Intracoronary administration of GMP-grade MSC-EVs modulates immunity and promotes angiogenesis in a translational porcine MI-reperfusion model

Background

Mesenchymal stromal cell extracellular vesicles (MSC-EVs) have shown potential to improve myocardial infarction (MI) outcomes due to their immunomodulatory and reparative properties. The objective of this study aims to evaluate the effects of GMP-grade MSC-EVs from human Wharton’s Jelly in a clinically relevant large animal model of MI.

Methods

Clinically compatible MSC-EVs meeting stringent quality attributes were produced using a GMP-compliant workflow involving bioreactor expansion, tangential flow filtration, and size-exclusion chromatography (Fig1A).

Twenty pigs (50% female) underwent 90min balloon-assisted occlusion of the left anterior descending coronary artery and were randomized to receive a single intracoronary dose of MSC-EVs (10¹¹ particles, n=11) or Vehicle (n=9) (Fig1B). Immunomodulatory systemic effects were assessed via immune cell phenotyping and cytokine analysis on days 0, 2, 5, 15 and 30 post-MI. Cardiac function and myocardial scar size progression were quantified by cardiac magnetic resonance at baseline, 48h, and 30 days post-MI. At day 30, myocardial vascular density and fibrosis were evaluated by immunohistochemistry and histological analysis, respectively.

Results

The study recorded a 0% mortality rate. Compared to Vehicle, MSC-EV-treated pigs showed increased circulating monocyte levels at days 2 and 5 post-MI (p=0.007 and p=0.053), accompanied by higher frequency (p=0.056) and expression (p=0.042) of the anti-inflammatory marker CD163, with no changes in recruitment markers CCR2 and CX3CR1 (Fig1C).

Lymphocyte responses were more variable, with a trend toward increased total lymphocyte counts at day 5 (p=0.071) in MSC-EV-treated animals. While CD4+ T-cell levels were similar between groups, activated CD4+/CD25+ cells were reduced at days 5 and 30 (p=0.057 and p=0.036). Conversely, CD8⁺ T cells exhibited fewer total CD8⁺ cells (p=0.033), but higher proportions of activated CD8⁺/CD25⁺ cells (p=0.007) at day 15, along with a significant early increase in the immunomodulatory CD8⁺/CD25⁺/CD39⁺ subset at day 2 post-MI (p=0.006) in MSC-EV-treated animals (Fig1C). Cytokine and chemokine serum levels were comparable between groups.

Locally, treated animals exhibited significantly higher vascular density within the infarct core (p=0.023) (Fig1D), while scar size and composition, as well as cardiac functional parameters, did not differ between groups.

Conclusion

A single minimally invasive intracoronary dose of GMP-grade MSC-EVs significantly modulated the systemic inflammatory response and enhanced myocardial vascular density following MI. However, no differences in scar size or cardiac function were observed at 30 days. These results highlight the immunomodulatory and pro-angiogenic potential of MSC-EVs, while suggesting that alternative dosing, timing, or administration strategies may be required to achieve functional cardiac improvement.Figure 1.