UV Radiation Effect on Hair
We know that direct sunlight and ultraviolet radiation can affect the growth of hair follicles negatively. There is new research resulting on profiling the response of human hair follicles to ultraviolet radiation that was published in the Journal of Investigative Dermatology this month (January 2009). The joint effort work Department of Dermatology at the University of Lübeck in Lübeck, Germany and Zhejiang University in Hangzhou, China showed that excessive UVR ranks among the most harmful environmental influences on human skin.
The research was mainly done on organ-cultured human anagen hair follicles in vitro were irradiated with UVB (one of the two main types of Ultra Violet light), and reduction of hair shaft elongation, premature catagen entry, and reduced hair matrix keratinocyte proliferation were observed.
Upon irradiation with UVB at lower powers apoptotic cell death prevailed, whereas at higher power, necrotic cell death was predominant. These investigators concluded that UVR differentially modifies hair growth and cycle, promotes cell death, and induces complex regulatory events in human hair follicles in vitro. The leads from this human organ model, which is a living and human tissue interaction system under physiologically relevant in situ conditions, may encourage its use for general investigation of UV-induced effects as well as for testing possible agents for their UV-protective agents.
We can see that some patients who are exposed to sunlight for extended periods of time experience hair loss on unprotected parts of their scalp skin. I personally have a no sun exposure policy for 6 months after hair transplantation for all my patients at our Los Angeles hair transplant clinics. Now it is becoming even clearer that both native hair and transplanted hair could get hurt by being exposed to direct sunlight.
Tags: anagen, apoptotic, catagen, hair growth, hair growth cycle, in situ, in vitro, keratinocyte, ultra violet, UV, UVR