Affiliation between vascular pericytes and renin producing cells in the human foetal kidney
Stefanska, Anna Maria
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Pericytes, progenitor cells embedded in the microvascular wall, are crucial for vascular homeostasis. Renin is the rate-limiting enzyme that regulates blood pressure and fluid/electrolyte balance. Previous work suggested the relationship between renin-expressing/ producing cells and pericytes, however human kidney pericytes have not been characterized in depth and the molecular switch controlling renin cell plasticity is not understood. Here, I describe a method of isolation of CD146+CD34-CD45-CD56- pericytes, putative progenitors for renin-producing cells, from the human foetal kidney and demonstrate their potential in vitro to express and produce renin. Co-staining of pericyte markers (CD146 and NG2) and renin showed coincidence in the juxtaglomerular region and along renal arterioles in the human foetal kidney. I have obtained primary cultures of renal pericytes from the developing human kidney that were purified via fluorescence-activated cell sorting. Primary cultures of renal pericytes exhibited tri-lineage mesodermal differentiation potential. Renin expression was triggered by cAMP induction (10μM forskolin and 100μM 3-isobutyl-1- methylxanthine [IBMX] and resulted in 64.3 fold increase of renin mRNA (p <0.01) and 41.5 fold increase in enzymatic activity of renin (p <0.05) over controls. Pericytes derived from non-renal tissues (placenta and foetal adrenal glands) also expressed renin in an inducible fashion. Renin positive cells following induction were confirmed to be CD146+/NG2+. Interestingly, alpha-smooth muscle actin expression was not always correlated with renin immunostaining. Wnt/β-catenin signalling plays a crucial role during kidney development and in disease, specifically; in pericyte modulation of the Wnt pathway has been shown to regulate cell differentiation. CHIR 99021, a specific inhibitor of glycogen synthase kinase 3, mimicking Wnt signalling, and C59, a potent Porcupine acyltransferase inhibitor that is required for Wnt biological activity, were tested in renin induction experiments. Preliminary data showed that renin expression was blocked by Wnt activation, whereas Wnt suppression increased renin mRNA levels above the level of stimulation achieved with cAMP inducers. These findings provide evidence that renin expression is an intrinsic feature of pericytes and can be regulated through the Wnt pathway.