THE EFFECT OF AUTOLOGOUS PLATELET RICH PLASMA (PRP) ON PATIENTS WITH ALOPECIA AREATA

Document Type : Original Article

Authors

1 Departments of Dermatology ,Venereology & Andrology, Faculty of Medicine, Al-Azhar University

2 Departments of Clinical Pathology, Faculty of Medicine, Al-Azhar University

Abstract

Background: Alopecia areata (AA) is a non-scarring, autoimmune hair loss condition. Despite available therapeutic options, searching for new and more effective treatment is continuous.
Objective:Evaluation of  the efficacy of autologous platelet-rich plasma (PRP) for the treatment of localized AA.
Patients and methods: This was a prospective study that conducted at Al-Azhar University Hospital  in which 30 patients who attended the outpatient clinic were enrolled. All the patients had age range from 14 to 50 years  with localized AA "patchy AA", normal laboratory parameters for CBC, and thyroid functions. None of them had hematological disorders, thyroid dysfunction, low pain threshold, malnutrition, cicatricial alopecia, alopecia total is, alopecia universal is or other dermatological disorders contributing to hair loss.
Results: Eighteen patients (60.0%) were responders and twelve patients (40.0%) were non-responders. From 18 responders, 16 (88.9%) were good responders,  and 2 (11.1%) were partial responders.
Conclusion: PRP has emerged as a new treatment modality in AA, and showed effective results and safety in treatment of alopecia areata.

Keywords


THE EFFECT OF AUTOLOGOUS PLATELET RICH PLASMA (PRP) ON PATIENTS WITH ALOPECIA AREATA

 

By

 

Abd El-Hamid Mohamed Abd Al-Aziz, Shady Mahmoud Attia,

Adel Mahmoud Mohamed Abdo* and Hossam Ibrahim El-Hossiny

                                                                                                              

Departments of Dermatology ,Venereology & Andrology andClinical Pathology*,

Faculty of Medicine,  Al-Azhar University

 

ABSTRACT

Background: Alopecia areata (AA) is a non-scarring, autoimmune hair loss condition. Despite available therapeutic options, searching for new and more effective treatment is continuous.

Objective:Evaluation of  the efficacy of autologous platelet-rich plasma (PRP) for the treatment of localized AA.

Patients and methods: This was a prospective study that conducted at Al-Azhar University Hospital  in which 30 patients who attended the outpatient clinic were enrolled. All the patients had age range from 14 to 50 years  with localized AA "patchy AA", normal laboratory parameters for CBC, and thyroid functions. None of them had hematological disorders, thyroid dysfunction, low pain threshold, malnutrition, cicatricial alopecia, alopecia total is, alopecia universal is or other dermatological disorders contributing to hair loss.

Results: Eighteen patients (60.0%) were responders and twelve patients (40.0%) were non-responders. From 18 responders, 16 (88.9%) were good responders,  and 2 (11.1%) were partial responders.

Conclusion: PRP has emerged as a new treatment modality in AA, and showed effective results and safety in treatment of alopecia areata.

Key words:Platelet Rich Plasma (PRP), Alopecia areata (AA).

 

 

