Platelet-derived growth factor receptor alpha-positive cells: A new cell type in the human ureteropelvic junction

Abstract

Background:Ureteropelvic junction (UPJ) obstruction is the most common cause of congenital hydronephrosis. Normal ureteral motility requires coordinated interaction between neurons, smooth muscle cells (SMCs), and interstitial Cajal-like cells (IC-LCs). Recently, a new type of interstitial cell, platelet-derived growth factor receptor α-positive (PDGFRα +) cells, was discovered in the gastrointestinal tract and bladder.MethodsWe used immunohistochemistry to study PDGFRα protein distribution in normal human UPJ and congenital UPJ obstruction. Western blot and real-time PCR (RT-PCR) were used to study PDGFRα protein and gene expression levels. In addition, closely associated cells and small conductance Ca 2+ -activated K + (SK) channels were investigated.ResultsPDGFRα + cells were distinct from IC-LCs and SMCs and were in close proximity to nerve fibers. PDGFRα + cells expressed SK3 channels, which are thought to mediate purinergic inhibitory neurotransmission in SMCs. The distribution of PDGFRα + cells was similar in UPJ obstruction vs. Controls. However, the expression of SK3 channels in PDGFRα + cells was decreased in UPJ obstruction vs. Controls.ConclusionThis study shows, for the first time, the PDGFRα + cell expression in the human UPJ. Altered SK3 channel expression observed in PDGFRα + cells in UPJ obstruction suggests that the impairment of SK3 activity across the UPJ may perturb upper urinary tract peristalsis in this urological condition.