Platelet-Rich Plasma for Androgenetic Alopecia:
A Pilot Study
Giovanni Schiavone, MD,* Desanka Raskovic, MD,† Joseph Greco, PhD, PA/C,‡
and Damiano Abeni, MD, MPHx

BACKGROUND Androgenetic alopecia is a common condition, with severe attendant psychosocial implications, and for which it is difficult to obtain a satisfactory degree of clinical improvement.
OBJECTIVE To explore the possible clinical benefit of injecting platelet-derived growth factors into the scalpof patients using a specific autologous blood concentrate.
MATERIALS AND METHODS Two injections of a leukocyte platelet–rich plasma (L-PRP) with the addition ofconcentrated plasmatic proteins were administered at baseline and after 3 months (single spin at baseline anddouble-spin centrifugation at 3 months). Macrophotographs were taken at baseline and after 6 months, and 2
independent evaluators rated them using Jaeschke rating of clinical change.
RESULTS Sixty-four consecutive patients were enrolled. Some improvement was seen in all patients by 1
evaluator and in 62 by the other. The mean change in clinical rating was 3.2 (95% confidence interval [CI], 2.9–3.5) and 3.9 (95% CI, 3.5–4.3), and the proportion of patients reaching a clinically important difference was 40.6%
and 54.7%, according to the 2 evaluators, respectively.
CONCLUSION Our pilot study may provide preliminary evidence that this treatment may induce somedegree of clinical advantage for male- and female-pattern baldness. This may warrant the design ofrandomized controlled clinical trials to formally test this procedure.
The authors have indicated no significant interest with commercial supporters.

asic science and research ﬁndings have pointed
out the role of platelet-derived growth factors(PDGFs) to be biologically active in many key
regenerative steps, such as the development ofangiogenesis, the formation of the protein matrix, andthe enhancement of cell proliferation. Autologous bloodconcentrates, aimed at both the delivery of biologically
active substances such as growth factors, cytokines,
ﬁbrin, and at autologous blood cell transplantation (e.g.,
leukocytes), have recently been involved in a large
number of new clinical applications in different medicalﬁelds. The use of platelet concentrates has spreadworldwide, fueling a large clinical interest inBregenerative medicine, in which it has been directed
to many diverse conditions in several specialties, suchas orthopedics, sport medicine, plastic and aesthetic
surgery, and in the treatment of diabetic ulcers. In
fact, it is so widespread that terms such as “platelet-richplasma” (PRP) and “platelet gel” have rapidly become
popular among doctors and patients.
Whereas, androgenetic alopecia causes many maleand female patients worldwide to feel uncomfortablewith their appearance, and affected individuals feelthat alopecia is a serious condition with major implications in their daily life, often leading to high levels of*Plastic Surgery and Regenerative Surgery Unit, IDI-IRCCS, Rome, Italy; †Second Clinical Dermatology Unit, IDI-IRCCS,
Rome, Italy; ‡Hair Restoration Surgery, Greco Medical Group, Sarasota, Florida; xHealth Services Research Unit,
IDI-IRCCS, Rome, Italy
Supported in part (D.A.) by the “Progetto Ricerca Corrente 2012 and 2013” of the Italian Ministry of Health.

·© 2014 by the American Society for Dermatologic Surgery, Inc. Published by Lippincott Williams & Wilkins
ISSN: 1076-0512 Dermatol Surg 2014;40:1010–1019 DOI: 10.1097/01.DSS.0000452629.76339.2b

