Sinoatrial node pacemaker cells share dominant biological properties with glutamatergic neurons

Activation of the heart normally begins in the sinoatrial node (SAN). Electrical impulses spontaneously released by SAN pacemaker cells (SANPCs) trigger the contraction of the heart. However, the cellular nature of SANPCs remains controversial. Here, we report that SANPCs exhibit glutamatergic neuron-like properties. By comparing the single-cell transcriptome of SANPCs with that of cells from primary visual cortex in mouse, we found that SANPCs co-clustered with cortical neurons. Tissue and cellular imaging confirmed that SANPCs contained key elements of glutamatergic neurotransmitter system, expressing genes encoding glutamate synthesis pathway (Gls), ionotropic and metabotropic glutamate receptors (Grina, Gria3, Grm1 and Grm5), and glutamate transporters (Slc17a7). SANPCs highly expressed cell markers of glutamatergic neurons (Snap25 and Slc17a7), whereas Gad1, a marker of GABAergic neurons, was negative. Functional studies revealed that inhibition of glutamate receptors or transporters reduced spontaneous pacing frequency of isolated SAN tissues and spontaneous Ca

Effect of genipin cross-linking on the biocompatibility of rabbit acellular tracheal matrix / 国际生物医学工程杂志

Objective:To investigate the biocompatible properties of tissue-engineered rabbit trachea treated by Triton-X 100 processed method (TPM) and detergent enzymatic method (DEM) with genipin cross-linking.Methods:TPM and DEM were used to decellularize New Zealand rabbit trachea, and then genipin was used for cross-linking. The mechanical properties of each tracheal sample were measured by universal tensile testing machine. The structure of the sample was observed by scanning electron microscope. The cytotoxicity of the sample was detected by cell contact toxicity assay. Fifteen healthy adult New Zealand rabbits with no specific pathogens were divided into the native tracheal transplantation group, the genipin cross-linked TPM acellular tracheal matrix transplantation group and the genipin cross-linked DEM acellular tracheal matrix transplantation group according to the random number table, 5 animals for each group. Animals in each group were sacrificed 30 days after transplantation, and graft samples were obtained. The microstructure was observed by hematoxylin-eosin staining and CD68 molecular immunohistochemical staining.Results:Biomechanical results showed that the mechanical properties of decellularized tracheas with genipin cross-linking were similar to native tracheas. The results of scanning electron microscopy showed that the matrix of cross-linked decellularized tracheas was more dense comparing with native tracheas, and the mesh-like ultrastructure formed on the outer surface of the genipin cross-linked DEM acellular tracheal matrix was conducive to cell adhesion. The results of cell contact toxicity results showed that the genipin cross-linked decellularized tracheas treated by DEM had better biocompatibility. The results of in vivo implantation and histological staining showed that genipin cross-linked DEM acellular tracheal matrix was less immunogenic comparing with genipin cross-linked TPM acellular tracheal matrix.Conclusions:Genipin can improve the ultrastructure of decellularized tracheal matrix without causing inflammatory. The genipin cross-linked decellularized tracheas treated by DEM has better biocompatibility and lower immunogenicity, which make it suitable for the replacement of tissue engineering trachea.