RESUMEN
Background & Aim: Ricin is one of the most lethal toxins, particularly if inhaled, and is considered a biological threat agent due to its wide availability and ease of production. Pulmonary ricin intoxication manifests in ARDS, cytokine storm, immune infiltration, and severe edema. Passive immunization is the preferred measure against pulmonary ricinosis, but only if administered shortly after exposure. Despite their potential to remedy pulmonary injury and inflammation, mesenchymal cell (MSC) therapies were never investigated in ricinosis. Here, we report the potential for treating pulmonary ricinosis with MesenCure, a professionalized allogeneic MSC therapy shown to reduce the mortality of patients suffering from severe pulmonary manifestations of COVID by 68%. Methods, Results & Conclusion(s): Preliminary studies demonstrated positive MesenCure effects in a sub-lethal pulmonary ricinosis model in CD1 mice. This model is regarded as highly translational due to the broad heterogeneity of these outbred mice. Positive effects included a reduction in excess protein content of the bronchoalveolar lavage fluid (BALF) by 45% when MesenCure was injected intravenously (IV) at 125k cells/animal, 48h post-exposure (PE) and evaluated one day later (p<0.05, Fig. 1A). Moreover, we found up to 52% reduction in the excess BALF leukocytes, when MesenCure was injected IV, 24h PE using the same dose (p<0.05, Fig. 1B) or 6h PE using a double dose (p<0.01, Fig. 1C), and evaluated two days PE. Optimizing the dose and administration route further improved the therapeutic outcome of MesenCure applied 6h PE as assessed by weight loss. As shown in Fig. 1D-E, IV injection of 250k-500k MesenCure cells/animal slightly protected the intoxicated animals against weight loss (p for treatment x time interaction <0.01 or <0.05 for 250k and 500k cells/animal, respectively). Interestingly, one million cells IV resulted in a lesser effect (not shown), however when injected subcutaneously (SC), 1M cells were very effective (p<0.001, Fig. 1F), seemingly even more effective than 2M cells/animal SC (Fig. 1G). Surprisingly, 2M thawed cells/animal injected SC protected the animals against weight loss almost completely (p<0.0001, Fig. H). In conclusion, we provide evidence for the potential of SC MSCs, specifically MesenCure, for treating pulmonary ricinosis and possibly other forms of ARDS. In agreement with Giri and Galipeau (2020), we provide further evidence for the dependency of MSC outcomes on their specific state and administration route. [Figure presented]Copyright © 2023 International Society for Cell & Gene Therapy