All you need to know

Platelet Rich Plasma (PRP), 

adjuvant treatment of alopecia.

Pr Barbara Hersant

Plastic Surgery, Henri Mondor Hospital, APHP

Scientific Director of the AIME Congress

The 3 main causes of alopecia are: androgenic alopecia, telogen effluvium and alopecia (1).

In front of any alopecia, a medical assessment is essential and will allow to look for :

The martial deficiencies corresponding to iron deficiencies, malnutrition.

Endocrine causes: dysthyroidism, hyperandrogenism.

Toxic causes: chemotherapy, taking estrogen-progestin.

Causes related to autoimmune diseases: lupus erythematosus, scleroderma.

Infectious causes: folliculitis, HIV infection, syphilis and ringworm

Physical causes: after a trauma, a burn.

Acquired causes: trichotillomania.

Platelet-rich plasma (PRP) is : defined as an autologous biological product derived from the patient's blood and in which (after a centrifugation process) a plasma fraction is obtained with a higher platelet concentration than in the circulating blood.

This therapeutic technology is gaining interest for the regenerative medicine because of its potential to stimulate and accelerate tissue regeneration (2).

The preparation of PRP requires blood sampling. (Figure 1).

Before centrifugation, 8 ml of blood are collected in a tube containing an anticoagulant (sodium citrate).

After centrifugation at 1500G for 5 minutes, the PRP is separated from the red blood cells that sediment at the bottom of the tube.

The tube is inverted several times to re-suspend the platelets contained in the plasma.

Each platelet contains more than 3000 biomolecules.

After activation, the platelet degranulates and releases all these molecules into the recipient tissue.

Figure 1: Preparation of PRP from a blood sample (8 ml) with the RegenKI-BCT® device.

The essential growth factors of the PRP are represented in Table 1.

They include:

The transforming growth factor (TGF β-1)

Platelet derived growth factors (PDGF- α β and PDGF- ββ),

Insulin growth factor (IGF),

Vascular endothelial growth factor (VEGF),

Epidermal growth factor (EGF)

and fibroblast growth factor (FGF-2)

TGF-β1 and PDGF stimulate mesenchymal cell proliferation. 

TGF-ß1 also stimulates the production of extracellular matrix, including collagen. 

Primarily, these factors stabilize damaged tissue during the initial stages of tissue repair and direct local mesenchymal and epithelial cells to migrate, divide and increase collagen and matrix synthesis, ultimately leading to fibrous connective tissue and wound healing.

VEGF and FGF-2 are important in stimulating the formation of new blood vessels to deliver nutrients (3-5).

Table 1. Summary of growth factors in platelet-rich plasma (3-5).
Continued. Table 1. Summary of growth factors in platelet-rich plasma (3-5).

Each growth factor can have different effects on the wound healing process and acts by binding to specific receptors on the cell membranes of the target cells. 

These effects include chemotaxis (cell attraction), inducing cell migration and proliferation, and they stimulate cells to upregulate protein production.

These growth factors not only regulate cell migration and proliferation, but also remodel the extracellular matrix and promote angiogenesis, creating an ideal environment for the regenerative process.

There is no consensus on the preparation of PRP, but the use of a closed circuit kit is preferable to avoid contamination.  Attached, in table 2 see the different kits that have a CE mark.

There is not one PRP but many PRPs. The PRP depends on the donor, but also on the kit used and the method of preparation.

Table 2. Comparison of PRP preparation with different medical devices (6).

One of the methods of preparing the PRP (Figure 2. )

The American Association of Blood Banks technical manual (44) states that "platelet-rich plasma is separated from whole blood by centrifugation. The basic principle of the PRP separation procedure is shown in Figure 2.

Following centrifugation, the blood is fractionated and cellular elements sediment on the surface of the gel in the tubes RegenBCT® (Blood Cell Therapy).

The centrifugation process separates the blood components due to their different densities, i.e. the red blood cells are the heaviest (are trapped by the separating gel), followed by the platelets contained in the plasma, which are the lightest. 

Centrifugation is performed at 1500 g for 5 minutes. 

The platelet yield depends mainly on certain parameters such as the size and shape of the container used, the speed and time of centrifugation and the anticoagulant used. 

There is a significant lack of comparative studies to standardize the procedural parameters of PRP. However, in our laboratory practice, we have used the RegenKit-BCT kit which allows us to have from the same volume of blood a 1.6-fold platelet concentration.

Thus, the PRP obtained with RegenKit®-BCT contains compared to a "natural clot

  • very few red blood cells (< 0.3% recovery),
  • significantly fewer leukocytes (11-13% recovery, or 0.2x),
  • an equivalent amount of fibrin, and 1.6 times more platelets, i.e. 1.6 times more platelet-derived growth factors delivered in their natural relative proportions. (Table 3).