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SCHIAVONE ET AL

anxiety and depression.1,2 Currently available treatments are at times perceived as having limited effectiveness. For example, topical minoxidil has to be
used twice daily, which can be inconvenient; it canalso cause scalp itching, dryness, scaling, ﬂaking,irritation, or burning. Side effects are also a concern
for oral ﬁnasteride, especially in young males, because
it could decrease sexual ability/desire and the amountof semen released during sex. In addition, the safety
and effectiveness of oral ﬁnasteride should be morethoroughly assessed in women.
The trend in therapies and clinical studies seems now tofocus with a new, more “biologically oriented” approachto male- and female-pattern hair loss since new ﬁndings
pointing out the inﬂuence of hair follicle stem cells in thehair growth cycle have been reported.3
We now know that progenitor stem cells in the bulge
area play a key role in igniting the hair cycle4; furthermore, PDGF may have related functions in theinteractions arising between the bulge and associatedtissues starting with follicle morphogenesis.5,6 We
have also considered the hypothesis that PDGFs
seem to act on speciﬁc populations of progenitor
cells that give rise to several different cell types with
distinct functions in a variety of developmental
processes.7
Furthermore, various reports suggest other possible
interactions between hair follicles and PDGF. Plateletderived growth factor signals, in fact, seem to playa role in hair canal formation,8 whereas vascularendothelial growth factor (VEGF)-mediated angiogenesis involvement9 was demonstrated in the controlof hair growth and follicle size.
Recently, activated PRP has been reported to stimulate
the proliferation of human dermopapillar cells,
thereby increasing the survival of hair follicle cells
through its antiapoptotic effects on dermopapillar
cells and possibly stimulating hair growth by prolonging the anagen phase of the hair cycle. The in vitro
ﬁndings were conﬁrmed by in vivo results, whichshowed faster growth of hair in mice treated with PRP
every 3 days for 3 weeks than that in the untreatedcontrols.10

Most recently, intradermal injections of PRP at thethinning scalp site in 26 patients were shown tomarkedly increase hair diameter, whereas histologic
ﬁndings showed a thickened epithelium, proliferationof collagen ﬁbers and ﬁbroblasts, and increased vessels
around follicles.11,12
We conducted this study to verify whether sucha cellular and biologically oriented approach could
represent an alternative to traditional therapies in maleand female-pattern androgenetic alopecia. In
fact, miniaturized hair follicles maintain the same
number of epithelial hair follicle stem cells in the bulge
region on their outer root sheath as do the large terminal
follicles.13 The aim of our study was to demonstratethat transplanted autologous PDGFs, cytokines, andleukocytes, when compounded with a plasmatic protein concentrate, may stimulate the activation of thestem cells in the miniaturized hair follicles, thus
favoring the conversion of hair follicle stem cells toprogenitor cells.14,15 This would induce a new anagen
phase and, consequently, a clinical improvement due toa consistent and clinically evident increase both inquantity of hair and in hair shaft diameter.

Materials and Methods
After having received approval from the Ethical Committee of IDI-IRCCS, a clinical protocol for the treatmentof the male- and female-pattern baldness was started at
our hospital, a national reference center for skin conditions. All diagnoses were conﬁrmed by dermatologists,
who were with at least 15 years of clinical experience andspecialized in conditions that affect the hair and scalp.
The approved protocol consisted of:
1. Induction of cutaneous inﬂammation on the affected
scalp to favor the activation of the injected platelets.
2. Intradermal/subdermal delivery in the thinningareas using the same syringe injection of:• Autologous platelet and leukocyte concentrate
at high concentration levels (L-PRP).
• Autologous concentrated plasmatic protein
solution as a biologically active scaffold.
Only patients whose blood test revealed a platelet
count above 140,000 platelets per microliter were

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PLATELET-RICH PLASMA TREATMENT FOR HAIR LOSS

included in the study. Also, in this study we, included
only patients who had never been treated with ﬁnasteride or minoxidil, or patients who had used ﬁnasteride or minoxidil for at least 2 years.
A 2-injection approach was then planned, witha 3-month interval between the 2 interventions. At thetime of the ﬁrst procedure, 60 mL of venous wholeblood were drawn, and then processed through the
GPS III Platelet Separation System (Biomet, Warsaw,
IN), thus obtaining 6 to 8 mL of a solution rich inleukocytes and platelets. On average, when comparedwith the baseline, a sixfold to sevenfold increase in theplatelet concentration was obtained according toquality control tests performed by our blood unit on all
patients at the time of the ﬁrst injection.
Based on the assumption that PRPs with a high plateletconcentration could be more effective in promoting
a better stem cell proliferation as compared with PRP
with lower platelet concentration, we always injected thehighest possible concentration. Both the single-spin anddouble-spin PRP systems that were used in this study(Figure 1) yielded concentrations of approximately
1,000,000 platelets per microliter in each patient.

