Valli, Hanna Preserving male fertility with spermatogonial stem cells. Doctoral Dissertation, University of Pittsburgh. Improved therapies for cancer and other conditions have resulted in a growing population of long-term survivors. Infertility is an unfortunate side effect of some cancer therapies that impacts the quality of life of survivors who are in their reproductive or pre-reproductive years.
Id4 Marks Spermatogonial Stem Cells in the Mouse Testis
Molecular function of the RNAbinding protein NANOS2 in mouse spermatogonial stem cells
The project included two main objectives; 1 Develop a means for isolating an SSC-enriched cell fraction from bull testes, and 2 Optimize media conditions and growth factor supplementation to support long-term self-renewing proliferation of bovine SSCs in vitro. For objective 1, we have found that undifferentiated spermatogonia including spermatogonial stem cells express the membrane localized protein THY1. Using an antibody that recognizes THY1 we developed a magnetic activated cell sorting technique to isolate the undifferentiated spermatogonial stem cell faction from bull testes. While this methodology was effective at isolating the stem cell component cell viability was compromised due to the long time period required to carry out the isolation procedure. Therefore, we developed a more efficient method for isolating undifferentiated spermatogonia. We found that multiparameter selection including fractionation through a continuous percoll gradient and subsequent differential plating also results in isolation of undifferentiated spermatogonia from bull testes.
Sertoli cells dictate spermatogonial stem cell niches in the mouse testis
A spermatogonial stem cell SSC , also known as a type A spermatogonium , is a spermatogonium that does not differentiate into a spermatocyte , a precursor of sperm cells. Instead, they continue dividing into other spermatogonia or remain dormant to maintain a reserve of spermatogonia. Type B spermatogonia, on the other hand, differentiate into spermatocytes, which in turn undergo meiosis to eventually form mature sperm cells. During foetal development, gonocytes develop from primordial germ cells and following this SSCs develop from gonocytes in the testis.
Sustained spermatogenesis in adult males relies on the activity of spermatogonial stem cells SSCs. In general, tissue-specific stem cell populations such as SSCs are influenced by contributions of support cells that form niche microenvironments. Previous studies have provided indirect evidence that several somatic cell populations and the interstitial vasculature influence SSC functions, but an individual orchestrator of niches has not been described. In this study, functional transplantation of SSCs, in combination with experimental alteration of Sertoli cell content by polythiouracil PTU -induced transient hypothyroidism, was used to explore the relationship of Sertoli cells with SSCs in testes of adult mice.