Light stimulation makes bones heavier

Date:
October 8, 2020
Source:
Tokyo Medical and Dental University
Summary:
Researchers showed that laser ablation of bone inhibits
expression of the osteogenesis inhibitor protein sclerostin
without causing inflammation, unlike the conventional bur-drilling
technique. Further investigations confirmed that this beneficial
bio-stimulation works by inducing mechanical stress. These findings
help advance research into the treatment of osteoporosis as well
as specific enhancement of bone regrowth in orthopedic and dental
surgery.



FULL STORY ========================================================================== Osteoporosis is a disease in which bone loses mass as a result of age
or other influences. This weakening is the leading cause of fractures
in the elderly, often after trivial injuries, and makes treating these "pathological fractures" a challenge. Bone health is a dynamic process
of continual remodeling controlled by multiple factors. Sclerostin,
a glycoprotein coded by the gene SOST, is produced by bone cells and
suppresses bone formation. Now, researchers at Tokyo Medical and Dental University (TMDU) have shown that laser irradiation, by inhibiting
sclerostin expression without inducing inflammation, shows promise as
a new treatment modality for osteoporosis.


========================================================================== Lasers have been used in medical and dental practice for their beneficial photo-biomodulation effects on tissue healing. The benefits of low-level
laser therapy are now gaining increased attention in spheres of medicine
and dentistry that require enhanced bone regeneration.

The team knew that in periodontal surgery, bone that underwent controlled destruction using a specific type of laser known as an Er:YAG laser
healed faster than bone subjected to conventional bur drilling. Thus,
they wondered whether Er:YAG laser irradiation modified SOST expression in bone. "We set out to compare comprehensive and sequential gene expression
and biological healing responses in laser-ablated, bur-drilled, and
untreated bone, as well as investigating the bio-stimulation effect of
an Er:YAG laser on osteogenic cells," explains Yujin Ohsugi, lead author.

Using microarray analysis, the researchers first studied gene expression patterns in rat skull bones during healing at 6, 24, and 72 hours after drilling or laser treatment. Immunohistochemical analysis at 1 day was performed to detect sclerostin expression. Additionally, oseteogenic
cell cultures were irradiated in vitro and assessed for cell death and sclerostin concentration.

"We confirmed decreased sclerostin expression after laser irradiation
both in vivo and in vitro," affirms Sayaka Katagiri, corresponding author.

"Interestingly, sequential microarray analysis revealed a clear
distinction in the gene expression pattern between bur-drilled and laser-ablated bones at 24 hours, with the former alone showing enriched inflammation-related pathways.

Significantly, at 6 hours following laser ablation, the Hippo
signaling pathway that limits tissue overgrowth was enriched but inflammation-related pathways remained unaffected, suggesting that laser irradiation worked thorough mechanical bio-stimulation." The finding
that mechanical stimulation of laser irradiation inhibits the pathways
that suppress bone regeneration without provoking inflammation may
aid development of laser-based therapeutic methods. Such methods might
be used in treatments for osteoporosis and to induce or promote bone regeneration in medical and dental procedures.


========================================================================== Story Source: Materials provided by
Tokyo_Medical_and_Dental_University. Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Yujin Ohsugi, Sayaka Katagiri, Tomomitsu Hirota, Hiromi Niimi,
Masahiro
Hatasa, Kazuki Watanabe, Tsuyoshi Shimohira, Koji Mizutani,
Moe Kitazawa, Ayumi Matsuzawa, Hiroshi Kadokura, Satoshi Yokose,
Takanori Iwata, Akira Aoki. Laser irradiation decreases sclerostin
expression in bone and osteogenic cells. The FASEB Journal, 2020;
34 (9): 12877 DOI: 10.1096/ fj.202001032R ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201008104243.htm

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