Detailed information about cell implantation and hair growth

Cell Implantation

Everybody wants to look good and hair forms one of the most important aspects of our appearance. That’s why people going bald or losing hair rather rapidly look for treatments to somehow arrest the hair loss and grow it back. Treatment approaches are wide ranging from using drug medications to exploring surgical options such as hair transplants.

But all the medical or surgical therapies presently available for hair restoration leave a lot to be desired. Scientists have thus been exploring alternative treatments.

One such option is follicular cell implantation (FCI). This treatment would be permanent as it involves transplantation of the hair producing factory i.e. the follicular cells. Not only is it permanent, unlike transplantation it would not be limited by the quantity of donor hair. The ability to expand cells in culture would provide enough cells to induce a plentiful number of new follicles from a small number of donor ones.

In FCI, new follicles are induced by the cultured dermal papilla (DP) or dermal sheath cup (DSC) cells in conjunction with existing epidermis in the scalp, so that new follicles are a combination of the implanted cells and target epidermis. DP or DSC cells are not cloned, nor are whole follicles multiplied, although the idea that many new follicles are formed is correct.

The first versions of FCI are likely to be autologous, in which the patient’s own cells are used. There are two major technical challenges inherent in the procedure: (1) the expansion of cells in culture and (2) the implantation of cells into the patient’s scalp to effect hair restoration.

Challenges of follicular cell implantation

Challenges related to culture of follicular tissues have been dealt with in other articles in the site. So far as the challenge regarding implantation of cultured cells into the patient’s scalp is concerned, the primary consideration is that the signaling molecules involved in follicular morphogenesis only act over very short distances. Hence, implanted cells need to be placed in immediate proximity to keratinocytes for meaningful signaling to occur.

Another consideration is that the extracellular matrix in the adult scalp is much denser and more collagenous than the matrix surrounding the developing follicle, and it is not known if a nascent follicle will penetrate the adult matrix and grow down into the dermis like it does during normal development. If the new follicle were to remain superficial, it’s possible it may not be anchored well enough to withstand damage through normal pulling from brushing or washing.

A likely target for implantation in the scalp is interfollicular epidermis. It has been demonstrated that new follicles could be induced in the hairless skin of rats. In this model, implanted cells aggregated near the epidermis and signaled keratinocytes to form a hair peg, which then grew down into the dermis and surrounded the aggregated DP cells as in embryonic development.

Another possible route is intrafollicular implantation of cells into preexisting follicles. The targets would be the miniaturized follicles that are cosmetically insignificant, and the strategy would be to rejuvenate miniaturized follicles by the insertion of hair-inductive DP cells.

Because the cellular target in androgenetic alopecia is the dermal papilla, providing the follicle with new, androgen-insensitive DP or DSC cells might reactivate the follicle to form a normal (terminal) hair. The mechanism of intrafollicular FCI would probably resemble reentry into anagen in the hair cycle, except from a new dermal papilla.

In conclusion, the small size and relative accessibility of the hair follicle, the demonstrable hair induction by adult dermal papilla and sheath cells, and the ability to expand them in culture make FCI a feasible therapy that should be available in the near future. Successful interfollicular FCI would mean that hair restoration could be achieved in patients with hair loss due to burns, trauma, or scarring alopecias who otherwise have too little donor hair for traditional transplants.