Spermatogonial stem cell (SSCs) system

Abstract

One of the most important stem cell systems in the body is the spermatogonial stem cell (SSC) system. Although its importance in transmitting genetic information from generation to generation through specialized sperm cells may be obvious, various studies have recently uncovered an ostensible function involving the remarkable plasticity of SSCs. Recent investigations have shown that putative mouse SSCs and human SSCs from the testis of deceased organ donors could be reprogrammed to pluripotency, without the addition of genes. This has prompted the idea that human SSCs may have great potential for cell-based, autologous stem cell therapy(s). The present understanding of SSCs is mostly based on information obtained from rodents and nonhuman primates. The bulk of the human SSC knowledge has derived from Clermont and colleagues who, during the 1960s, showed that two different populations of stem cells existed: the reserve and renewing populations. In light of recent studies using SSCs, characterization of the human spermatogonial population – either by using a panel of antibodies to known stem cell markers (surface, cytoplasmic, and nuclear) or more precisely by utilizing various molecular biology techniques (e.g., gene expression, methylation patterns, miRNA identification) – has become paramount. Investigations focusing on human SSCs will provide essential information that will be crucial for future studies on their biology and plasticity. Keywords: Spermatogonia (Spga); Spermatogonial stem cell (SSC); Germline pluripotent stem cells (gPSCs); Glial cell line-derived neurotrophic factor (GDNF); GDNF family receptor alpha-1 (GFRA1); cKIT- Mast/stem cell growth factor receptor (SCFR); Promyelocytic leukemia zinc finger (PLZF); G-protein-coupled receptor 125 (GPR125); Melanoma antigen family A (MAGE-A4); Bone morphogenetic protein (BMP); Ak mouse strain, t-thymoma (Akt); Stem Cell factor (SCF); Creb binding protein (CBP); Sedimentation at unit gravity (STAPUT)