Lyophilized Synthetic Platelets: In Vitro Characterization and In Vivo Evaluation in Mouse Thrombocytopenia Model

ABSTRACT Platelet transfusions to treat bleeding complications use donor‐derived platelets stored at room‐temperature, that have a shelf‐life of only 5–7 days due to bacterial contamination risks. Cold‐stored and freeze‐dried platelets are being investigated for extending shelf‐life, but these still have the inherent challenge of donor‐dependency. To address this, we developed a liposome‐based synthetic platelet (SP) nanoconstruct that mimics the primary hemostatic mechanisms of platelets, and have previously reported its efficacy. However, a logistical limitation of SP is its susceptibility to environment‐induced physico‐chemical instabilities that reduces shelf‐life when stored as aqueous suspension, impacting its availability and bioactivity. Lyophilization of liposomal nanotherapeutics utilizing anhydrobiosis‐inspired lyoprotectants can enhance shelf‐life, but this has not been explored for synthetic platelets. With these considerations, we report advancing SP into a lyophilized product (Lyo‐SP) that can be rapidly aqueous‐reconstituted for on‐demand use. Lyo‐SP retained morphology, size, and charge in long‐term storage at various temperatures, and conserved platelet‐mimetic functions in multiparametric assays with human plasma and blood. Lyo‐SP demonstrated biosafety in its effect analysis on endothelial cells, neutrophils, RBCs and complement C3. Lyo‐SP significantly reduced bleeding in a tail‐clip model in thrombocytopenic mice. These studies establish the potential of Lyo‐SP as a shelf‐stable platelet surrogate for treating bleeding complications.