Electrospun Poly-l-Lactic Acid Membranes Promote M2 Macrophage Polarization by Regulating the PCK2/AMPK/mTOR Signaling Pathway.

Electrospun membranes are widely used in tissue engineering. Regretfully, there is limited research on how its morphological characteristics precisely regulate macrophage activation and immune response. Therefore, electrospun poly-l-lactic acid (PLLA) membranes with different alignments (align and random) and diameters (nanoscale and microscale) are prepared to investigate the effects of different surface morphologies on M2 macrophage polarization. Additionally, transcriptome, proteome, and phosphoproteome sequencings are combined to examine the underlying regulatory mechanisms. The results show that the electrospun PLLA membranes with different surface morphologies have good biocompatibility and can regulate the phenotype and function of macrophages by changing the micromorphology of the matrix surface. Especially, macrophages cultured on the electrospun membranes of the A600 group exhibit higher M2 macrophage polarization than the other three groups. Furthermore, the findings demonstrate that electrospun PLLA membranes enhance AMP-activated protein kinase (AMPK)/ mammalian target of rapamycin (mTOR) signaling activation by upregulating the expression of integrin phosphoenolpyruvate carboxykinase 2 (PCK2), which is critical for M2 macrophage polarization. Taken together, electrospun PLLA membranes promote M2 macrophage polarization by regulating the PCK2/AMPK/mTOR signaling pathway. This research can provide further theoretical bases for scaffold design, immunoregulatory mechanisms, and clinical application based on electrospinning technology in the future.

Random and aligned electrostatically spun PLLA nanofibrous membranes enhance bone repair in mouse femur midshaft defects.

Long-segment bone defects are a common clinical challenge and abstract biomaterials are a promising therapy. Poly-L-lactic acid (PLLA) nanofibrous membranes prepared by electrostatic spinning have a good bone repair potential. However, there are random and aligned surface morphologies of electrostatic spun PLLA nanofibrous membranes, which can affect the migration, proliferation, and differentiation ability of cells. The role of surface morphology in the repair of long bone defects in vivo is currently unknown. In this study, random and aligned electrostatically spun PLLA nanofibrous membranes were prepared, characterised, and implanted into a femur midshaft defect mouse model. The ability of electrostatically spun PLLA nanofibrous membranes to enhance bone repair was tested using X-ray photography, high-resolution micro-computed tomography (micro-CT), and pathological section specimens. The results showed that both random and aligned electrostatically spun PLLA nanofibrous membranes enhanced bone regeneration at bone defects, but the aligned ones exhibited superior results. These results provide a theoretical basis for engineering the surface morphology of bone repair materials.

[Expression and Role of PD-L1 in a Mouse Model of Necrotizing Enterocolitis].

Objective: To investigate the expression and role of programmed death ligand-1 (PD-L1) in a mouse model of necrotizing enterocolitis (NEC). Methods: A total of 20 wild-type C57 BL/6 J mice were randomly assigned to the control and the model groups. Mice in the control group were breastfed, while mice in the model group were given lipopolysaccharide, formula feeding, hypoxia, and cold stimulation for NEC induction. Then, the intestines of the mice were collected in order to assess the pathological changes through HE staining, to examine PD-L1 expression and localization with immunofluorescence co-localization, and to evaluate intestinal PD-L1 expression with Western blot. Peripheral blood was collected for flow cytometry to examine leukocyte subpopulations and their PD-L1 expression. On the other hand, 14 PD-L1 (+/+) mice and 14 PD-L1 (-/-) mice were randomly divided into their respective genotype control groups and model groups. The same induction method as was already mentioned was adopted for the model groups. The intestines of the mice were collected for HE staining to evaluate the pathological change and peripheral blood was collected to examine the expression of inflammatory factors. Results: The NEC mouse model was successfully constructed. PD-L1 was widely expressed in enterocytes and inflammatory cells in the mouse intestines and in T cells, monocytes, and neutrophils in peripheral blood. The expression of PD-L1 in NEC mouse intestines increased in comparison with that of the control group. In the peripheral blood of NEC mice, the proportion of T cells and monocytes and their PD-L1 expression showed no significant changes compared with those of the control group, while the proportion of neutrophils and their PD-L1 expression increased by about 140% and 150%, respectively, in comparison with those of the control group ( P<0.05). According to the results of the PD-L1 gene mouse experiment, the control groups of PD-L1 (+/+) mice and PD-L1 (-/-) mice showed no significant difference in their intestinal conditions and serum inflammatory factor levels, while the PD-L1 (-/-) NEC mouse had worse intestinal pathological changes and increased mean pathological scores compared with those of PD-L1 (+/+) NEC mouse ( P<0.05). In addition, serum interleukin (IL)-10 in PD-L1 (-/-) NEC mouse decreased by about 44% compared with that of PD-L1 (+/+) NEC mice, and chemokine (C-X-C motif) ligand 1/IL-6/IL-1ß all increased by more than 25% (all P<0.05). Conclusion: PD-L1 is widely expressed in inflammatory cells and enterocytes in mice. Knocking out PD-L1 aggravates the degree of NEC inflammation and intestinal pathological changes. PD-L1 plays a protective role by reducing inflammation in the pathogenesis of NEC, the mechanism of which may be related to the regulation of neutrophils/enterocytes.

