Photoacoustic imaging for assessing ischemic kidney damage in vivo

Ischemic reperfusion injuries (IRIs) occur after blood returns to a tissue or organ after a period without oxygen or nutrients, which causes an inflammatory response leading to heterogeneous scarring of the nearby tissue and vasculature. This is associated with long-term decreases blood flow, and necrosis. Although most commonly associated with heart attacks and strokes, IRIs are also a side effect of organ transplants, when the organ is reperfused in the recipient’s body after being transported from the donor to the transplant hospital. Currently, the optimal method of monitoring for IRI is limited to biopsies, which are invasive and poorly monitor the spatial heterogeneity of the damage. To non-invasively identify changes in kidneys, the left renal artery in mice (n=3) was clamped for 45 minutes to create an IRI event. Both kidneys of each animal were monitored using photoacoustics (PA) with the VevoLAZR system (Fujifilm-VisualSonics, Toronto) three, four and eight weeks after surgery. IRI-treated kidneys show increased picosirius red staining, indicative of collagen (0.601 vs 0.042, p 2 vs 35.9 mm 2 , p -3 vs 3.0 * 10 -3 , p = 0.013) are both able to differentiate between IRI-treated and healthy kidneys. These data suggest that photoacoustics can be used as a non-invasive method to observe in vivo changes in the kidney due to IRI.