Identification, Proliferation, and Differentiation of Adult Leydig Stem Cells

Abstract

Leydig cells, the testosterone-producing cells of the adult testis, rarely turn over. However, their elimination with ethane dimethanesulfonate (EDS) is followed by the appearance of new, fully functional adult Leydig cells. The cells that give rise to the new Leydig cells have not been well characterized, and little is known about the mechanism by which they are regulated. We isolated cells expressing platelet-derived growth factor receptor-α, but not 3β-hydroxysteroid dehydrogenase (3β-HSD(neg)) from the testes of EDS-treated adult rats. Depending on conditions, these cells proliferated indefinitely or differentiated and produced testosterone. To localize these cells and to determine the effect of the testicular environment on their function, the seminiferous tubules and testicular interstitium were physically separated and cultured. During the first 72 h in culture, 3β-HSD(neg) cells on the tubule surfaces underwent divisions. Some of these cells later expressed 3β-HSD and produced testosterone. Removal of the newly formed 3β-HSD(pos) cells from the tubule surfaces with EDS, followed by further culture of the stripped tubules, resulted in the reappearance of testosterone-producing cells. These results, taken together, suggest that the precursors for newly formed Leydig cells are stem cells, with many if not all situated on the surfaces of the seminiferous tubules. Although normally quiescent, the stem cells are capable of self-renewal and differentiation. The development of the tubule culture system should provide a valuable in vitro approach to assess the role(s) of niche components on the function of adult Leydig stem cells despite their residing in a complex mammalian tissue.

Fetal programming of adult Leydig cell function by androgenic effects on stem/progenitor cells

“…This conclusion is supported by our lineage tracing experiment. In keeping with earlier studies (27,29,57), we noted that adult Leydig cells commonly derive from (COUP-TFII + ) cells that border the seminiferous tubules, although in contrast to other studies (29), we did not find any cells coexpressing the peritubular myoid (PTM) cell marker SMA, COUP-TFII, and early Leydig cell markers. However, our findings do not exclude the possibility that, after EDS treatment, regenerating adult Leydig cells could also derive from interstitial cells that have dedifferentiated (e.g., pericytes that have switched off CD146 or PTM cells that have switched off SMA) and then either switched on COUP-TFII (pericytes) or maintained their COUP-TFII expression (PTM cells).…”

Regulation of seminiferous tubule-associated stem Leydig cells in adult rat testes

“…Cells on the tubule surfaces first underwent division, and then differentiated and produced T (17). These results suggested that in addition to reported perivascular locations in the interstitial compartment (18), stem cells also were located on the surfaces of the seminiferous tubules (16,19,20).…”

“…We showed previously that functional Leydig cells can be generated by culturing Leydig cell-free seminiferous tubules with LH (16,17). With the intent to identify the tubule-associated cells that give rise to T-producing Leydig cells, seminiferous tubule fragments of comparable lengths were cultured in medium containing LH for up to 4 wk.…”

“…However, when these cells are eliminated from adult testes by treating the rats with ethane dimethanesolfonate (EDS), new, fully functional adult Leydig cells reappear (14,15). In initial efforts to localize the precursor cells, seminiferous tubules were isolated from EDS-treated testes and cultured with luteinizing hormone (LH) (16). Cells on the tubule surfaces first underwent division, and then differentiated and produced T (17).…”

Cell‐specific ablation in the testis: what have we learned?

“…The identity of the adult Leydig cell precursor population has been contentious for a number of years with pericytes, peritubular cells, fibroblasts, and endothelial cells all suggested (Jackson et al ., 1986; Kerr et al ., 1987; Teerds et al ., 1990; Davidoff et al ., 2004; O'Shaughnessy et al ., 2008b; Stanley et al ., 2012). Recent data indicates, however, that the major source of adult Leydig cells after EDS treatment are peritubular cells (O'Shaughnessy et al ., 2008b; Stanley et al ., 2012) although a contribution from other sources cannot be ruled out. The role of gonadotrophins in Leydig cell regeneration was established in early EDS studies using hypophysectomised rats or testosterone implants.…”