INTRODUCTION

     Alopecia areata (AA) is a common disease whose clinical manifestations range from mild lesions (plaques) to total hair loss (universal). Most cases can be recognized by well-defined patches of hair loss with exclamation mark hairs at the periphery (Spano and Donovan, 2015). Of unknown etiology, AA is autoimmune and genetic-related, affecting people of all ages. The lifetime prevalence of AA is about 2%  (Wu et al., 2013).  The loss of hair is related to alterations in the normal cycle of hair growth. A he­reditary component has been identified in patients with AA, and according to current information it is most likely a polygenic disease. Substantial progress in basic and clinical immunology research suggests that AA is a CD8+ cell, Th1-type autoimmune reaction against anagen stage hair follicles (McElwee et al., 2013 and Watanabe  et al., 2015). Many other cell types, including keratinocytes, fibroblasts, mast cells and dendritic cells also contribute to AA pathogenesis (Bertolini  et al., 2014, Kurashima   et al., 2014 and Xing  et al., 2014 ). There is no evidence that treatment changes the individual patient’s final outcome. However, before counseling patients, one must take into account individual psychological states as hair loss can have a profound effect, and many patients will elect to undergo therapy (Messenger et al., 2012).Platelet-rich plasma (PRP) is an autologous preparation of platelets in concentrated plasma. Although the optimal  PRP  platelet concentration is unclear, the current methods by which PRP is prepared report 300-700% enrichment, with platelet concentrations consequently increasing to more than 1,000,000 platelets/L ( Li et al., 2012 and Moon  et al., 2013). PRP has attracted attention in several medical fields because of its ability to promote wound healing . Activation of alpha granules of platelets releases numerous proteins  including platelet-derived growth factor (PDGF) and interleukin (IL)-1 (Takikawa et al., 2011). The mechanism of PRP in the treatment of AA remains unknown, but it is hypothesised that growth factors released from platelets may act on stem cells in the bulge area of the follicles, stimulating the development of new follicles and promoting neova-scularisation (Chaudhari et al., 2012).

PATIENTS AND METHODS

     This was a prospective study that conducted at Al-Azhar University Hospitals from March 2015 to November 2015  in which 30 patients who attended the outpatient clinic were enrolled. All the patients had age range from 14 to 50 years  with localized AA "patchy AA", normal laboratory parameters for CBC and normal thyroid functions tests (TSH, T3, T4). None of them had hematological disorders, thyroid dysfunction, low pain threshold, malnutrition, cicatricial alopecia, alopecia totalis, alopecia universalis or other dermatological disorders contributing to hair loss.

    Before being admitted to the clinical study, the patients gave consents to participate after the nature, scope, and possible consequences of the clinical study have been explained in a form understandable to them. The patients were evaluated clinically and digitally photographe in every session.

    PRP was prepared by collecting 10-20 cc of fresh blood in sodium citrate containing vaccutainers in minor operation theatre under proper aseptic precaution. The tubes were rotated in a centrifugation machine at 1500 revolutions per minute for 6 minutes. The first centrifugation is called “soft spin”, which allowed blood separation into three layers, namely bottom RBC layer (55% of total volume), topmost acellular plasma layer called platelet poor plasma (PPP, 40% of total volume) and an intermediate PRP layer (5% of total volume) called the “buffy coat”. Separated buffy coat with PPP was collected with the help of Finn pipette in another test tube. This tube was undergone a second centrifugation, which was longer and faster than the first, called “hard spin”, comprising at 2500 revolutions per minute for 15 minutes. This allowed the platelets (PRP) to settle at the bottom of the tube. The upper layer containing PPP was discarded, and the lower layer of PRP was loaded in an insulin syringe containing calcium chloride (1 part calcium chloride and 9 parts of PRP) as an activator. One hour prior to administration of PRP, anesthetic cream was applied over the bald area. Area of the scalp to be treated was cleaned with alcohol. With the help of insulin syringe, PRP was intradermally injected over affected through multiple small injections under proper aseptic precaution in minor operation theatre. A total volume of 1-2 cc was injected. The treatment was repeated every 2 weeks for 4 sessions. Clinical assessment of the degree of AA was determined according to the percentage of hair loss as regard to base line in affected sites by the Severity of Alopecia Tool score, i.e. SALT score (Figure 1 - Olsen, 2011). We evaluated all the patients clinically and digital photography at each visit and at the end of 12 weeks.

 

 

 
   
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Figure (1): SALT score: The percentage of hair loss in any one of the four views (areas) of the scalp = the percentage hair loss X percent surface area of the scalp in that area. The percentage equals the sum of the scalp hair loss in each area. (a) Top (left side view) = 95% X .18 = 17.1(b) Second (right side view) = 90% X.18 = 16.2c) Third (top of scalp) = 95% X .40 = 38 (realizing that most of hair loss is probably male pattern hair loss) (d) Bottom (back of scalp) = 55% X.24 = 13.2+b+c+d = 17.1 + 38 + 16.2 + 13.2 = 84.5% hair loss (Olsen, 2011).

