The biological behavior of autologous collagen injected into the rabbit bladder

Local tissue reaction and histopathological characteristics of three different bulking agents: a rabbit model

Purpose:

We assessed the efficacy and safety of a single injection of three bulking agents over the short- and long-term follow-ups in rabbits. Dermal and preputial matrices were compared with Deflux (DxHA) injection.

Material and methods:

Twenty-four rabbits were divided into three groups. Group I (n=8) underwent the injection of a lyophilized dermal matrix (LDM) beneath the seromuscular layer of the bladder wall. Rabbits in group II (n=8) were injected with lyophilized preputial matrix (LPM). Rabbits of group III (n=8) were injected with DxHA as the control group. They were followed up for 1 and 6 months after the injection. Subcutaneous injection of all bulking agents was also performed in nude mice. Biopsies were stained with LCA (leukocyte common antibody), CD68, CD31, and CD34. Scanning electron microscopy (SEM) and MTT assay were also performed.

Results:

Immunohistochemistry staining with CD68 and LCA revealed higher inflammation grade in LDM as compared with LPM and DxHA. Fibrosis grade was also higher in LDM both in short- and long-term follow-ups. However, no significant difference was detected in CD31 and CD34 staining between control and experimental groups. SEM analysis showed that the particle size of LPM was more similar to DxHA. MTT assay revealed that cell proliferation was similar in DxHA, LDM, and LPM. In-vivo assay in nude mice model showed more promising results in LPM as compared with LDM.

Conclusion:

The long-term results demonstrated that LPM was more similar to Deflux with the least local tissue reaction, inflammation, and fibrosis grade.

Transplantation of mature adipocyte-derived dedifferentiated fat cells for the treatment of vesicoureteral reflux in a rat model

PURPOSE

Autologous cells potentially provide an ideal injectable substance for management in vesicoureteral reflux (VUR). The aim of this study is to examine the effects of mature adipocyte-derived dedifferentiated fat (DFAT) cell transplantation on VUR in a rat bladder pressurization-induced VUR model.

METHODS

To create VUR, Sprague-Dawley rats underwent urethral clamping and placement of cystostomy followed by intravesical pressurization. Rat DFAT cells (1 × 10⁶ cells, DFAT group, n = 5) or saline (control group, n = 5) was then injected into the bilateral vesicoureteral junctions. Two weeks later, VUR grade was evaluated on cystography. The number of apoptotic cells in the renal pelvic urothelium, the ureteral inner/outer diameter ratio and the area of connective tissue in the posterior bladder wall were measured.

RESULTS

The reflux grade in the DFAT group was significantly lower than that in the control group. The number of apoptotic cells in the renal pelvic urothelium, ureteral inner/outer diameter ratio and connective tissue area in DFAT group were significantly lower in comparison with the control group.

CONCLUSIONS

DFAT cell transplantation improved VUR and exerted nephroprotective effects in a rat VUR model.