It is still controversial whether renal tubular interstitial fibrosis (TIF) is a reversible process. Although previous studies examining TIF have been carried out in rodents, their kidney size and physiological character differ with humans, and the difference among diverse individuals before and after damage was obvious. Thus an experimental animal model to simulate human kidney disease was urged to be established. In order to clarify whether TIF is reversible, and the exact time points that the kidney has the capacity to be repaired, a porcine relief of unilateral ureteral obstruction (R-UUO) model was developed. Kidney damage and reparation were observed dynamically in vivo over various time points. Pigs were randomized divided into three groups (n = 6): UUO 5 days group, UUO 7 days, and UUO 10 days group. Each porcine in that groups underwent UUO and subsequent R-UUO for three time points. Renal function, histological structure, and protein expressions of α-smooth muscle actin (α-SMA), vimentin and E-cadherin were evaluated at different time points. Following R-UUO after 5 and 7 days of UUO, compared to UUO, serum creatinine levels were significantly decreased. Renal pathological tissue damage was repaired. The expressions of α-SMA and vimentin were decreased and E-cadherin expression was increased (P < 0.05). However, during R-UUO 14, 28, and 56 days after 10 days of UUO, serum creatinine was not decreased significantly. The expressions of α-SMA and vimentin consistently remained at high levels. Renal damage was unable to be restored and resulted in chronic lesions. Kidney damage induced by UUO can be reversed in early stages. However, longer time of UUO with significant levels of TIF showed limited reversibility. The porcine R-UUO model provides an ideal animal model for the investigation of kidney injury and repair as well as for the evaluation of the effect of drug treatment.
Keywords: Animal model; Fibrosis; Kidney; Ureteral obstruction.