Hyperforin/HP-ß-Cyclodextrin Enhances Mechanosensitive Ca2+ Signaling in HaCaT Keratinocytes and in Atopic Skin Ex Vivo Which Accelerates Wound Healing.

Cutaneous wound healing is accelerated by mechanical stretching, and treatment with hyperforin, a major component of a traditional herbal medicine and a known TRPC6 activator, further enhances the acceleration. We recently revealed that this was due to the enhancement of ATP-Ca2+ signaling in keratinocytes by hyperforin treatment. However, the low aqueous solubility and easy photodegradation impede the topical application of hyperforin for therapeutic purposes. We designed a compound hydroxypropyl-ß-cyclodextrin- (HP-ß-CD-) tetracapped hyperforin, which had increased aqueous solubility and improved photoprotection. We assessed the physiological effects of hyperforin/HP-ß-CD on wound healing in HaCaT keratinocytes using live imaging to observe the ATP release and the intracellular Ca2+ increase. In response to stretching (20%), ATP was released only from the foremost cells at the wound edge; it then diffused to the cells behind the wound edge and activated the P2Y receptors, which caused propagating Ca2+ waves via TRPC6. This process might facilitate wound closure, because the Ca2+ response and wound healing were inhibited in parallel by various inhibitors of ATP-Ca2+ signaling. We also applied hyperforin/HP-ß-CD on an ex vivo skin model of atopic dermatitis and found that hyperforin/HP-ß-CD treatment for 24 h improved the stretch-induced Ca2+ responses and oscillations which failed in atopic skin.

Mechanosensitive ATP release from hemichannels and Ca²âº influx through TRPC6 accelerate wound closure in keratinocytes.

Cutaneous wound healing is accelerated by exogenous mechanical forces and is impaired in TRPC6-knockout mice. Therefore, we designed experiments to determine how mechanical force and TRPC6 channels contribute to wound healing using HaCaT keratinocytes. HaCaT cells were pretreated with hyperforin, a major component of a traditional herbal medicine for wound healing and also a TRPC6 activator, and cultured in an elastic chamber. At 3 h after scratching the confluent cell layer, the ATP release and intracellular Ca(2+) increases in response to stretching (20%) were live-imaged. ATP release was observed only in cells at the frontier facing the scar. The diffusion of released ATP caused intercellular Ca(2+) waves that propagated towards the rear cells in a P2Y-receptor-dependent manner. The Ca(2+) response and wound healing were inhibited by ATP diphosphohydrolase apyrase, the P2Y antagonist suramin, the hemichannel blocker CBX and the TRPC6 inhibitor diC8-PIP2. Finally, the hemichannel-permeable dye calcein was taken up only by ATP-releasing cells. These results suggest that stretch-accelerated wound closure is due to the ATP release through mechanosensitive hemichannels from the foremost cells and the subsequent Ca(2+) waves mediated by P2Y and TRPC6 activation.

Preclinical studies on safety of fullerene upon acute oral administration and evaluation for no mutagenesis.

Fullerenes characterized as an antioxidant are believed to reduce various reactive chemical species, such as free radicals, and their characteristic features have been disclosed to furnish many useful medical technologies. Despite the numerous applications for the biological efficacy of fullerenes, less is known about the toxicity of fullerenes in mammals. Hence, the protocol was designed to determine the acute oral median lethal dose and evaluate the acute toxicity of fullerenes when administrated as a single dose to Sprague-Dawley rats. In an acute toxicity test, fullerenes were administered once orally to a single group of male and female at a dose level of 2000 mg/kg. No deaths were observed and the body weights in both sexes of 2000 mg/kg group increased in a similar pattern to the control group. Genotoxicity of fullerenes was also assessed in a bacterial reverse mutation assay (Ames test) and the chromosomal aberration test in cultured Chinese hamster lung (CHL/IU) cells. Although structural chromosomal aberrations were induced at up to 5000 microg/mL, there was no significant increase in the frequency of chromosomal aberrations at any dose level regardless of presence of S9. Fullerenes did not cause genetic damage in Salmonella typhimurium TA100, TA1535, TA98 and TA1537 and Escherichia coli WP2uvrA/pKM101. These results indicate that fullerenes are not of high toxicological significance.