 

 

Statistical analysis of data: The collected data were organized, tabulated and statistically analyzed using statistical package for social sciences (SPSS) version 19 (SPSS Inc, Chicago, USA), running on IBM compatible computer. For qualitative data, frequency and percent distributions were calculated and for comparison between numeric groups, (t) test was used. For comparison between categorical groups, the Chi square (X2) test was used. For quantitative data, mean, standard deviation (SD), minimum and maximum were calculated, Paired t-test was used to assess the statistical significance of the difference between two means measured twice for the same study group, Student's t-test was used to assess the statistical significance of the difference between two study group means. Mann Whitney test (U test) was used to assess the statistical significance of the difference of a nonparametric variable between two study groups. Fisher’s exact test was used to examine the relationship between two qualitative variables when the expected count was less than 5 in more than 20% of cells, Correlation analysis, by Pearson's method, was used to assess the strength of association between two quantitative variables. The correlation coefficient, denoted symbolically "r", defined the strength and direction of the linear relationship between two variables. For all tests, p value <0.05 was considered significant.

RESULTS

In the present work, 30 patients with patchy AA with age ranged from 15 to 50 years, the mean age was 30.50±11.05. The majority of patients were males (86.7%), and females represented 13.3%. Seventy percent of studied populations had a work, and 30.0% had no work. In addition, 63.3% of studied patients were married, and 36.7% were single. Smoking was reported in 76.7% of patients (Table 1).

 

 

Table (1): Characteristics of AA studied populations.

Characteristics

Statistics

Age (mean ± SD; minimum – maximum)

30.50±11.05; 15.0- 50

Sex (n,%)

Male

26(86.7%)

Female

4 (13.3%)

Work (n,%)

Positive

21(70.0%)

Negative

9(30.0%)

Marital state (n,%)

Single

11(36.7%)

Married

19(63.3%)

Smoking

Positive

23(76.7%)

Negative

7(23.3%)

 

90.0% of patients had negative past history of medical drugs, while 6.7% received anti-diabetic drugs, and 3.3% received anti-hypertensive drugs. In addition, 11 patients (36.7%) had previous treatment for alopecia areata, and 63.3% had no previous drugs for alopecia areata (Table 2).

 

 

Table (2): Past history of drug’s treatment in studied populations.

Parameters

Statistics

Past history of

Medical drugs

Negative

27(90.0%)

Anti-Diabetic

2 (6.7%)

Anti-hypertensive

1 (3.3%)

Past history of drugs

Treatment for alopecia A.

Positive

11(36.7%)

Negative

19(63.3%)

 

 

      The family history was positive in 16.7%. The number of patches was one patch in 73.3%, two patches in 23.3% and three patches in 3.3%. The site of lesion was scalp in 73.3%, and other sites occurred in 26.7%. Finally, the nail was normal in 83.3%, while nail pitting was reported in 16.7% (Table 3).

 

 

Table (3): Data related to AA disease populations

Parameters

Statistics

Family history

Positive

5(16.7%)

Negative

25(83.3%)

Number of

Patches

One

22(73.3%)

Two

7(23.4%)

Three

1(3.3%)

Site

Scalp

22(73.3%)

Beard

8(26.7%)

Nail condition

Normal

25(83.3%)

Nail pitting

5(16.7%)

 


    Patients were subdivided according to regrowth of hair to responders (Figure 2), partial (Figure 3),  and   non-responders.


 

 

 

       
       
 

       

 

 

 

 

                                      (A)                                                         (B)

Figure (2): AA patch in the scalp: A. before and B. after PRP injection showing complete hair regrowth at the end of the study.

 

       
   
     
 

 

 

 

 

 

 


                                      (A)                                                           (B)

 

Figure  (3): AA patch in the scalp: A. before and B. after PRP injection showing partial hair regrowth at the end of the study.