Mesenchymal stem cells prevent ovariectomy-induced osteoporosis formation in mice through intraosseous vascular remodeling.

Mesenchymal stem cells (MSCs) can promote osteogenesis and are a promising therapy for postmenopausal osteoporosis. However, the relationship between improved intraosseous microcirculation and increased bone mass induced by MSCs in postmenopausal osteoporosis remains unclear. After the primary MSCs were characterized, they were transplanted into ovariectomized mice. MSCs transplantation enhanced the trabecular number, trabecular bone volume/total volume, and trabecular bone mineral density in ovariectomized mice. To determine the role of MSCs in vascular repair, mice were subjected to femoral artery ligation. Through laser speckle flowmetry, vascular perfusion and femoral trabecular bone and cortical bone analyses, we determined the effects of MSCs in promoting intraosseous angiogenesis and preventing osteoporosis in mice. MSCs effectively prevented postmenopausal osteoporosis development, which is associated with the involvement of MSCs in reestablishment of microcirculation within the skeleton.

Impact of extent of resection on survival in high-risk neuroblastoma: A systematic review and meta-analysis.

BACKGROUND: Despite the development of new treatment options, the prognosis of high-risk neuroblastoma patients is still poor. Many studies designed to elaborate the association between the extent of resection (EOR) and outcome have reported conflicting results. We performed a meta-analysis to assess whether greater EOR is associated with improved overall survival (OS) and event-free survival (EFS) in patients with high-risk neuroblastoma. METHODS: Embase, PubMed, Cochrane library, and conference proceedings were searched between March 10 and October 1, 2017. Studies of pediatric patients with newly diagnosed high-risk neuroblastoma comparing various EOR and presenting objective overall or event-free survival data were included. Primary outcomes were relative risk (RR) for mortality at 3 and 5 years. Secondary outcomes were 3-year and 5-year EFS rates. RESULTS: 19 retrospective studies including a total of 2358 cases were identified. Compared with subtotal resection (STR), patients who underwent gross total resection (GTR) had significantly decreased mortality at 3 years (RR, 0.69; 95% CI, 0.58-0.82; P < 0.001; I2 = 27%) and 5 years (RR, 0.70; 95% CI, 0.60-0.82; P < 0.001; I2 = 38%). A similar decrease was revealed in the 3-year risk for mortality for STR compared with biopsy (RR, 0.71; 95% CI, 0.53-0.95; P = 0.02; I2 = 0%). When comparing any resection with biopsy, resection group also showed a decreased risk for mortality at 3 years (RR, 0.66; 95% CI, 0.53-0.83; P < 0.001; I2 = 8%) and 5 years (RR, 0.67; 95% CI, 0.50-0.91; P = 0.009; I2 = 61%). With respect to the risk ratio for EFS, there were no significant differences in any comparisons. CONCLUSION: This literature highlights the importance of "extent of resection" in treating high-risk neuroblastoma, and when feasible, the currently available evidences in favor of the use of GTR for high-risk neuroblastoma for reducing 3- and 5-year mortality. LEVEL OF EVIDENCE: 3A.