Evaluation of kidney repair capacity using Tc-DMSA in ischemia/reperfusion injury models

Quantitative ^99mTc-DMSA renal uptake was studied in different renal ischemia/reperfusion (I/R) mice models for the assessment of renal repair capacity. Mice models of nephrectomy, uni- and bi-lateral I/R together with sham-operated mice were established. At 1 h, 1 d, 4 d, 1, 2 and 3 wk after I/R, ^99mTc-DMSA (27.7 ± 1.3 MBq) was injected via tail vein and after 3 h post-injection, the mice were scanned for 30 min with pinhole equipped gamma camera. Higher uptake of ^99mTc-DMSA was measured in normal kidneys of uni-lateral I/R model and nephrectomized kidney I/R model at 3 wk post-surgery. Comparing the restoration capacities of the affected kidneys of nephrectomy, uni- and bi-lateral I/R models, higher repair capacity was observed in the nephrectomized model followed by bi-lateral then uni-lateral models. The normal kidney may retard the restoration of damaged kidney in uni-lateral I/R model. Moreover, 3 wk after Uni-I/R, the size of injured kidney was significantly smaller than non-ischemic contralateral and sham operated kidneys, while nephrectomy I/R kidneys were significantly enlarged compared to all others at 3 wk post-surgery. Very strong correlation between ^99mTc-DMSA uptake and weight of dissected kidneys in I/R models was observed. Consistent with ^99mTc-DMSA uptake results, all histological results indicate that kidney recovery after injury is correlated with the amount of intact tubules and kidney sizes. In summary, our study showed good potentials of ^99mTc-DMSA scan as a promising non-invasive method for evaluation of kidney restoration after I/R injuries. Interestingly, mice with Bi-I/R injury showed faster repair capacity than those with uni-I/R.