Exosomes Engineered to Express a Cardiomyocyte Binding Peptide Demonstrate Improved Cardiac Retention in Vivo

Abstract

Injury to the heart results in cardiomyocyte cell death and can lead to pathological remodeling of remaining cells, contributing to heart failure. Despite the therapeutic potential of new drugs and small molecules, there remains a gap in the ability to efficiently deliver cardioprotective agents in a cell specific manner while minimizing nonspecific delivery to other organs. Exosomes derived from cardiosphere-derived cells (CDCs) have been shown to stimulate angiogenesis, induce endogenous cardiomyocyte proliferation and modulate cardiomyocyte apoptosis and hypertrophy. While innately cardioprotective at high doses, unmodified CDC-exosomes demonstrate limited cardiac tropism. To generate an efficient exosomal delivery system that can target cardiomyocytes, we engineered CDCs to express Lamp2b, an exosomal membrane protein, fused to a cardiomyocyte specific peptide (CMP), WLSEAGPVVTVRALRGTGSW. Exosomes isolated from engineered CDCs expressed CMP on their surface and retained their native physical properties. Targeted exosomes resulted in increased uptake by cardiomyocytes, decreased cardiomyocyte apoptosis, and higher cardiac retention following intramyocardial injection when compared with non-targeted exosomes. Importantly, we established a novel targeting system to improve exosomal uptake by cardiomyocytes and laid the foundation for cell-specific exosomal delivery of drug and gene therapies to improve the functional capacity of the heart following both ischemic and non-ischemic injury.

Mircrining the injured heart with stem cell-derived exosomes: an emerging strategy of cell-free therapy

“…A step forward is the use of induced pluripotent stem cells (iPSCs) derived MSCs as a renewable source of exosomes [139]. Another important step forward would be to enhance exosomal tropism for the cardiomyocytes [140]. The expression of the cardiomyocyte-specific peptide on the exosomal surface may improve homing-in of the delivered exosomes and promote their fusion with the recipient cardiomyocyte membrane as a mechanism for the delivery of their miR payload via endocytosis.…”

Message in a Bottle: Upgrading Cardiac Repair into Rejuvenation

“…Several studies have been lately reported suggesting alternative strategies to functionalise EVs for more accurate targeting of the damaged heart [220,221]. These include: lentiviral vector-based engineering of secreting cells to upregulate the expression of cardiomyocyte-specific binding peptides fused to the murine transmembrane protein Lamp2b, in order to enrich the targeting epitope on the exosomal surface [222]; overexpression of exosomal CXCR4 to push their bioavailability towards the ischaemic heart [156]; membrane anchoring systems to directly dock tissue-specific antibodies or homing antigens on the EV surface [223,224].…”

Roles and Clinical Applications of Exosomes in Cardiovascular Disease

“…To promote the cardiac tropism of CDC-derived exosomes, CDCs are engineered to connect a cardiomyocytespecific binding peptide to the N-terminus of Lamp2b, which is a transmembrane protein on the exosomes. This engineered exosomes show better cardiomyocyte-specific uptake and enhanced protective effect [56].…”