Abstract

Myostatin (MSTN) is a key negative regulator of skeletal muscle development and has emerged as an attractive target for improving chicken growth performance and meat production. The integration of CRISPR/Cas9 genome editing with PGC-based technology provides a promising platform for generating heritable MSTN modifications while reducing mosaicism through ex vivo editing, molecular validation, and germline transmission. This review critically evaluates the current evidence on CRISPR/Cas9-mediated MSTN editing in chicken PGCs, focusing on the biological role of MSTN in muscle development, recent advances in genome-editing technologies, the advantages of PGC-mediated germline engineering, and their potential applications for enhancing poultry productivity. Available chicken-specific studies indicate that MSTN disruption promotes skeletal muscle growth, improves breast muscle yield, and alters muscle fiber characteristics. However, evidence supporting improvements in feed efficiency, growth rate, reproductive performance, long-term physiological health, and animal welfare remains limited and should be interpreted with caution. The review also discusses major technical challenges, including variable editing efficiency, unintended off- and on-target genomic alterations, PGC germline competency maintenance during in vitro culture, and inconsistent germline transmission. Furthermore, ethical considerations, biosafety issues, regulatory uncertainty, and consumer acceptance are highlighted as critical factors influencing the future implementation of gene-edited poultry. Overall, CRISPR/Cas9-mediated MSTN editing in chicken PGCs represents a promising strategy for precision poultry breeding, offering opportunities to enhance growth and productivity while enabling stable inheritance of desirable traits. Nevertheless, a broader application will require stronger chicken-specific evidence, comprehensive long-term phenotypic and welfare evaluations, PGC-based editing protocol optimization, and harmonized regulatory frameworks to ensure safe, sustainable, and socially acceptable implementation.

Key words: CRISPR/Cas9; MSTN; Muscle growth; Primordial germ cells; Productivity.