This 2023 study grew human cartilage cells at 18.9%, 6% or 1% oxygen. Cells from osteoarthritic cartilage made more MMP13 than cells from macroscopically normal cartilage at 18.9% and 6% oxygen, but not at 1%. Low oxygen helped the normal cells make cartilage proteins, while the osteoarthritic cells relied more on glycolysis.
The researchers compared chondrocytes from osteoarthritic and from macroscopically normal human cartilage. They kept the cells at 18.9% oxygen, the standard for tissue culture, at 6%, close to the surface layer of cartilage in the body, or at 1%, close to the deep layer. They then measured MMP13, the cartilage-building proteins SOX9, type II collagen (COL2A1) and aggrecan (ACAN), and how the cells made their energy.
MMP13 production was higher in osteoarthritic than in normal chondrocytes at 18.9% and 6% oxygen, but not at 1%. Low oxygen raised SOX9, COL2A1 and aggrecan protein in normal cells but not in osteoarthritic ones. Osteoarthritic cells used more glycolysis whatever the oxygen level. The authors point to another study showing oxygen levels are raised in osteoarthritic cartilage in the body, and suggest this extra oxygen may promote cartilage loss.
These are isolated cells in a dish, and the abstract does not give the number of donors or how long the cells were kept at each oxygen level. It cannot show that oxygen in a living joint drives MMP13. The link to raised oxygen in real cartilage comes from a different study the authors cite, not from this one.
Much lab work on cartilage cells is done at room-air oxygen, far above what cartilage sees in the body. This study shows the MMP13 difference between worn and healthy-looking cartilage depends on oxygen, which matters for how other cell studies are read. Jain's 2024 glucose study used the same 18.9% and 1% conditions.
In human cartilage cells, MMP13 rose in response to inflammatory messengers such as IL-1, oxidative stress, calcium phosphate crystals, a disrupted cell body clock...
In the lab, it can. University of Auckland researchers found that raising glucose from 4 to 10 mM, within the range from normal to high blood sugar, made cells from...