Hemorrhagic shock (HS) and trauma is currently the leading cause of death in young adults worldwide. Morbidity and mortality after HS and trauma is often the result of multi-organ failure such as acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), conditions with few therapeutic options. Bone marrow derived mesenchymal stem cells (MSCs) are a multipotent stem cell population that has shown therapeutic promise in numerous pre-clinical and clinical models of disease. In this paper, in vitro studies with pulmonary endothelial cells (PECs) reveal that conditioned media (CM) from MSCs and MSC-PEC co-cultures inhibits PEC permeability by preserving adherens junctions (VE-cadherin and β-catenin). Leukocyte adhesion and adhesion molecule expression (VCAM-1 and ICAM-1) are inhibited in PECs treated with CM from MSC-PEC co-cultures. Further support for the modulatory effects of MSCs on pulmonary endothelial function and inflammation is demonstrated in our in vivo studies on HS in the rat. In a rat "fixed volume" model of mild HS, we show that MSCs administered IV potently inhibit systemic levels of inflammatory cytokines and chemokines in the serum of treated animals. In vivo MSCs also inhibit pulmonary endothelial permeability and lung edema with concurrent preservation of the vascular endothelial barrier proteins: VE-cadherin, Claudin-1, and Occludin-1. Leukocyte infiltrates (CD68 and MPO positive cells) are also decreased in lungs with MSC treatment. Taken together, these data suggest that MSCs, acting directly and through soluble factors, are potent stabilizers of the vascular endothelium and inflammation. These data are the first to demonstrate the therapeutic potential of MSCs in HS and have implications for the potential use of MSCs as a cellular therapy in HS-induced lung injury.
Over the past 10 years, a great deal has been learned about the fundamental biology and therapeutic application of bone marrow-derived human mesenchymal stem cells (MSCs). Intravenous administration of these cells is the preferred route for therapeutic delivery of MSCs. Vascular endothelial cells (ECs) are the first cell type that MSCs encounter following IV administration. However, little is known about the biological consequences of interactions between MSCs and ECs, and if any therapeutic benefit results from this interaction. We show that MSCs exert potent stabilizing effects on ECs using an in vitro coculture system. Such effects include decreased EC proliferation and the reduction of EC vascular network formation in matrigel. Interestingly, these effects appear to require EC-MSC contact and result in enhanced colocalization of VE-Cadherin and β-catenin at the cell membrane. Disruption of the VE-Cadherin/β-catenin interaction abrogates the observed effects. As a functional in vivo correlate, we show that intravenously administered MSCs strongly inhibit angiogenesis in a matrigel plug assay. Taken together, these results identify a novel mechanism of action of MSCs that involves a contact-dependent EC interaction. These findings are relevant to intravenous use of MSCs and provide insight into further optimizing therapeutic strategies involving MSCs.
BACKGROUND Clinical benefits of plasma as an adjunct for treatment of hemorrhagic shock (HS) have been well established. However, its use is not without risk. Little is understood regarding the clinical implications of plasma variability. We hypothesized there to be interdonor variability in plasma that would impact endothelial and organ function postinjury. METHODS Pulmonary endothelial cells (ECs) were incubated with plasma from 24 random donors, and transendothelial electrical resistance was measured. Plasma units with a more or less protective effect on reducing EC permeability were selected for testing in vivo. Syndecan-1 and cytokines were measured. Mice underwent laparotomy and then HS followed by resuscitation with the selected plasma units and were compared with mice receiving no resuscitation and shams. Lung tissue was sectioned and stained for myeloperoxidase and pulmonary syndecan-1 and scored for lung histopathologic injury. RESULTS Plasma from 24 donors revealed variability in the reversal of EC monolayer hyperpermeability; transendothelial electrical resistance for the more protective plasma was significantly higher than that for the less protective plasma (0.801 ± 0.022 vs. 0.744 ± 0.035; p = 0.002). Syndecan-1 was also markedly increased in the less protective compared with the more protective plasma (38427 ± 1257 vs. 231 ± 172 pg/mL, p < 0.001), while cytokines varied. In vivo, the more protective plasma mitigated lung histopathologic injury compared with the less protective plasma (1.56 ± 0.27 vs. 2.33 ± 0.47, respectively; p = 0.005). Similarly, myeloperoxidase was significantly reduced in the more protective compared with the less protective plasma group (2.590 ± 0.559 vs. 6.045 ± 1.885; p = 0.02). Lastly, pulmonary syndecan-1 immunostaining was significantly increased in the more protective compared with the less protective plasma group (20.909 ± 8.202 vs. 9.325 ± 3.412; p = 0.018). CONCLUSION These data demonstrate significant interdonor variability in plasma that can adversely influence the protective effects of plasma-based resuscitation on HS-induced lung injury. This may have important implications for patient safety and clinical outcomes.
As with all areas of medicine, high‐quality clinical research is essential to improving the care of trauma patients. This research is crucial in developing evidence‐based treatments that decrease cost, decrease morbidity, and improve mortality. Trauma continues to extract a significant toll on society and is the single largest cause of years of life lost in the United States. The need to conduct high‐quality clinical research in trauma is not disputed. However, significant challenges and barriers unique to the field of trauma make performing this research more difficult. It is critical to be aware of these challenges and barriers to performing clinical research involving trauma patients so these challenges can be accounted for and solutions implemented to minimize their impact on research. This review will focus on the barriers and challenges that are encountered while performing clinical research in trauma.
