Hair is a filament like biomaterial, that grows form its follicle situated in the inner layer of skin known as dermis. Amongst animals, only mammals possess hair. In human body, normally, only palms, soles and red area of lips (vermilion), lack hair. Most of the human body especially in females, is covered with thin vellus type of hair, that are difficult to see. Thicker, terminal hair is present in both sexes in scalp, underarms, pubic area and also variably in other areas in men. Natural colour of hair is due to a pigment, which is eumelanin in case of black, dark blonde and brown hair and pheomelanin in case of red hair. With age, melanin production decreases or stops, resulting in gray hair.
While in animals, hair serves a greater purpose and has different functions, in humans also, it serves to protect from wounds, insect bites, heat, cold and ultraviolet radiation. Eyebrows and eyelashes, by being in immediate proximity to eyes, serve a protective function. In addition, eyebrow help in non verbal communication, by a display of emotions such as sadness, anger, surprise and excitement.
In addition to being a biomaterial and having functions, hair play a greater role in interactions, society and culture. Having long and lustrous hair not only indicate good health of the individual, in many societies, these indicate a higher social and cultural position of the individual. A recession/ loss of hair changes the frontal profile of the individual, making the person look older, more mature. The impact of hair loss on our personality and psychological well being can be substantial. It may lead to avoidance of social interactions and inability to concentrate on work. For most individuals, a recession/ loss of hair is a reason of great personal anguish and its restoration, a matter of priority.
There are many reasons for hair recession/ loss. With advancing age, most males experience a recession of frontal hairline. In females, by contrast, there is generalized thinning while the frontal hairline is maintained. In androgenetic alopecia (AGA), which is the most common cause of baldness, these effects are more pronounced. In AGA, there is thinning of hair with loss occuring at crown and temples under the influence of androgens in genetically predisposed individuals. there is sparing of hair at sides and back of the head. Other causes of baldness could be alopecia areata (autoimmune disorder), telogen effluvium (high fever, crash diets, childbirth, thyroid disorders, severe infections, major surgery, drugs, psychological stress etc.), tinea capitis (fungal infection), anagen effluvium (due to anticancer medicines) etc.
The cause of hair loss requires a proper diagnosis and treatment. Treating the underlying cause such as thyroid disorder, antifungal therapy, completion of cancer chemotherapy etc with often restore hair. As AGA is the commonest cause of baldness, the rest of this article will concentrate on this. It is estimated that 60-70% men and 30-40% women will suffer from AGA at some point of time.
Each hair consists of a shaft and a follicle. While shaft essentially is non living tissue and consists of keratin, the follicle is living, dynamic tissue containing stem cells, which generate the hair shaft. Each hair (follicle + shaft) passes through an active growth phase (anagen), cessation phase (catagen) and rest phase (telogen). While anagen lasts 2-6 years, catagen 2-3 weeks, and telogen 3 months. 85- 90% of scalp hair are in anagen phase at any moment, 10-15% in telogen and 1-2% in anagen. Only anagen phase hair are visible as strong, long terminal hair. In contrast to scalp hair, the anagen phase in eyebrows lasts only 4-7 months and hence, these hair can't be as long as scalp hair, before being shed.
Hair follicles (the site where hair is made) have receptors for androgen (male hormone). The follicles also have an enzyme (5 alpha reductase in two variants I and II) which converts testosterone (an androgen) to dihydrotestosterone (DHT) which is 5 times more effective in binding to receptors. DHT binding to receptor results in production of harmful cytokines (TGF beta 1 and 2), which forces the hair follicle to go from growth phase (anagen) to resting phase (telogen). As a result, the hair shaft becomes thinner and ultimately sheds off, resulting in baldness. Since these receptors are mostly present in hair follicles at frontal area and crown, these hair are most affected in genetically predisposed males. In females, dehydroepiandrosterone (DHEA) and other weak androgens are present, which get converted to DHT, producing the same sequence of events.
The age of onset, extent, and rate of hair loss vary from person to person. In those with less severe hair loss medical therapeutic agents are tried first. In those with more advanced hair loss injectable and/or surgical approach is also recommended along with medical management.There is extensive research going on in this field. Both medical and surgical options are available. Some exciting new medicines are completing the final phases of trials.
a) Minoxidil- This medicine was made for treatment of high blood pressure. It was found that patients taking this medicine had increased hair growth. Hence, a local(topical) application was developed. It is available in2%, 5% and 10% strengths. Application of minoxidil leads to a higher number of visible hair and increase in hair shaft diameter. It acts by cutting short the resting phase of hair follicle (telogen) and recruiting more hair follicles into growing phase (anagen). The diameter of hair follicle and as a result, shaft increases. The effects are maintained as long as the medicine is applied.
b) Finasteride- This medicine is available as tablet for oral intake. The strength of 1mg. Is used for purpose of hair regrowth. This medicine acts by inhibiting the 5 alpha reductase enzyme type I, thus causing the level of 5DHT to fall. Thus the follicle is free from inhibitory effect of 5DHT and free to grow. Dutasteride, which is effective against both types I and II isoenzymes is more effective.The tablet is safe for long term use in consultation with your doctor.
