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 Ca-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.