To compare the preservation efficacy of a novel ex vivo organ preservation solution (Solution A) was compared with that of University of Wisconsin solution (UW solution) and hypertonic citrate adenine solution (HCA solution) on isolated rat kidneys.

The physicochemical properties and stability of the novel ex vivo organ preservation solution developed at our center were validated by measuring its ion concentration, pH value, and osmolality. The cytotoxicity and apoptosis effects of Solution A on human embryonic renal epithelial cell line (293T) and renal tubular epithelial cells (HK-2) were investigated using the CCK-8 assay. A rat kidney donor model was established. A total of 30 kidneys from 15 rats were randomly divided into three groups (UW solution group, HCA solution group, and Solution A group) using a random number table method, with 10 kidneys in each group. The isolated kidneys were placed in the corresponding preservation solutions, and renal tissue samples were collected at 0, 6, 12, 24, 48, and 72 hours. Histopathological damage was assessed by HE staining, ATPase activity and malondialdehyde (MDA) content were determined using colorimetric assays. Apoptosis was quantitatively analyzed by TUNEL staining, and the expression of apoptosis-related proteins (Caspase-3, Cleaved Caspase-3, Bax, Bcl-2) as well as inflammatory factors (HO-1, TNF-α) was detected by Western blotting. All experimental data were obtained from at least three indepent replicates. Comparisons of experimental data among multiple groups were performed using analysis of variance (ANOVA), followed by pairwise comparisons using Dunnett′s test. A P value <0.05 was considered statistically significant.

In vitro experiments demonstrated that the cell viability of the Solution A group was significantly higher than that of the UW solution group and lower than that of the HCA solution group (all P<0.05). In vitro rat kidney preservation experiments showed that at 48 hours of preservation, the degree of tubular vacuolization in the Solution A group was significantly lower than that in the HCA solution group (P<0.05), but no statistically significant difference was observed compared to the UW solution group (P>0.05). For oxidative stress indicators, the ATPase activity of the Solution A group was significantly higher than that of the UW solution and HCA solution groups at 48 and 72 hours of preservation (all P<0.05). In addition, the MDA accumulation rate in the Solution A group was lower than that in the HCA and UW solution groups, and the MDA content at 48 and 72 hours (0.27%, 0.28%) was significantly lower than that of the HCA solution group (0.42%, 0.42%) (all P<0.05). After 24 hours of preservation, the Solution A group exhibited a significantly lower TUNEL apoptosis index and a higher Bcl-2/Bax ratio compared with the HCA solution group (all P<0.05), as well as a lower relative expression level of Cleaved Caspase-3 protein compared with both the UW and HCA solution groups (P<0.05). In terms of inflammatory factors, the TNF-α expression level in the Solution A group was significantly lower than that in the HCA solution group (P<0.05), and the HO-1 expression level was significantly lower than that in both the UW and HCA solution groups (P<0.05).

The novel organ preservation solution exhibited renal protective potential comparable to, or even better than, that of commercially available classic preservation solutions within 48 hours in rats. Under prolonged preservation conditions up to 72 hours, the novel solution further exhibited excellent renal protective efficacy by maintaining ATPase activity, reducing MDA content, and regulating apoptosis-related pathways.