After the injection of a local anesthetic (xylocaine 1%,
with adrenaline 1:100,000), a cutaneous inﬂammatory
response was induced through gentle pressure of a 1.0mm deep Scalproller (Nanogen Pangaea Laboratories,UK) on the thinned scalp areas to be treated. The liquidplatelet-poor plasma layer, harvested from the blood
centrifugation, was then ﬁltered using a mini-hemoconcentrator (Glo plasma ﬁlter; surface area 0.06 m2,
priming volume 5 mL; Gloﬁnn OY, Salo, Finland).
Then, 3 to 4 mL of this dense plasmatic protein concentrate were then added to the previously obtained“buffy coat” layer, yielding a total estimated concentration of platelets 3.5 to 4 times higher as comparedwith the baseline, in a total volume of 9 to 12 mL.
This solution was then injected through a 24-to
26-gauge needle in a 10 mL Luer-lock syringe on the
superﬁcial cutaneous scalp layers. Injections were 1 cm
apart, that is, 4 injections would be on the vertices ofa square with sides = 1 cm. The amount injected, pereach injection, was approximately 0.2 to 0.3 mL.
No new oral or topical treatments, such as antidihydrotestosterone or topical minoxidil were instituted, but patients who were already undergoing suchtreatments were encouraged not to quit.

Figure 1. Diagram of the steps to produce l-PRP. Peripheral venous blood was centrifuged using a single-spin (1) ora double-spin (2) system, during which red blood cells were first separated (2a) and then discarded (2b). The obtained
platelet-poor plasma (yellow lines) was filtered through a plasma-filter to reach a higher concentration of proteins (3) andthen mixed (4) with the ready-to-be-injected l-PRP (red lines) to obtain a PRP richer in fibrin and proteins (5).

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SCHIAVONE ET AL

Three months after the ﬁrst injection, a second procedure
was carried out, drawing 40 mL of venous blood, thistime using a double-spin16 centrifugation method (Glo
PRP; Gloﬁnn Oy, Glotech, Asan City, Chungnam,
Korea). The concentrated solution of plasmatic protein
was then added to the obtained platelet concentrate, as
described for the ﬁrst procedure. Platelet concentration
after this procedure was estimated at approximately
4 times the baseline concentration. We were able tochoose this dosing regimen for 2 main reasons: (1)because we delivered a higher concentration of platelets (obtained, of course, from a larger blood sample),
as compared with other recent studies on hair restoration; (2) because we used a ﬁbrin matrix: theentrapment of the platelets in the ﬁbrin matrix has been
demonstrated to give PDGFs a longer release potential.

Because our study was ethically approved as anobservational study, our evaluation was necessarily
constrained to “before/after” observations, using eachpatient as his/her own control. The clinical change
between the ﬁrst assessment and the end of the followup was rated by 2 independent evaluators according to
the 15-point scale proposed by Jaeschke and colleagues.20 Each evaluator had to answer the following
question: “Overall, has there been any change in thispatient’s condition since the ﬁrst visit? Please indicate if
there has been any change by choosing one of thefollowing options. Compared to the previous datacollection visit, the hair condition is [. . .]”. The answers
ranged from 27, corresponding to “A very great deal
worse,” to +7, corresponding to “A very great deal
better,” and with 0 corresponding to “About the same.”

