Effects of hyperbaric oxygen and platelet derived growth factor on medial collateral ligament fibroblasts

Purpose: This study investigated hyperbaric oxygen (HBO₂) and platelet-derived growth factor-BB (PDGF-BB) to determine their combined effects on fibroblasts from rabbit medial collateral ligament (MCL). Method: Cells were divided into four groups: (I) Control, (II) HBO₂ treatment, (III) PDGF- BB treatment and (IV) HBO₂ combined with PDGF-BB treatment. All hyperoxic cells were exposed to 100% O₂ at 2.5 atmospheres absolute (ATA) in a hyperbaric chamber for 120 minutes per 48 hours. Measurement of cell growth was based on increase in cell number. Cell cycle modulations were analyzed by fluorescence- activated cell sorter (FACS). Quantity of Type I and Type III collagen was determined by western blotting and image analyzer. Results: Treatment doses of HBO₂ alone or PDGF-bb alone dependently increased cell growth. A combination of HBO₂ treatment plus PDGF-bb treatment had an additive effect on cell growth in comparison with HBO ₂ treatment alone or PDGF-bb treatment alone. FACS analysis revealed that HBO₂ alone, PDGF-bb alone and PDGF-bb plus HBO₂ treatment increase the percentage of cells accumulated in S-phase. Western blotting analysis revealed that Type III collagen content was decreased significantly after HBO₂ treatment alone or HBO₂ plus PDGF-bb treatment but not in PDGF-bb treatment alone. In contrast, although Type I collagen content was increased after HBO₂ treatment, the increase in Type I collagen (increase/original) was not statistically significant. Conclusion: HBO₂ or HBO₂ plus PDGF-bb treatment decreases the Type III collagen/Type I collagen content, which could result in mechanically stronger collagen fibrils. We propose HBO₂ therapy as a potentially effective treatment for MCL healing.