Activation of vasculogenic progenitor cells by ent-16α,17-dihydroxy-kauran-19-oic acid

Simultaneous quantification of Kirenol and ent-16β,17-dihydroxy-kauran-19-oic acid from Herba Siegesbeckiae in rat plasma by liquid chromatography-tandem mass spectrometry and its application to pharmacokinetic studies

A rapid and specific liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method was developed for the simultaneous determination of two active diterpenoids: Kirenol and ent-16β,17-dihydroxy-kauran-19-oic acid (DHKA) from Herba Siegesbeckiae in rat plasma using osthole as an internal standard (IS). Plasma sample pretreatment involved a one-step liquid-liquid extraction with ethyl acetate. Chromatographic separation was performed on a Waters Symmetry C18 column (2.1mm×100mm, 3.5μm) with isocratic elution using methanol-5mmol/L aqueous ammonium acetate (80:20, v/v) as the mobile phase at a flow rate of 0.2mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer in multiple reaction monitoring (MRM) mode under positive and negative electrospray ionization. The calibration curves were linear over the range of 50.0-25,000ng/mL for Kirenol, and 25.0-12,500ng/mL for DHKA. The extraction recoveries of the two analytes and the IS were all over 85%. The intra- and inter-day precision (relative standard deviation) values were less than 16.8% and the accuracy (relative error) ranged from -10.7 to 10.6% at four quality control levels. The validated method was successfully applied to a comparative pharmacokinetic study of the two diterpenoids in rat plasma after intragastric administration of Kirenol, DHKA and Herba Siegesbeckiae extract. The results showed that there were obvious differences between the pharmacokinetic behaviors after oral administration of Herba Siegesbeckiae extract compared with each of the substances alone.

Ultraviolet B preconditioning enhances the hair growth-promoting effects of adipose-derived stem cells via generation of reactive oxygen species

Hypoxia induces the survival and regenerative potential of adipose-derived stem cells (ASCs), but there are tremendous needs to find alternative methods for ASC preconditioning. Therefore, this work investigated: (1) the ability of low-dose ultraviolet B (UVB) radiation to stimulate the survival, migration, and tube-forming activity of ASCs in vitro; (2) the ability of UVB preconditioning to enhance the hair growth-promoting capacity of ASCs in vivo; and (3) the mechanism of action for ASC stimulation by UVB. Although high-dose UVB decreased the proliferation of ASCs, low-dose (10 or 20 mJ/cm(2)) treatment increased their survival, migration, and tube-forming activity. In addition, low-dose UVB upregulated the expression of ASC-derived growth factors, and a culture medium conditioned by UVB-irradiated ASCs increased the proliferation of dermal papilla and outer root sheet cells. Notably, injection of UVB-preconditioned ASCs into C(3)H/HeN mice significantly induced the telogen-to-anagen transition and increased new hair weight in vivo. UVB treatment significantly increased the generation of reactive oxygen species (ROS) in cultured ASCs, and inhibition of ROS generation by diphenyleneiodonium chloride (DPI) significantly attenuated UVB-induced ASC stimulation. Furthermore, NADPH oxidase 4 (Nox4) expression was induced in ASCs by UVB irradiation, and Nox4 silencing by small interfering RNA, like DPI, significantly reduced UVB-induced ROS generation. These results suggest that the primary involvement of ROS generation in UVB-mediated ASC stimulation occurs via the Nox4 enzyme. This is the first indication that a low dose of UVB radiation and/or the control of ROS generation could potentially be incorporated into a novel ASC preconditioning method for hair regeneration.