Tissue-engineered tubular substitutions for urinary diversion in a rabbit model

A tissue-engineered urinary conduit in a porcine urinary diversion model

The use of an ileal segment is a standard method for urinary diversion after radical cystectomy. Unfortunately, utilization of this method can lead to numerous surgical and metabolic complications. This study aimed to assess the tissue-engineered artificial conduit for urinary diversion in a porcine model. Tissue-engineered tubular polypropylene mesh scaffolds were used for the right ureter incontinent urostomy model. Eighteen male pigs were divided into three equal groups: Group 1 (control ureterocutaneostomy), Group 2 (the right ureter-artificial conduit-skin anastomoses), and Group 3 (4 weeks before urostomy reconstruction, the artificial conduit was implanted between abdomen muscles). Follow-up was 6 months. Computed tomography, ultrasound examination, and pyelogram were used to confirm the patency of created diversions. Morphological and histological analyses were used to evaluate the tissue-engineered urinary diversion. All animals survived the experimental procedures and follow-up. The longest average patency was observed in the 3rd Group (15.8 weeks) compared to the 2nd Group (10 weeks) and the 1st Group (5.8 weeks). The implant's remnants created a retroperitoneal post-inflammation tunnel confirmed by computed tomography and histological evaluation, which constitutes urostomy. The simultaneous urinary diversion using a tissue-engineered scaffold connected directly with the skin is inappropriate for clinical application.

Evaluation of PC12 Cells' Proliferation, Adhesion and Migration with the Use of an Extracellular Matrix (CorMatrix) for Application in Neural Tissue Engineering

The use of extracellular matrix (ECM) biomaterials for soft tissue repair has proved extremely successful in animal models and in some clinical settings. The aim of the study was to investigate the effect of the commercially obtained CorMatrix bioscaffold on the viability, proliferation and migration of rat pheochromocytoma cell line PC12. PC12 cells were plated directly onto a CorMatrix flake or the well surface of a 12-well plate and cultured in RPMI-1640 medium and a medium supplemented with the nerve growth factor (NGF). The surface of the culture plates was modified with collagen type I (Col I). The number of PC12 cells was counted at four time points and then analysed for apoptosis using a staining kit containing annexin V conjugate with fluorescein and propidium iodide (PI). The effect of CorMatrix bioscaffold on the proliferation and migration of PC12 cells was tested by staining the cells with Hoechst 33258 solution for analysis using fluorescence microscopy. The research showed that the percentage of apoptotic and necrotic cells was low (less than 7%). CorMatrix stimulates the proliferation and possibly migration of PC12 cells that populate all levels of the three-dimensional architecture of the biomaterial. Further research on the mechanical and biochemical capabilities of CorMatrix offers prospects for the use of this material in neuro-regenerative applications.

Novel therapeutic approaches of tissue engineering in male infertility

Male reproductive organ plays an important role in sperm production, maintenance and entry to the female reproductive tract, as well as generation and secretion of male sex hormones responsible for the health of male reproductive system. The purpose of this paper is to discuss the experimental and clinical evidence on the utilization of tissue engineering techniques in treating male infertility. Tissue engineering (TE) and regenerative medicine have developed new approaches to treat patients with reproductive disorders such as iatrogenic injuries, congenital abnormalities, and trauma. In some cases, including congenital defects and undescended testis or hypogonadism, the sperm samples are not retrieved. This makes TE a possible future strategy for restoration of male fertility. Here, we have summarized the recent advances in experimental and clinical application of cell-, tissue-, and organ-based regenerative medicine in male reproductive disorders.

Use of the extracellular matrix from the porcine esophagus as a graft for bladder enlargement

INTRODUCTION

Some patients with diseases that involve increased bladder pressure or low-capacity bladders may need bladder enlargement surgery. In current techniques for bladder enlargement, autologous tissue such as small intestine or colon tissue is used to perform cystoplasties, which is far from ideal for these patients. In search of biomaterials with appropriate regeneration and safety profiles, tissue engineering has resulted in preclinical studies with acellular matrices in animal models that have yielded positive preliminary results with respect to the urothelial cell and smooth muscle repopulation; these studies have primarily been performed with matrices originating from the bladder or intestinal submucosa.