Figure 2. Autologous preparation of platelet-rich plasma (A-PRP) using the RegenBCT® device.
Table 3: Characteristics of the PRP obtained with the RegenKit-BCT kit.

PRP: an adjuvant treatment for alopecia.

To the question is there an increase in hair density? The answer is YES.

Various studies have evaluated hair density and have shown an increase in hair density (7-9).

The study by Gentile et al (8) was a randomized, double-blind trial of 23 patients treated with 3 sessions of PRP injections on a monthly basis or 3 sessions of saline injections.

Hair density was assessed by Trichoscan and the results showed an average increase of 45.9 hairs/cm2 in the treated group versus an average decrease of 5.6 hairs/cm2 in the control group (P < 0.05).

The study by Alves et al (9) was a randomized, double-blind trial of 25 patients treated with 3 sessions of PRP injections on a monthly basis or 3 sessions of saline injections.

Hair density was assessed by trichoscan and the results showed an average increase of 12.8 hairs/cm2 in the treated group versus an average decrease of 2.1 hairs/cm2 in the control group (P < 0.05).

What increase can we expect? An increase of 10 to 20 %.

One of the first articles on PRP for the treatment of alopecia was published in 2006 by Uebel and colleagues, who described a 15 % greater capillary yield in follicular unit density in areas pretreated with PRP compared with controls (10).

The study by Kang et al. was a prospective controlled study of 26 patients treated with 2 sessions of PRP injections at 3-month intervals or with weekly placental extract injections. Hair density was assessed by phototrichogram, and the results showed a mean increase of 29.2 % in hair density in the PRP group (P < 0.0001). (11)

To the question, does hair loss slow down? The answer is YES.

Hair loss has been assessed in studies by the pull test, which was negative in more than 95% of patients.

The study by Singhal et al (12) was a prospective controlled study of 20 patients treated with 4 sessions of PRP injections at 2-week intervals. All patients had a negative traction test result after receiving 4 sessions of PRP injections.

The study by Gkini et al (13) was a prospective, uncontrolled study of 20 patients treated with 3 sessions of PRP injections at 3-week intervals and a final session 6 months later.

The traction test result was negative in all patients after the first of 3 injection sessions and became positive again 3 months after the last PRP injection session.

To the question is there an increase in hair thickness? The answer is YES.

Hair thickness was measured objectively in 2 studies.

In the study by Kang et al (11) Hair diameter increased by an average of 31.3% (P < 0.0001) 3 months after the first injection session and 46.4% (P < 0.0001) 3 months after the second injection session.

In the study by Sclafani (14), the "Hair density index" (15) (composed of the density and thickness of the hair). Part of the increase in this index to 106.4% was due to the increase in hair diameter.

To the question is there creation of new follicles? The answer is no. PRP does not replace hair transplantation.

The growth factors in PRP act on the stem cells present in the bulge area of the follicles, resulting in neovascularization and neofolliculogenesis (16-17). They can improve graft take, but PRP cannot create new follicles on hairless skin.

It is not uncommon to see new hair growing in an area that has been treated but already has a hair bulb. Therefore, we prefer to say that PRP does not allow the creation of new hair.

To the question are there any side effects? The answer is: these effects are minimal to non-existent.

The PRP procedure is a relatively effective and safe procedure with minimal side effects, including temporary and tolerable pain during treatment, mild headaches that may subside with acetaminophen, minimal itching, transient erythema and edema, and scaling. 

To date, none of these effects have been reported: infections, folliculitis, panniculitis, hematoma or seroma formation (19).

Contraindications to the PRP procedure include platelet dysfunction, thrombocytopenia, coagulation disorders, anticoagulant therapy, hepatitis, hemodynamic instability, local infection at the blood collection or PRP injection site, and patients prone to keloid formation


Our Protocol 

We recommend PRP as an adjuvant treatment for androgenetic alopecia and encourage patients to continue topical and/or oral treatments (e.g., minoxidil, spironolactone, and finasteride), because PRP does not suppress the hormonal component of androgenetic alopecia.

Three sessions at 1 month intervals as an initial treatment, then 2 sessions per year for life.

PRP can also be used during and after hair grafting to improve graft yield and maintain graft survival.

PRP administration: Intradermal injection (0.1mL/cm2). By mesotherapy using an injector gun (Figure 3).

Studies recommend subdermal bolus injections because this technique is less painful and overall more effective.

Subcutaneous bolus injections allow the PRP to spread and result in fewer injections. Injections should be spaced in the area of thinning, which is usually along the hairline, part, vertex and crown of the scalp.

Injections according to the topping technique (several small injections in line at 1 cm intervals).

Volumes of PRP injected. The volume of PRP varied considerably between studies between 6 and 20 ml.

Figure 3: Mesotherapy of the scalp by injection of PRP using an injector gun (B. Hersant).


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