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

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 Ca2+-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.