A comprehensive atlas of testicular interstitium reveals Cd34+/Sox4+ mesenchymal cells as potential Leydig cell progenitors

The declining rates of male fertility pose a significant clinical challenge, primarily due to our limited understanding of the testicular interstitium, which is crucial for male reproductive health. Here, we conducted a comprehensive analysis of the single-cell transcriptomic landscape of the murine testicular interstitium across the postnatal lifespan. Our investigation unveiled a previously unrecognized population of Cd34⁺/Sox4⁺ mesenchymal cells nestled within the interstitium, hinting at their potential as Leydig cell progenitors. During the aging process of Cd34⁺/Sox4⁺ mesenchymal cells, we observed a decline in glutathione levels within the testicular interstitium. Remarkably, these Cd34⁺/Sox4⁺ mesenchymal cells exhibited clonogenic self-renewal capacity and an impressive propensity to differentiate into Leydig cells. Intriguingly, when transplanted into Leydig cell-disrupted or failure models, Cd34⁺/Sox4⁺ cells efficiently colonized the testicular interstitium, resulting in a notable increase in testosterone production. Exploring the epigenetic landscape, we identified critical transcription factors, most notably Sox4, governing the stem cell fate of Cd34⁺/Sox4⁺ mesenchymal cells. Overall, this comprehensive reference atlas of lifespan testicular Leydig cells presents significant findings that may guide the development of cell-based strategies for treating testicular hypogonadism in elderly individuals.