Skin and dermal appendages stem cells exposure to tobacco smoke.

Stem cells are thought to persist throughout human life possessing enormous capacity for proliferation and differentiation. These cells and their microenvironment are potential targets for environmental pollutions, for example tobacco smoke. Tobacco smoke consists of thousands of substances which can disturb stem cell homeostasis by evoking, in particular, oxidative stress and hypoxia. It causes also deep, irreversible changes in the affected tissues. It is strongly linked with carcinogenesis. Skin is one of the most exposed tissues to tobacco smoke. Self-renewal dermal tissues, such as epidermis and its appendages, are composed of various stem cell populations. The tissue of the skin that is richest in SC is the hair follicle. In wound healing are involved: epidermal KSC population and stem populations from hair follicle, such as CD34+ and Lrig6+ cells. Some skin cancers, i.e., squamous cell carcinoma, originate from skin stem cells and are considered to be most associated with long-term smoking. Dermal stem cells can be affected by tobacco smoke components in two ways: internal, where xenobiotics are delivered with blood stream, and external, where the tissues are directly exposed to environmental tobacco smoke, as well as to third-hand smoke. Assessment of the dose- and time-response of the skin and dermal appendages to tobacco smoke exposure can allow to estimate the adverse health effects risk. Usually, to assess tobacco smoke exposure time, hairs and toenails are used. This is because they have a unique ability to store xenobiotics for longer periods of time in respect to their temporal appearance in the blood. Current scientific and medical problem is searching for more adequate biomarkers for TS exposure assessment. The unresolved question is, if stem cells isolated from the skin and its appendages might be good biomarkers for tobacco smoke exposure. We should take into consideration stem cell biology (proliferation vs. differentiation), expression of specific markers, half-live, regenerative potential, signs of malignant transformation etc. For practical purposes, human stem cell populations from the epidermis, hair follicles and nails, their microenvironment and mutual relations should be well recognized. These cells might be an interesting source of information on tobacco smoke exposure.