Risk Factors at Presentation Predict Outcomes of Pediatric Myocarditis: A Contemporary Multi-Center Cohort

Abstract

Methods: We infused MSC using a dose escalation model: 3 patients received a low volume infusion (1 million MSC/Kg), 3 received an intermediate volume (2 million MSC/kg) and 3 received high volume infusion (4 million MSC/Kg). Blood samples were collected as baseline (day-1), on day +1 and day +7 following infusion to measure biomarker assays (B cells, natural killer-NK-cells), and T cell enumerations (T-regulatory cells). We used a multiplex cytokine assay to assess pro-inflammatory cytokine (TH1) and tolerogenic cytokine (TH2) levels and pro-angiogenic factors (vascular endothelial growth factor-VEGF). Changes in cytokine levels greater or less than 1 standard deviation from the mean baseline levels was considered significant. Results: We observed no increment in circulating MSC on days +1 and +7 regardless of the volume of MSC infused, suggesting that MSC were trapped in the lung as has been reported. Blood levels of tolerance-inducing T regulatory cells doubled in patients receiving low infusion MSC. NK and B cell numbers decreased in the low volume group. Contrarily, an increase or no change was observed in the other groups. Epidermal Growth Factor (EGF), a potent promoter of cell proliferation, anti-apoptotic and pro-angiogenic factor was significantly increased in the low volume group while no significant change was observed in other groups. Tolerance-inducing TH2 cytokines such as IL-4 significantly increased on patients receiving low and intermediate volume MSC infusion. Pro-inflammatory TH1 cytokines(IL-1, IL-6, and IL-8), and pro-inflammatory chemokines (MCP-1, MIP-1α , and MIP-1β) significantly decreased in patients receiving low volume infusion. Overall, the biological effects of the MSC therapy appeared to decrease with increasing cell volumes infused. Conclusion: Low volume MSC infusion induces anti-inflammatory effects and promotes cell proliferation and angiogenesis in patients with obstructive CLAD. Higher MSC volumes appear to have less positive biological effects. These results need clinical correlation.