Novel cellular mechanism that mediates the collecting duct formation during postnatal renal development

Abstract

We have previously demonstrated that kidney embryonic structures are present in rats, and are still developing until postnatal Day 20. Consequently, at postnatal Day 10, the rat renal papilla contains newly formed collecting duct (CD) cells and others in a more mature stage. Performing primary cultures, combined with immunocytochemical and time‐lapse analysis, we investigate the cellular mechanisms that mediate the postnatal CD formation. CD cells acquired a greater degree of differentiation, as we observed that they gradually lose the ability to bind BSL‐I lectin, and acquire the capacity to bind Dolichos biflorus. Because CD cells retain the same behavior in culture than in vivo, and by using DBA and BSL‐I as markers of cellular lineage besides specific markers of epithelial/mesenchymal phenotype, the experimental results strongly suggest the existence of mesenchymal cell insertion into the epithelial CD sheet. We propose such a mechanism as an alternative strategy for CD growing and development.

Influence of sphingomyelin metabolism during epithelial–mesenchymal transition associated with aging in the renal papilla

“…In a recent study performed with time‐lapse microscopy, we demonstrated that a very active MET occurs in the postnatal development of renal CD, where mesenchymal cells migrate and insert into the tubules being formed and after insertion, the cells undergo effective MET (Guaytima et al,2019). Thereafter, we also reported that in the mature kidney, there is a balance between the CD cells that carry out EMT and those that carry out MET, thus maintaining tissue homeostasis.…”

“…In a previous study, we showed that cultured renal papillary CD cells from young rats expressed the epithelial cell marker cytokeratin 7, whereas only some cells expressed VIM, and few CD cells lightly expressed α ‐SMA, resembling the epithelial phenotype of CD cells (Brandán et al,2018). On the other hand, overlapping cells with high expression of α ‐SMA and with mesenchymal phenotype, first insert into the colony, adhere to other cells, and then they progressively lose the mesenchymal markers and acquire the epithelial ones (Guaytima et al,2019). In the present study, we found that during renal aging, CD cells undergo several steps of EMT.…”

“…One colony organized population of CD cells bound to each other, with epithelial phenotype; and another population of cells, isolated and with a mesenchymal phenotype. In a previous study, we characterized and described the behavior of these isolated cells (Guaytima et al, 2019), and throughout the current study, we will refer to them as overlapping cells. Few of the organized CD cell population from 70 days old rats expressed VIM with a reticular pattern of immunostaining distribution (Figure 2a,b, arrows, magnification 2a' and quantitative analysis 2g).…”