Low-intensity laser irradiation stimulates bone nodule formation via insulin-like growth factor-I expression in rat calvarial cells
✍ Scribed by Noriyoshi Shimizu; Kotoe Mayahara; Takeshi Kiyosaki; Akikuni Yamaguchi; Yasuhiro Ozawa; Yoshimitsu Abiko
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 228 KB
- Volume
- 39
- Category
- Article
- ISSN
- 0196-8092
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✦ Synopsis
Abstract
Background and Objective
We previously reported that low‐intensity laser irradiation stimulated bone nodule formation through enhanced cellular proliferation and differentiation. However, the mechanisms of irradiation are unclear. Thus, we attempted to determine the responsibility of insulin‐like growth factor (IGF)‐I for the action observed.
Study Design/Materials and Methods
Osteoblast‐like cells were isolated from fetal rat calvariae and cultured with rat recombinant (r) IGF‐I, IGF‐I‐antibody (Ab), and/or the cells were irradiated once (3.75 J/cm^2^) with a low‐intensity Ga‐Al‐As laser (830 nm). The number and area of bone nodules formed in the culture were analyzed, and IGF‐I expression was also examined.
Results
Treatment with rIGF‐I significantly stimulated the number and area of bone nodules. This stimulatory effect was quite similar to those by laser irradiation, and this stimulation was abrogated dose‐dependently by treatment with IGF‐I‐Ab. Moreover, laser irradiation significantly increased IGF‐I protein and gene expression.
Conclusion
The stimulatory effect of bone nodule formation by low‐intensity laser irradiation will be at least partly mediated by IGF‐I expression. Lasers Surg. Med. 39:551–559, 2007. © 2007 Wiley‐Liss, Inc.