Early gestational mesenchymal stem cell secretome attenuates experimental bronchopulmonary dysplasia in part via exosome-associated factor TSG-6

Abstract

BackgroundMesenchymal stem cells (MSCs) are promising tools for the treatment of human lung disease and other pathologies relevant to newborn medicine. Recent studies have established MSC exosomes (EXO), as one of the main therapeutic vectors of MSCs in mouse models of multifactorial chronic lung disease of preterm infants, bronchopulmonary dysplasia (BPD). However, the mechanisms underlying MSC-EXO therapeutic action are not completely understood. Using a neonatal mouse model of human BPD, we evaluated the therapeutic efficiency of early gestational age (GA) human umbilical cord (hUC)-derived MSC EXO fraction and its exosomal factor, tumor necrosis factor alpha-stimulated gene-6 (TSG-6).MethodsConditioned media (CM) and EXO fractions were isolated from 25 and 30 weeks GA hUC-MSC cultures grown in serum-free media (SFM) for 24 h. Newborn mice were exposed to hyperoxia (> 95% oxygen) and were given intraperitoneal injections of MSC-CM or MSC-CM EXO fractions at postnatal (PN) day 2 and PN4. They were then returned to room air until PN14 (in a mouse model of severe BPD). The treatment regime was followed with (rh)TSG-6, TSG-6-neutralizing antibody (NAb), TSG-6 (si)RNA-transfected MSC-CM EXO and their appropriate controls. Echocardiography was done at PN14 followed by harvesting of lung, heart and brain for assessment of pathology parameters.ResultsSystemic administration of CM or EXO in the neonatal BPD mouse model resulted in robust improvement in lung, cardiac and brain pathology. Hyperoxia-exposed BPD mice exhibited pulmonary inflammation accompanied by alveolar-capillary leakage, increased chord length, and alveolar simplification, which was ameliorated by MSC CM/EXO treatment. Pulmonary hypertension and right ventricular hypertrophy was also corrected. Cell death in brain was decreased and the hypomyelination reversed. Importantly, we detected TSG-6, an immunomodulatory glycoprotein, in EXO. Administration of TSG-6 attenuated BPD and its associated pathologies, in lung, heart and brain. Knockdown of TSG-6 by NAb or by siRNA in EXO abrogated the therapeutic effects of EXO, suggesting TSG-6 as an important therapeutic molecule.ConclusionsPreterm hUC-derived MSC-CM EXO alleviates hyperoxia-induced BPD and its associated pathologies, in part, via exosomal factor TSG-6. The work indicates early systemic intervention with TSG-6 as a robust option for cell-free therapy, particularly for treating BPD.Electronic supplementary materialThe online version of this article (10.1186/s13287-018-0903-4) contains supplementary material, which is available to authorized users.

Mesenchymal Stem Cell Therapy for Spinal Cord Contusion: A Comparative Study on Small and Large Animal Models

“…The identification of astroglial activation in pigs supports the capacity of AD-MSCs to reduce GFAP expression predominantly in the caudal direction from the epicenter of injury, similar to what we found in rats although to a lesser degree. The potential reduction in astroglial activation was attributed to the ability of MSCs to decrease cyclooxygenase-2 and IL-6 cytokine levels [18,59] and secretion of TNF-stimulated gene-6 [69][70][71][72], which consequently decreases NF-κB signaling, resulting in modulation of A1 neuroinflammatory reactive astrocytes [73,74]. We found no effect of AD-MSCs treatment on microglial activation in pigs, similar to results in rats.…”

Mesenchymal stem cell-derived secretomes for therapeutic potential of premature infant diseases

“…Willis et al [73] showed that MSC-derived exosomes modulated the lung macrophage phenotype by suppressing the pro-inflammatory 'M1' state and enhancing an anti-inflammatory 'M2-like' state both in vitro and in vivo. Interestingly, another study demonstrated the repair effect of MSC-derived exosomes in a BPD animal model [74]. MSC-derived exosomes can repair the lung injury and improve BPD-associated brain injury as revealed by decreased brain cell death and reversed hypomyelination.…”

“…Yan et al demonstrated that human umbilical cord MSC (hUC-MSC) exosomes promoted hepatocyte recovery from oxidative stress via the antioxidant and antiapoptotic effects of exosomal glutathione peroxidase1 (GPX1) both in vitro and in vivo, however, GPX1 knockdown was found to delay this hepatoprotective effect [72]. MSC exosomes have also been reported to mediate several known functions of MSCs in premature infant diseases, including modulating inflammatory/immune responses and reducing fibrosis, apoptosis, and oxidative stress [73][74][75][76]. However, more in-depth research is required to explore the mechanisms underlying the effects of exosomes.…”

“…Several studies have indicated that soluble factors, such as macrophage colony-stimulating factor 1, osteopontin [86], and STC1 [54], may be principally responsible for the therapeutic abilities of MSC-derived CM. MSC-derived EV [87] and exosome [73,74,88] treatments also block inflammation and reduce fibrosis and pulmonary vascular remodeling, resulting in improved lung function and the amelioration of pulmonary hypertension in hyperoxia-induced BPD. Willis et al [73] showed that MSC-derived exosomes modulated the lung macrophage phenotype by suppressing the pro-inflammatory 'M1' state and enhancing an anti-inflammatory 'M2-like' state both in vitro and in vivo.…”

“…TSG-6 has also been detected in MSC-derived exosome fractions and can decrease the pro-inflammatory cytokines, IL-6, TNF-α, and IL-1β; it can also decrease cell death in lungs and reverse BPD-associated cardiac and brain pathologies in BPD mouse models. However, the knockdown of TSG-6 in MSC-derived exosomes abolishes the therapeutic effects of the exosomes [74]. Furthermore, Braun et al [88] demonstrated that MSC-derived exosomes in vitro stimulated the extensive capillary network formation of human umbilical vein endothelial cells (HUVECs) in vitro, but this function was diminished by anti-VEGF antibodies.…”