Skeletal muscle regeneration is a complex process where various cell types and cytokines are involved.  Single-cell RNA-sequencing (scRNA-seq) provides the opportunity to deconvolute heterogeneous tissue into individual cells based on their transcriptomic profiles.  Recent scRNA-seq studies on mouse muscle regeneration have provided insights to understand the transcriptional dynamics that underpin muscle regeneration.  However, a database to investigate gene expression profiling during skeletal muscle regeneration at the single-cell level is lacking.  Here, we collected over 105 000 cells at 7 key regenerative time-points and non-injured muscles and developed a database, the Single-cell Skeletal Muscle Regeneration Database (SCSMRD).  SCSMRD allows users to search the dynamic expression profiles of genes of interest across different cell types during the skeletal muscle regeneration process.  It also provides a network to show the activity of regulons in different cell types at different time points.  Pesudotime analysis showed the state changes trajectory of muscle stem cells (MuSCs) during skeletal muscle regeneration.  This database is freely available at https://scsmrd.fengs-lab.com.

Type A spermatogonial stem cells are the only immortal diploid cells in the postnatal animal that undergo self-renewal through the lifetime of an animal and transmit genes to subsequent generations. In this paper, the generation and characterization of double-transgenic mice co-expressing the Escherichia coli appA gene and human MxA gene generated via the in vivo transfection of type A spermatogonial cells were reported for the first time. The dicistronic expression vector pcDNA-appA-MxA(AMP) and ExGen500 transfection reagent were injected into the testicular tissue of 7-d-old male ICR mice. The mice that underwent testismediated gene transfer were mated with wild-type female mice, and the integration and expression of the foreign genes in the offspring were evaluated. Transgenic mice that co-expressed appA and MxA showed a gene integration rate of 8.89% (16/180). The transgenic mice were environmentally friendly, as the amount of phosphorous remaining in the manure was reduced by as much as 11.1% by the appA gene (P<0.05); these animals also exhibited a strong anti-viral phenotype.