Recent Nature This study uses a combination of single-cell ribonucleic acid (scRNA) sequencing and high-resolution multiplexed error-robust fluorescence. on site Hybridization to better understand the types of cardiac cells that form the human heart (MERFISH).

study: Spatially organized cell communities form the developing human heart. Image credit: liseykina / Shutterstock.com

background

The heart is the first organ to develop and its function depends on its morphological features. These changes in heart structure can lead to congenital heart disease, one of the most common birth defects. In addition to children, adults with abnormal heart morphology are also at increased risk of developing valvular heart disease and hypertrophic cardiomyopathy.

Therefore, it is essential to understand the diverse, spatially coordinated cell types that form the complex cardiac structure and are critical to its function. To date, the interactions of cardiac cell types and how they are organized to form a fully functional heart are not fully understood.

About research

This study identifies cooperative cellular interactions directly related to cardiac morphogenesis. In this context, comprehensive scRNA sequencing was performed along with her MERFISH of the developing human heart. Here, we exploited the potential of single-cell transcriptomics and spatial biology to analyze RNA transcripts from large numbers of genes within individual cells.

research result

First, the specific cell lineages that make up the developing heart were studied using scRNA-seq. This technique has enabled replication of the human heart between 9 and 16 weeks postconception (pcw).

The developing heart, which is significantly smaller than a fully formed adult heart, was dissected to form an intact heart chamber. This strategy enabled investigation of the interventricular septum (IVS) and improved the ability to identify more cell types, especially from underrepresented regions.

A total of 142,946 single cells were collected from heart samples and analyzed using scRNA-seq. Within these cells, endothelial, cardiomyocyte, blood mesenchymal, and neuronal compartments were separated.

Genetic marker analysis and graph-based clustering identified 12 cell classes within each cell compartment, and cell clustering analysis further identified 39 populations. Remarkably, the newly identified cell lineages exhibited heterogeneity that could be attributed to their anatomical location and developmental state, thus highlighting the complexity of human heart development.

MERFISH imaging elucidated the spatial organization of cardiovascular cells identified by scRNA-seq. Applying the NS-Forest2 classifier to scRNA-seq clustering analysis enabled the identification of genes specific to 238 cell subpopulations targeted by probes encoding MERFISH.

Through cell segmentation and adaptive filtering, a total of 108.2 million transcripts were generated from 258,237 cells. RNA transcripts identified in MERFISH experiments showed significant correlation with experimental replicates and scRNA-seq datasets.

Cardiac genetic marker analysis identified 27 distinct MERFISH cell populations potentially related to the developmental classes discovered by scRNA-seq.

Taken together, the multimodal analysis led to the discovery of diverse cardiovascular lineages involved in human heart development and morphogenesis. Correlation of MERFISH imaging analysis and scRNA-seq data provided new insights into the spatially resolved transcriptional profiles of individual cells and the function of specific genes.

The role of specific genes influencing cell-cell interaction (CCI) algorithms may also include identifying different cell signaling ligand-receptor pairs expressed between spatially adjacent cell populations to facilitate interactions. investigated by. To this end, a unique plexin-semaphorin (PLXN-SEMA) signaling pathway was observed between different combinations of interacting cell populations within specific layers of the ventricular wall.

Aberrant multicellular interactions between PLXNA2+ PLXNA4+ ventricular cardiomyocytes, SEMA6A+ SEMA6B+ endothelial cells, and SEMA3C+ SEMA3D+ fibroblasts were identified. These interactions may regulate cardiomyocyte positioning during ventricular wall compaction morphogenesis.

conclusion

By combining scRNA-seq and MERFISH approaches, researchers were able to construct a comprehensive cardiac cell atlas of human heart development with spatial and molecular single-cell resolution.

Here, new cardiac cell populations from underappreciated regions of the heart, such as the conduction system and heart valves, have been identified, thereby enhancing current knowledge about the cell types that make up the human heart.

A MERFISH-based high-resolution spatial cardiac cell atlas provided new insights into how identified cell types interact and influence the formation of different cardiac structures. Overall, the results of this study may support future studies aimed at better understanding the pathological mechanisms determining congenital and adult structural heart disease.