Click chemistry extracellular vesicle/peptide/chemokine nanocarriers for treating central nervous system injuries

Central nervous system(CNS)injuries,including stroke,traumatic brain injury,and spinal cord injury,are essential causes of death and long-term disability and are difficult to cure,mainly due to the limited neuron regeneration and the glial scar formation.Herein,we apply extracellular vesicles(EVs)secreted by M2 microglia to improve the differentiation of neural stem cells(NSCs)at the injured site,and simultaneously modify them with the injured vascular targeting peptide(DA7R)and the stem cell recruiting factor(SDF-1)on their surface via copper-free click chemistry to recruit NSCs,inducing their neuronal differentiation,and serving as the nanocarriers at the injured site(Dual-EV).Results prove that the Dual-EV could target human umbilical vascular endothelial cells(HUVECs),recruit NSCs,and promote the neuronal differentiation of NSCs in vitro.Furthermore,10 miRNAs are found to be upregulated in Dual-M2-EVs compared to Dual-M0-EVs via bioinformatic analysis,and further NSC differentiation experiment by flow cytometry reveals that among these miRNAs,miR30b-3p,miR-222-3p,miR-129-5p,and miR-155-5p may exert effect of inducing NSC to differentiate into neurons.In vivo experiments show that Dual-EV nanocarriers achieve improved accumulation in the ischemic area of stroke model mice,potentiate NSCs recruitment,and increase neurogenesis.This work provides new insights for the treatment of neuronal regeneration after CNS injuries as well as endogenous stem cells,and the click chemistry EV/peptide/chemokine and related nanocarriers for improving human health.

Regulated macrophage immune microenvironment in 3D printed scaffolds for bone tumor postoperative treatment

The 3D printing technique is suitable for patient-specific implant preparation for bone repair after bone tumor resection.However,improving the survival rate due to tumor recurrence remains a challenge for implants.The macrophage polarization induction to M2-type tumor-associated macrophages(TAMs)by the tumor microenvironment is a key factor of immunosuppression and tumor recurrence.In this study,a regenerative scaffold regulating the macrophage immune microenvironment and promoting bone regeneration in a dual-stage process for the postoperative treatment of bone tumors was constructed by binding a colony-stimulating factor 1 receptor(CSF-1R)inhibitor GW2580 onto in situ cosslinked hydroxybutylchitosan(HBC)/oxidized chondroitin sulfate(OCS)hydrogel layer covering a 3D printed calcium phosphate scaffold based on electrostatic interaction.The hydrogel layer on scaffold surface not only supplied abundant sulfonic acid groups for stable loading of the inhibitor,but also acted as the cover mask protecting the bone repair part from exposure to unhealthy growth factors in the microenvironment at the early treatment stage.With local prolonged release of inhibitor being realized via the functional material design,CSF-1R,the main pathway that induces polarization of TAMs,can be efficiently blocked,thus regulating the immunosuppressive microenvironment and inhibiting tumor development at a low therapeutic dose.At the later stage of treatment,calcium phosphate component of the scaffold can facilitate the repair of bone defects caused by tumor excision.In conclusion,the difunctional 3D printed bone repair scaffold regulating immune microenvironment in stages proposed a novel approach for bone tumor postoperative treatment.

Targeted regulation of neuroinflammation via nanobiosignaler for repairing the central nerve system injuries

Neuroinflammation,commonly associated with various central nervous system(CNS)diseases such as postoperative cognitive dysfunction(POCD),is primarily mediated by the disruption of biological signals in microglia.However,the effective treatment of CNS diseases remains an ongoing challenge as biological signals show limited microglia-targeting effect.In this study,taking advantage of the highly expressed lipoprotein receptor-related protein-1(LRP1)on the microglia,a nanobiosignal delivery system modified by LRP1 high-affinity peptide ligand RAP12(RAP:receptor-associated protein)was constructed to specifically regulate neuroinflammation via targeting microglia.The uptake of the RAP12 modified-nanobiosignaler by microglia increased significantly,indicating its microglia-targeting ability.Both in vitro/vivo studies proved that the“nanobiosignaler”significantly reduced the secretion of pro-inflammatory cytokines,induced specific M2(anti-inflammatory type)microglia differentiation,and remarkably alleviated cognitive function impairment in the mice model when compared with unmodified groups.It was indicated that the“nanobiosignaler”could target microglia to deliver the biological signal and inhibit the excessive activation of microglia.Overall,the cell-targeted biological signal transmission system inspired by“nanobiosignaler”has broad application prospects in the future.

Advances in extracellular vesicle functionalization strategies for tissue regeneration

Extracellular vesicles(EVs)are nano-scale vesicles derived by cell secretion with unique advantages such as promoting cell proliferation,anti-inflammation,promoting blood vessels and regulating cell differentiation,which benefit their wide applications in regenerative medicine.However,the in vivo therapeutic effect of EVs still greatly restricted by several obstacles,including the off-targetability,rapid blood clearance,and undesired release.To address these issues,biomedical engineering techniques are vastly explored.This review summarizes different strategies to enhance EV functions from the perspective of drug loading,modification,and combination of biomaterials,and emphatically introduces the latest developments of functionalized EV-loaded biomaterials in different diseases,including cardio-vascular system diseases,osteochondral disorders,wound healing,nerve injuries.Challenges and future directions of EVs are also discussed.

Engineered extracellular vesicles for ischemic stroke treatment

Dear Editor,Nanotechnology-based therapeutic strategies have been proven effective in diseases including cancer,infection,inflammation,etc.1 However,the application of nanotechnology is greatly restricted in the treatment of central nervous system(CNS)disorders due to physiological CNS barriers.For example,the blood-brain barrier(BBB)can be the“Maginot line”for pharmacologically active molecules,blocking them out of the CNS.