OBJECTIVE

The aim of the study was to assess an extracellular matrix device derived from the porcine esophagus for augmentation cystoplasty in an animal model.

STUDY DESIGN

Seven male Wistar rats weighing 357-390 g were subjected to augmentation cystoplasty with a circular segment of the acellular matrix from the porcine esophagus. Daily postoperative follow-up was performed with evaluation of changes in body weight, behavior, and wound status.

RESULTS

During follow-up, there were no complications associated with the process. Three specimens were sacrificed at day 30, and three, at day 60. Necropsy was performed, with a description of the macroscopic findings and a morphological study. Epithelialization was observed, with different stages of mucosal development in all specimens analyzed. Repopulation of smooth muscle cells, mixed inflammatory infiltrate, and vascular neoformation were identified in the matrices.

DISCUSSION

The urothelium and fibers of the smooth muscle were observed inside the implanted matrix. Additional investigations in larger animal models that allow urodynamic evaluation of the bladder with the matrix implanted are needed. However, to compare the results of this study model with those reported in the literature, a matrix derived from an organ different from the bladder was used because it could prevent the use of an intestinal segment in augmentation cystoplasty.

CONCLUSION

The acellular porcine esophagus matrix offers positive results regarding the repopulation of the urothelium and smooth muscle when used in augmentation cystoplasty in a murine model.

The effects of adipose-derived stem cells on CD133-expressing bladder cancer cells

Mesenchymal stem cells (MSCs) hold great promise as therapeutic agents in regenerative medicine. They are also considered as a preferred cell source for urinary tract reconstruction. However, as MSCs exhibit affinity to tumor microenvironment, possible activation of tumor-initiating cells remains a major concern in the application of stem cell-based therapies for patients with a bladder cancer history. To analyze the influence of adipose-derived stem cells (ASCs) on bladder cancer cells with stem cell-like properties, we isolated CD133-positive bladder cancer cells and cultured them in conditioned medium from ASCs (ASC-CM). Our results showed that parental 5637 and HB-CLS-1 cells showed induced clonogenic potential when cultured in ASC-CM. Soluble mediators secreted by ASCs increased proliferation and viability of unsorted cells as well as CD133+ and CD133- subpopulations. Furthermore, incubation with ASC-CM modulated activation of intracellular signaling pathways. Soluble mediators secreted by ASCs increased phosphorylation of AKT1/2/3 (1.4-fold, P < 0.05), ERK1/2 (1.6-fold, P < 0.02), and p70 S6K (1.4-fold) in CD133+ cells isolated from 5637 cell line. In turn, decreased phosphorylation of those three proteins involved in PI3K/Akt and MAPK signaling was observed in CD133+ cells isolated from HB-CLS-1 cell line. Our results revealed that bladder cancer stem-like cells are responsive to signals from ASCs. Paracrine factors secreted by locally-delivered ASCs may, therefore, contribute to the modulation of signaling pathways involved in cancer progression, metastasis, and drug resistance.

Constructing artificial urinary conduits: current capabilities and future potential

INTRODUCTION

Intestinal segments are currently used in reconstructive urology to create urinary diversion after cystectomy. Ileal conduit (IC) is the dominant type of urinary diversion. Nevertheless, IC is not an ideal solution as the procedure still requires entero-enterostomy to restore the bowel continuity. This step is a source of relevant complications that might prolong recovery time. Fabrication of artificial urinary conduit is a tempting idea to introduce an alternative form of urinary diversion which might improve cystectomy outcomes.

AREAS COVERED

The aim of this review is to discuss available research data about artificial urinary conduit and identify major challenges for future studies.

EXPERT OPINION

Fabrication of artificial urinary conduit is in range of current tissue engineering technology but there are still many challenges to overcome. There is an urgent need for studies to be conducted on large animal models with long follow up to expose the limitation of experimental strategies and to gather data for translational research.

