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Male and Female Hair Loss (Alopecia)

Expert Insight

Alopecia is a chronic and progressive disorder of complex hair follicle biology, affecting at least 40% of women and 50% of men by the age of 50.  Recent research suggests that hair loss may occur from multi-factorial factors such as genetic susceptibility, chronic inflammation, hormonal imbalance, psychological stress, immunological influences, and environmental pressures.  Across the spectrum of hair loss disorders, dysregulation of growth factors and cytokine pathways may ultimately be responsible for disruption of normal follicle physiology.  The changes in molecular expression may alter the normal cycling dynamics and follicle stem cell balances that eventually lead to follicular miniaturization and loss over time.

Since 1970’s, platelet-rich plasma (PRP) has received significant attention as a rich source of growth factor and cytokines for tissue repair and hemostasis.  More recently, exosomes have been found to provide hair growth perhaps more consistently and with greater density. 

Peer-review studies have investigated the clinical results of PRP, as well as exosomes, to promote hair growth in the treatment of alopecia.  Platelet-rich plasma contains a high number of platelet particles that are concentrated above levels normally found in whole blood.  Experimental studies have demonstrated that activated platelets release a number of potent growth factors, that include platelet-derived growth factor (PDGF), fibroblast growth factor (FGF), hepatocyte growth factor (HGF), transforming growth factor (TGF), vascular endothelial growth factor (VEGF), epithelial growth factor (EGF), and insulin-like growth factor (IGF).  The paracrine action of growth factors and cytokines are believed to be generally responsible for angiogenesis, stem cell proliferation and differentiation, anti-apoptotic properties, anagen induction, cyclic growth and follicle development, and proliferation of dermal papilla cells through a number of stem cell niches within the follicle.

Despite the growing interest in PRP efficacy and safety on hair growth, there remains insufficient information for meta-analysis of current treatment protocols.  In 2015, Gkini’s group3 conducted an evidence-based review of 12 selected clinical trials.  Without a consensus protocol, outcomes in these trials were different as a result of variations of platelet dosages and concentrations, use of activators, employment of single-or-double spin cycles, centrifugation times and g-forces, controlled or randomized protocols, different PRP delivery techniques, and various standardized quantified assessment methods.  For PRP usage to be safe, reliable, and useful therapy for alopecia, larger randomized, and controlled trials with approved devices for PRP preparation, are needed.

For the past seven years, we have been using a paradigm shift in hair loss treatment from mono-targeting to multi-targeting therapeutic approaches in order to promote hair stimulation and growth.  Our medical center offers novel off-label, multi-targeted therapies such as lipo- injections with their nanofraction-derived regenerative cells, low-level laser light, and nutraceuticals with botanical growth factors, in addition to FDA-approved drugs such as Minoxidil and Finasteride.  Currently, we have just completed one of the first IRB-approved, randomized-controlled clinical trial to study the safety and efficacy of low vs high numbers of platelet-rich plasma for hair regrowth in androgenetic alopecia.  By 4 months, increased terminal and vellus hair densities have been documented by serial phototrichogram evaluations.  Minimal to no side-effects or complications have been observed in over a hundred patients.

In 2013, a classification for platelet concentrates was published to clarify of PRP preparation and terminology is considered as a basis of consensus for all publications in many fields.  The classification was based on the presence of two key parameters: 1) presence of a cell content (mostly leukocytes) and 2) the presence of a fibrin architecture.

  1. Pure Platelet-rich plasma (P-PRP) represents preparations without leukocytes and a low fibrin network after activation. All the products in this family are used in the liquid form or in an activated gel form.
  2. Leukocyte-and Platelet-rich Plasma (L-PRP) represents products with leukocytes and a low-density fibrin network after activation.  Similar to P-PRP, all the products in this family can be used as liquid solutions or in an activated gel form.  L-PRP is the most commonly used preparation with the largest number of commercial systems used in aesthetic procedures, orthopedics and sports medicine. 
  3. Pure Platelet-rich Fibrin (P-PRF) – or Leukocyte-poor Platelet-rich Fibrin- represent preparations without leukocytes and with a high-density fibrin network.  These preparations exist only in a strongly activated gel form whose strong matrix is more applicable for orthopedic applications.  
  4. Leukocyte- and Platelet-rich Fibrin (L-PRF) preparations contain leukocytes and a high-density fibrin network.  These products exist in a strongly activated gel form and cannot be injected or used like traditional fibrin glues. 


The PRF family accommodates the needs for applications in oral and maxillofacial surgery, skin ulcer treatments, and orthopedic/sports medicine, as L-PRF clots and presents a volume and shape necessary for most of their surgical procedures.  These structures are strong and provide a slow release of many growth factors over prolong periods.  They are easy to prepare in larger quantities and relatively inexpensive for daily clinical practices. The PRP family solutions have the advantage to be liquid before activation and therefore, can be injected or topically applied to skin.  However, controversy still continues concerning the exact cell content and dosages of growth factors/cytokines, significant roles of leukocytes and red blood cells, and the need for activation to achieve consistent and safe outcomes. 


With the increased utilization of PRP, it is important for clinicians and researchers to understand the United States Food and Drug Administration (FDA) regulatory role and position on PRP.  Blood products such as PRP fall under the purview of the FDA’s Hematological Section in the Center for Biologics Evaluation and Research (CBER) that is responsible for regulating human cells, tissues, and cellular and tissue-based products (HCT/P).  Currently, blood products such as PRP are exempt and therefore do not follow the FDA’s traditional pathways for clinical trials, described in the FDA’s 21 CFR 1271 of the Code of Regulations.  The use of PRP outside this setting would be considered “off-label” and may be used as long as clinicians are well informed about the product, practice evidence-based, and safe therapies with 510(k) cleared devices.  Finally, despite PRP being exempted, the activation of PRP has cause for concern in the language in 21 CFR 12715.  In general, the FDA has five major concerns: 1) transmission of communicable disease 2) processing control to prevent contamination and preserve product-integrity and function 3) clinical safety and efficacy 4) promotional claims and labeling, and 5) optimal monitoring and education of industry and clinicians. Currently, there are no FDA-approved pathways for the use of Stem cells or their products for the Treatment of Hair loss.      



  1. Sasaki GH. Review of human hair follicle biology: Dynamics of niches and stem cell regulation for possible therapeutic hair stimulation for plastic surgeons.  Aesthetic Plast Surg. 2019;43:253-266. 
  2. Sasaki GH. Hair biology and androgenetic alopecia: Diagnosis, neogenesis and management. Advances in Cosmetic Surgery. 2018;1:185-192.
  3. Gkini MA, Kouskoukis AE, Rigopoulos D, et al.  Platelet-rich plasma as a potential treatment for noncicatricial alopecias.  Int J Trichology. 2015;7(2):54-63.
  4. Dohan Ehrenfest DM, Sammartino G, Shibil JA, et al.  Guidelines for the publication of articles related platelet concentrates (Platelet-Rich Plasma – PRP, or Platelet-Rich Fibrin – PRF): the international classification of the POSEIDO. POSEIDO 2013;1:85-92.
  5. Beitzel K, Allen D, Apostolakos J, et al.   US definitions, current use, and FDA stance on the use of Platelet-rich Plasma in sports medicine.  J of Knee Surgery. 2015;28:29-33.

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