Role of follicular stem cells in wound healing

Role of follicular stem cells in wound healing

The research in hair growth and skin care has taken new strides with the discovery of adult stem cells, which are sometimes also referred to as progenitor cells. The scientific world got a major boost with the findings that stem cells can be used to cure genetic diseases by replacing damaged cells. And no wonder that the area of the body that has maximum frequency of wounds, the skin, is benefiting from this theory.

Scientists and researchers have tried their hardest to find a way to correct or replace skin that has been burnt or damaged through wounds by using cosmetic and plastic surgery. So far though the success of new methods of surgery and treatment for extensive skin damage have been mixed. But stem cells have given new hope to the scientists as well as to the patients that receive such burns and wounds. With advanced scientific techniques, researchers have been able to make new discoveries, which can be used in the science of skin care and dermatology.

It is a well known fact that epidermal cells cover the human skin. Hair follicle cells and these epidermal cells are under the constant microscope of dermatologists and skin specialists, as there are some contrasting and insufficient theories about the involvement of epidermal cells for production of hair follicle cells in the cases of burnt skin of patients.

• Some theories state that if epidermal cells are lost, there are chances of keratinocytes migrating from hair follicles and re-establishing the lost epidermis.
• Some theories, however, maintain the fact that there is no such trafficking between epidermis cells and hair follicle cells, and they are both independently self-sufficient.

Which basic theory is correct is a topic of hot debate, and no conclusive evidence has yet been found in support of one or other. Some recent investigations suggest that there are chances of some traffic of cells between the epidermis and the hair follicles. However, the research data is not conclusive due to the limited number of subjects that have been examined by the researchers. Utmost care needs to be taken while taking observations in experiments and it is a well-known fact that the environment effects the skin of the subjects, which can alter the nature of results, significantly.

Techniques used for checking the traffic

There is a particular biological property that can be used to identify the keratinocyte stem cells. They are normally very slow cycling and researchers can identify these sow growing keratinocyte stem cells with some special scientific techniques. In this study, the scientists used a technique to identify these keratinocyte stem cells known as the label retention technique.

Though the overall reliability of this technique still remains to be vindicated, the technique has received wide support from dermatological scientists, and some important results have been obtained by using this technique. This technique inovles exposing skin cells to a supply of tritiated thymidine (a radioactive substance). All the cells take up the radioactive thymidine and incorporate it into themselves. Then the tritiated thymidine is taken away and the cells get normal non-tritiated thymidine for the rest of the experiment. As cells grow and multiply, the tritiated thymdine gets spread progressively thinner between the daughter cells. The radioactivity subsides and eventually disappears in growing cells. However, stem cells don’t grow and proliferate much, so the tritiated thymidine in these cells stays in them at fairly high concentrations (I.e. they retain the “label” of radioactivity – they are label retaining cells). The radioactive cells can be tracked over a long time period and only the slow cycling cells retain the label while others eventually lose it. In this way the scientists can follow the stem cells and see where they go.

The questions that arise from the results of this technique are both interesting and important, as they may present a total new face to the theories that deal with the formation of epidermis cells with the migration of keratinocyte cells from hair follicles and also the ones that state that no such thing happened and epidermis cells and hair follicles are distinct and there is no connection between the two.

Recent studies about the connection

Some very recent studies have suggested and supported the fact that there may be a chance of some trafficking of keratinocyte stem cells from a part of the hair follicle which is known as Bulge. What makes these findings more striking is the fact that they also suggest formation of epidermal cells with these bulge stem cells. The data and the investigation results can be used for further examination to establish a clear and permanent relationship between the formation of hair follicles and epidermal cells with the help of Bulge stem cells.

This property could actually help a lot in the field of skin care. These studies support the idea that, though the epidermal cells are self-sufficient under normal conditions, if the need arises, stem cells can move from Bulge area of hair follicles to form epidermal cells. The conditions under which this trafficking may occur may include neonatal expansion of the skin and during adult skin wound repair. The main point to be taken care of is that the subjects that are examined in these studies have different kinds of skin on different parts of the body. In humans, there are some parts which have no hair follicles on the skin surface like the palms and soles of the feet. In these areas clearly wounds cannot be supplied with stem cells from hair follicles because there are no hair follicles nearby.

Conclusion

The similarities of microenvironment and other properties between epidermal cells and hair follicle cells present a clear picture that the trafficking of stem cells does happen under certain circumstances. The authenticity of the label retention technique has also been supported by the fact that researchers are able to examine the stem cells from epidermis cells and hair follicle cells. This gives an added advantage to researchers for further studies and investigation about stem cells and their microenvironment. So, in the end we can say that there is a definite role played by follicular cells in the formation of epidermal skin during a time of need.