PB0135 - Expression of an Antifibrinolytic Peptide in Donor Platelets Extends Clot Stability

Sunday, June 25, 2023

18:30 – 19:30 ET

Room: Exhibition

Presenting Author(s)

Colton Strong (he/him/his)

PhD Candidate
The University of British Columbia
Vancouver, British Columbia, Canada

Co-Author(s)

Jerry Leung (he/him/his)

PhD Candidate
The University of British Columbia
Vancouver, British Columbia, Canada
Katherine Badior, PhD

Post-doctoral Research Fellow
Versiti Blood Research Institute
Wauwatosa, Wisconsin, United States
EK

Emma Kang

Graduate Student
University of British Columbia
Vancouver, British Columbia, Canada
Madelaine K. Robertson

PhD Candidate
University of British Columbia
Vancouver, British Columbia, Canada
EJ

Eric Jan

Professor
University of British Columbia
Vancouver, British Columbia, Canada
PC

Pieter Cullis

Professor
The University of British Columbia
Vancouver, British Columbia, Canada
DD

Dana Devine

Professor
The University of British Columbia
Vancouver, British Columbia, Canada
Christian Kastrup, PhD

Senior Investigator
Versiti Blood Research Institute
Wauwatosa, Wisconsin, United States

Background: Despite being anucleate, platelets actively synthesize new proteins from endogenous mRNA both in circulation and during storage, making them amenable to genetic engineering. Advancements in lipid nanoparticle (LNP) technology has enabled leading COVID-19 vaccines and is an efficient method to deliver nucleic acids into target cells. We have developed an LNP agent optimized for delivering mRNA into donor platelets that results in robust reporter protein expression. This presentation will describe our effort using this technology to achieve the expression of exogenous proteins that specifically modify donor platelet function.

Aims: Demonstrate that platelet function can be modified by delivering mRNA encoding hemostatic peptides using our platelet-optimized LNP platform.

Methods: As proof-of-concept, mRNA encoding an antifibrinolytic peptide was delivered using LNPs into platelets obtained from pooled platelet concentrates produced by the Canadian Blood Services Blood4Research facility. After 24 hours of storage, rotational thromboelastometry was used to assess in vitro clot formation and fibrinolysis of plasma containing control platelets or platelets modified to express the antifibrinolytic peptide. Parameters reported include the average rate of clot lysis.

Results: Preliminary results indicate that platelets expressing an antifibrinolytic peptide retain coagulability and generate clots with an extended fibrinolytic profile compared to control platelets (Fig 2A). The average rate of clot lysis was reduced in plasma containing antifibrinolytic peptide expressing platelets compared to control platelets (Fig 2B).

Conclusion(s): LNPs are an effective way to deliver exogenous nucleic acids into platelets. Here we report preliminary data demonstrating that ex vivo clot fibrinolysis may be measurably changed through the delivery of mRNA encoding an antifibrinolytic peptide into platelets. We anticipate significant opportunities to expand and enhance the therapeutic potential of platelets for hemorrhage control. [This work is supported by the U.S. Department of Defense Investigator-Initiated Research Award]