follicles filled with hyperkeratotic plugs, assumed incapable of forming new hair, actually grew new hair.

Interestingly Giordano S et al.14 conducted a meta-analysis on the evidence for platelet-rich plasma for androgenetic alopecia by comparing local injection of PRP versus control groups to investigate the efficacy of local PRP injections in AGA. They performed a systematic literature search. The increase in the number of hairs was the primary outcome. Secondary outcomes were the increase of hair thickness and the percentage increase in hair number and thickness. Seven studies involving 194 patients were retrieved and included in the present analysis. The conclusion found local injection of PRP for androgenic alopecia might be associated with an increased number of hairs in the treated areas with minimal morbidity.

Hausauer AK and Jones DH15 conducted a single-centre, blinded, randomised clinical trial to evaluate the efficacy of different platelet-rich plasma regimens for the management of moderate androgenetic alopecia among 40 patients. Folliscope hair count and shaft calibre, global photography, and patient satisfaction questionnaires were obtained at baseline, 3 months, and 6 months.

They concluded that subdermal PRP injections are an efficacious and tolerable therapy among men and women with AGA. The benefits may be greater if first administered monthly.

Figure 4 Patient (A) before and (B) 3 months after calecim hair microneedling

In February 2018, Ahmad M.16 conducted his study in a private setting in which patients were undergoing PRP treatment. The baseline platelets count was noted for each subject and three PRP treatments were performed at 0, 1, and 3-month intervals.

The diameter of 10 hairs (1 cm sq) was measured randomly using the calliper (2 hairs on each side of the square and 4 in the centre). After 6 months of the third injection, the hair calibre was measured, and the results were analysed statistically. At the beginning of the experiment, the mean hair calibre was 37.3 μm (39.1 μm in men and 33.0 μm in women). At the end of the study, the mean hair calibre was 53.9 μm in men and 48.7 μm in women (P<.01). The increase in the hair calibre was noted to be 27.5% more in men and 31.3% more in women (P<.01). The author concluded PRP injections could increase the hair diameter.

In 2018, Starace M et al.17 investigated the efficacy, tolerability, and clinical improvement of PRP for the treatment of female alopecia. 

A total of 10 female patients affected by AGA and not responding to treatment with minoxidil and/or oral antiandrogens were enrolled. 

After 24 weeks, the median relative percentage change (%RC) for all the parameters of hair density was mostly positive. They concluded that platelet-rich plasma injections have a positive therapeutic effect on hair density and hair diameter improvement.

In Egypt, Tawfik A and Osman M18 conducted a randomised placebo-controlled study. The objective was to evaluate the efficacy and safety of autologous platelet-rich plasma in the treatment of female pattern hair loss.

Thirty female patients with female pattern hair loss were randomly assigned to receive autologous PRP injections into a selected area, while another area was injected with normal saline as a placebo.

Sessions were performed weekly for a maximum total of four sessions. Patients were followed up 6 months after the end of the last session. The outcome was assessed both subjectively and objectively.

There was a statistically significant difference between PRP and placebo areas (P<.005) regarding both hair density and hair thickness as measured by a folliscope. The hair pull test became negative in PRP-injected areas in 25 patients (83%) with an average number of three hairs.

Androgenetic alopecia is characterised by a shortened anagen phase and miniaturisation of the terminal to vellus hair. 

PRP appears to prolong the anagen phase of the hair growth cycle through increased expression of FGF-7, as well as increase cell survival by inhibiting apoptosis (associated with increased Bcl-2 protein levels as well as activated Akt signalling). It also appears to increase the perifollicular vascular plexus through the increase of two major growth hormone levels (VEGF and PDGF), which increase the micro vascularisation potential. Activated PRP seems to promote differentiation of stem cells into hair follicle cells through the upregulation of transcriptional activity of beta-catenin. In vitro, it demonstrated the proliferation of dermal papilla cells and an increase of dermal papilla cell growth by activating ERK signalling. Therefore, it constitutes a potent and useful tool for androgenetic alopecia treatment.

Maria-Angeliki Gkini et al.19 published their results on studies of PRP injections in the treatment of androgenetic alopecia.

Twenty patients (18 men and two women) were included and concluded one study. The mean age of patients was 34 years (24–72). Among men, according to the Hamilton-Norwood scale, five patients suffered from type II androgenetic alopecia, eight from type III, four from type IV and one from type V alopecia. Both women suffered from I-3 androgenetic alopecia, according to the Ludwig scale. Six patients had previously sought medical help for their hair loss and they had been treated with topical minoxidil lotion 5%. During the last six months since the onset of PRP therapy, they had not received any medication. None had undergone hair transplantation. 

All patients were evaluated at six time points: T1– beginning of the study, T2–3 weeks, T3–6 weeks, T4–3 months, T5–6 months, T6–1 year.

In terms of satisfaction, 85% of patients reported an improvement in hair quality and thickness with a mean result rating of 7.1 on a linear analogue scale of 1–10 (1 = no result, 10 = best result), and 65% reported an increase in hair density. At six months, all patients (100%) wanted and/or needed a booster session, while, at the conclusion of the study (1 year), 75% only needed one.

Patients with grade II–III alopecia, according to the Norwood-Hamilton scale, had better results compared to patients with more advanced alopecia. Both women were satisfied with the results. Furthermore, patients with vellus hair had better results compared to those who had few but normal hair, as PRP appeared to act on hair diameter, causing thin hair to become thicker.

Macroscopic photographs showed an overall improvement in hair density and quality, as lanugo-like hair became thicker, normal hair.

