The optimum oxygen level in hypoxic culture conditions of ligament derived stem cells: experimental research

The hypoxic condition is a physiological norm for various stem cells. The natural microenvironment contains lower oxygen pressures. Recent studies reported significant increases in the cultured cells' proliferation in the presence of a low oxygen pressure.

Objective: This study aimed to investigate the optimum oxygen level for rabbit cruciate ligament fibroblast cells culture and Ligament Derived Conditioned Medium/LD-CM (Secretome) preparation in vitro.

Materials and methods: Fibroblasts were isolated from the cruciate ligament of the rabbit's knee. Cultured of rabbit cruciate ligament Fibroblast Cells (fifth passage) were assigned to the slight (5% O₂), middle (3% O₂), and severe hypoxia (1% O₂) groups and the normoxia (21% O₂) group. Measurement of growth factors: TGF-β1, PDGF, FGF, and VEGF in LD-CM (Secretome) used an enzyme-linked immunosorbent assay.

Results: The highest number of cultured cells were in the 5% O₂ group compared to the normoxia, 1 and 3% groups. The hypoxia 5% group also had increased productions of PDGF, FGF, and VEGF proteins in LD-CM (secretome) compared to the 1, 3%, and normoxia groups. TGF-β1 production was slightly higher in the 3 group than the 5% group.

Conclusion: The hypoxic precondition of 5% oxygen was the optimum condition for ligament culture and ligament derived conditioned medium (secretome) preparation in vitro.