Prize-winning 4th NEEM abstract: tissue engineering of the urinary bladder in a rat model

13 September 2010

Marta Pokrywczynska and colleagues of Bydgoszcz, Poland won the first prize Karl Storz Award for the best abstract during the 4th North Eastern European Meeting (NEEM) held over the weekend in Riga, Latvia.

Below is the abstract titled “Tissue engineering of the urinary bladder: Trophic effects of mesenchymal stem cells in reconstruction of the rat bladder wall,” which was published in a special supplement issue of the European Urology:

The main goal of the tissue engineering is to provide opportunities for defective tissue replacement using in vitro tissue founding’s. A new promising method
using a cellular matrix seeded with autologous cells obtained from bone marrow mesenchymal stem cells (MSCs) capable to differentiation in muscle cells is necessary to achieve physiological contractility of the urinary bladder.

The study was performed to evaluate the tropic effects of the MSCs in the rat urinary bladder wall remodelling.

MSCs and urinary bladders were harvested from ten male Wistar rats. Cells were cultivated in Dulbecc’s modified essential medium supplemented with 10% of fetal bovine serum (PAA, Austria) and fibroblast growth factor (10ng/ml;Sigma, Germany). The a cellular matrices from the lamina propria of the bladder submucosa (BAM, Bladder A cellular Matrix) were prepared. 20 female Wistar rats were divided into four equal groups.

The first group of animals were implanted with the cells seeded matrices. Before transplantation MSCs were seeded on the BAM. The cells were seeded at number of 1×106 cells/cm2 allowed to attached and proliferate over 5 days. Augmentation cystoplasty was performed in the earlier created dome defect.

In the second group the bladder defect were supplied by BAM only. In the group three the amount of 1×106 MSCs were injected in the bladder wall. Animals of the group four- control group do not undergo any bladder augmentation procedures. All the animals were sacrificed after three months observation. Macroscopic evaluation of the reconstructed bladders was performed. Bladder samples were embedded for histological and immunohistochemical evaluation including angiogenesis and innervations assessment.

The results showed that the bladder volume assessment were comparable in all groups, respectively. No peritoneal adhesion were observed in all groups after bladder augmentation.

Reconstructed bladders in a group I contracted and filled properly. In a group II implant shrinkage and disfigured shape of the bladder were observed. The intensity of angiogenesis, innervations and muscles regeneration were significantly higher in bladders grafted with cell-seeded BAM compared to bladders reconstructed with a cellular BAM.

Implantation of MSCs seeded on matrix stimulated the strongest expression of IL-4 and TGF-beta which favourable bladder wall remodelling. Simultaneous induction of IL-4 and TGF-beta were correlated with proinflammatory cytokines (TNF-alpha and IL-6) decrease.

“MSC are an attractive outsource for muscular layer regeneration of a rat bladder destructor. MSC- secretion of bioactive molecules affect the local microenviroment of reconstructed bladder wall. The tropic factors secreted by MSC anchored on scaffold support the repair and promote the regeneration process including muscle, vessels and nerves in reconstructed bladder wall,” the researchers concluded.

Source: M. Pokrywczynska, et al., “Tissue engineering of the urinary bladder: Trophic effects of mesenchymal stem cells in reconstruction of the rat bladder wall,” Abstract Nr. N48, 4th North Eastern European Meeting (NEEM), Riga, Latvia, September 10-11, 2010.