Hyperbaric oxygen therapy suppresses osteoclast formation and bone resorption.

Area of Science:

• Biomedical Engineering
• Cell Biology
• Orthopedics

Background:

• Osteonecrosis (ON) pathogenesis involves complex cellular and molecular mechanisms.
• The precise role of hyperbaric oxygen therapy (HBO) in improving ON remains incompletely understood.
• Osteoclast formation and activity are critical in bone resorption and ON progression.

Purpose of the Study:

• To investigate the cellular and molecular effects of HBO, hyperbaric pressure, and hyperoxia on osteoclastogenesis.
• To elucidate the mechanisms by which HBO influences osteoclast formation and bone resorption.
• To determine if HBO can inhibit osteoclast activity in hypoxic conditions, characteristic of osteolytic disorders.

Main Methods:

• Utilized RAW 264.7 cells and human peripheral blood monocytes (PBMC) to model osteoclast formation.
• Exposed cells to daily HBO (2.4 ATA, 97% O2), hyperbaric pressure (2.4 ATA, 8.8% O2), or normobaric hyperoxia (1 ATA, 95% O2) for 90 minutes.
• Assessed osteoclast formation, bone resorption, and expression of key regulatory genes (RANK, NFATc1, Dc-STAMP, HIF-1α) under normoxic and hypoxic conditions.

Main Results:

• HBO, hyperbaric pressure, and normobaric hyperoxia significantly reduced RANKL-induced osteoclast formation and bone resorption in normoxic settings.
• HBO demonstrated a more potent anti-osteoclastic effect compared to hyperoxia or pressure alone.
• HBO effectively inhibited osteoclast formation and resorption even under hypoxic conditions, unlike hyperoxia or pressure alone.
• The suppressive effects of HBO were linked to decreased expression of RANK, NFATc1, Dc-STAMP, and reduced hypoxia-induced HIF-1α.

Conclusions:

• HBO exhibits significant anti-osteoclastic and anti-resorptive properties, offering a mechanistic basis for its therapeutic use in osteonecrosis.
• HBO is effective in mitigating osteoclast formation and bone loss, even in the low-oxygen environments typical of osteolytic skeletal conditions.
• The findings support HBO as a valuable adjunctive therapy for preventing bone loss associated with hypoxia-related skeletal disorders.