The Effects of Ischemia and Hyperoxygenation on Hair Growth and Cycle.

Alopecia has several causes, but its relationship with ischemia/hypoxia has not yet been investigated in detail. In this study, we studied the changes of hair follicles induced by ischemia and potential effects of normobaric hyperoxygenation (NBO) on the hair cycle and growth. We found that skin ischemia reduced hair growth rate, hair shaft size, and its pigmentation in the anagen phase of mice, which may reflect an aspect of pathophysiology of hair loss (alopecia) and depigmentation (gray/white hairs). Hyperoxygenation increased hair growth rate in organ culture of both human and murine hair follicles. Systemic NBO promoted hair growth in early anagen and mid-anagen, and delayed catagen onset in mice. However, telogen-to-anagen transition was not affected by NBO as far as non-ischemic skin is concerned. The results of this study indicated that the hair follicle is very sensitive to oxygen tension and oxygen tension affects the regulation of hair growth and cycle in vitro and in vivo. It was suggested that systemic NBO can be safely applied for a long period and can be a noninvasive therapeutic approach to alter hair growth and cycle by manipulating the microenvironment of hair follicles.

Combination of Dual Wavelength Picosecond and Nanosecond Pulse Width Neodymium-Doped Yttrium-Aluminum-Garnet Lasers for Tattoo Removal.

BACKGROUND AND OBJECTIVES: Tattoo removal by laser has been mostly performed using Q-switched laser, which has nanosecond pulse width. In recent years, the efficacy of treatment with picosecond pulse width laser has also been reported. STUDY DESIGN/MATERIALS AND METHODS: Using a picosecond-domain, neodymium-doped yttrium-aluminum-garnet laser with a potassium-titanyl-phosphate frequency-doubling crystal, we performed a retrospective clinical study with combination treatment using pulse widths of 750 ps and 2 ns. The number of treatments was compared with the Kirby-Desai score. Tissue changes immediately after laser irradiation at 2 ns and 750 ps were compared using an electron microscope. RESULTS: The combination treatment using pulse widths of 2 ns and 750 ps was safe and more effective than the Q-switched neodymium-doped yttrium-aluminum-garnet laser treatment. Tattoo removal was possible with significantly fewer treatment numbers than the Kirby-Desai score, without adverse events. The results from the scanning electron microscope revealed that ink particles irradiated by 750 ps were more dispersed than those by 2 ns. CONCLUSIONS: The combination treatment with pulse widths of 2 ns and 750 ps and 1064 nm and 532 nm wavelengths using the neodymium-doped yttrium-aluminum-garnet laser was safe and effective and can be a useful option for tattoo removal. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Normobaric hyperoxygenation enhances initial survival, regeneration, and final retention in fat grafting.

BACKGROUND: Fat grafting is a promising modality for soft-tissue augmentation/reconstruction. However, grafted fat tissue is not initially perfused and relies on plasmatic diffusion from the recipient bed until revascularization occurs. The authors evaluated the therapeutic effects of normobaric hyperoxygenation for enhancing fat graft retention. METHODS: Aspirated human fat tissue was cultured under tissue hypoxia (1% oxygen), normoxia (6%), and hyperoxia (20%) levels, and evaluated for adipocyte viability. Inguinal fat pads were autografted under mouse scalps (n=36), and mice were housed in either 20% (control) or 60% (normobaric hyperoxygenation) atmospheric oxygen for the first 3 days, and then returned to normoxia. Samples harvested at 0, 1, 2, 4, 8, and 12 weeks were analyzed immunohistochemically for adipocyte viability and regeneration. RESULTS: Organ culture adipocytes died more quickly under lower oxygen tensions; thus, hyperoxygenation of recipient tissues may delay adipocyte death after fat grafting. Autografted mouse adipose tissue underwent dynamic remodeling, from ischemic degeneration to partial regeneration, over 12 weeks. Normobaric hyperoxygenation grafted samples showed significantly larger survival zones and engraftment scores (calculated using sample weight and adipocyte viability) at 1 and 12 weeks, respectively, than control samples. In addition, adipocyte regeneration (number of perilipin-positive preadipocytes), which peaked at 4 weeks, was significantly increased in normobaric hyperoxygenation samples. CONCLUSION: The normobaric hyperoxygenation protocol using 60% oxygen can be safely applied to enhance adipocyte survival, regeneration, and final engraftment after fat grafting.