Hair follicle regeneration after ionizing radiation: the dynamic coordination of distinct compartments
碩士 === 國立臺灣大學 === 醫學工程學研究所 === 106 === The hair follicle (HF) is a dynamic organ that continuously cycles through anagen (growth), catagen (regression) to telogen (relative quiescence). HF is composed of epithelial cells and dermal papilla (DP) compartments and interaction between these two compartm...
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| Format: | Others |
| Language: | en_US |
| Published: |
2018
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| Online Access: | http://ndltd.ncl.edu.tw/handle/g8jd69 |
| Summary: | 碩士 === 國立臺灣大學 === 醫學工程學研究所 === 106 === The hair follicle (HF) is a dynamic organ that continuously cycles through anagen (growth), catagen (regression) to telogen (relative quiescence). HF is composed of epithelial cells and dermal papilla (DP) compartments and interaction between these two compartments play an important role in the regulation of HF regeneration. The responses of anagen HFs to ionizing radiation (IR) can be divided into dystrophic anagen and dystrophic catagen pathways. However, the detailed cellular dynamics of such regenerative responses of anagen HFs is still unclear. In this study, we first characterized how IR-induced apoptotic cells are removed. The results of transmission electron microscopy and TUNEL assay showed that apoptotic cells were engulfed by surviving epithelial cells in the hair bulb. Time-lapse intravital imaging in K14-H2B-EGFP/LEF1-RFP transgenic mice with two-photon microscopy showed that the basal lower proximal cup cells and basal outer root sheath cells non-collectively migrated downward toward the proximal HFs along the basement membrane. In addition, cell mitosis was only observed in lower proximal end of HFs. The results showed that the regenerative process of HFs following IR injury involved elimination of apoptotic cells by non-professional phagocytosis and active cell migration of lower proximal cup cells and basal outer root sheath cells along the basement membrane to replenish the lost cells. We propose that timely HF regeneration following IR is accomplished by coordination of different behaviors of distinct cell populations. The regenerative principle we revealed here may also be employed by other epithelial organs.
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