 

 

     Administration   of autologous PRP has led to an observable hair regrowth in AA lesions. There was hair regrowth evaluated by clinical and digital photography  at the end of the study. Responding  patients  18  (60%)  showed  regrowth at the end of the study. As regard to the severity of disease before treatment, the mean SALT score was 3.46±1.8. After treatment, the mean was 1.56±2.14. There was a statistically significant decrease of severity after treatment when compared to corres-ponding values before treatment (Table 4).


 

Table (4): Severity percentage of alopecia in studied patients before and after treatment.

 

% Before treatment

% After treatment

P

 mean±SD

3.46±1.8

1.56±2.14

<0.001

 

     As regard to response, 18 patients (60.0%) were responders and 12 patients (40.0%) were non-responders. From 18 responders, 16 (88.9%) were good responders, and 2 (11.1%) were partial responders (Table 5).


 

Table (5): Response in studied populations.

Parameters

n

%

Response

Responder

18

60.0

Non-responder

12

40.0

Type of response

Good

16

88.9

Partial

2

11.1

 

 

     There was no significant difference between responders and non-responders as regard to age. The mean age in responders was 30.44±10.27 compared to 30.58 ± 12.60 in non-responders (Table 6).

 


 

Table (6): Comparison  between ages of responders and non-responders.

                  Age

Response

Mean (years)

S D

Minimum

Maximum

P

Responder

30.44

10.27

15.00

50.00

0.97

Non-responder

30.58

12.60

15.00

49.00

 

 

     There was no association between response and previous treatment for alopecia areata, where only 33.3% of responder received previous treatment compared to 41.7% of non-responders (Table 7).


 

Table (7): Relation between response and previous treatment for alopecia areata.

Response

 

Drugs for AA

Responder

Non-responder

P

N

%

N

%

Positive

6

33.3%

5

41.7%

0.64

Negative

12

66.7%

7

58.3%

 

 

    In the present study, there was a statistically significant moderate positive (proportional) correlation between change in response and age. On the other hand, no significant difference was found between duration of disease (Table 8).


Table (8): Correlation between improvement change and each patient  age and duration of disease.

Change

Parameters

r

P

Age

0.525

0.025

Duration

0.446

0.064

 


DISCUSSION

   Alopecia areata (AA) is an autoimmune, reversible, initially patchy  hair loss  most  commonly  involving  the  scalp, although other regions of the body may be affected (Garcia and Blume, 2008).

   Therapies are mostly immunosuppres-sive. Nevertheless, treatment is still a challenge in AA, and no treatment is either completely curative or preventive. Finding new therapies for this condition, and improving effectiveness of existing ones, are therefore of utmost important (Alkhalifah, 2011).

    Platelet rich plasma (PRP) is an autologous preparation of platelets in concentrated plasma (Choi et al., 2012). The role of PRP in promoting hair growth has also been investigated. It has been shown to promote hair survival and growth (Trink  et al., 2013).

     The aim of the present study was to evaluate the efficacy of autologous PRP injection in treating AA. The study included 30 male and female patients with localized AA that ranged from 5 to 6 months  duration, with normal blood parameters and normal thyroid functions tests.

   At the end of the study,  about 53.3% of  patients had a complete  regrowth of the hair, 6.6% of patients had partial hair regrowth, and 40% of patients showed no regrowth of hair. Our results showed statistically significant improvement with an increased hair densities in patches which treated by PRP for 8 weeks duration. As we rely on the percentage of hair loss as regard to base line to assess the severity, there was also a significant difference in the mean score after treatment. There was a statistically significant moderate positive (propor-tional) correlation between change in response and age. On the other hand, no significant difference was found between duration of disease.

     Clark (2008) has studied AA in patients that were subjected to PRP therapy after traumatizing the scalp using micro needling roller, then PRP was injected in a retrograde fashion (from deep to superficial). His results had shown that patients grew hair one month after injection and hairs continued to grow over the next 10 months. He interpreted that the effect of PRP worked through initiation of signal transducer and activator of transduction (STAT) dependent keratino-cyte migration toward the anagen progression and wound healing.