Plasma has been shown to mitigate the endotheliopathy of trauma. Protection of the endothelium may be due in part to fibrinogen and other plasma-derived proteins found in cryoprecipitate; however, the exact mechanisms remain unknown. Clinical trials are underway investigating early cryoprecipitate administration in trauma. In this study, we hypothesize that cryoprecipitate will inhibit endothelial cell (EC) permeability in vitro and will replicate the ability of plasma to attenuate pulmonary vascular permeability and inflammation induced by hemorrhagic shock and trauma (HS/T) in mice.In vitro, barrier permeability of ECs subjected to thrombin challenge was measured by transendothelial electrical resistance. In vivo, using an established mouse model of HS/T, we compared pulmonary vascular permeability among mice resuscitated with (1) lactated Ringer's solution (LR), (2) fresh frozen plasma (FFP), or (3) cryoprecipitate. Lung tissue from the mice in all groups was analyzed for markers of vascular integrity, inflammation, and inflammatory gene expression via NanoString messenger RNA quantification.Cryoprecipitate attenuates EC permeability and EC junctional compromise induced by thrombin in vitro in a dose-dependent fashion. In vivo, resuscitation of HS/T mice with either FFP or cryoprecipitate attenuates pulmonary vascular permeability (sham, 297 ± 155; LR, 848 ± 331; FFP, 379 ± 275; cryoprecipitate, 405 ± 207; p < 0.01, sham vs. LR; p < 0.01, LR vs. FFP; and p < 0.05, LR vs. cryoprecipitate). Lungs from cryoprecipitate- and FFP-treated mice demonstrate decreased lung injury, decreased infiltration of neutrophils and activation of macrophages, and preserved pericyte-endothelial interaction compared with LR-treated mice. Gene analysis of lung tissue from cryoprecipitate- and FFP-treated mice demonstrates decreased inflammatory gene expression, in particular, IL-1β and NLRP3, compared with LR-treated mice.Our data suggest that cryoprecipitate attenuates the endotheliopathy of trauma in HS/T similar to FFP. Further investigation is warranted on active components and their mechanisms of action.
BACKGROUND Although a majority of the studies conducted to date on platelet (PLT) storage have been focused on PLT hemostatic function, the effects of 4°C PLTs on regulation of endothelial barrier permeability are still not known. In this study, we compared the effects of room temperature (22°C) stored and (4°C) stored PLTs on the regulation of vascular endothelial cell (EC) permeability in vitro and in vivo. STUDY DESIGN AND METHODS Day 1, Day 5, and Day 7 leukoreduced apheresis PLTs stored at 4 or 22°C were studied in vitro and in vivo. In vitro, PLT effects on EC permeability and barrier function, adhesion, and impedance aggregometry were investigated. In vivo, using a mouse model of vascular leak, attenuation of vascular leak and circulating PLT numbers were measured. RESULTS Treatment of EC monolayers with Day 5 or Day 7 PLTs, stored at both 22°C and 4°C, resulted in similar decreases in EC permeability on average. However, analysis of individual samples revealed significant variation that was donor dependent. Additional in vitro measurements revealed a decrease in inflammatory mediators, nonspecific PLT‐endothelial aggregation and attenuated loss of aggregation over time to TRAP, ASPI, ADP, and collagen with 4°C storage. In mice, while 22°C and 4°C PLTs both demonstrated significant protection against vascular endothelial growth factor A (VEGF‐A)‐induced vascular leak 22°C PLTs exhibited increased protection compared to 4°C PLTs. Systemic circulating levels of 4°C PLTs were decreased compared to 22°C PLTs. CONCLUSIONS In vitro, 4°C‐stored PLTs exhibit a greater capacity to inhibit EC permeability than 22°C‐stored PLTs. In vivo, 22°C PLTs provide superior control of vascular leak induced by VEGF‐A. This discrepancy may be due to increased clearance of 4°C PLTs from the systemic circulation.
Mechanisms by which hemorrhagic shock leads to hemodynamic disturbances are not fully understood. Nuclear factor kB (NF‐kB) is a nuclear transcription factor that regulates expression of genes critical for the regulation of diseases. We hypothesize that NF‐kB is responsible for the hemodynamic changes associated with hemorrhagic shock in conscious rats. Under isoflurane, catheters were implanted into the aorta to record mean blood pressure (MAP) and heart rate (HR) and in the femoral vein for drug administrations. Cardiac output (CO) was recorded through Doppler flow probe. A blood volume of 2.0 ml/100 g of body weight was withdrawn over a 5‐min to induce moderate hemorrhage. Group 1 (n=6) was subjected to moderate hemorrhage only. Group 2 (n=5) was hemorrhaged in the presence of TPCK, an inhibitor of NF‐kB at 10 mg/kg sc. Our data show that hemorrhagic shock induced decreases in MAP by 30%, HR by 40% whereas CO remained unchanged. Moderate hemorrhage induced significant systemic vasoconstriction. As compared to hemorrhaged animals, TPCK restored MAP to baseline. Furthermore, moderate hemorrhage‐induced systemic vasoconstriction was significantly reduced in the presence of TPCK. Our data suggest that NF‐kB plays a major role in the hemodynamic changes induced by moderate hemorrhage. Development of NF‐kB inhibitors that will be tissue‐specific and/or isoform‐specific as therapeutic agents need to be pursued.
