Regulation of Stem Spermatogonia in the Mature Testis

Status Completed

Clinical Trial Summary

Investigative trial to evaluate the role of a glial cell lined derived neurotrophic factor (GDNF) in regulation of spermatogonial renewal and testicular function. Goal of the trial is to provide greater information on the mechanisms that effect stem spermatogonial maintenance renewal and proliferation in its relation to male infertility.

Clinical Trial Description

An essential requirement for sustaining male fertility is maintaining an adequate number of stem spermatogonia, the foundation of spermatogenesis. To achieve this, when the stem cells divide, some progeny must remain stem spermatogonia while other progeny differentiate. It is obvious that the correct balance between self-renewing replication and differentiation of stem spermatogonia is crucial to male fertility, and there is a indirect evidence that GDNF plays an important role in maintaining this balance in the normal mature testis. However, almost nothing is known about the in vivo regulation of this balance in the mature organ, of the specific function of GDNF in the adult testis, or if physiological changes in GDNF expression significantly affect the replication or differentiation of the stem cells. To address these critical issues, a unique mouse model that allows GDNF signaling to the stem spermatogonia to be specifically and reversibly inhibited in vivo by an ATP antagonist. With this model, the first direct evidence that GDNF is required for maintaining the stem spermatogonial pool in a normal mature testis. Additionally, the investigators have shown that when inhibition of GDNF signaling is reversed, the stem cells begin to rebuild the stem cell pool. Importantly, our data demonstrate that some stem spermatogonia are lost when GDNF signaling is inhibited for as little as 2 days, while other stem cells survive for up to 11 days. This suggests that factors intrinsic or extrinsic to the stem cells modulate the response to GDNF. Using this new mouse model the mechanisms responsible for the loss of stem spermatogonia proliferation and regeneration will be investigated along with GDNF signaling and inhibition. At the end of all of this these studies will be done on waste tissue obtained from normal men and men with infertility who otherwise have testicular surgery for therapeutic purposes. ;

Study Design

Related Conditions & MeSH terms

Clinical Trial Details

NCT number	NCT02756923
Study type	Observational
Source	Weill Medical College of Cornell University
Contact
Status	Completed
Phase
Start date	April 2012
Completion date	December 5, 2019

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Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.

Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.