   Our findings were in agreement with the study of Rinaldi et al. (2012) who examined 45 male and female AA patients with a chronic recurring disease with at least 2 years duration. They have shown that PRP administration lead to major difference in AA lesions, with 60% of patients achieving complete remission.

     There was a significantly higher response with autologous PRP than TrA administration, which is classically considered as treatment of choice for patch-stage AA and concluded that PRP is a safe simple and effective treatment in AA (Shumez  et al., 2015).

   This regenerative effect of PRP might be powered by the action of many GFs in PRP on dermal papillae and may indirectly act on hair follicles, thus improving involution of the vascular plexus around each hair follicle (Nakamura et al., 2009).

     PRP is a potential useful therapeutic tool for alopecias, without major adverse effects (Trink  et al., 2013).

CONCLUSION

    PRP has emerged as a new treatment modality in A.A., and showed effective results and safety in treatment of alopecia areata.

REFERENCES

1. Alkhalifah A (2011): Topical and intralesional therapies for alopecia areata. Dermatol Ther., 24:355-63.

2. Bertolini M, Zilio F and Rossi A (2014): Abnormal interactions between perifollicular mast cells and CD8+ T-cells may contribute to the pathogenesis of alopecia areata. PLoS One, 9(5):e94260.

3. Chaudhari ND, Sharma YK, Dash K and Deshmukh P (2012): Role of platelet-rich plasma in the management of androgenetic alopecia. Int J Trichology, 4:291–2.

4. Choi HI, Li ZJ, Choi DK, Sohn KC, Im M and Seo YJ (2012): Autologous platelet-rich plasma: A potential therapeutic tool for promoting hair growth. Dermatol Surg., 38:1040-6

5. Clark RA (2008):  Synergestic signaling from extracellular matrix-growth factor complexes. J Invest Derm., 128(6):1354-5.

6. Garcia BN  and Blume PU (2008): Hair loss in children In: Hair growth and disorders. Edited by: U Blume-Peytavi, A Tosti, DA Whiting, and R Trueeb. Published by Berlin: Springer Verlag, Hiesenberg, pp 273–309.

7. Kurashima Y, Amiya T and Fujisawa K (2014):  The enzyme Cyp26b1 mediates inhibi-tion of mast cell activation by fibroblasts to maintain skin-barrier homeostasis. Immunity, 40(4):530–541.

8. Li ZJ, Choi HI, Choi DK , Sohn KC, Im M and Seo YJ (2012): Autologous platelet-rich plasma: a potential therapeutic tool for promoting hair growth. Dermatol Surg., 38: 1040-6.

9. McElwee  KJ, Gilhar A and Tobin DJ (2013):  What causes alopecia areata? Experimental Dermatology, 22(9):609–626.

10. Messenger AG, McKillop J, Farrant P, McDonagh AJ and Sladden M (2012): British Association of Dermatologists’ guidelines for the management of alopecia areata 2012. Br J Dermatol., 166(5):916–26.

11. Moon PG, Kwack MH, Lee JE, Cho YE, Park JH and Hwang D (2013):  Proteomic analysis of balding and non-balding mesenchyme-derived dermal papilla cells from androgenetic alopecia patients using on-line two-dimensional reversed phase-reversed phase LC-MS/MS. J Proteomics, 85:174–91.

12. Nakamura  S,  Kanatani  Y and  Kishimoto S  (2009): Controlled release of FGF-2 using Fragmin/protamine microparticles and effect on neovascularization. J Biomed Mater Res., 91A:814– 23.

13. Olsen EA (2011): Investigative guidelines for alopecia areata. Dermatologic Therapy, 24(3):311-19

14. Rinaldi F, Sorbellini E and Bezzola P (2012): the role of up-stimulation of growth factors in hair transplantation: improve the revascularization of transplanted hair growth mediated by angiogenesis. British J of Dermatol., 167(4): 409–17.

