Hair follicle cycle

                                                                                         

The regulation and structure of hair follicle are rather complex - they are composed of more than 20 cells and involve numerous signalling events. These complexities make the experimental hair research a challenging task. The scientists proceed with utmost care in choosing the experimental model for finding the answer to each question related to hair growth or diseases.
Analysis in Humans
The task of monitoring hair growth and hair abnormalities apparently appears to be easy due to their localization on the skin surface. Then you can easily access the hair fibers and hair roots for non-invasive collection. Then, the hair cycling anomalies can also be easily evaluated in clinical diagnostics, using simple light microscopy. Phototrichograms, and the recent development of the “trichoscan™” technique, allow quantification of hair growth in vivo. Moreover, the use of global photography techniques has emerged as the most popular approach in treatment evaluation. It is true that these approaches prove to be effective in the diagnosis of disease and clinical treatment trials; but they provide only limited information about the hair follicle in the skin. More invasive techniques are needed to characterise hair follicles. So far the clinics use techniques such as tissue biopsy and histological analysis of the hair follicle structure.
Animal models

Using animal models in the experimentations relating to hair follicle development and hair diseases have become more popular in recent decades. Developmental biology is increasingly making use of model organisms such as Drosophila, Xenopus and Zebrafish. These have provided valuable insights into the role of conserved signalling pathways including Hedgehog or Wingless in pattern formation and formation of skin appendages in general. Genetically engineered mice are being used as mammalian models, to study the regulatory events in hair follicle development and hair growth. These studies are directly relevant to hair follicle biology in humans. Rodent models are especially valued in many researches due to a number of reasons, such as 1. their ready availability, 2. rapid breeding, 3. known genetics in inbred strains, 4. the ability to modify their genetic profile, 5. the ability to control environmental input, and 6. the ability to conduct invasive procedures.

Transplant models

Tissue transplant models open up new possibilities; this approach involves the transplantation of diseased hair-bearing human skin onto immunodeficient mice. This approach is helpful in the study and manipulation of human hair growth. This method has been applied in research on androgenetic alopecia where no satisfactory rodent model was available, alopecia areata, and for the study of several forms of genetic trichoses. This method was also proved to be helpful in understanding basic hair biology. The advantage of this approach particularly relates to the evaluation of drugs and their impact on hair growth. However, the approach has its limitations too.

Cell culture

Culture techniques provide another useful tool for functional research. Hair follicles are composed of populations of interacting cells that can be readily identified and are clustered in discrete sites. This allows the isolation of different cell types to observe pronounced interactive abilities when cultured in vitro. Primary cell cultures from mouse and human hair follicles, including hair follicle keratinocytes, dermal papilla cells and melanocytes, provide important information on the expression of mediators and the behaviour of single cell populations.

About the author:
Maria Karla is deeply involved with research on Hair Biology . She wants people to benefit from his articles by getting the right information on Hair Fiber and Experimental hair techniques. For more information visit: www.hairbiology.com.



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