Photothermal stress triggered by near-infrared-irradiated carbon nanotubes up-regulates osteogenesis and mineral deposition in tooth-extracted sockets.

Abstract

PURPOSE:

The bone regenerative healing process is often prolonged, with a high risk of infection particularly in elderly and diseased patients. A reduction in healing process time usually requires mechanical stress devices, chemical cues, or laser/thermal therapies. Although these approaches have been used extensively for the reduction of bone healing time, the exact mechanisms involved in thermal stress-induced bone regeneration remain unclear.

METHODS:

Photothermal stress (PTS) stimulation was carried out using a novel photothermal device, composed of an alginate gel (AG) including carbon nanotubes (CNT-AGs) and their irradiator with near-infrared (NIR) light. We investigated the effects of optimal hyperthermia on osteogenesis, its signalling pathway in vitro and mineral deposition in tooth-extracted sockets in vivo.

RESULTS:

The PTS (10 min at 42 °C, every day), triggered by NIR-induced CNT, increased the activity of alkaline phosphatase (ALP) in mouse osteoblast MC3T3-E1 cells in a time-dependent manner compared with the non-thermal stress control. PTS significantly induced the expression of osteogenic-related molecules such as ALP, RUNX2 and Osterix in a time-dependent manner with phosphorylated mitogen-activated protein kinases (MAPK). PTS increased the expression of heat shock factor (HSF) 2, but not HSF1, resulting in activation of heat shock protein 27. PTS significantly up-regulated mineral deposition in tooth-extracted sockets in normal and ovariectomised osteoporotic model mice in vivo.

CONCLUSIONS:

Our novel CNT-based PTS up-regulated osteogenesis via activation of heat shock-related molecules, resulting in promotion of mineral deposition in enhanced tooth-extracted sockets.

• Authors: Hiroshi Kajiya, Yuri Katsumata, Mina Sasaki, Takashi Tsutsumi, Minoru Kawaguchi, Tadao Fukushima
• Journal: International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group (Int J Hyperthermia) Vol. 31 Issue 6 Pg. 635-42 ( 2015) ISSN: 1464-5157 [Electronic] England
• PMID: 26000973 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Alginates
• DNA-Binding Proteins
• Gels
• Heat Shock Transcription Factors
• Heat-Shock Proteins
• Hexuronic Acids
• Hsf1 protein, mouse
• Hsf2 protein, mouse
• Nanotubes, Carbon
• RNA, Messenger
• Transcription Factors
• Glucuronic Acid
• Mitogen-Activated Protein Kinases

Topics

• Alginates
• Animals
• Bone Density
• Cell Line
• DNA-Binding Proteins (genetics)
• Female
• Gels
• Glucuronic Acid
• Heat Shock Transcription Factors
• Heat-Shock Proteins (genetics)
• Heat-Shock Response (physiology)
• Hexuronic Acids
• Hyperthermia, Induced (adverse effects)
• Light
• Male
• Mice
• Mitogen-Activated Protein Kinases (metabolism)
• Nanotubes, Carbon
• Osteogenesis
• Osteoporosis (metabolism)
• Ovariectomy
• RNA, Messenger (metabolism)
• Tooth Extraction
• Tooth Socket (metabolism)
• Transcription Factors (genetics)