15. Shumez H, Prasad P, Kaviarasan P and Deepika R (2015): Intralesional platelet rich plasma vs Intralesional triamcinolone in the treatment of alopecia areata : a comparitve study. Int J Med Res Health Sci., 4(1):118-122

16. Spano F and Donovan J (2015): Alopecia areata. Part 1: pathogenesis, diagnosis, and prognosis. Can Fam Physician, 61:751–5. (Eng), e401–5 (Fr).

17. Takikawa M, Nakamura S and Nakamura A(2011): Enhanced effect of platelet rich plasma containing a new carrier on hair growth. Dermatol Surg., 37:1721–1729.

18. Trink A, Sorbellini E and Bezzola P (2013):  A randomized, double-blind, placebo- and active-controlled, half-head study to evaluate the effects of platelet rich plasma on alopecia areata. Br J Dermatol., 169:690–694

19. Watanabe R, Gehad A and Yang C  (2015): Human skin is protected by four functionally and phenotypically discrete populations of resident and recirculating memory T cells. Sci Transl Med., 7(279):279ra239.

20. Wu MC, Yang CC, Tsai RY and Chen WC (2013): Late-onset alopecia areata a retrospective study of 73 patients from Twain. J Eur Acad Dermatol Venereol., 27:468–472.

21. Xing L, Dai Z and Jabbari A (2014):  Alopecia areata is driven by cytotoxic T lymphocytes and is reversed by JAK inhibition. Nat Med., 20(9):1043–1049.


 تأثیر البلازما الغنیة بالصفائح الدمویة فی علاج مرضى الثعلبة

 

عبد الحمید محمد عبد العزیز, شادی محمود عطیة, عادل محمود محمد عبده*,

حسام إبراهیم الحسینی

قسمی الأمراض الجلدیة والتناسلیة و الذکورة و الباثولوجیا الإکلینیکیة*- کلیة الطب - جامعة الأزهر

 

خلفیة البحث: تعتبر الثعلبة من الأمراض الجلدیة الشائعة التی تؤدی إلی سقوط الشعر الغیر مصحوب بندابات. والثعلبة أحد أمراض المناعة الذاتیة. وعلى الرغم من وجود العدید من العلاجات المتاحة إلا أن البحث عن علاج جدید وفعال مازال مستمرا.

الهدف من البحث: هو تقییم فاعلیة البلازما الغنیة بالصفائح الدمویة فی علاج الثعلبة .

المرضى وطرق البحث: أجریت الدراسة علی ثلاثین  مریضا من المترددین علی العیادة الخارجیة وقد تراوحت أعمارهم ما بین 15-50 عاما. و قد تم حقن البلازما الغنیة بالصفائح الدمویة مرة کل أسبوعین لمدة أربعة جلسات  لکل المرضی الذین شملتهم الدراسة وتم تصویر المریض قبل وبعد العلاج .

النتائج: نتج عن الدراسة مجموعتین:

1- المجموعة المستجیبة للعلاج (18 مریضا) : لوحظ وجود زیادة فی نمو الشعر و کثافته  وتقلیص مساحة المنطقة المصابة وتمثل 60% من المرضى الذین شملتهم الدراسة منهم 16 مریضا کانت إستجابتهم للعلاج جیدة ومریضین کانت إستجابتهم جزئیة.

2- المجموعة الغیر مستجیبة للعلاج (12 مریضا) : لوحظ عدم وجود زیادة فی نمو الشعر أو کثافته وتمثل 40% من المرضى الذین شملتهم الدراسة.

الاستنتاج: یمکن أن تستخدمالبلازما الغنیة بالصفائح الدمویة کعلاج جدید وفعال  للثعلبة ، ویمکن أن تستخدم بأمان دون وجود أثار جانبیة تذکر.    

