Search For A Kidney Stem Cell

With the population aging and rates of hypertension and diabetes higher than ever, there is a growing importance to understand how the kidney works to repair itself in order to guide the development of much needed future therapies. Researchers at Brigham and Women's Hospital (BWH) examined cells in the kidney to determine which cells are responsible for generating repair. Their results are published in the March issue of Cell Stem Cell.

"There has not been a new therapy developed to treat kidney failure since dialysis was introduced in the 1950's," said Benjamin Humphreys, MD, PhD, in the Renal Division at BWH and lead author of the study. "We have known for some time that the kidney can often repair itself after acute injury, and our goal is to understand this kidney repair process in hopes that it will lead us to pathways that can be used to guide the development of much needed clinical therapies."

In recent years there have been reports that an adult kidney stem cell may exist in the kidney and be responsible for repair. If an adult stem cell does exist though, researchers have yet to define its location. Humphreys and colleagues genetically marked tubular epithelial cells in adult mice kidneys, but not other cells present between the tubules, where studies have suggested the kidney stem cell might reside. Researchers then caused injury to the kidney, allowed the kidney to repair and tested whether the repaired epithelial cells still carried the genetic marker, or if they had been replaced by the non-marked cells adjacent to the tubules. They found that repaired tubules retained the genetic marker, indicating that epithelial cells have the full capacity to repair themselves without any contribution from other adult kidney cell types.

Researchers conclude that if an adult stem cell does exist in the kidney, it is located within the tubular epithelial population, not outside of them, and emphasize that further research is needed to determine whether all tubular cells have the same ability to generate growth, or if an adult stem cell with the capacity to repair is responsible for generating the growth.

"Defining the specific cell type responsible for repair after kidney injury is the first step toward designing regenerative therapies that ultimately will accelerate repair or slow chronic damage to the kidney," said Humphreys.