Pre-vascularisation of the acellular bladder matrix using the omentum in a porcine model prior for bladder reconstruction-a step towards clinical application?

Aim: Research studies with porcine acellular bladder matrix (PABM) showed integration of only small sized stamps in recipient bladders, however for clinical use in bladder augmentation significantly larger patches are needed. We hypothesised pre-vascularisation with omentum may be a step towards clinical translation.

Method: Eight domestic pigs were operated three times 8-10 weeks apart: 1-Implantation; PABM with recorded dimensions were sutured around a tissue expanding device, wrapped in omentum and sutured to the anterior abdominal wall. 2-Augmentation; hemi-cystectomy and bladder augmentation was performed with the pre-vascularized PABM using non-absorbable suture 3-Sacrifice; The dimensions of the PABMs were measured macroscopically, the in-vivo microcirculation of the PABMs were assessed using laser speckle contrast imaging. HE staining, uroplakin 3 and CK7 immunohistochemistry was performed.

Results: In seven animals, the bladder augmentation was successful without complication. One animal was lost in bowel obstruction and in two animals enteric fistula was found after the first intervention. The rectangular shape of the initial tissue expander was subsequently changed. All the seven patches were strong, compliant and had integrated with the surrounding native bladder and were 83% (48-100%) of the original patch size. Laser speckle contrast imaging already showed microcirculation at the patch edges at augmentation and this further improved towards the centre of the patches by the end of the study. Histology demonstrated acute inflammatory response with fibroblast infiltration after implantation and full coverage by urothelium was seen with positive staining for CK7 antibodies.

Conclusion: Pre-vascularization of PABM in the omentum of healthy porcine models allows larger PABM patches to integrate this may be a step towards clinical application.