Generation of functional posterior spinal motor neurons from hPSCs-derived human spinal cord neural progenitor cells.

Spinal motor neurons deficiency results in a series of devastating disorders such as amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA) and spinal cord injury (SCI). These disorders are currently incurable, while human pluripotent stem cells (hPSCs)-derived spinal motor neurons are promising but suffered from inappropriate regional identity and functional immaturity for the study and treatment of posterior spinal cord related injuries. In this study, we have established human spinal cord neural progenitor cells (hSCNPCs) via hPSCs differentiated neuromesodermal progenitors (NMPs) and demonstrated the hSCNPCs can be continuously expanded up to 40 passages. hSCNPCs can be rapidly differentiated into posterior spinal motor neurons with high efficiency. The functional maturity has been examined in detail. Moreover, a co-culture scheme which is compatible for both neural and muscular differentiation is developed to mimic the neuromuscular junction (NMJ) formation in vitro. Together, these studies highlight the potential avenues for generating clinically relevant spinal motor neurons and modeling neuromuscular diseases through our defined hSCNPCs.

Three-dimensional molecular architecture of mouse organogenesis.

Mammalian embryos exhibit sophisticated cellular patterning that is intricately orchestrated at both molecular and cellular level. It has recently become apparent that cells within the animal body display significant heterogeneity, both in terms of their cellular properties and spatial distributions. However, current spatial transcriptomic profiling either lacks three-dimensional representation or is limited in its ability to capture the complexity of embryonic tissues and organs. Here, we present a spatial transcriptomic atlas of all major organs at embryonic day 13.5 in the mouse embryo, and provide a three-dimensional rendering of molecular regulation for embryonic patterning with stacked sections. By integrating the spatial atlas with corresponding single-cell transcriptomic data, we offer a detailed molecular annotation of the dynamic nature of organ development, spatial cellular interactions, embryonic axes, and divergence of cell fates that underlie mammalian development, which would pave the way for precise organ engineering and stem cell-based regenerative medicine.

High-throughput single nucleus total RNA sequencing of formalin-fixed paraffin-embedded tissues by snRandom-seq.

Formalin-fixed paraffin-embedded (FFPE) tissues constitute a vast and valuable patient material bank for clinical history and follow-up data. It is still challenging to achieve single cell/nucleus RNA (sc/snRNA) profile in FFPE tissues. Here, we develop a droplet-based snRNA sequencing technology (snRandom-seq) for FFPE tissues by capturing full-length total RNAs with random primers. snRandom-seq shows a minor doublet rate (0.3%), a much higher RNA coverage, and detects more non-coding RNAs and nascent RNAs, compared with state-of-art high-throughput scRNA-seq technologies. snRandom-seq detects a median of >3000 genes per nucleus and identifies 25 typical cell types. Moreover, we apply snRandom-seq on a clinical FFPE human liver cancer specimen and reveal an interesting subpopulation of nuclei with high proliferative activity. Our method provides a powerful snRNA-seq platform for clinical FFPE specimens and promises enormous applications in biomedical research.

OrthReg: a tool to predict cis-regulatory elements based on cross-species orthologous sequence conservation.

Cis-regulatory elements play an important role in the development of traits and disease in organisms (Ma et al., 2020; Woolfe et al., 2005) and their annotation could facilitate genetic studies. The Encyclopedia of DNA Elements (ENCODE) (Davis et al., 2018) and Functional Annotation of Animal Genomes (FAANG) (FAANG Consortium et al., 2015) offer pioneering data on regulatory elements in several species. Currently, however, regulatory element annotation data remain limited for most organisms. In this study, we developed a tool (OrthReg) for annotating conserved orthologous cis-regulatory elements in targeted genomes using an annotated reference genome. Cross-species validation of this annotation tool using human and mouse ENCODE data confirmed the robustness of this strategy. To explore the efficiency of the tool, we annotated the pig genome and identified more than 28 million regulatory annotation records using the reference human ENCODE data. With this regulatory annotation, some putative regulatory non-coding variants were identified within domestication sweeps in European and East Asian pigs. Thus, this tool can utilize data produced by ENCODE, FAANG, and similar projects, and can be easily extended to customized experimental data. The extensive application of this tool will help to identify informative single nucleotide polymorphisms (SNPs) in post-genome-wide association studies and resequencing analysis of organisms with limited regulatory annotation data.