Extracellular Vesicles from Interferon-γ–primed Human Umbilical Cord Mesenchymal Stromal Cells Reduce Escherichia coli–induced Acute Lung Injury in Rats

Abstract

Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New Background Human umbilical cord mesenchymal stromal cells possess considerable therapeutic promise for acute respiratory distress syndrome. Umbilical cord mesenchymal stromal cells may exert therapeutic effects via extracellular vesicles, while priming umbilical cord mesenchymal stromal cells may further enhance their effect. The authors investigated whether interferon-γ–primed umbilical cord mesenchymal stromal cells would generate mesenchymal stromal cell–derived extracellular vesicles with enhanced effects in Escherichia coli (E. coli) pneumonia. Methods In a university laboratory, anesthetized adult male Sprague–Dawley rats (n = 8 to 18 per group) underwent intrapulmonary E. coli instillation (5 × 109 colony forming units per kilogram), and were randomized to receive (a) primed mesenchymal stromal cell–derived extracellular vesicles, (b) naïve mesenchymal stromal cell–derived extracellular vesicles (both 100 million mesenchymal stromal cell–derived extracellular vesicles per kilogram), or (c) vehicle. Injury severity and bacterial load were assessed at 48 h. In vitro studies assessed the potential for primed and naïve mesenchymal stromal cell–derived extracellular vesicles to enhance macrophage bacterial phagocytosis and killing. Results Survival increased with primed (10 of 11 [91%]) and naïve (8 of 8 [100%]) mesenchymal stromal cell–derived extracellular vesicles compared with vehicle (12 of 18 [66.7%], P = 0.038). Primed—but not naïve—mesenchymal stromal cell–derived extracellular vesicles reduced alveolar–arterial oxygen gradient (422 ± 104, 536 ± 58, 523 ± 68 mm Hg, respectively; P = 0.008), reduced alveolar protein leak (0.7 ± 0.3, 1.4 ± 0.4, 1.5 ± 0.7 mg/ml, respectively; P = 0.003), increased lung mononuclear phagocytes (23.2 ± 6.3, 21.7 ± 5, 16.7 ± 5 respectively; P = 0.025), and reduced alveolar tumor necrosis factor alpha concentrations (29 ± 14.5, 35 ± 12.3, 47.2 ± 6.3 pg/ml, respectively; P = 0.026) compared with vehicle. Primed—but not naïve—mesenchymal stromal cell–derived extracellular vesicles enhanced endothelial nitric oxide synthase production in the injured lung (endothelial nitric oxide synthase/β-actin = 0.77 ± 0.34, 0.25 ± 0.29, 0.21 ± 0.33, respectively; P = 0.005). Both primed and naïve mesenchymal stromal cell–derived extracellular vesicles enhanced E. coli phagocytosis and bacterial killing in human acute monocytic leukemia cell line (THP-1) in vitro (36.9 ± 4, 13.3 ± 8, 0.1 ± 0.01%, respectively; P = 0.0004) compared with vehicle. Conclusions Extracellular vesicles from interferon-γ–primed human umbilical cord mesenchymal stromal cells more effectively attenuated E. coli–induced lung injury compared with extracellular vesicles from naïve mesenchymal stromal cells, potentially via enhanced macrophage phagocytosis and killing of E. coli.

Pro-Inflammatory Priming of Umbilical Cord Mesenchymal Stromal Cells Alters the Protein Cargo of Their Extracellular Vesicles

“…This study found that EV morphology and size did not differ between conditions. This is not unexpected as previous research has also found similar results, showing no statistical differences in size, shape and electrodensity between EVs from normoxic and hypoxic conditions [12], but a study by Varkouhi et al found that IFN-γ primed EVs were approximately 1.5 times larger than their non-primed counterparts; however, this study used a higher concentration of IFN-γ for a shorter time than the current study [9]. In all, it remains unclear if subtle changes in EV size has a major bearing on their downstream paracrine functions.…”

“…The cargo is often representative of their cell of origin [3]; this is thought to be why EVs derived from umbilical cord mesenchymal stromal cells (UCMSCs) have shown similar immunosuppressive effects to the UCMSCs themselves [2,5]. Indeed it has been shown in vitro that UCMSC-EVs can inhibit T-cell proliferation [6], and also in animal studies, where UCMSC-EVs are found to ameliorate hyperglycaemia in rats with type 2 diabetes mellitus [7], reduce neuroinflammation in a rat brain injury model [8] and improve acute respiratory distress symptoms in rats [9]. The evidence that UCMSCs and their EVs can suppress immune responses is appealing; however, in order to harness the full immunomodulatory properties of UCMSCs and their EVs, the best conditions for growing these cells must be established.…”

Cytokine pre-activation of cryopreserved xenogeneic-free human mesenchymal stromal cells enhances resolution and repair following ventilator-induced lung injury potentially via a KGF-dependent mechanism

“…Recent studies have shown that MSCs pre-activated with inflammatory cytokines possess enhanced therapeutic properties [48]. Several other promising MSC activation strategies have been elucidated, including IL-10 overexpression [49] and interferon-γ priming [50]. Our studies advance our understanding of the therapeutic potential of priming by demonstrating that cytokine pre-activation can restore and/or enhance the function of cryopreserved XF-cultured hMSCs.…”

Systematic review of extracellular vesicle‐based treatments for lung injury: are EVs a potential therapy for COVID‐19?

“…Only MSC-EVs with high miR-30b-3p levels increased cell proliferation and reduced cell apoptosis and pro-inflammatory cytokines Varkouhi et al 2019 [46] Human interferon-γ-primed MSC-EVs vs. naïve MSC-EVs Both EV populations enhanced survival and bacterial phagocytosis in THP-1 cells and reduced the alveolar wall thickness. Only IFN-γ-primed MSC-EVs decreased proinflammatory cytokines Zhou et al 2019 [47] Human EPC-EVs vs. NIH3T3-EVs EPC-EVs (but not NIH3T3-EVs) reduced pro-inflammatory cytokine and chemokine production and lung tissue injury and restored alveolar barrier Tan et al 2018 [54] Human AEC-EVs vs. HLF-EVs AEC-EVs and HLF-EVs similarly reduced neutrophil infiltration and interstitial macrophages.…”