To document any possible clinical change in the scalp
region and in the hair, we adopted a macrophotographic
protocol. We preferred this to the spot and ultraspot
images obtained with software-assisted methods,
because techniques such as the tricho-scan, although very
popular, have been criticized17–19 over the last decade. In
fact, although relying on such images would havestressed the almost-microscopic details of the follicularunits emerging on the scalp, this technique would havemissed the “wider shot” images that may provide an
idea of the “scalp framed as a whole,” which we rated
as the most relevant aesthetic parameter for a realistic
evaluation of any kind of clinical improvement.

We report here the whole Jaeschke scale:

Our photographic protocol required patients to wet
their hair by wiping their scalp with a sponge soakedwith 5 mL of saline solution. No products were added
to the patients’ hair. Pictures were taken at the time of
the ﬁrst injection, at the time of the second procedure,
and then at a 6-month follow-up (i.e., 3 months after
the second procedure).
Pictures were always shot with the same FX reﬂex digital
camera (Nikon d-700, d-800), same lens (Nikkor micro
60 mm f. 2.8), using as far as possible the same patient
position (3 angles for the parietal/frontal scalp and 2
angles for the crown) and maintaining approximately
the same head angle. Pictures were all taken by the sameauthor (G.S.) even if in different light conditions. A totalof 576 pictures were examined.

• 27: A very great deal worse• 26: A great deal worse• 25: A good deal worse• 24: Moderately worse• 23: Somewhat worse• 22: A little worse• 21: A little worse, hardly any worse at all• 0: About the same
• +1: A little better, hardly any better at all• +2: A little better• +3: Somewhat better• +4: Moderately better• +5: A good deal better• +6: A great deal better• +7: A very great deal better.
We compared the ratings of clinical change obtained
independently from 2 of the authors (G.S., a surgeon,
designated as Evaluator 1, and D.A., an epidemiologist,
designated as Evaluator 2) using intraclass correlation
coefﬁcients (ICC) that were obtained by the R freestatistical software, Nonlinear Mixed Effects Models
package (www.r-project.org). The ICC is equivalent to
the kappa statistic for continuous values. It has theadvantage over the Pearson or Spearman correlation
coefﬁcient in that it is a true measure of agreement,
combining information on both the correlation and thesystematic differences between the readings.21

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PLATELET-RICH PLASMA TREATMENT FOR HAIR LOSS

The baseline severity of the condition was estimatedusing the global physician assessment (GPA) score.
The author who performed the clinical intervention
evaluated each patient answering this question: “In
your experience, among all patients you have seen
with this condition, how severe is the condition of thispatient today?” On a 5-point scale, the possible
answers were: very mild, mild, moderate, severe, andvery severe. In the analysis, the 2 extreme categories
were grouped together.
The ratings of clinical change were dichotomized, using
as a cutoff point the score of +4 (i.e., “moderately better”), because it was deemed—by a consensus among
the authors—a conservative indication for the minimal
clinically important difference.
The differences in clinical change within groups were
tested using Fisher exact test. Also, to assess the possible
independent role of the variables of interest, while
simultaneously controlling for each considered variable, a logistic regression model was implemented
including gender, age group, number of platelets before
the intervention, and the GPA as predictor variables,
and using the dichotomized rating of clinical change as
outcome variable.

Results
Forty-two men and 22 women were enrolled in thisstudy, of a total of 64 studied patients. The median age
was 28 in the male group and 32 in the female group.
Patients were all affected by different degrees of maleor female-pattern baldness, ranging from Hamilton
Class 2 to 5 for men, and Ludwig Class 1 and 2 forwomen. No immediate adverse effects, such as allergic
reactions, postoperative pain or fever, prolonged
redness, nor delayed side effects such as telogen efﬂuvium were reported.
Only 10 patients (15.6%) were classiﬁed as “severe orvery severe” according to the GPA at baseline. The
characteristics of the study population are displayedin the ﬁrst columns of Table 1.
An improvement (i.e., positive scores) was observed in
62/64 patients by Evaluator 1 and in all 64 patients by1014

