The regeneration of articular cartilage, which scarcely shows innate self-healing ability, is a great challenge in clinical treatment. Stem cell-derived exosomes (SC-Exos), an important type of extracellular nanovesicle, exhibit great potential for cartilage regeneration to replace stem cell-based therapy. Cartilage regeneration often takes a relatively long time and there is currently no effective administration method to durably retain exosomes at cartilage defect sites to effectively exert their reparative effect. Therefore, in this study, we exploited a photoinduced imine crosslinking hydrogel glue, which presents excellent operation ability, biocompatibility and most importantly, cartilage-integration, as an exosome scaffold to prepare an acellular tissue patch (EHG) for cartilage regeneration. It was found that EHG can retain SC-Exos and positively regulate both chondrocytes and hBMSCs in vitro. Furthermore, EHG can integrate with native cartilage matrix and promote cell deposition at cartilage defect sites, finally resulting in the promotion of cartilage defect repair. The EHG tissue patch therefore provides a novel, cell-free scaffold material for wound repair.

A novel photogelling mechanism by the phototriggered-imine-crosslinking (PIC) reaction is demonstrated. Hyaluronic acid grafted with o-nitrobenzene, a photogenerated aldehyde group, can quickly photo-crosslink with amino-bearing polymers or proteins. Once the in situ photogelling on a wound occurs, the PIC gelling process can well integrate a hydrogel with surrounding tissue by covalent bonding, thus making it a powerful tool for tissue engineering and regenerative medicine.

Background Angiogenesis, as an endogenous repair mechanism, plays crucial roles in wound healing and tissue regeneration. However, this process is impaired in the elderly due to aging-related vascular endothelial dysfunction. This study was aimed to explore the pro-angiogenic effects of exosomes from human embryonic stem cells (ESC-Exos) in aged mice of pressure-induced ulcer model and the underlying mechanism. Methods Pressure ulcer wounds were created on the back of d -galactose-induced aging mice. ESC-Exos were locally applied onto the wound beds, with PBS as control. The effects of ESC-Exos on wound healing were analyzed by measuring wound closure rates, histological and immunofluorescence analyses. Then, the anti-aging effect of ESC-Exos on vascular endothelial cells was tested in an in vitro d -galactose-induced HUVEC senescence model. Results ESC-Exos could accelerate wound closure and enhance angiogenesis, and the senescence of vascular endothelial cells was significantly ameliorated after ESC-Exos treatment. In vitro, ESC-Exos could rejuvenate the senescence of endothelial cells and recover compromised proliferation, migratory capacity, and tube formation. This recovery was Nrf2-activation-dependent, since cotreatment with Nrf2 inhibitor Brusatol could abolish the rejuvenative effects of ESC-Exos. Further study revealed that miR-200a was highly enriched in ESC-Exos and played a crucial role in ESC-Exos-mediated rejuvenation through downregulating Keap1, which negatively regulates Nrf2 expression. Conclusions ESC-Exos ameliorate endothelial senescence by activating Nrf2 and recover aging-related angiogenic dysfunction, thereby accelerating wound healing in aged mice. ESC-Exos might be a natural nano-biomaterial for aging-related diseases therapy. Electronic supplementary material The online version of this article (10.1186/s13287-019-1253-6) contains supplementary material, which is available to authorized users.

An ultimately selective photorelease system of chitosan-nanoparticles is constructed. Only under unique aspects of tumor-hypoxia physiological conditions, the preliminary locked phototrigger is unlocked by biological reduction to enable the release of the caged drug either by visible light or two-photon near-IR (NIR) excitation. This approach provides a highly discriminating photorelease of anticancer drug to hypoxic tumor cells, but not to healthy normal cells.

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The design of organic liquids in DMSO after CO2 capture created a new solvent capable of dissolving up to 10 wt% of cellulose under mild conditions.

Endogenous neurogenesis holds promise for brain repair and long‐term functional recovery after ischaemic stroke. However, the effects of exosomes from human urine‐derived stem cells (USC‐Exos) in neurogenesis remain unclear. This study aimed to investigate whether USC‐Exos enhanced neurogenesis and promoted functional recovery in brain ischaemia. By using an experimental stroke rat model, we found that intravenous injection of USC‐Exos enhanced neurogenesis and alleviated neurological deficits in post‐ischaemic stroke rats. We used neural stem cells (NSCs) subjected to oxygen‐glucose deprivation/reoxygenation (OGD/R) as an in vitro model of ischaemic stroke. The in vitro results suggested that USC‐Exos promoted both proliferation and neuronal differentiation of NSCs after OGD/R. Notably, a further mechanism study revealed that the pro‐neurogenesis effects of USC‐Exos may be partially attributed to histone deacetylase 6 (HDAC6) inhibition via the transfer of exosomal microRNA‐26a (miR‐26a). Taken together, this study indicates that USC‐Exos can be used as a novel promising strategy for brain ischaemia, which highlights the application of USC‐Exos.

1,8-Diazabicyclo[5.4.0]undec-7-ene, in conjunction with methanol after CO2 capture in DMSO created a new solvent capable of dissolving up to 8 wt% of cellulose, which could be applied as a highly efficient reaction media for the synthesis of cellulose esters under mild conditions.