Spatial and temporal immunoreaction of nestin, CD44, collagen IX and GFAP in human retinal Muller cells in the developing fetal eye

The purpose of this study was to investigate Muller cells during the fetal development of the human eye. Willer cells in eyes of 39 human fetuses (11-38 weeks of gestation, WOG) and 6 infants (5 died of abusive head trauma, AHT, aged 1-9 months) were immunohistochemically stained and investigated for spatial and temporal immunoreaction of nestin, CD44, collagen IX and GFAP, which are stem cell markers or markers of intermediate filaments, respectively, in one of the hitherto largest cohorts of fetal eyes. Willer cells could be detected immunohistochemically as early as 12 WOG by immunohistochemical staining with nestin. Nestin was more strongly expressed in Willer cells of the peripheral retina and a centroperipheral gradient of immunoreaction over time was observed. CD44 was predominantly expressed in fetal eyes of the late second and early third trimester between (23 and 27 WOG) and significantly stronger in the infant eyes. Collagen IX labeling in the central retina was significantly stronger than in more peripheral sectors and increased with fetal age. GFAP staining in Muller cells was seen in the eye of a fetus of 38 WOG who died postnatally and in the infant eyes with and without history of AHT. Additionally, GFAP staining was present in the astmcytes of fetal and infant eyes. All examined markers were expressed by Willer cells at different developmental stages highlighting the plasticity of Willer cells during the development of the human eye. GFAP should be cautiously used as a marker for AHT as it was also expressed in fetal astmcytes and Willer cells in eyes without history of AHT.