Evaluator 2. The 2 patients not improved, according
to Evaluator 1, were scored as zero, that is, “about
the same.” Figure 2A,B show the condition of
a 24-year-old female patient at baseline and at the
6-month follow-up, whereas Figure 3A,B show thecondition of a 26-year-old male patient, at the sametime points. The visible improvement at follow-up
should not be attributed to increased hair length, butrather to an increase in the hair thickness.
The crude correlation between the clinical change scoresof the 2 evaluators was .932 (using Pearson correlation
coefﬁcient) and .803 (using Spearman correlation
coefﬁcient). The 2-way mixed-effects model for intraclass correlation coefﬁcient yielded an estimate of .903
(95% conﬁdence interval [CI], .845–.940). All theseestimates were statistically signiﬁcant, with p < .01.
Table 1 also shows the changes in rating of clinicalchange—as evaluated independently by the 2authors—both in terms of mean change and of proportion of patients reaching an improvement of 4 ormore—which was deemed to be clinically important.
The overall mean change in clinical rating was 3.2(95% CI, 2.9–3.5) and 3.9 (95% CI, 3.5–4.3), and theoverall proportion of patients reaching a clinicallyimportant difference was 40.6% and 54.7%,
according to the 2 evaluators, respectively.
No signiﬁcant differences were observed in the ratingof clinical change for gender, age group, and number ofplatelets before the intervention, and GPA, although on
average, a greater degree of improvement was seen inpatients with a higher GPA score at baseline. The proportion of patients reaching a clinically important
improvement in the different GPA levels ranged from
21.7% to 60.0% in Evaluator 1 and from 39.1% to80.0% in Evaluator 2 (p = .027, and = .030, respectively, using the chi-square test for linear trend).
The logistic regression model conﬁrmed the aboveﬁndings. No statistically signiﬁcant results wereobserved for gender, age group, and number of platelets before the intervention. However, when simultaneously adjusting for the aforementioned variables
included in the model, the GPA reached statistical

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SCHIAVONE ET AL

TABLE 1. Changes in Rating of Clinical Change Scores, by 2 Independent Evaluators: Mean Change at
6-Month Follow-up and Proportion (%) of Patients Reaching a Minimal Clinically Important Difference(MCID, i.e., a Score of At Least 14 on the Rating of Clinical Change)
Mean Change
Total
Variable

Level

Overall
GenderAge, years

Platelets,
thousands
per microliter

GPA

Evaluator 1

N%

Mean SD

64

—

3.2

1.4

p
—

Proportion Reaching the MCID

Evaluator 2
Mean SDp

Evaluator 1
N%

Evaluator 2

p*

N

%

p*
—

3.9

1.6

26

40.6

35

54.7

Men

43

67.2

3.2

1.4

4.0

1.5

18

41.9

25

58.1

Women
20–25

21
19

32.8
29.7

3.2
3.2

1.2 .707
1.3

3.7
3.9

1.7 .4591.7

8738.1 .794
36.8

10
10

47.6
52.6

26–30

21

32.8

3.2

1.4

3.6

1.8

9

42.9

10

47.6

31+

24

37.5

3.2

1.5 .993

4.1

1.2 .5001041.7 .902

15

62.5

<200

22

35.9

3.5

1.4

4.1

1.4

10

45.5

13

59.1

200–224

18

28.2

3.1

1.5

3.9

1.8

8

44.4

10

55.6

225+

22

35.9

3.0

1.3 .503

3.6

1.6 .573

7

31.8 .648

11

50.0

Mild

23

35.9

2.8

1.3

3.5

1.5

5

21.7

9

39.1

Moderate 31

48.4

3.3

1.4

3.9

1.7

15

48.4

18

58.1

Severe15.7

3.5

1.3 .271

4.5

1.1 .245660.0 .055†

8

80.0

10

.593

.601

.858

.093†

*Fisher exact test.
†Chi-square for linear trend was .027 and .030 for Evaluator 1 and 2, respectively.

signiﬁcance. In fact, the “risk” of reaching a clinicallyimportant improvement according to Evaluator 1, as
estimated through the adjusted odds ratios (OR), was

4.1 (95% CI, 1.04–16.3) for “moderate” patients and7.0 (95% CI, 1.2–41.1) for “severe and very severe”
patients compared with the “very mild and mild”

Figure 2. Baseline (A) and follow-up (B) condition of a 24-year-old patient. Preoperative platelet count 285,000 per microliter.
Baseline GPA rated as “very severe,” rating of clinical change rated as +5 (i.e., “a good deal better”) by both evaluators.

