Background
From a biological and clinical perspective, it is imperative to establish primate spermatogonial cultures. Due to limited availability of human testicular tissues, the macaque (
Macaca fascicularis
) was employed as non-human primate model. The aim of this study was to characterize the expression of somatic as well as germ cell markers in testicular tissues and to establish macaque testicular primary cell cultures.
Materials and methods
Characterization of macaque testicular cell population was performed by immunohistochemical analyses for somatic cell markers (SOX9, VIM, SMA) as well as for germ cell markers (UTF1, MAGEA4, VASA). Testicular cells from adult macaque testes (n = 4) were isolated and cultured for 21 days using three stem cell culture media (SSC, PS and SM). An extended marker gene panel (
SOX9
,
VIM
,
ACTA2; UTF1
,
FGFR3
,
MAGEA4
,
BOLL
,
DDX4
) was then employed to assess the changes in gene expression levels and throughout the
in vitro
culture period. Dynamics of the spermatogonial population was further investigated by quantitative analysis of immunofluorescence-labeled MAGEA4-positive cells (n = 3).
Results
RNA expression analyses of cell cultures revealed that parallel to decreasing
SOX9
-expressing Sertoli cells, maintenance of
VIM
and
ACTA2-
expressing somatic cells was observed. Expression levels of germ cell marker genes
UTF1
,
FGFR3
and
MAGEA4
were maintained until day 14 in SSC and SM media. Findings from MAGEA4 immunofluorescence staining corroborate mRNA expression profiling and substantiate the overall maintenance of MAGEA4-positive pre- and early meiotic germ cells until day 14.
Conclusions
Our findings demonstrate maintenance of macaque germ cell subpopulations
in vitro
. This study provides novel perspective and proof that macaques could be used as a research model for establishing
in vitro
germ cell-somatic cell cultures, to identify ideal culture conditions for long-term maintenance of primate germ cell subpopulation
in vitro
.