A Novel Standardized Method of Renal Biopsy in Mice

Abstract

Introduction: In animal models, it can be difficult to confirm therapeutic effects due to technical inconsistencies and other reasons. Although renal biopsy is widely used in clinical diagnosis, it is rarely used in animal experimental models, especially in mice, because the problems of surgery-induced renal injury and bleeding have not been solved.

Methods: We developed an easy-to-use method of renal biopsy in mice and evaluated whether 3 consecutive renal biopsies can be performed in the same kidney in a standardized manner. This method was verified using 2 mouse models, a healthy mouse model and a unilateral ureteral obstruction (UUO) mouse model, and evaluated based on renal function and histological changes.

Results: There were no perioperative complications in any of the model mice. There was no significant difference in serum Cr, 24-h urine protein, or kidney/body weight ratio between the biopsy and control groups. Each biopsy sample contained sufficient renal tissue. The damage to the operated tissue was limited to the tissue near the biopsy site. Compared with renal tissues in the corresponding control group, the renal tissues obtained from the 3 biopsies (healthy model days 0, 4, and 7 and UUO model days 3, 7, and 10) and the remnant renal tissues after the biopsy showed no significant difference in the glomerular sclerosis index, degree of renal tubular damage, inflammatory response and renal fibrosis in these 2 models.

Conclusions: Our new standardized method of renal biopsy in mice is a safe and cost-saving approach that allows repeated renal biopsies and ensures minimal trauma and sufficient sample size to quality in experimental disease models.

Keywords: New standardized method; Renal biopsy.

Fig. 1

Operational principle of the biopsy apparatus. a The cone hole of a 1-mL syringe is pressed firmly on the surface of the renal tissue to be biopsied, forming a seal. By applying pressure, kidney tissue with a diameter of 2 mm is pulled into the cone head hole. While maintaining the position of the pulled piston, an assistant places a polyester wire (8/0) wrapped around the syringe cone head around the tissue that is being aspirated; quickly pulling the polyester wire cuts the aspirated tissue. b Kidney biopsies of the same size were obtained by 3 identical pulls. c The full size of the renal biopsy specimen could be clearly observed by PASM staining. PASM, periodic acid-silver methenamine.

Fig. 2

Histological changes and analysis of GSI score, tubular injury, inflammatory response, and kidney fibrosis in healthy model mice. a Representative images of HE, PASM, PAS, Masson's trichrome, Sirius red and Kim-1, F4/80, and α-SMA immunohistochemical staining among different groups in healthy model mice. b GSI score. c Proportion of renal tubular injury by PAS staining. d The proportion of Kim-1 positive areas. e The proportion of F4/80 positive areas. f Proportion of kidney fibrosis by Masson staining. g The proportion of Sirius positive areas. h The proportion of α-SMA positive areas. Data are means ± SEM (n = 6). ns, no significance versus sham control; PASM, periodic acid-silver methenamine; PAS, periodic acid-Schiff.

Fig. 3

Histological changes and analysis of GSI score, tubular injury, and inflammatory response in UUO model mice. a Representative images of PASM, PAS staining and Kim-1, and F4/80 immunohistochemical staining among different groups in UUO model mice. b GSI score. c Proportion of renal tubular injury by PAS staining. d The proportion of Kim-1 positive areas. e The proportion of F4/80 positive areas. Data are means ± SEM (n = 6). ns, no significance versus control; UUO, unilateral ureteral obstruction; PASM, periodic acid-silver methenamine; PAS, periodic acid-Schiff.

Fig. 4

Analysis of kidney fibrosis in UUO model mice. a Representative images of Masson, Sirius red, and α-SMA immunohistochemical staining among different groups in UUO model mice. b Proportion of kidney fibrosis by Masson staining. c The proportion of Sirius positive areas. d The proportion of α-SMA positive areas. Data are means ± SEM (n = 6). ns, no significance versus control; UUO, unilateral ureteral obstruction; PAS, periodic acid-Schiff.