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PLATELET-RICH PLASMA TREATMENT FOR HAIR LOSS

Figure 3. Baseline (A) and follow-up (B) condition of a 26-year-old patient. Preoperative platelet count 210,000 per microliter.
Baseline GPA rated as “severe,” rating of clinical change rated as +6 (i.e., “a great deal better”) by both evaluators.

ones. The estimates according to Evaluator 2 weresimilar, although the ﬁrst one did not reach statisticalsigniﬁcance: OR = 3.0 (95% CI, .8–11.1) for“moderate” patients, and OR = 8.4 (95% CI, 1.2–
57.7) for “severe or very severe” patients, comparedto the “very mild and mild” ones.
Discussion
In our pilot study, we observed that patients treated with
our plasmatic protein–rich l-PRP almost invariably
showed some degree of clinical improvement at
6-month follow-up, and that—according to the moreconservative of the 2 evaluators in our study, that is,
the plastic surgeon—approximately 2 of 5 (i.e., 40.6%)
reached at least a moderate level of improvement,
which was deemed to be clinically relevant.
It should be noted that because the rate of growth ofhair is approximately 0.3 mL per day—or 1 cm (i.e.,
approximately one-third of an inch) per month—theclinical result visible at a 6-month follow-up is mainly
due to increased thickness and/or higher number ofhairs, rather than increased length, of the hair.
Of course, in this ﬁrst phase of the investigation on thepossible effectiveness of PRP for androgenetic alopecia, we have to acknowledge that our observational

1016

study has the limitation of having included only treated patients. Although it is accepted that spontaneousrecoveries in a 6-month observation period are rare, it
is clear that any further study will have to include
a control group, possibly within the setting of a randomized controlled clinical trial. Such a study would
also help in deﬁning an appropriate timeframe for the
possible continuation of the treatment. As of now, ourpreliminary evidence indicates that a retreatment may
be advisable at 10 to 12 months from baseline, but
a prolonged more systematic observation on a larger
number of patients will be needed to ﬁrmly establish
a retreatment schedule.
In addition, the follow-up period will have to beextended, to verify whether the improvement observedat an interval of 6 months after the intervention may be
maintained over time.
Both measures used to assess the clinical severity andthe possible improvement at follow-up, that is, the
GPA and the rating of clinical change are subjective,
and so are exposed to some extent to the bias of theinvestigator. However, the GPA is currently accepted
and used in many clinical trials—including, forinstance, those evaluating the new and expensive“biological” treatments for psoriasis. As for the
rating of clinical change, although it is also currently