The interplay between adipose-derived stem cells and bladder cancer cells

Tissue engineering approaches offer alternative strategies for urinary diversion after radical cystectomy. Possible triggering of cancer recurrence remains, however, a significant concern in the application of stem-cell based therapies for oncological patients. Soluble mediators secreted by stem cells induce tissue remodelling effects, but may also promote cancer cells growth and metastasis. We observed a substantial increase in the concentration of IL-6 and IL-8 in the secretome of adipose-derived stem cells (ASCs) co-cultured with bladder cancer cells. Concentrations of GM-CSF, MCP-1 and RANTES were also elevated. Bioactive molecules produced by ASCs increased the viability of 5637 and HT-1376 cells by respectively 15.4% and 10.4% (p < 0.0001). A trend in reduction of adhesion to ECM components was also noted, even though no differences in β-catenin expression were detected. When HT-1376 cells were co-cultured with ASCs their migration and invasion increased by 24.5% (p < 0.0002) and 18.2% (p < 0.002). Expression of p-ERK1/2 increased in 5637 cells (2.2-fold; p < 0.001) and p-AKT in HB-CLS-1 cells (2.0-fold; p < 0.001). Our results confirm that ASCs crosstalk with bladder cancer cells in vitro what influences their proliferation and invasive properties. Since ASCs tropism to tumour microenvironment is well documented their application towards post-oncologic reconstruction should be approached with caution.

Biofabrication and biomaterials for urinary tract reconstruction

Reconstructive urologists are constantly facing diverse and complex pathologies that require structural and functional restoration of urinary organs. There is always a demand for a biocompatible material to repair or substitute the urinary tract instead of using patient's autologous tissues with its associated morbidity. Biomimetic approaches are tissue-engineering tactics aiming to tailor the material physical and biological properties to behave physiologically similar to the urinary system. This review highlights the different strategies to mimic urinary tissues including modifications in structure, surface chemistry, and cellular response of a range of biological and synthetic materials. The article also outlines the measures to minimize infectious complications, which might lead to graft failure. Relevant experimental and preclinical studies are discussed, as well as promising biomimetic approaches such as three-dimensional bioprinting.

Decellularized scaffolds in regenerative medicine

Allogeneic organ transplantation remains the ultimate solution for end-stage organ failure. Yet, the clinical application is limited by the shortage of donor organs and the need for lifelong immunosuppression, highlighting the importance of developing effective therapeutic strategies. In the field of regenerative medicine, various regenerative technologies have lately been developed using various biomaterials to address these limitations. Decellularized scaffolds, derived mainly from various non-autologous organs, have been proved a regenerative capability in vivo and in vitro and become an emerging treatment approach. However, this regenerative capability varies between scaffolds as a result of the diversity of anatomical structure and cellular composition of organs used for decellularization. Herein, recent advances in scaffolds based on organ regeneration in vivo and in vitro are highlighted along with aspects where further investigations and analyses are needed.

Tubular Constructs as Artificial Urinary Conduits

PURPOSE

A readily available artificial urinary conduit might be substituted for autologous bowel in standard urinary diversions and minimize bowel associated complications. However, the use of large constructs remains challenging as host cellular ingrowth and/or vascularization is limited. We investigated large, reinforced, collagen based tubular constructs in a urinary diversion porcine model and compared subcutaneously pre-implanted constructs to cell seeded and basic constructs.

MATERIALS AND METHODS

Reinforced tubular constructs were prepared from type I collagen and biodegradable Vicryl® meshes through standard freezing, lyophilization and cross-linking techniques. Artificial urinary conduits were created in 17 female Landrace pigs, including 7 with a basic untreated construct, 5 with a construct seeded with autologous urothelial and smooth muscle cells, and 5 with a free graft formed by subcutaneous pre-implantation of a basic construct. All pigs were evaluated after 1 month.

RESULTS

The survival rate was 94%. At evaluation 1 basic and 1 cell seeded conduit were occluded. Urinary flow was maintained in all conduits created with pre-implanted constructs. Pre-implantation of the basic construct resulted in a vascularized tissue tube, which could be used as a free graft to create an artificial conduit. The outcome was favorable compared to that of the other conduits. Urinary drainage was better, hydroureteronephrosis was limited and tissue regeneration was improved.

CONCLUSIONS

Subcutaneous pre-implantation of a basic reinforced tubular construct resulted in a vascularized autologous tube, which may potentially replace bowel in standard urinary diversions. To our knowledge we introduce a straightforward 2-step procedure to create artificial urinary conduits in a large animal model.