Previous studies demonstrated that bone marrow-derived mesenchymal stem (stromal) cells (MSCs) reduce the severity of acute lung injury in animal models and in an ex vivo perfused human lung model. However, the mechanisms by which MSCs reduce lung injury are not well understood. In the present study, we tested the hypothesis that human MSCs promote the resolution of acute lung injury in part through the effects of a specialized proresolving mediator lipoxin A4 (LXA4). Human alveolar epithelial type II cells and MSCs expressed biosynthetic enzymes and receptors for LXA4. Coculture of human MSCs with alveolar epithelial type II cells in the presence of cytomix significantly increased the production of LXA4 by 117%. The adoptive transfer of MSCs after the onset of LPS-induced acute lung injury (ALI) in mice led to improved survival (48 h), and blocking the LXA4 receptor with WRW4, a LXA4 receptor antagonist, significantly reversed the protective effect of MSCs on both survival and the accumulation of pulmonary edema. LXA4 alone improved survival in mice, and it also significantly decreased the production of TNF-α and MIP-2 in bronchoalveolar lavage fluid. In summary, these experiments demonstrated two novel findings: human MSCs promote the resolution of lung injury in mice in part through the proresolving lipid mediator LXA4, and LXA4 itself should be considered as a therapeutic for acute respiratory distress syndrome.

CF33-hNIS-anti-PD-L1 is an oncolytic chimeric poxvirus encoding two transgenes: human sodium iodide symporter and a single-chain variable fragment against PD-L1. Comprehensive preclinical pharmacology studies encompassing primary and secondary pharmacodynamics and biodistribution and safety studies were performed to support the clinical development of CF33-hNIS-anti-PD-L1. Most of the studies were performed in triple-negative breast cancer (TNBC) models, as the phase I trial is planned for patients with TNBC. Biological functions of virus-encoded transgenes were confirmed, and the virus demonstrated anti-tumor efficacy against TNBC models in mice. In a good laboratory practice (GLP) toxicology study, the virus did not produce any observable adverse effects in mice, suggesting that the doses proposed for the clinical trial should be well tolerated in patients. Furthermore, no neurotoxic effects in mice were seen following intracranial injection of the virus. Also, the risk for horizontal transmission of CF33-hNIS-anti-PD-L1 was assessed in mice, and our results suggest that the virus is unlikely to transmit from infected patients to healthy individuals. Finally, the in-use stability and compatibility of CF33-hNIS-anti-PD-L1 tested under different conditions mimicking the clinical scenarios confirmed the suitability of the virus in clinical settings. The results of these preclinical studies support the use of CF33-hNIS-anti-PD-L1 in a first-in-human trial in patients with TNBC.