Biomedical subjects

J E Nuininga

Publications and source records attributed to J E Nuininga.

3 recordsLinked to original sources

PubMed2004

A rabbit model to tissue engineer the bladder.

A rabbit model was used for the evaluation of a collagen-based biomatrix of small intestinal submucosa (SIS, COOK) in comparison to a biochemically reconstructed biomatrix for bladder tissue regeneration. Rabbits underwent partial cystectomy and cystoplasty with SIS patch graft or with a biochemically defined collagen biomatrix. The grafts of the regenerated bladder wall were harvested at different intervals and tissue regeneration was evaluated. The results of the SIS and biochemically defined biomatrix grafts were comparable. At harvesting, we found five bladder stones and encrustation of the biomatrix in 21/56 animals. No stone formation was observed in the control group. The results of the molecularly defined biomatrix are thus far comparable to SIS. Both matrices show good epithelialization and ingrowth of smooth muscle cells. Both biomatrices show considerable encrustation, which appears to disappear in time. The rabbit model is suitable for bladder tissue engineering studies as it is an easy model to use. In this model, besides tissue regeneration, also some of the clinical problems are seen such as encrustation of foreign body material in the bladder. These aspects are subject for further pre-clinical studies in this animal model.

Absorbable Implants↗

PubMed2003

Rabbit urethra replacement with a defined biomatrix or small intestinal submucosa.

OBJECTIVE: The evaluation of collagen-based biomatrix (SIS COOK((R))) in comparison to a biochemically reconstructed biomatrix for replacement of the urethra in a rabbit model as a preclinical model. MATERIAL AND METHODS: Rabbits underwent partial urethra replacement (resection of 0.5 to 1.0 cm segment of the urethra), which was replaced with 1 or 4 layers Small Intestinal Submucosa (SIS COOK) patch grafts or with a biochemically defined collagen biomatrix, partly sutured with unresolvable sutures for future reference. Six animals underwent a sham control operation. The grafts of regenerated urethras were harvested at 1, 3 and 9 months after implantation. Urethrography was performed pre-operatively and before sacrificing. The animals were evaluated macroscopically and by routine histology and immunohistochemistry. RESULTS: At 1 month after implantation, the biomatrices (1 layer, 4 layers and our biochemically defined biomatrix) were well distinguishable from the normal surrounding tissues and showed blood vessels at the periphery. Macroscopically, the unresolvable reference sutures were easy to find at all time points. At 3 months the graft was still distinguishable in the 4 layers SIS group. In the 1 layer and the defined biomatrix group a good regeneration of the urethra within the graft was seen with some central fibrosis. Histological and immunohistochemical evaluation showed urothelium regeneration on the 1 layer and on biochemically defined biomatrix with decreasing number of inflammatory cells from 1 month on. In the group treated with 4 layers SIS the urothelium was completely regenerated at 3 months. Histologically, the regeneration of muscle cells in the three biomatrices was comparable. The smooth muscle cells regenerated very slowly as 1 month after implantation no muscle cells were detectable within the grafts. At 3 months a few muscle cells were present in the graft, but cell density did not increase in the following 6 months. Strictures were not observed on control urethrography pre-operatively in the animals. In one case slight narrowing of the urethra on urethrography was seen, but apparently without causing voiding problems. One rabbit developed a fistula near the operation site. CONCLUSION: The biomatrices investigated are feasible scaffolds to repair urethral lesions. The results with our biochemically defined biomatrix are comparable to one layer Small Intestinal Submucosa. Almost no smooth muscle cells population was observed after nine months for the three biomatrices. We conclude that an improved molecularly defined biomatrix focussed on stimulation of smooth muscle cell growth may be necessary to obtain optimal cellular grafting results.

Animals↗

PubMed2001

Urological complications in pediatric renal transplantation.

OBJECTIVE: In this study, we evaluated the urological complications and their consequences after renal transplantation in children. MATERIALS AND METHODS: A retrospective study was performed concerning urological complications after kidney transplantation in children at the University Medical Center St Radboud Nijmegen from August 1977 until July 1999. The mean age of the cadaver kidney donors was 23.2 (range 1-74.3) years. RESULTS: In this period 146 children received 183 renal allografts. Twenty-four urological complications (13.1%) were noted in 23 patients. Urinary leakage was seen in 8 cases (4.4%) and a ureteral stenosis was present in 7 cases (3.8%), 5 patients developed stones (2.7%) and 4 severe lymph leakage needing surgical treatment (2.2%). In 3 patients the urological complication induced graft loss. In cadaver kidneys from donors younger than 5 years there was no significantly increased complication rate in comparison to older cadaver kidneys [2/32 (6.3%) versus 16/125 (12.2%)]. In a subgroup of 24 patients treated for severe posterior urethral valves the complication rate was not significantly increased in comparison to the others (8.3% in the group with posterior urethral valves against 13.7% in the group without). CONCLUSIONS: Urological complications are a small threat for graft function and the results are comparable with earlier studies. Routine ultrasound can be important for early detection of problems in the postoperative period. A close observation in the postoperative care and good collaboration between pediatric nephrologist and urologist is mandatory. Sometimes, early intervention can be undertaken with the possibility of saving graft function and reducing morbidity.

Adolescent↗