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Vitamin K3 is a potential ultraviolet photosensitizer for pathogen reduction in human platelets

Wednesday, October 10, 2012 — Poster Session II

Noon – 2:00 p.m

Natcher Conference Center, Building 45




  • Fei Xu
  • Jaro Vostal


Human platelets stored at room temperature may promote bacterial growth before transfusion. UV light with vitamin K3 (VK3) photosensitizer was tested to reduce bacterial growth in platelet. Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella pneumoniae, Escherichia coli are common bacterial contaminants of platelets and they were spiked into PBS buffer or platelet concentrates (PCs) diluted with platelet additive solution. VK3 at 400 uM exposed to UVA-irradiation (2.88 J/cm2) significantly reduced bacteria colony forming units (CFU) in PBS spiked with bacteria. When bacteria were spiked into 10% PCs 400 uM VK3 twice the UVA-irradiation (5.76 J/cm2) was required for bacterial load reduction. UVB and VK3 had a biphasic inhibitory effect. The VK3 at 200 uM plus UVB-irradiation (0.015 J/cm2 ) also significantly reduced the CFU of bacteria spiked into PBS. However higher concentrations of VK3 reversed the inhibition, and less inhibition was observed at 1600 uM VK3 plus UVB-irradiation (0.015 J/cm2 ). These findings suggest that VK3 may serve as an effective UVA photosensitizer for pathogen reduction in human platelets. With UVB exposure, low concentrations of VK3 are effective inhibitors of bacterial proliferation, however high concentrations of VK3 may serve as UVB blocker and prevent pathogen reduction.

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