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SCHIAVONE ET AL

used in many studies, including those to validate theevaluative properties of instruments such as quality oflife questionnaires, we resorted to 2 independent
evaluators with different expertise: one was the surgeon who performed the intervention, and the otherthe epidemiologist who managed and analyzed thedata. It is noteworthy that the epidemiologist, who hadin no way participated in the clinical intervention andnever had any contact with the patients, gave a lessconservative evaluation of the clinical improvement. In
addition, the very high intraclass correlation coefﬁcientindicates that there was a high level of agreement
between the 2 independent evaluators.
Another possible limit of our study is that it included
patients with mostly mild or moderate clinical severityof androgenetic alopecia, who may not be representative of the whole population of patients with thiscondition. But, concerning the baseline level of clinicalseverity, it is interesting to note that higher levels ofclinical improvement were observed by both of theevaluators in those few patients who were deemed tobe “severe or very severe” at baseline. Although it
could be argued that more severe patients, in general,
have a higher probability of showing a larger degreeof regression to the mean, it has to be considered—as
noted above—that in androgenetic alopecia, a relevant spontaneous clinical improvement in the shortterm is quite unlikely.
The generic term “platelet-rich plasma” basically does
not allow for a clear distinction anymore between theavailable products, because it does not take into
account some key speciﬁcations such as plateletconcentration potential, presence or absence of cells
such as leukocytes, and of plasmatic proteins such as
ﬁbrinogen, vitronectin, ﬁbronectin, and cytokines.
Not all platelet concentrates are created equal, andﬁne-tuning the PRP production methods for our
required clinical purpose seemed to be an essential
step, because the many different products that areavailable in an ever-expanding market today, often
lead to different types of blood aggregates, with different biology and potential uses.22–24
We ﬁrst estimated that a signiﬁcant volume of wholeblood (i.e., 40–120 mL) was necessary to inject thescalp surface with an adequate volume of 5 to 15 mL(depending on the extent of baldness) of highly
platelet-enriched plasma.
Regarding the issue related to the dependence of clinical beneﬁt on platelet concentration, this is stilla chapter under investigation, because concentration
ratios of less than twofold to 8.5-fold have beenreported,25–30 and some authors31 suggest that different individuals may require different platelet concentration ratios to achieve comparable biologicaleffects. Nevertheless, we have based this study on thevision that Marx and other investigators have suggested: that PRP should achieve a threefold to ﬁvefold
increase in platelet concentration over baseline32–34 tobe effective and successfully targeting in our case,follicular stem cells.
Although researchers have mainly considered only
PDGFs to be responsible for all the PRP’s biologicaleffects, we hypothesize that the presence of cells, suchas leukocytes, and/or the addition of some plasmatic
proteins that could carry a biologically active role,
have to be seriously considered; this is why both were
included in our plasmatic concentrate. In fact, several
studies have pointed out the importance of leukocytes
in PRP35 for their anti-infectious action36,37 andimmune regulation,38,39 outlining their capability to
produce large amounts of VEGF.40
At the same time, the presence of some cytokines andthe density and composition of the ﬁbrin matrix(which supports their release) should be considered asanother key parameter of any platelet concentrate.41
In fact, we argue that the “entrapment” of platelet
and leukocyte growth factors into the ﬁbrin
matrix,38,42 as it is hypothesized to occur at the PRP
injection site when the ﬁbrinogen-enriched plasmaticconcentrate we injected interacts with the local
autologous thrombin (produced by the previously
induced local tissue trauma-inﬂammation), promotesa slower and more efﬁcient platelet and leukocyte
growth factor release.43
At the same time, we hypothesize that concentratingﬁbrinogen, plasmatic vitronectin, and ﬁbronectinfrom the platelet-poor plasma layer obtained after

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PLATELET-RICH PLASMA TREATMENT FOR HAIR LOSS

centrifugation would be another key explanation for
the encouraging clinical outcomes of this study. Thesesame proteins in fact have been demonstrated to bind
growth factors and to enhance their activity in theextracellular matrix environment,44,45 while wholehuman plasma itself has been shown to be effective inpromoting in vitro angiogenesis.46,47
All this, taken together, indicates that our pilot study
may provide at least preliminary evidence that thebiological background and rationale for this treatment
may be translated into some degree of clinical advantage for patients with androgenetic alopecia of mild tomoderate clinical severity. This may prompt othergroups to perform studies on this procedure, possiblyusing a control group and ideally using the constraintsof a well-designed randomized controlled clinical trial.
Acknowledgments We thank Mario Ventura for his
assistance in the preparation of the ﬁgures for thisarticle, and Moira Egan for her invaluable help inediting the article.
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2. Sampogna F, Tabolli S, Abeni D. Impact of different skin conditions on
quality of life. G Ital Dermatol Venereol 2013;148:255–61.
3. Paus R. Do we need hair follicle stem cells, hair follicle neogenesis tocure common hair loss disorders? Hair Transplant Forum Int’l 2008;
18:89–90.
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