Bioprocessing of human platelet concentrates to generate lysates and extracellular vesicles for therapeutic applications

This work describes protocols for preparing specific forms of human platelet lysates from pooled platelet concentrates (PCs) and the isolation of platelet-derived extracellular vesicles (p-EVs). Clinical-grade PCs can be sourced from blood establishments immediately following expiration for transfusion use. Here, we describe methods to process PCs into specific lysates from which pEVs can be isolated. Each lysate type is prepared using platelet activation and processing methods which produce distinct products that may be useful in different applications. For example, serumconverted platelet lysate (SCPL)-EVs were recently shown to have powerful therapeutic properties following myocardial infarction in mice. EVs can be isolated from all products using size exclusion chromatography, producing pure and consistent p-EVs from multiple batches. Together, these methods allow isolation of p-EVs with excellent potential for clinical and preclinical applications. center dot Platelet concentrates (PCs) obtained from local blood establishments are reliable and sustainable sources to generate biomaterials. center dot We outline five distinct methods of platelet lysate generation and one method for extracellular vesicle isolation. center dot Each platelet lysate form has different biological properties which may be suitable for certain applications.