c) Bimatoprost- This medicine was developed in the form of eye drops for treatment of glaucoma. The patients using this were found to have longer and darker eyelashes. Bimatoprost acts by stimulating prostamide alpha F2 receptors in hair follicles. In 2008, it found U.S.F.D.A. approval for this purpose. The medicine and its analog lanatoprost are the subject of intense research for scalp hair growth and show promising initial results.
d) Biotin supplementation- Biotin is also known as Vitamin H, Vitamin B7 and coenzyme R. Its deficiency leads to hair loss, alopecia, dermatitis and neurologic symptoms. It is normally synthesized in body and this is sufficient for body needs. However, it is also available in egg yolk, liver, green leafy vegetables and peanuts. Role of biotin supplementation for hair growth in the absence of deficiency is a subject of debate. Still, it is often prescribed to eliminate possible deficiency, causing hair loss.
e) Laser Haircomb- Lasers in the range of 650 and 670nms increase nutrient uptake and cellular ATP production in hair follicles through increased mobilization of calcium ions. This counteracts the effect of 5DHT on hair follicles. This leads to maintenance of healthy scalp hair.
f) PRP therapy- PRP (platelet rich plasma) is prepared from a small amount of patient’s blood and injected into areas of scalp, where hair have become thin/ are being lost. Platelets are tiny cells, normally present in blood and contain a good amount of growth factors such as Platelet Derived Growth Factor (PDGF), Transforming Growth Factor Beta (TGF-b), Vascular Endothelial Growth Factor (VEGF), Epidermal Growth factor (EGF), Fibroblast Growth Factor (FGF2) and Insulinlike Growth Factor (IGF). These act on the dormant hair follicles, stimulating these to begin the production of hair. Enhanced hair growth and diameter is noted, beginning at 4 months post treatment. PRP is typically used after preparing scalp with a dermaroller and also, injected. As it is prepared from patient’s own blood and used immediately, there is no risk of transmission of diseases or reaction.
a) Hair Transplant Surgery (FUG)- Hair transplant surgery is the most common surgical treatment for hair loss today. Hair transplantation is an operation that takes a strip of hair from back of the head. This area is then closed in a trichophytic manner so that it always remains covered with hair. This hair bearing strip is the divided into single hair follicles, under magnification by the hair transplant team. Individual follicles are then implanted into bald areas of scalp so that the area is covered. These follicles then consolidate and start growing hair. Transplanted hair will continue to grow throughout life, at a normal rate. Typically, the hair at back and sides of scalp are genetically less susceptible to the effects of androgens (as they lack 5DHT receptors) and hence continue to grow life-long, while the genetically more susceptible front and top of the scalp hair fall out in cases of male pattern baldness. The donor hair follicles from back and sides of head carry this same genetic strength even after transfer and hence continue to grow lifelong. Candidates for hair transplant surgery are those individuals that have sufficient donor hair in back and sides of the scalp to transplant to the balding area.Case -1
b) Hair Transplant Surgery (FUE)- In this method, the hair are extracted individually, by a machine from donor area. These are then transplanted in a normal manner into bald areas of scalp. The advantages of this method are- no requirement of removal of hair bearing skin strip, use of body hair also for transplantation in those people, who have insufficient scalp donor hair. The disadvantages are a higher percentage of hair loss during surgery, requirement of a 4-5 times larger donor area and the limitation of body hair in terms of length.
c) Hair-bearing Flap Transfer- This method is used occasionally. In this, a flap of tissue containing hair follicles is transferred from the scalp donor are (sides and back), to the bald area in front. The advantage of this method is natural hair density in recipient area. The disadvantage is in it being a major surgical procedure.Case -5
d) Artificial Hair (Biofibre) Implantation- For those who do not have sufficient donor areas, artificial hair implantation is a good alternative. In this novel technique, sterilized and biocompatible artificial hair fibres.(Biofibre® CE 0373/TGA,Medicap Ltd, Carpi (MO), Italy) developed in Italy are implanted surgically into the scalp skin under strict aseptic conditions. As with other techniques, a healthy and disease free scalp skin is required. The Biofibre is made from a special polyamide compound, with diameter 80µm and length of 15 cm. It is available in 13 different shades of black, brown, blond, and gray colors. Initially only100 fibers are with the help of a specialized instrument in a localized area of the scalp. This area is then observed for 6 weeks for any allergic reactions . If the test area showed allergic reaction, then all the implanted fibers are removed, and further implantation is not done. On the contrary, if implantation is tolerated with no signs of allergy or infection, this is followed by subsequent sessions of up to 500 fibers every 4–6 weeks as needed. This is one surgical technique, which gives immediate result and relief from baldness. There is no downtime and one can return back to work immediately. As Biofibres are artificial, these do not grow and around 10-20% fall out in a year’s time, thus requiring replacement.
These are used in cases of extensive baldness, where sufficient donor area is not available. These are also used in cases of alopecia totalis/ universalis, telogen effluvium, anagen effluvium as a temporary measure, extensive cicatricial alopecia and many a times to supplement the results of medical and surgical treatment of baldness. These consist of hair weaving, extensions, fusion, hair pieces, hair prosthesis and hair replacing wigs. The material used is human hair, synthetic material or a combination. This external hair bearing device is secured to existing hair or scalp with the help of glue, weave or clips. Topical powders/ fibres are also available for purpose of camouflage and when applied, make the hair loss seem less extensive.