Kidney Tubular Cell Proliferation in Burned Mice

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Abstract
Kidney tubular cell proliferation after a 17%, sublethal, third-degree burn injury in mice was studied in vivo using tritiated thymidine. Changes in cell morphology were also followed. Total incorporation of 3H-TdR in renal cells was measured and autoradiographic analyses of the tubular cells in the renal cortex and in the stratum subcorticale were made 2 hours to 30 days after the injury. After the second day postburn there was a 3.5-fold stimulation in the total incorporation of 3H-TdR in DNA, and an 18-fold increase in the labelling index of tubular cells. The majority of the labelled cells were proximal tubular cells. After the third day postburn a moderate increase in the labelling index (7.5-fold) was observed; 40% of the labelled cells were distal tubular cells. No morphological signs of frank necrosis of the tubular cells could be observed in the burned mice within 3 days postburn, which indicates that the stimulated proliferation of the kidney tubular cells was induced by minor reversible tubular cell damage during the first few hours postburn. It is suggested that the tubular cells loose their normal growth-inhibiting factors through an altered cell wall which results in an abnormal stimulation of cell growth 2 days later. These findings support the idea that there are abnormalities in the regulation of cell growth in several organs after burn injury; in some tissues—as in the kidney—this results in a temporary insufficiency of organ function.