The Impact of Amotosalen Photochemical Pathogen Inactivation on Human Platelet Lysate

Background: Human Platelet Lysate (hPL) is a platelet-derived and growth factor-rich supplement for cell culture. It can be prepared from surplus platelet concentrates initially intended for transfusion. Amotosalen-based photochemical pathogen inactivation of platelet concentrates is used in a number of blood establishments worldwide to minimize the risk of pathogen transmission from donor to patient. Method: This pathogen inactivation method has not been formally validated for direct use on hPL. Here, we have studied the impact of pathogen inactivation on hPL and compared it to untreated hPL prepared from pathogen-inactivated platelet concentrates or control hPL. We used mass spectrometry, ELISA, and in vitro mesenchymal stem cell culture for determining residual amotosalen, final growth factor content, and cell doubling, respectively. Result: The data have shown amotosalen concentrations to be reduced a thousand-fold following pathogen inactivation, leaving trace quantities of photosensitizer molecules in the final hPL product. Some growth factors have been reported to be significantly more impacted in hPL that is directly pathogen-inactivated compared to both control conditions. This has no significant effect on the growth kinetics of adipose-derived mesenchymal stem cells. Conclusion: We have concluded direct amotosalen-based pathogen inactivation to have a measurable impact on certain growth factors in hPL, but this does not outweigh the likely benefits of reducing the odds of donor-to-patient pathogen transmission.