2.8 Histology

Histologic samples were embedded in paraffin, sectioned at 5 µm thickness, and were stained with hematoxylin and eosin (H&E) and Masson’s Trichrome staining procedures (Scientific Solutions, LLC). Imaging was performed using Zeiss Zen software and Axiocam 105 color brightfield microscope camera. For explanted patent kidney grafts, the pigs were euthanized with intravenous barbiturate and the graft was excised and flushed with 300 mL PBS followed by 300 mL 10% neutral buffered formalin (NBF, VWR). If the kidneys could not be fully flushed due to thrombosis, they were cut into 1 cm slices and submerged in 10% NBF to enable further processing similar to the patent kidneys. Regions (1 cm thick) were cut from the upper and lower pole as well as the midline of the kidney and were submerged in 10% NBF for 2 days.