Rinaldi4 described the use of PRP in alopecia areata. Activated autologous PRP has been reported to bring about the proliferation of dermal papilla cells by up-regulating fibroblast growth factor 7 (FGF-7) and b-catenin as well as extracellular signal-related kinase (ERK) and Akt signalling. Anagen-associated angiogenesis is one of the important factors in active hair growth due to the secretion of vascular endothelial growth factor (VEGF) by the keratinocytes of the outer root sheath and fibroblasts of the dermal papilla. Increased secretion of VEGF influences the growth of normal and pathological dermal structures. Tobin et al.20 reported that the hair follicle mesenchyme exhibits significant hair cycle-associated plasticity. Modulation of these cell interchanges is likely to be important during clinically important hair follicle transformations, for example, value-to-terminal and terminal-to-vellus transformations during androgenetic alopecia. Injection of PRP has been demonstrated to improve cutaneous ischemic conditions and to increase vascular structures around hair follicles. 


My approach is based on a study by Pietro Gentile et al.21 published in March 2020 evaluating the interest of PRP and PPP in a retrospective, blinded, randomised evaluation in androgenetic alopecia in hair growth; in which 90 patients, 63 males showing AGA in stage I–V by the Norwood-Hamilton scale and 27 females with AGA in stage I–III by the Ludwig scale, treated since 2013, were analysed. 

In total, 57 patients were treated with non-activated (A)-PRP injections and 33 patients were treated with autologous activated (AA)-PRP in three sessions spaced 30 days on average. Assessment of hair regrowth was evaluated several weeks (Ws) after the treatment, summarised in four phases: T0, before the first infusion, T1–12 Ws, T2–23 Ws, T3–44 Ws, and T4–58 Ws after the last treatment.


Twelve weeks, 23 Ws, 44 Ws, and 58Ws after the last treatment, hair density measurements for patients treated with A-PRP and AA-PRP were 65 ± 5 and 28 ± 4 hairs/cm2 at T1, 28 ± 2 and 15 ± 3 hairs/cm2 at T2, 25 ± 3 and 14 ± 3 hairs/cm2 at T3, and 23 ± 3 and 13 ± 3 hairs/cm2 at T4. The positive effects of A-PRP and AA-PRP on hair regrowth during a long-term follow-up was demonstrated.

Personally, I take at least 20 cc of blood in a specific kit without a chemical buffer to separate the erythrocytes and the plasma. 

The result after centrifugation (8 minutes at 450g) is about 10 cc of plasma (platelet-rich and platelet-poor plasma). 

The whole of the plasma (PRP and PPP) with a specific 2 ml stem cell extract (Calecim Hair) is then injected superficially under the scalp (0.1 ml) every cm and massaged onto the scalp. 

Another method based on W. M. Ramadan et al.22  would be to traumatise the scalp with a derma roller prior to injections. The study was done on 126 AGA patients, 84 patients were subdivided into two groups, and they received PRP sessions as co-adjuvant therapy using different methods of administration. Patients were evaluated clinically by digital dermoscopy to measure hair density and diameters before and after treatment. The PRP-treated patients showed statistically significant increases in hair density and diameter measurements than the control group. These results increased by using micro-needling as a method of PRP administration. This study justified the cocktail of PRP and Calecim.

According to Dr Li Chun Xiang and Dr Yin Hui of the Singapore Polytechnic, Dept of Technology, Innovation and Enterprise, at the optimum concentration of CALECIM®, dermal papilla cells displayed positive growth of 24%23.

This measurement of DP cell growth is comparable to the cell growth shown when hair follicle cells were exposed to Minoxidil.  

Also, tumour necrosis factor-alpha (TNF-alpha) is an inflammatory cytokine produced by macrophages/monocytes during acute inflammation and is responsible for a diverse range of signalling events within cells, leading to necrosis or apoptosis. When exposed to CALECIM®, TNF-alpha was demonstrated to be reduced by up to 30x, which is comparable to that of Vitamin D.


The latest development is the proof of positive results with stem cell extract and, therefore, the logic using PRP and stem cells.

Pietro Gentile et al.21 performed a systematic review of platelet-rich plasma use in androgenetic alopecia compared with Minoxidil®, Finasteride®, and adult stem cell-based therapy by assessing local injections of PRP compared to any control for AGA. The protocol was developed in accordance with the Preferred Reporting for Items for Systematic Reviews and Meta-Analyses-Protocols (PRISMA-P) guidelines. A multistep search of PubMed, MEDLINE, Embase, PreMEDLINE, Ebase, CINAHL, PsycINFO,, Scopus database, and Cochrane databases was performed to identify studies on hair loss treatment with platelet-rich plasma. 

Of the 163 articles initially identified, 123 articles focusing on AGA were selected and, consequently, only 12 clinical trials were analysed. The studies included had to match predetermined criteria according to the PICOS (patients, intervention, comparator, outcomes, and study design) approach. In total, 84% of the studies reported a positive effect of PRP for AGA treatment. Among them, 50% of the studies demonstrated a statistically significant improvement using objective measures and 34% of the studies showed hair density and hair thickness improvement. Only 17% of the studies reported that PRP was not effective in treating AGA. The information did not show any major side-effects, and thus, it may be considered as a safe and effective alternative procedure to treat hair loss compared with Minoxidil® and Finasteride®.

  Declaration of interest None

  Figures 1 Text description © Calecim, illustration
© Adobe Stock , 2-4 © Dr Daniel Sister, K Morell



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