Platelet rich plasma (PRP) was described as a small volume of plasma containing higher concentrations of platelets than those found in peripheral blood and initially used as a transfusion product for treatment of thrombocytopenia. To date, it was discovered that there are several growth factors and cytokines that can accelerate wound healing and tissue regeneration, leading to a wider range of applications in the medical field, such as in sport medicine, regenerative medicine, and aesthetic medicine. Several studies have shown that PRP can be used effectively for treatment of hair loss. Although it has been widely used, the exact mechanism of action of PRP is still not fully elucidated. In this article, we aim to review and update current information on the definition, classification, mechanism of action, clinical efficacy in hair regrowth, and adverse events of PRP.

The hair research field has seen great improvement in recent decades, with in vitro hair follicle (HF) models being extensively developed. However, due to the cellular complexity and number of various molecular interactions that must be coordinated, a fully functional in vitro model of HFs remains elusive. The most common bioengineering approach to grow HFs in vitro is to manipulate their features on cellular and molecular levels, with dermal papilla cells being the main focus. In this study, we focus on providing a better understanding of HFs in general and how they behave in vitro. The first part of the review presents skin morphology with an emphasis on HFs and hair loss. The remainder of the paper evaluates cells, materials, and methods of in vitro growth of HFs. Lastly, in vitro models and assays for evaluating the effects of active compounds on alopecia and hair growth are presented, with the final emphasis on applications of in vitro HFs in hair transplantation. Since the growth of in vitro HFs is a complicated procedure, there is still a great number of unanswered questions aimed at understanding the long-term cycling of HFs without losing inductivity. Incorporating other regions of HFs that lead to the successful formation of different hair classes remains a difficult challenge.

Evolving hair transplantation (HT) techniques have offered new possibilities for hair restoration. However, the role of HT in patients with frontal fibrosing alopecia (FFA) and lichen planopilaris (LPP) remains unclear. This study aims to evaluate the outcomes and temporal relationship of HT in this population.
A literature search of three databases was conducted. We reviewed 1) literature reporting outcomes of patients with LPP or FFA who received HT, and 2) studies reporting the development of LPP or FFA resulting from HT.
Thirteen articles included 42 patients that provided data for evaluation. Fifteen patients had previously been diagnosed with FFA or LPP, and the remaining 27 patients developed disease after undergoing HT. Seven patients with FFA and eight patients with LPP received HT, with a mean sustained disease remission of 2.69 years prior to HT. In total, two of seven (29%) patients with FFA and five of eight (75%) patients with LPP experienced positive HT results over a follow-up period of 8-72 months. Interestingly, 27 patients without evidence of previous disease developed FFA or LPP following HT after a median duration of 16 months.
HT for LPP and FFA is feasible but results may be less favorable compared to HT for other causes. Outcomes may be more favorable for LPP than FFA but this was not statistically significant and evidence is very limited. FFA and LPP can also develop following HT in patients without previous evidence of disease.
NA Laryngoscope, 131:59-66, 2021.

The decision of surgical approach for hair restoration often involves evaluation of the type of alopecia; however, the impact of surgical hair restoration from existing techniques in specific population subsets has not been comprehensively investigated.
The authors sought to systematically review the literature on micrografts, minigrafts, mini-micrografts, tissue grafts, tissue flaps and expanders, as well as evaluate graft survival and satisfaction within specific populations in a meta-analysis.
PubMed and Scopus literature searches between 1980 and 2018 yielded 57 articles for systematic review and 34 articles for meta-analysis. Study design, mean patient age and gender, patient alopecia type, surgical hair restoration technique, number of treatment areas, mean follow-up, graft survival rate and satisfaction rate were extracted from each study, and a meta-analysis was performed.
The pooled rates of graft survival were 84.98% (95% CI 78.90-91.06) using micrografts and 93.11% (95% CI 91.93-94.29) using micrografts and minigrafts in nonscarring alopecia patients, as well as 88.66% (95% CI 80.12-97.20) using micrografts and 86.25% (95% CI 74.00-98.50) using micrografts and minigrafts in scarring alopecia patients. The pooled rates of satisfaction were 89.70% (95% CI 82.64-96.76) using micrografts and 97.00% (95% CI 92.48-100.0) using micrografts and minigrafts in nonscarring alopecia patients, as well as 97.80% (95% CI 94.59-100.0) using micrografts and 88.70% (95% CI 66.49-100.0) using micrografts and minigrafts in scarring alopecia patients. Dot plots depict rates of graft survival rate from micrografts and satisfaction from micrografts and minigrafts.
Surgical hair restoration for nonscarring and scarring alopecia yields high graft survival and satisfaction rates.
This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

This systematic review aims to examine surgical and non-surgical treatments and identify those procedures that are most effective in terms of patient satisfaction.
A systematic review protocol was developed a priori in accordance with the Preferred Reporting for Items for Systematic Reviews and Meta-Analyses-Protocols (PRISMA-P) guidelines. The search was conducted in accordance with the PRISMA guidelines, the Cochrane handbook. A multistep search of the PubMed, MEDLINE, Embase, PreMEDLINE, Ebase, CINAHL, PsycINFO, and Cochrane databases was performed to identify studies on hair loss causes and hair loss treatment with different surgical and non-surgical techniques RESULTS: Our search generated a total of 781 articles; 646 studies were excluded based on the content of the abstracts, and an additional 105 studies were excluded based on the content of the complete article. We performed a review of the 30 remaining studies, which had sufficient data for inclusion, and met all the aforementioned inclusion criteria. Of the 30 studies, four were about minoxidil, four about finasteride, two about dutasteride, three about phototherapy, six about platelet-rich plasma injection, four about follicular unit transplantation technique, six about follicular unit extraction technique, and one about patient satisfaction following surgical treatment without a specified surgical technique. Only three studies used a patient-reported outcome measurement.
Our study is the first comprehensive systematic review of hair loss, looking at the problem from different points of view, and focusing on finding the best solution for the patient. In the literature, there is currently no algorithm for the management of patients who go to a plastic surgeon for a solution to the problem of hair loss.
This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Great strides have been made in hair restoration over the past 20 years. A better understanding of natural balding and non-balding patterns along with more respect for ageing has helped guide proper hairline design. Additionally, the use of smaller grafts has created a significantly improved natural appearance to the transplanted grafts. Inconsistent growth and survival of follicular grafts, however, has continued to be a problem that has perplexed hair restoration surgeons. This review attempts to explore the stresses affecting grafts during transplantation and some of the complexities involved in graft growth and survival. These authors reviewed the literature to determine the primary scope of aspects influencing growth and survival of follicular grafts. This scope includes patient selection, operating techniques, graft care, storage solutions and additives. The primary focus of the hair restoration surgeons should first be attention to the fundamentals of hair care, hydration, temperature, time out of body and gentle handling. Factors such as advanced storage solutions and additives can be helpful once the fundamentals have been addressed.