A therapeutic strategy to target CD47 using SIRP alpha expressed extracellular vesicles derived fromengineered mesenchymal stem cells to promote liver regeneration following severe injury

Abstract

Background and aims: CD47 is known to transmit a ‘don’t eat me’ signal to immune cells and is overexpressed in pathological cells, including inflammatory dying cells. Consequently, uncleared dead cells in liver injury significantly contribute to a high pro-inflammatory process, exacerbating the condition. In this study, we aim to develop and validate the therapeutic efficacy of SIRP alpha overexpressed mesenchymal stem cell-derived extracellular vesicles (SIRP-EVs). SIRP-EVs can effectively block CD47 on dying hepatocytes, thereby facilitating their clearance through macrophages, mediating anti-inflammatory and pro-resolutive effects in acute liver injury.

Method: To explore CD47 as a promising therapeutic target in acute liver injury, we established various severe injury models using acetaminophen (APAP), thioacetamide (TAA), or carbon tetrachloride (CCl4) and evaluated through histological analysis and spatial transcriptomics. SIRP-EV we developed strongly binds and blocks CD47, the ‘don’t eat me signal.’ Using the IVIS Spectrum in vivo imaging system, we validated the biodistribution of SIRP-EV in normal and liver-injured mice. The therapeutic potential of SIRP-EV was evaluated in diverse mouse models by treating them with SIRPEV and subsequently assessing liver enzyme levels, histological changes, survival rates, and inflammatory cytokine profiles.

Results: In this study, we observed CD47 overexpression in severely injured liver, predominantly on necroptotic hepatocytes. We found that SIRP-EV preferentially accumulated in the injured liver in a CD47-dependent manner; however, this accumulation was noticeably reduced when CD47 was pre-blocked using an anti-CD47 antibody. Treatment with SIRP-EV in acute liver-injured mice led to a notable improvement in liver histology and reductions in serum ALT and AST levels. Furthermore, SIRP-EV significantly increased survival rates, and the immune profile was transmitted from pro-inflammatory to pro-resolutive. We also demonstrated the therapeutic superiority of SIRP-EV over na？ve MSC derived EVs and CD47 antibodies.

Conclusion: CD47 is a potent therapeutic target for acute liver injury. Importantly, SIRP-EV, which targets CD47, offers a promising strategy for treating acute liver injury by mitigating the inflammatory responses and inducing pro-resolutive immune responses.