An international expert consensus statement focusing on pre and post hair transplantation care

AIM

To achieve international expert consensus and give recommendations on best practices in hair transplantation surgery, focusing on pre- and post-transplantation care.

METHODS

A modified Delphi method was used to reach consensus. An international scientific committee developed an 81-statement questionnaire. A panel of 38 experts in hair transplantation from 17 countries across 4 continents assessed the questionnaire.

RESULTS

Two consensus rounds were carried out, with 59 out of 81 statements (73%) reaching consensus. Expert recommendations emphasize the correct selection of candidates for hair transplantation and the need for patients to have received adequate medical treatment for alopecia before transplant. Comorbidities should be assessed and considered while planning surgery, and an individualized plan for perioperative care should be drawn up before transplant. Certain medications associated with increased risk of bleeding should be withdrawn before surgery. Specific recommendations for post-transplantation care are given. After transplantation, patients should gradually resume their normal haircare regimen. Close follow-up should be carried out during the first year after transplant.

CONCLUSIONS

This study presents numerous consensus-based recommendations on general aspects of hair transplantation, including candidate selection, medical therapy prior to transplantation, anesthesia, and resuming haircare after transplantation.

Male pattern hair loss: Can developmental origins explain the pattern?

Male pattern hair loss (MPHL), also referred to as male androgenetic alopecia (AGA) is the most common type of non-scarring progressive hair loss, with 80% of men suffering from this condition in their lifetime. In MPHL, the hair line recedes to a specific part of the scalp which cannot be accurately predicted. Hair is lost from the front, vertex, and the crown, yet temporal and occipital follicles remain. The visual effect of hair loss is due to hair follicle miniaturisation, where terminal hair follicles become dimensionally smaller. Miniaturisation is also characterised by a shortening of the growth phase of the hair cycle (anagen), and a prolongation of the dormant phase (kenogen). Together, these changes result in the production of thinner and shorter hair fibres, referred to as miniaturised or vellus hairs. It remains unclear why miniaturisation occurs in this specific pattern, with frontal follicles being susceptible while occipital follicles remain in a terminal state. One main factor we believe to be at play, which will be discussed in this viewpoint, is the developmental origin of the skin and hair follicle dermis on different regions of the scalp.

Hair transplantation in burn scar alopecia

Treating patients with burn alopecia or hair loss can often be a challenge to both the surgeon and the patient. As with other reconstructive procedures that are required in the post-burn phase, this is usually a multiple stage process often requiring surgery over several years. This is because graft take is not as reliable as in healthy non-scarred skin and may need repeating to achieve adequate density. Also, different areas of hair loss may need to be addressed in separate procedures. There are several limiting factors that will determine whether or not a patient is a candidate for hair restoration which includes but is not limited to the amount of hair loss and the availability of suitable donor hair. Here we discuss how the current surgical technique of hair transplant surgery by follicular unit extraction (FUE) or strip follicular unit transplant (FUT) has become the treatment of choice for alopecic areas that require a more refined aesthetic result. Eyebrow, eyelash, beard and scalp hair loss can all have a negative impact on a burn survivor’s self-esteem and even if surgery is not a possibility, there are non-surgical options available for hair restoration and these are also discussed.

This article explores the procedure of hair transplantation in the context of general options for hair restoration for individuals that have suffered hair loss due to burn injuries. Treating hair loss due to burns can often be a difficult process for both the surgeon and the patient. As with other surgical procedures that are required in the post-burn phase, hair restoration is usually a multiple stage process often requiring surgery over several years. This is because transplanted hairs are not as reliably successful as in healthy non-scarred skin and many repeat treatments may be needed to achieve adequate density, which is important for a natural look. In addition, different areas of hair loss may need to be addressed in separate procedures. There are several factors that will determine whether or not a patient is a good candidate for hair restoration which includes such things as the amount of hair loss and how much suitable donor hair (the donor is the area from which hair is taken, or donated) is available if the scalp has been affected by scarring. Eyebrow, eyelash, beard and scalp hair loss can all have a negative impact on a burn survivor’s self-esteem and confidence. Even if surgery is not a possibility there are non-surgical options, outlined in this article, which may be available for hair restoration. In this article we explain why the current surgical technique of hair transplant surgery has become the surgical treatment of choice for restoring areas of hair loss, especially in areas that require a more refined and natural result such as eyebrows.

