Tomasz Drewa

Hair stem cells for bladder regeneration in rats: preliminary results.

BACKGROUND A variety of tissue engineering techniques are currently under development or investigation for bladder augmentation, but so far no approach is clearly superior. The aim of this study was to compare the suitability for cystoplasty augmentation in rats of in vivo implanted acellular bladder matrices (BAM) previously seeded with hair follicle stem cells and that of matrices implanted without the cells. MATERIALS AND METHODS The rat hair follicle stem cell line was positive for CD34, p63, and Ki-67. 1 x 10(6) cells from 34 to 40 passages seeded onto nine BAM scaffolds were cultured for one week. Nine other scaffolds were left unseeded. Scaffolds were grafted into a surgically created defect within the anterior bladder wall: nine rats with acellular matrices and nine with cell-seeded BAM. Rats observed for six months were killed in monthly intervals. We performed gross examination, X-ray cystography, and hematoxylin-eosin, cytokine (CK)-7, CK-20, myoglobin, and desmin staining of the excised bladders. RESULTS Minimal adhesions were observed and urinary leakage was noted in one case. Two animals died in the acellular group. Rats developed stone disease in bladders reconstructed with acellular BAM. Bladder capacity was similar, but the shape was regular and characteristically oval only in bladders grafted with cell-seeded BAM. Muscle layers in the apical parts of the reconstructed bladder walls were extremely thin in the cases of acellular grafts and thicker in bladders reconstructed with cell-seeded grafts. Muscle layer regeneration was better in the cell-seeded group. Urothelium regenerated in all animals. CONCLUSIONS We have shown that hair follicle stem cells may be used for rat bladder wall regeneration.

Adipose-Derived Stem Cells as a Tool in Cell-Based Therapies

Recent development in stem cell isolation methods and expansion under laboratory conditions create an opportunity to use those aforementioned cells in tissue engineering and regenerative medicine. Particular attention is drawn towards mesenchymal stem cells (MSCs) being multipotent progenitors exhibiting several unique characteristics, including high proliferation potential, self-renewal abilities and multilineage differentiation into cells of mesodermal and non-mesodermal origin. High abundance of MSCs found in adipose tissue makes it a very attractive source of adult stem cells for further use in regenerative medicine applications. Despite immunomodulating properties of adipose-derived stem cells (ASCs) and a secretion of a wide variety of paracrine factors that facilitate tissue regeneration, effectiveness of stem cell therapy was not supported by the results of clinical trials. Lack of a single, universal stem cell marker, patient-to-patient variability, heterogeneity of ASC population combined with multiple widely different protocols of cell isolation and expansion hinder the ability to precisely identify and analyze biological properties of stem cells. The above issues contribute to conflicting data reported in literature. We will review the comprehensive information concerning characteristic features of ASCs. We will also review the regenerative potential and clinical application based on various clinical trials.

Human urinary bladder regeneration through tissue engineering – An analysis of 131 clinical cases

Replacement of urinary bladder tissue with functional equivalents remains one of the most challenging problems of reconstructive urology over the last several decades. The gold standard treatment for urinary diversion after radical cystectomy is the ileal conduit or neobladder; however, this technique is associated with numerous complications including electrolyte imbalances, mucus production, and the potential for malignant transformation. Tissue engineering techniques provide the impetus to construct functional bladder substitutes de novo. Within this review, we have thoroughly perused the literature utilizing PubMed in order to identify clinical studies involving bladder reconstruction utilizing tissue engineering methodologies. The idea of urinary bladder regeneration through tissue engineering dates back to the 1950s. Many natural and synthetic biomaterials such as plastic mold, gelatin sponge, Japanese paper, preserved dog bladder, lyophilized human dura, bovine pericardium, small intestinal submucosa, bladder acellular matrix, or composite of collagen and polyglycolic acid were used for urinary bladder regeneration with a wide range of outcomes. Recent progress in the tissue engineering field suggest that in vitro engineered bladder wall substitutes may have expanded clinical applicability in near future but preclinical investigations on large animal models with defective bladders are necessary to optimize the methods of bladder reconstruction by tissue engineering in humans.

3D composites based on the blends of chitosan and collagen with the addition of hyaluronic acid

3D porous composites based on blends of chitosan, collagen and hyaluronic acid were obtained through the lyophilization process. Mechanical properties, swelling behavior and thermal stability of the blends were studied. Moreover, SEM images were taken and the structure of the blends was studied. Biological properties of the materials obtained were investigated by analyzing of proliferation rate of fibroblast cells incubated with biomaterial extract using MTT assay (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide). The results showed that the properties of 3D composites based on the blends of chitosan and collagen were altered after the addition 1%, 2% and 5% of hyaluronic acid. Mechanical properties and thermal stability of chitosan/collagen blends were improved in the presence of hyaluronic acid in the composite. New 3D materials based on the blends of chitosan, collagen and hyaluronic acid were non-toxic and did not significantly affect cell morphology.

