Biomechanical Motion-Activated Endogenous Wound Healing through LBL Self-Powered Nanocomposite Repairer with pH-Responsive Anti-Inflammatory Effect.

Wound care is still worthy of concern, and effective measures such as electrical stimulating therapy (EST) have sparked compellingly for wound repair. Especially, portable and point-of-care EST devices get extremely desired but these are often limited by inevitable external power sources, lack of biological functions, and mechanical properties conforming to skin tissue. Herein, a dress-on-person self-powered nanocomposite bioactive repairer of wound is designed. As such, the cooperation of the film prepared by layer-by-layer self-assembling 2-hydroxypropyltrimethyl ammonium chloride chitosan (HTCC), alginate (ALG), and poly-dopamine/Fe3+ nanoparticles (PFNs), with a self-powered nanogenerator (SN) driven by motion into a nanocomposite repairer (HAP/SN-NR) is conducted. The HAP/SN-NR not only guides cell behavior (proliferation and migration rate ≈61.7%, ≈52.3%), but also facilitates neovascularization (enhanced CD31 expression >4-fold) through its self-powered EST, and the endogenous wound closure with no inflammatory in rats owing to reactive oxygen species (ROS)-clearance of HAP/SN-NR in vitro/vivo through responsively releasing poly-dopamine nanoparticles at wound pH. Enormous efforts illustrate that the repairer is endowed with high self-adhesion to tissue, self-healing, and biodegradation, accelerating wound healing (50% closure ≈5 days). This strategy sheds light on novel multifunctional portable sensor-type dressings and propels the development of intelligent medical devices.

An optimized method for the induction and purification of mouse bone marrow dendritic cells.

Dendritic cells (DCs) play an essential role in the initiation of adaptive immune responses, but they are rare in all organs. The traditional methods used to increase the yield and purity of DCs are the early removal of granulocyte culture medium and the isolation of high-purity DCs by magnetic-activated cell sorting (MACS). This study provides a more rapid and economical optimization method to obtain more high-purity DCs. (i) We harvested 18% more bone marrow (BM) cells by using forceps to crack the epiphysis instead of cutting it with scissors during BM cell extraction. (ii) When the cells in the culture medium that is discarded on day 3 in the traditional method were centrifuged and then added back to the petri dish, the DC yield on day 5 increased by 61%. (iii) On the third day, the addition of fresh medium and the retention of the original medium rather than discarding it increased the number of DCs harvested on the fifth day by 137%. (i-iii) The improved method cost an average of 74% less than the conventional method and yielded the same number and function of cells. (iv) The initial number of BM cells was increased by 15% in 4-week-old mice compared with 8-week-old mice. (v) The Percoll density centrifugation (PDS) method was used to purify DCs on day 6 after induction, and the purity of the DCs was greater than 90%, which showed no significant difference from the MACS method. However, the yield of the PDS method increased by 21%. In addition, the PDS method has a lower cost, with an average purification cost of 4 CNY ($0.58) compared with 648 CNY ($93.25) for MACS, reducing the cost by 99%. Therefore, high-purity and high-yield DCs can be rapidly obtained through a five-step improvement in the process of BM cell extraction, induction and purification.

Mesenchymal stem cells activate Notch signaling to induce regulatory dendritic cells in LPS-induced acute lung injury.

BACKGROUND: Mesenchymal stem cells (MSCs) have been shown to alleviate acute lung injury (ALI) and induce the production of regulatory dendritic cells (DCregs), but the potential link between these two cell types remains unclear. The goal of this study was to investigate the effect and mechanism of MSC-induced regulatory dendritic cells in ALI mice. MATERIAL/METHODS: In vivo experiments, C57BL/6 wild-type male mice were sacrificed at different times after intratracheal injection of LPS to observe changes in lung DC maturation and pathological damage. MSCs, DCregs or/and carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled DCs were administered to the mice by tail vein, and flow cytometry was performed to measure the phenotype of lung DCs and T cells. Lung injury was estimated by the lung wet weight/body weight ratio and histopathological analysis. In vitro, Western blotting or flow cytometry was used to detect the expression of Notch ligand or receptor in MSCs or DCs after coculture or LPS stimulation. Finally, in vivo and in vitro, we used the Notch signaling inhibitor DAPT to verify the effect of the Notch pathway on MSC-induced DCregs and their pulmonary protection. RESULTS: We showed significant accumulation and maturation of lung DCs 2 h after intratracheal injection of LPS, which were positively correlated with the lung pathological injury score. MSC treatment alleviated ALI lung injury, accompanied by a decrease in the number and maturity of classical DCs in the lungs. CFSE-labeled DCs migrated to the lungs of ALI mice more than those of the normal group, and the elimination of CFSE-labeled DCs in the blood was slower. MSCs inhibited the migration of CFSE-labeled DCs to the lung and promoted their elimination in the blood. DCregs, which are obtained by contact coculture of mDCs with MSCs, expressed reduced levels of MHCII, CD86, CD40 and increased levels of PD-L1, and had a reduced ability to stimulate lymphocyte proliferation and activation (expression of CD44 and CD69). mDCs expressing Notch2 significantly increased after coculture with MSCs or rhJagged1, and MSCs expressed more Jagged1 after LPS stimulation. After stimulation of mDCs with recombinant Jagged1, DCs with low expression of MHCII, CD86 and CD40 were also induced, and the effects of both rhJagged1 and MSCs on DCs were blocked by the Notch inhibitor DAPT. Intra-airway DAPT reversed the inhibitory effect of mesenchymal stem cells on DC recruitment to the lungs and its maturation. CONCLUSIONS: Our results suggested that the recruitment and maturation of lung DCs is an important process in early ALI, MSCs attenuate LPS-induced ALI by inducing the production of DCregs by activating Notch signaling.