The effect of near-infrared low-level light on the in vitro quality of platelets during storage

Background and Objectives Near-infrared (NIR) light has been successfully applied to improve the quality of mouse platelets during storage. Because it is suspected that the mitochondria contain the primary photon acceptor, we hypothesized that human platelets for transfusion may be affected similarly and could benefit from NIR light treatment. Materials and Methods The optimal light dose was determined using portions of platelet concentrates (PCs) in PAS-E. A pool-and-split design was used to prepare PCs in PAS-E or plasma (n = 6). On day 1, one unit of both pairs was illuminated with 830 nm light (light-emitting diodes, 15 J/cm(2)). PCs were stored at 22 degrees C and sampled regularly for analysis. Data were compared with their corresponding controls with a paired two-sided t-test. Results Illuminated platelets in PAS-E were less activated with significantly lower CD62P expression (day 8: 10.8 +/- 1.8 vs. 12.2 +/- 2.6, p < 0.05) and lower Annexin A5 binding (day 8: 11.8 +/- 1.9 vs. 13.1 +/- 2.4, ns). They produced significantly less lactate resulting in a higher pH (days 6-10). ATP content and mitochondrial membrane potential were not affected. Although these trends were also observed for PCs in plasma, the differences did not reach statistical significance as compared with the control group. Conclusion Our study demonstrates that the glycolysis rate of human platelets can be modulated through the use of NIR, possibly through mitochondrial aerobic metabolism, but this requires confirmation. If NIR illumination can be further optimized, it may potentially become a useful tool in situations in which glycolysis and platelet activation are exacerbated.