Tissue engineering for the oncologic urinary bladder

Urinary diversion after radical cystectomy in patients with bladder cancer normally takes the form of an ileal conduit or neobladder. However, such diversions are associated with a number of complications including increased risk of infection. A plausible alternative is the construction of a neobladder (or bladder tissue) in vitro using autologous cells harvested from the patient. Biomaterials can be used as a scaffold for naturally occurring regenerative stem cells to latch onto to regrow the bladder smooth muscle and epithelium. Such engineered tissues show great promise in urologic tissue regeneration, but are faced with a number of challenges. For example, the differentiation mesenchymal stem cells from various sources can be difficult and the smooth muscle cells formed do not precisely mimic the natural cells.

Alginate is not a good material for growth of rapidly proliferating cells.

INTRODUCTION Alginate scaffolds are widely used in tissue engineering. The aim of this study was to evaluate alginate as a scaffold for 3D cultures of rapidly proliferating cells. MATERIALS AND METHODS Murine 3T3 fibroblasts were cultured in an alginate scaffold for 30 days. Cells growing in alginate were observed under the inverted microscope. Pathologic examination by hematoxylin and eosin staining was done at the end of the experiment. RESULTS Migration of rapidly proliferating cells from the 3D scaffold and an inappropriate growth pattern were observed during the experiment. Cells and scaffold did not form a solid graft. CONCLUSIONS The results obtained in this study indicated that alginate is not a good biomaterial for a durable implant.

Tissue engineering of urinary bladder - current state of art and future perspectives.

Introduction Tissue engineering and biomaterials science currently offer the technology needed to replace the urinary tract wall. This review addresses current achievements and barriers for the regeneration of the urinary blad- der based on tissue engineering methods. Materials and methods Medline was search for urinary bladder tissue engineering regenerative medicine and stem cells. Results Numerous studies to develop a substitute for the native urinary bladder wall us- ing the tissue engineering approach are ongoing. Stem cells combined with biomaterials open new treatment methods, including even de novo urinary bladder construction. However, there are still many issues before advances in tissue engineering can be introduced for clinical application. Conclusions Before tissue engineering techniques could be recognize as effective and safe for patients, more research stud- ies performed on large animal models and with long follow–up are needed to carry on in the future.

Is the Poly (L- Lactide- Co– Caprolactone) Nanofibrous Membrane Suitable for Urinary Bladder Regeneration?

The purpose of this study was to compare: a new five-layered poly (L–lactide–co–caprolactone) (PLC) membrane and small intestinal submucosa (SIS) as a control in rat urinary bladder wall regeneration. The five-layered poly (L–lactide–co–caprolactone) membrane was prepared by an electrospinning process. Adipose tissue was harvested from five 8-week old male Wistar rats. Adipose derived stem cells (ADSCs) were seeded in a density of 3×106 cells/cm2 onto PLC membrane and SIS scaffolds, and cultured for 5-7 days in the stem cell culture medium. Twenty male Wistar rats were randomly divided into five equal groups. Augmentation cystoplasty was performed in a previously created dome defect. Groups: (I) PLC+ 3×106ADSCs; (II) SIS+ 3×106ADSCs; (III) PLC; (IV) SIS; (V) control. Cystography was performed after three months. The reconstructed urinary bladders were evaluated in H&E and Massons trichrome staining. Regeneration of all components of the normal urinary bladder wall was observed in bladders augmented with cell-seeded SIS matrices. The urinary bladders augmented with SIS matrices without cells showed fibrosis and graft contraction. Bladder augmentation with the PLC membrane led to numerous undesirable events including: bladder wall perforation, fistula or diverticula formation, and incorporation of the reconstructed wall into the bladder lumen. The new five-layered poly (L–lactide–co–caprolactone) membrane possesses poorer potential for regenerating the urinary bladder wall compared with SIS scaffold.

Tissue Engineering and Ureter Regeneration: Is it Possible?:

Large ureter damages are difficult to reconstruct. Current techniques are complicated, difficult to perform, and often associated with failures. The ureter has never been regenerated thus far. Therefore the use of tissue engineering techniques for ureter reconstruction and regeneration seems to be a promising way to resolve these problems. For proper ureter regeneration the following problems must be considered: the physiological aspects of the tissue, the type and shape of the scaffold, the type of cells, and the specific environment (urine). This review presents tissue engineering achievements in the field of ureter regeneration focusing on the scaffold, the cells, and ureter healing.

Urine Is a Highly Cytotoxic Agent: Does It Influence Stem Cell Therapies in Urology?

The state of art of stem cell therapies in urologic regenerative medicine is still under development. There are still many issues before advances in tissue engineering can be introduced for clinical application. The essential question is whether stem cells should be seeded on the urinary tract lumen side. The present experiment, using Real-Time Cell Analyzer (RTCA) DP (Dual Plate) of the xCellligence system (Roche Applied Science, Mannheim, Germany), allowed us to monitor cellular events in real time. In this study we examined the influence of urine on bone marrow-derived mesenchymal stem cells (MSC). Cells were exposed to medium mixed with urine (1:1), medium mix with PBS (Phosphate Buffered Saline) (1:1), only urine, and whole medium without cells as background. The cell number was significantly lower in all groups exposed on medium mixed with urine and urine alone. The results showed that urine is a highly cytotoxic agent whose role in urologic regenerative medicine is underestimated.