A human embryonic limb cell atlas resolved in space and time

Area of Science:

• Developmental Biology
• Genomics
• Human Embryology

Background:

• Human limb development is a complex process orchestrated by gene expression programs.
• Previous research relied heavily on model organisms, leaving human limb development poorly characterized.
• Congenital limb alterations highlight the intricate nature of this developmental process.

Purpose of the Study:

• To provide an in-depth characterization of human embryonic limb development across space and time.
• To identify novel cell populations and gene expression patterns during human limb formation.
• To compare human limb development with that of model organisms.

Main Methods:

• Single-cell and spatial transcriptomics were employed to analyze human embryonic limb development.
• VisiumStitcher was used to assemble anatomically continuous spatial transcriptomic samples.
• Single-cell RNA sequencing was performed on mouse embryonic limbs for cross-species comparison.

Main Results:

• Demonstrated extensive cell diversification from multipotent progenitors to differentiated cell states, including novel populations.
• Uncovered two distinct waves of human muscle development regulated by separate gene expression programs.
• Identified musculin (MSC) as a key regulator of muscle stem cell identity and mapped gene segregation related to limb malformations.

Conclusions:

• This study provides a comprehensive spatiotemporal map of human embryonic limb development.
• Novel insights into muscle development, stem cell regulation, and genetic underpinnings of limb malformations were revealed.
• Significant homology was found between human and mouse embryonic limb development, facilitating cross-species comparisons.