ObjectiveTo reveal the molecular mechanism of Angong Niuhuangwan（AGNH） in improving traumatic brain injury（TBI） based on single cell sequencing. MethodSeventy-five male SD rats were randomly divided into the sham group， model group， piracetam group（3.6 g·kg^-1）， AGNH low- and high-dose groups（0.09， 0.27 g·kg^-1）， with 15 rats in each group. In addition to the sham group， the other 4 groups used the modified Feeney free-fall impact method to prepare TBI model， and the drugs were administered by gavage immediately after modeling， 24 hours later， the modified neurological deficit score（mNSS） was performed， and brain tissue was isolated to determine the degree of cerebral edema. Hematoxylin-eosin（HE） staining was used to observe the injury degree in the cortex， CA1 region and CA3 region of brain tissue. The expression levels of cyclooxygenase-2（COX-2）， interferon regulatory factor 1（IRF1）， Janus kinase 2（JAK2） and suppressor of cytokine signaling 3（SOCS3） were observed by immunofluorescence（IF） staining. The levels of interleukin（IL）-6， IL-18， IL-1β， IL-17A， tumor necrosis factor-α（TNF-α）， Caspase-1 and nucleotide binding oligomerization domain（NOD）-like receptor heat protein domain associated protein 3（NLRP3） inflammasome were determined by enzyme-linked immunosorbent assay（ELISA）. The regulation of AGNH on each cell population was analyzed by single cell sequencing， and differentially expressed genes were analyzed by Gene Ontology（GO） and Kyoto Encyclopedia of Genes and Genomes（KEGG）， which led to construct microglia differentially expressed gene network to search for the key targets， and validated by ELISA and IF. ResultCompared with the sham group， the mNSS and brain water content were significantly increased in the model group（P<0.01）. Compared with the model group， mNSS and brain water content in the low and high dose AGNH groups were decreased（P<0.05，P<0.01）. HE staining results showed that compared with the sham group， the cells in the cerebral cortex and hippocampus of rats in the model group were seriously lost， and the cells were arranged loosely（P<0.01）. Compared with the model group， AGNH could significantly increase the density of neurons in the CA1 and CA3 regions of the cerebral cortex and hippocampus， making the arrangement more compact， as well as improved cell morphology（P<0.05，P<0.01）. ELISA and IF staining showed that AGNH could reduce the levels of Caspase-1， IL-17A， TNF-α， NLRP3 and COX-2 in brain tissue of TBI rats（P<0.05， P<0.01）. A total of 13 cell subsets were identified by single cell sequencing， among which microglia played an important role in neuroimmunity. The results of GO enrichment analysis of differentially expressed genes in microglia showed that AGNH improved TBI in response to inflammation and TNF-α. KEGG enriched IL-17 signaling pathway， TNF signaling pathway， Toll-like receptor signaling pathway， etc. The results of network analysis showed that the key targets of AGNH in regulating TBI might be IL-6， IL-1β， JAK2， SOCS3， IRF1. IF and ELISA verification results showed that compared with the sham group， SOCS3 expression in microglia was decreased in the model group， and the expressions of IL-6， IL-1β， JAK2 and IRF1 were increased（P<0.01）. Compared with the model group， AGNH could increase the expression of SOCS3， decrease the expression of IL-6， IL-1β， JAK2， IRF1 （P<0.05， P<0.01）. ConclusionAGNH can reduce the degree of brain edema and brain injury， decrease the expression of inflammatory factors， and inhibit the expression of NLRP3 and its downstream Caspase-1 in TBI rats， which may act on the targets of IL-6， IL-1β， JAK2， IRF1 and SOCS3 in microglia.

BACKGROUND:As tissue engineering brings new hope to the worldwide problem of articular cartilage repair,the construction of light-curing 3D printed hydrogel scaffolds with biomimetic composition is of great significance for cartilage tissue engineering. OBJECTIVE:To construct a biomimetic methacryloylated hyaluronic acid/acellular Wharton's jelly composite hydrogel scaffold by digital light processing 3D printing technology,and to evaluate its biocompatibility. METHODS:Wharton's jelly was isolated and extracted from human umbilical cord,then decellulated,freeze-dried,ground into powder,and dissolved in PBS to prepare 50 g/L acellular Wharton's jelly solution.Methylallylated hyaluronic acid was prepared,lyophilized and dissolved in PBS to prepare 50 g/L methylallylated hyaluronic acid solution.Acellular Wharton's jelly solution was mixed with methacrylyacylated hyaluronic acid solution at a volume ratio of 1:1,and was used as bio-ink after adding photoinitiator.Methylacrylylated hyaluronic acid hydrogel scaffolds(labeled as HAMA hydrogel scaffolds)and methylacrylylated hyaluronic acid/acellular Wharton's jelly gel scaffolds(labeled as HAMA/WJ hydrogel scaffolds)were prepared by digital light processing 3D printing technology,and the microstructure,swelling performance,biocompatibility,and cartilage differentiation performance of the scaffolds were characterized. RESULTS AND CONCLUSION:(1)Under scanning electron microscope,the two groups of scaffolds showed a three-dimensional network structure,and the fiber connection of HAMA/WJ hydrogel scaffold was more uniform.Both groups achieved swelling equilibrium within 10 hours,and the equilibrium swelling ratio of HAMA/WJ hydrogel scaffold was lower than that of HAMA hydrogel scaffold(P＜0.05).(2)CCK-8 assay showed that HAMA/WJ hydrogel scaffold could promote the proliferation of bone marrow mesenchymal stem cells compared with HAMA hydrogel scaffold.Dead/live staining showed that bone marrow mesenchymal stem cells grew well on the two groups of scaffolds,and the cells on the HAMA/WJ hydrogel scaffolds were evenly distributed and more cells were found.Phalloidine staining showed better adhesion and spread of bone marrow mesenchymal stem cells in HAMA/WJ hydrogel scaffold than in HAMA.(3)Bone marrow mesenchymal stem cells were inoculated into the two groups for chondrogenic induction culture.The results of qRT-PCR showed that the mRNA expressions of agglutinoglycan,SOX9 and type Ⅱ collagen in the HAMA/WJ hydrogel scaffold group were higher than those in the HAMA hydrogel scaffold group(P＜0.05,P＜0.01).(4)These findings indicate that the digital light processing 3D bioprinting HAMA/WJ hydrogel scaffold can promote the proliferation,adhesion,and chondrogenic differentiation of bone marrow mesenchymal stem cells.