(P-BT-14) Genetic Engineering of Transfusable Platelets with mRNA-Lipid Nanoparticles is Compatible with Blood Banking Practices

Platelets are involved in a variety of physiological process including inflammation, sepsis and cancer, however, their use as a cell therapy is largely restricted to managing thrombocytopenia. We have previously shown that lipid nanoparticles containing mRNA (mRNA-LNP) can be used to transfect washed platelets to express exogenous proteins, a new tool that could be used to create new platelet-based cell therapies. However, platelets currently collected for transfusion are not washed and instead stored in plasma or in plasma supplemented with platelet additive solution (PAS).  

Study

Design/Methods:

Pooled platelets, obtained from Canadian Blood Services’ NetCAD Blood4Research facility, were suspended in either 100% plasma (Plasma-PLT) or in 30% plasma supplemented with 70% SSP⁺ PAS (PAS-PLT). Plasma-PLT and PAS-PLT were transfected with NanoLuc luciferase mRNA encapsulated into a library of compositionally unique mRNA-LNP (Figure A). Each of the standard LNP lipid components were systematically optimized and NanoLuc expression, mRNA-LNP uptake and platelet activation was measured. Storage compatibility of mRNA-LNP modified platelets was measured using traditional flow markers and functional tests.

Results/Findings:

We identified a mRNA-LNP formulation capable of transfecting PAS-PLT and Plasma-PLT. Improved plasma transfection was uniquely enabled by a specific ionizable lipid, and the potency of the mRNA-LNP was further enhanced after optimizing the structural phospholipid and PEGylated lipid (Figure A). Platelet activation measured by CD62P was comparable between transfected platelets and normal platelets and mRNA-LNP uptake did not correlate with NanoLuc expression. Finally, mRNA-LNP modification did not affect platelet function or activation over standard storage timelines at both room and cold storage temperatures.

Conclusions:

Donor platelets collected for transfusion can be directly modified with mRNA-LNP to express exogenous protein in plasma and plasma-based systems storage systems. Furthermore, mRNA-LNP transfection does not significantly affect platelet activation nor function during storage and is clinically scalable.