 

REFERENCES
1. Alkhalifah A (2011): Topical and intralesional therapies for alopecia areata. Dermatol Ther., 24:355-63.
2. Bertolini M, Zilio F and Rossi A (2014): Abnormal interactions between perifollicular mast cells and CD8+ T-cells may contribute to the pathogenesis of alopecia areata. PLoS One, 9(5):e94260.
3. Chaudhari ND, Sharma YK, Dash K and Deshmukh P (2012): Role of platelet-rich plasma in the management of androgenetic alopecia. Int J Trichology, 4:291–2.
4. Choi HI, Li ZJ, Choi DK, Sohn KC, Im M and Seo YJ (2012): Autologous platelet-rich plasma: A potential therapeutic tool for promoting hair growth. Dermatol Surg., 38:1040-6
5. Clark RA (2008):  Synergestic signaling from extracellular matrix-growth factor complexes. J Invest Derm., 128(6):1354-5.
6. Garcia BN  and Blume PU (2008): Hair loss in children In: Hair growth and disorders. Edited by: U Blume-Peytavi, A Tosti, DA Whiting, and R Trueeb. Published by Berlin: Springer Verlag, Hiesenberg, pp 273–309.
7. Kurashima Y, Amiya T and Fujisawa K (2014):  The enzyme Cyp26b1 mediates inhibi-tion of mast cell activation by fibroblasts to maintain skin-barrier homeostasis. Immunity, 40(4):530–541.
8. Li ZJ, Choi HI, Choi DK , Sohn KC, Im M and Seo YJ (2012): Autologous platelet-rich plasma: a potential therapeutic tool for promoting hair growth. Dermatol Surg., 38: 1040-6.
9. McElwee  KJ, Gilhar A and Tobin DJ (2013):  What causes alopecia areata? Experimental Dermatology, 22(9):609–626.
10. Messenger AG, McKillop J, Farrant P, McDonagh AJ and Sladden M (2012): British Association of Dermatologists’ guidelines for the management of alopecia areata 2012. Br J Dermatol., 166(5):916–26.
11. Moon PG, Kwack MH, Lee JE, Cho YE, Park JH and Hwang D (2013):  Proteomic analysis of balding and non-balding mesenchyme-derived dermal papilla cells from androgenetic alopecia patients using on-line two-dimensional reversed phase-reversed phase LC-MS/MS. J Proteomics, 85:174–91.
12. Nakamura  S,  Kanatani  Y and  Kishimoto S  (2009): Controlled release of FGF-2 using Fragmin/protamine microparticles and effect on neovascularization. J Biomed Mater Res., 91A:814– 23.
13. Olsen EA (2011): Investigative guidelines for alopecia areata. Dermatologic Therapy, 24(3):311-19
14. Rinaldi F, Sorbellini E and Bezzola P (2012): the role of up-stimulation of growth factors in hair transplantation: improve the revascularization of transplanted hair growth mediated by angiogenesis. British J of Dermatol., 167(4): 409–17.
15. Shumez H, Prasad P, Kaviarasan P and Deepika R (2015): Intralesional platelet rich plasma vs Intralesional triamcinolone in the treatment of alopecia areata : a comparitve study. Int J Med Res Health Sci., 4(1):118-122
16. Spano F and Donovan J (2015): Alopecia areata. Part 1: pathogenesis, diagnosis, and prognosis. Can Fam Physician, 61:751–5. (Eng), e401–5 (Fr).
17. Takikawa M, Nakamura S and Nakamura A(2011): Enhanced effect of platelet rich plasma containing a new carrier on hair growth. Dermatol Surg., 37:1721–1729.
18. Trink A, Sorbellini E and Bezzola P (2013):  A randomized, double-blind, placebo- and active-controlled, half-head study to evaluate the effects of platelet rich plasma on alopecia areata. Br J Dermatol., 169:690–694
19. Watanabe R, Gehad A and Yang C  (2015): Human skin is protected by four functionally and phenotypically discrete populations of resident and recirculating memory T cells. Sci Transl Med., 7(279):279ra239.
20. Wu MC, Yang CC, Tsai RY and Chen WC (2013): Late-onset alopecia areata a retrospective study of 73 patients from Twain. J Eur Acad Dermatol Venereol., 27:468–472.
21. Xing L, Dai Z and Jabbari A (2014):  Alopecia areata is driven by cytotoxic T lymphocytes and is reversed by JAK inhibition. Nat Med., 20(9):1043–1049.