Near-infrared photobiomodulation stimulates viability and cartilage matrix synthesis in human chondrocytes

Oliveira S, Ferreira D, Padrão J, Catarino SO, Monteiro F, Zille A, Hinckel BB, Carvalho Ó, Leal A, et al. · Scientific Reports

Near-infrared LEDs at 850 and 940 nm significantly raised normalised chondrocyte metabolic activity across 4-17 mW/cm2, regardless of pulsing or of daily versus every-other-day stimulation, with a dose-dependent response that varied by parameter. Applied daily for seven days, 940 nm at 17 mW/cm2 consistently increased collagen type II, aggrecan and glycosaminoglycan deposition in the matrix while preserving the chondrocyte phenotype against the dedifferentiation that monolayer culture and passaging normally cause. Temperature rose less than 1.0 degrees Celsius during stimulation.

Population

Human chondrocytes in monolayer culture

Intervention

LEDs at 600-940 nm, 4-17 mW/cm2, continuous or pulsed, up to 4 minutes, daily or every other day; energy densities up to 3 J/cm2

Comparator

Unstimulated chondrocytes

Limitations

Monolayer culture, which the authors state does not fully replicate the physiological environment of cartilage; there is no animal or human arm. The most effective parameters align with WALT guidance, but that guidance covers laser diodes only, and the authors argue for extending it to LEDs rather than reporting that it already applies. Portuguese public funding (FCT, FEDER and PhD fellowships); the authors declare no competing interests.