[Tissue engineering of urinary bladder using acellular matrix]

Use of an acellular collagen-elastin matrix to support bladder regeneration in a porcine model of peritoneocystoplasty

Introduction

Bladder reconstruction without using the intestine remains a challenge to this day despite the development of new biomaterials and cell cultures. Human bladder engineering is merely anecdotic, and mostly in vitro and animal studies have been conducted.

Material and methods

In our study using a porcine model, we performed a bladder augmentation using an autologous parietal peritoneum graft (peritoneocystoplasty) and determined whether the attachment of an acellular collagen-elastin matrix (Group 1) or lack of (Group 2) had better histologic and functional results. Thus far, peritoneocystoplasty has rarely been performed or combined with a biomaterial.

Results

After 6 weeks, we observed different degrees of retraction of the new bladder wall in both groups, although the retraction was lower and the histological analysis showed more signs of regeneration (neoangiogenesis and less fibrosis) in Group 1 than when compared with Group 2. No transitional cells were found in the new bladder wall in any of the groups, and no differences were observed in the functional test results.

Conclusions

Performing a peritoneocystoplasty is an easy and safe procedure. The data supports the benefit of an acellular collagen–elastin matrix to reinforce bladder regeneration. However, in our study we observed too much retraction of the new wall and the histologic results were not acceptable to consider it an appropriate cystoplasty technique.

Current status of tissue engineering applied to bladder reconstruction in humans

CONTEXT AND OBJECTIVE

Bladder reconstruction is performed to replace or expand the bladder. The intestine is used in standard clinical practice for tissue in this procedure. The complications of bladder reconstruction range from those of intestinal resection to those resulting from the continuous contact of urine with tissue not prepared for this contact. In this article, we describe and classify the various biomaterials and cell cultures used in bladder tissue engineering and reviews the studies performed with humans.

ACQUISITION OF EVIDENCE

We conducted a review of literature published in the PubMed database between 1950 and 2017, following the principles of the PRISM declaration.

SYNTHESIS OF THE EVIDENCE

Numerous in vitro and animal model studies have been conducted, but only 18 experiments have been performed with humans, with a total of 169 patients. The current evidence suggests that an acellular matrix, a synthetic polymer with urothelial and autologous smooth muscle cells attached in vitro or stem cells would be the most practical approach for experimental bladder reconstruction.

CONCLUSIONS

Bladder replacement or expansion without using intestinal tissue is still a challenge, despite progress in the manufacture of biomaterials and the development of cell therapy. Well-designed studies with large numbers of patients and long follow-up times are needed to establish an effective clinical translation and standardisation of the check-up functional tests.