Part 1
Trichology plays a crucial role in dermatologists’ clinical practice. The aim of this review is to summarize the most relevant therapeutic advancements in trichology in a practical manner, grouping them into four categories: androgenetic alopecia (AGA), alopecia areata (AA), scarring alopecias, and hair transplantation.
In this Part 1, we cover the most prevalent condition with the latest advancements:
Androgenetic Alopecia
In recent years, new therapeutic options have emerged for both men and women with AGA. Additionally, significant advancements have been made in the use of minoxidil and antiandrogens.
Minoxidil
A recently published meta-analysis¹ confirms the effectiveness of minoxidil compared to a placebo for AGA. However, the authors highlight poor treatment adherence due to cosmetic concerns, which could be improved with new minoxidil formulations.
A Cochrane review² analyzing interventions for female AGA—including 47 studies and 5,290 patients—concluded that topical minoxidil at concentrations between 2% and 5% is both effective and safe, outperforming other treatments like antiandrogens and low-level laser therapy (LLLT).
Regarding new minoxidil formulations, research has demonstrated that foam-based minoxidil is more effective and better tolerated than the hydroalcoholic solution in both men³ and women⁴ with AGA. This is due to its lower propylene glycol content, which enhances cosmetic acceptability. Additionally, niosomes are being explored as a means to improve topical minoxidil absorption⁵.
Another innovation is nanoxidil, a molecule structurally similar to minoxidil but with a lower molecular weight, which theoretically enhances penetration and absorption. However, no solid scientific studies have yet been published on its effectiveness.
Anecdotal reports suggest that low-dose oral minoxidil (0.25 mg/day) may be effective for AGA (Sinclair, personal communication), chemotherapy-induced permanent alopecia⁶, and monilethrix⁷. If confirmed, low-dose oral minoxidil could become a valuable alternative for AGA patients.
Antiandrogens
Several high-evidence studies support the safety of finasteride and dutasteride for men and women with AGA, demonstrating:
- A low risk of sexual side effects, comparable to placebo⁸,⁹.
- No increased cancer risk, contrary to previous concerns¹⁰,¹¹.
One of the most significant developments in AGA treatment is the emergence of dutasteride as an effective and safe alternative for both men and women¹²-¹⁴. As a dual 5-alpha reductase inhibitor with a longer half-life than finasteride, dutasteride has proven more effective in treating frontal AGA in men, without additional adverse effects¹⁴-¹⁷.
New administration methods are also being explored:
- Dutasteride microinjections: Moftah et al.¹⁸ studied 86 women receiving scalp microinjections of dutasteride compared to 40 controls, finding a 63% increase in hair density in the treatment group vs. 17% in the control group (p<0.05), with no adverse effects.
- Localized dutasteride injections into the scalp, performed under nerve block anesthesia, may be a useful monotherapy (Figure 1) or complementary treatment. Our research group studied five men with AGA, finding that quarterly local injections of dutasteride improved hair density without side effects or systemic hormonal alterations (data pending publication).
- Topical finasteride (0.25%) has shown inhibitory effects on follicular 5-alpha reductase with lower systemic absorption than oral finasteride¹⁹,²⁰. A study by Milani et al. (personal communication) on 0.5% topical finasteride demonstrated hair growth improvement in 70% of men after six months.
Prostaglandins
Prostaglandin analogs, such as latanoprost and bimatoprost, stimulate hair growth by prolonging the anagen phase²¹,²². However, achieving clinically significant effects in AGA requires high concentrations (latanoprost 0.1%)²², making the treatment costly.
New research is investigating PGD2 receptor (GPR44) antagonists, as PGD2 inhibits hair growth and is found in higher concentrations in AGA-affected scalps²³-²⁵. One such drug, setipiprant (KITH-105), is an oral GPR44 antagonist currently being tested for asthma but may have potential AGA applications²⁶. A Phase II clinical trial is underway to compare setipiprant, placebo, and finasteride (1 mg/day) in male AGA patients aged 18-41 (NCT02781311).
Physical Therapies
Several well-structured studies support the use of LLLT for AGA in both men and women²⁷-³⁰. LLLT may:
- Convert telogen follicles into anagen follicles.
- Transform vellus hairs into terminal hairs.
- Enhance perifollicular inflammation, activating bulge stem cells.
- Increase local blood flow and release VEGF and inflammatory mediators, promoting hair growth.
Microneedling, another promising therapy, creates micro-injuries in the scalp to trigger endogenous growth factor release, stimulating hair growth³¹,³².
Regenerative Medicine Therapies
Trichologists are exploring regenerative treatments to stimulate follicular stem cells:
- Platelet-rich plasma (PRP): Studies³³-³⁵, including a meta-analysis³⁴, show that PRP increases hair density and anagen follicles with minimal side effects. However, patient responses vary significantly.
- Topical Wnt/β-catenin pathway activators: Compounds such as methyl vanillate³⁶, valproic acid³⁷, and SM04554³⁸ may stimulate hair follicle stem cells by activating this pathway.
- JAK/STAT and mTOR/PI3K inhibitors: Recent studies show that inhibiting these pathways induces hair growth in mouse models and human follicles in vitro³⁹,⁴⁰.
- Reactive oxygen species (ROS) induction via photodynamic therapy: This approach activates follicular stem cells, accelerating hair growth in mouse models⁴¹.
- Stem cell therapies: Two main techniques exist:
- Hair follicle cloning (E1): Involves injecting lab-expanded follicular stem cells to generate new follicles. While promising, human trials have shown limited effectiveness (6% hair growth; World Trichology Congress, Barcelona, 2012)⁴².
- Mesenchymal stem cell lipoaspirates (LPA) (E2): This technique extracts and injects mesenchymal stem cells into the scalp to stimulate hair growth. Preliminary studies⁴³-⁴⁵ show promise, but larger trials are needed to confirm safety and efficacy.
