Mapping the Development of Human Spermatogenesis Using Transcriptomics-Based Data: A Scoping Review.

Area of Science:

• Reproductive Biology
• Developmental Biology
• Genomics

Background:

• In vitro maturation (IVM) offers fertility restoration for nonobstructive azoospermia and prepubertal boys.
• Human in vitro spermatogenesis remains challenging, necessitating a deeper understanding of testicular development.
• Transcriptional profiling across human testicular development is crucial for optimizing IVM.

Purpose of the Study:

• To describe human testis development and maturation from fetal to adult stages.
• To identify factors influencing testicular maturation for optimizing IVM protocols.
• To review existing literature on native and in vitro cultured human testicular cells using scRNA-seq.

Main Methods:

• Scoping review of research papers on human testicular cells (native and in vitro).
• Analysis of single-cell RNA-sequencing (scRNA-seq) data.
• Focus on gene ontology terms to interpret gene functions.

Main Results:

• Human testicular maturation involves significant transcriptional changes around age 11.
• scRNA-seq data suggest a re-evaluation of spermatogonial stem cell (SSC) states (A dark/pale).
• Somatic cell data, particularly for Sertoli cells, are limited.
• In vitro culture favors undifferentiated SSCs with AKT-signaling pathway inhibitors.
• Oxidative phosphorylation pathway involvement is maturational state-dependent.

Conclusions:

• Understanding testicular development and maturation provides insights for improving IVM.
• Key cell signaling pathways identified during development may be crucial for IVM success.
• Further research on somatic cells and refined SSC classification is needed for IVM advancement.