The peripheral clock regulates human pigmentation

Although the regulation of pigmentation is well characterized, it remains unclear whether cell-autonomous controls regulate the cyclic on-off switching of pigmentation in the hair follicle (HF). As human HFs and epidermal melanocytes express clock genes and proteins, and given that core clock genes (PER1, BMAL1) modulate human HF cycling, we investigated whether peripheral clock activity influences human HF pigmentation. We found that silencing BMAL1 or PER1 in human HFs increased HF melanin content. Furthermore, tyrosinase expression and activity, as well as TYRP1 and TYRP2 mRNA levels, gp100 protein expression, melanocyte dendricity, and the number gp100+ HF melanocytes, were all significantly increased in BMAL1 and/or PER1-silenced HFs. BMAL1 or PER1 silencing also increased epidermal melanin content, gp100 protein expression, and tyrosinase activity in human skin. These effects reflect direct modulation of melanocytes, as BMAL1 and/or PER1 silencing in isolated melanocytes increased tyrosinase activity and TYRP1/2 expression. Mechanistically, BMAL1 knockdown reduces PER1 transcription, and PER1 silencing induces phosphorylation of the master regulator of melanogenesis, microphthalmia-associated transcription factor, thus stimulating human melanogenesis and melanocyte activity in situ and in vitro. Therefore, the molecular clock operates as a cell-autonomous modulator of human pigmentation and may be targeted for future therapeutic strategies.

Thyroxine differentially modulates the peripheral clock: lessons from the human hair follicle

The human hair follicle (HF) exhibits peripheral clock activity, with knock-down of clock genes (BMAL1 and PER1) prolonging active hair growth (anagen) and increasing pigmentation. Similarly, thyroid hormones prolong anagen and stimulate pigmentation in cultured human HFs. In addition they are recognized as key regulators of the central clock that controls circadian rhythmicity. Therefore, we asked whether thyroxine (T4) also influences peripheral clock activity in the human HF. Over 24 hours we found a significant reduction in protein levels of BMAL1 and PER1, with their transcript levels also decreasing significantly. Furthermore, while all clock genes maintained their rhythmicity in both the control and T4 treated HFs, there was a significant reduction in the amplitude of BMAL1 and PER1 in T4 (100 nM) treated HFs. Accompanying this, cell-cycle progression marker Cyclin D1 was also assessed appearing to show an induced circadian rhythmicity by T4 however, this was not significant. Contrary to short term cultures, after 6 days, transcript and/or protein levels of all core clock genes (BMAL1, PER1, clock, CRY1, CRY2) were up-regulated in T4 treated HFs. BMAL1 and PER1 mRNA was also up-regulated in the HF bulge, the location of HF epithelial stem cells. Together this provides the first direct evidence that T4 modulates the expression of the peripheral molecular clock. Thus, patients with thyroid dysfunction may also show a disordered peripheral clock, which raises the possibility that short term, pulsatile treatment with T4 might permit one to modulate circadian activity in peripheral tissues as a target to treat clock-related disease.

A meeting of two chronobiological systems: circadian proteins Period1 and BMAL1 modulate the human hair cycle clock

The hair follicle (HF) is a continuously remodeled mini organ that cycles between growth (anagen), regression (catagen), and relative quiescence (telogen). As the anagen-to-catagen transformation of microdissected human scalp HFs can be observed in organ culture, it permits the study of the unknown controls of autonomous, rhythmic tissue remodeling of the HF, which intersects developmental, chronobiological, and growth-regulatory mechanisms. The hypothesis that the peripheral clock system is involved in hair cycle control, i.e., the anagen-to-catagen transformation, was tested. Here we show that in the absence of central clock influences, isolated, organ-cultured human HFs show circadian changes in the gene and protein expression of core clock genes (CLOCK, BMAL1, and Period1) and clock-controlled genes (c-Myc, NR1D1, and CDKN1A), with Period1 expression being hair cycle dependent. Knockdown of either BMAL1 or Period1 in human anagen HFs significantly prolonged anagen. This provides evidence that peripheral core clock genes modulate human HF cycling and are an integral component of the human hair cycle clock. Specifically, our study identifies BMAL1 and Period1 as potential therapeutic targets for modulating human hair growth.

Dense packing: surgical indications and technical considerations

Dense packing is the philosophy of fitting more than 30 to 35 follicular unit grafts per square centimeter in one operation. The aim is to produce a more even, consistent, and natural looking flow of hair after just one procedure. Although desirable in principle, not all patients are suitable candidates nor is it possible to achieve in certain patients (eg, coarse or curly hair). Patients who have sufficient donor availability, reasonably stable hair loss, and high hair-to-skin color ratios are the ideal candidates. The authors highlight their philosophies and strategies for dense packing.