How sperm stem cells maintain their number

The steady production of sperm relies on the number of sperm stem cells in the testis remaining constant. Researchers including Asst. Prof. Yu Kitadate and Prof. Shosei Yoshida (developmental biologists at the National Institute for Basic Biology within the National Institutes of Natural Sciences in Japan) and Prof. Benjamin Simons (a theoretical physicist at the University of Cambridge in the UK) have revealed a novel mechanism for stem cell number control. Their results show that constant sperm stem cell numbers are achieved, in mouse testes, through a self-organized process in which they actively migrate and compete for a limited supply of self-renewal-promoting fibroblast growth factors (FGFs). This study was published on line in Cell Stem Cell on Nov. 20th, 2018.

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With Immense pleasure, Wound Care 2019 along with the Organizing Committee Members invites all the participants from all across the globe to attend 2nd International Conference on Wound Care, Tissue Repair and Regenerative Medicine which is slated on October 16-17, 2019 at London, UK with the theme Navigating the Future of Wound Healing, Tissue Regeneration and Regenerative Medicine.

To ensure a balance between the loss of differentiated cells and their replacement in long-lived multicellular organisms, it is critically important to keep the number of tissue stem cells constant. Failure to maintain stem cell number is thought to underlay the progression of ageing and disease. In tissues like the testis and ovary of the fruitfly Drosophila and intestine of mammalians, stem cells are clustered in their specialized home where self-renewal-promoting factors are abundant: the stem cell niche. In these tissues, stem cell numbers are controlled simply by the capacity of the niche. However, sperm stem cells are not clustered in mouse testis, but are highly motile and widely dispersed across the basement membrane. Yet, their density remains surprisingly uniform thus raising the question of how their numbers are regulated.

In this study, the researchers found that a subset of lymphatic endothelial (LE) cells produce FGFs (Fgf5, 8 and 4 in particular), which promote stem cell self-renewal.

Asst. Prof. Kitadate said, “The lymphatic endothelial cells in the testis were described via the use of electron microscopy in the 1970s, but had scant attention paid to them for a long time. By a stroke of good luck, our screening met these cells again and threw light on their hidden roles!”

 

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