In Vivo Monitoring of Survival and Proliferation of Hair Stem Cells in a Hair Follicle Generation Animal Model

The purpose of this study was to investigate in vivo monitoring of hair follicle stem cells (newborn mouse fibroblasts [NFs]) expressing enhanced firefly luciferase (effluc) (NF-effluc) using noninvasive bioluminescence imaging (BLI). Effluc gene transduction into NFs was performed by retroviral vector, and effluc messenger ribonucleic acid expression and function were evaluated by reverse transcription–polymerase chain reaction and luciferase assay. After in vivo transplantation of NF-effluc cells to generate hair follicles, BLI was performed on days 1, 3, 7, 14, and 21 after transplantation. Additionally, hair follicle generation by the implanted stem cells was investigated using microscopy. The luciferase activity of NF-effluc was 41,175-fold higher compared to that of untransfected NFs. Bioluminescence signals from the transplantation site decreased gradually over 2 weeks; then the signal plateaued. Hair follicles were confirmed at the NF-effluc cell implantation site on day 14 after transplantation. We successfully monitored hair generation by hair stem cell implantation noninvasively with optical molecular strategy in an in vivo model.