Old age is a known risk factor for mortality in acute respiratory distress syndrome (ARDS)/acute lung injury. Mesenchymal stem cells (MSCs) possess potent immunomodulatory properties, while aging MSCs have reduced capacity. Recent studies have demonstrated that MSC-derived extracellular vesicles (MSC-EVs) are able to mimic MSCs in alleviating acute lung injury. The goals of this study were to determine whether EVs from young and aging MSCs had differential effects on lipopolysaccharide (LPS)-induced lung injury in young mice and unravel the underlying mechanisms. Our results showed that both aging and young MSC-EVs had similar physical and phenotypical properties. As their parental cells, young MSC-EVs alleviated LPS-induced acute lung injury, while aging MSC-EVs did not exhibit the protective effects. In contrast to young MSC-EVs, aging MSC-EVs failed to alter macrophage phenotypes and reduce macrophage recruitment. In addition, the internalization of aging MSC-EVs by macrophages was significantly lower compared with that of young MSC-EVs. Furthermore, aging and young MSC-EVs differed in levels of several miRNAs relating macrophage polarization. In conclusion, aging and young MSC-EVs have differential effects in alleviating acute lung injury and macrophage polarization, which may be associated with internalization of EVs and their miRNA content.

Sepsis is a systemic, deleterious host response to widespread infection. Patients with sepsis will have documented or suspected infection which can progress to a state of septic shock or acute organ dysfunction. Since sepsis is responsible for nearly 3 million cases per year in China and severe sepsis is a common, expensive fatal condition in America, developing new therapies becomes a significant and worthwhile challenge. Clinical research has shown that sepsis-associated immunosuppression plays a central role in patient mortality, and targeted immune-enhancing therapy may be an effective treatment approach in these patients. As part of the inflammatory response during sepsis, there are elevations in the number of myeloid-derived suppressor cells (MDSCs). MDSCs are a heterogeneous population of immature myeloid cells that possess immunosuppressive activities via suppressing T-cell proliferation and activation. The role of MDSCs in sepsis remains uncertain. Some believe activated MDSCs are beneficial to the sepsis host by increasing innate immune responses and antimicrobial activities, while others think expansion of MDSCs leads to adaptive immune suppression and secondary infection. Herein, we discuss the complex role of MDSCs in immune regulation during sepsis, as well as the potential to target these cells for therapeutic benefit.

Background: Infantile myofibromatiosis (IM) is a rare benign tumor in the infants, but it has a bad prognosis if IM erncroaches on the viscera. Multiple tissues can be invaded by IM, including the subcutaneous tissue, the muscle of the neck, back, and head, but seldom in the bones and the viscera. The histopathologic and immunohistochemical examinations are necessary in daigonosis of IM as it might be misdiagnosed as the malignant tumor. Materials and Method: Thirty-two consecutive patients with IM in our hospital (2003-2013) were enrolled and the clinical date were analyzed to understand IM better, such as the feature of clinical manifestations, pathology, imaging tests, and treatment. Results: All of them underwent excision operations, 4 of them with invasion in the bones, 2 with invasion in the craniums, and the rest in the ulna and the humerus. The immunohistiochemical analysis shown that the tumor cells were positive to vimentin and smooth muscle actin while negative to the S100 protein and desmin. Twenty-five patients were in follow-up, 2 cases recurred. Conclusions: IM is a benign tumor, but IM with the viscera involvement has a bad prognosis. The strategy of waiting and observation for IM without visceral involvement could be selected.