Cell-seeded extracellular matrices for bladder reconstruction: an ex vivo comparative study of their biomechanical properties

Biofabrication of cell-laden allografts of goat urinary bladder scaffold for organ reconstruction/regeneration

INTRODUCTION

Bladder dysfunction has been considered as one of the most critical health conditions with no proper treatment. Current therapeutic approaches including enterocystoplasty have several limitations. Hence, biofabrication of cell-laden biological allografts using decellularized Goat urinary bladder scaffolds for organ reconstruction/regeneration was major objective of this study.

MATERIALS AND METHODS

An efficient method for decellularization of Goat urinary bladder (N = 3) was developed by perfusion of gradient change of detergents through ureter. The retention of organ architecture, extracellular matrix composition, mechanical properties and removal of cellular components was characterized using histological, cellular and molecular analysis. Further, mesenchymal stem cells (MSCs) from human umbilical cord blood (UCB) were used for preparing biological construct of decellularized urinary bladder (DUB) scaffolds to augment the urinary bladder reconstruction/regeneration.

RESULTS

The decellularization method adopted in this study generated completely DUB scaffolds within 10 h at 100 mm Hg pressure and constant flow rate of 1 mL/min. The DUB scaffold retains organ architecture, ECM composition, and mechanical strength. No significant amount of residual nucleic acid was observed post-decellularization. Furthermore, MSCs derived from human UCB engrafted and proliferated well on DUB scaffolds in highly aligned manner under xeno-free condition.

CONCLUSION

Biofabricated humanized urinary bladder constructs provides xeno-free allografts for future application in augmenting urinary bladder reconstruction/regeneration with further development.

Tissue engineered extracellular matrices (ECMs) in urology: Evolution and future directions

Autologous gastrointestinal tissue has remained the gold-standard reconstructive biomaterial in urology for >100 years. Mucus-secreting epithelium is associated with lifelong metabolic and neuromechanical complications when implanted into the urinary tract. Therefore, the availability of biocompatible tissue-engineered biomaterials such as extracellular matrix (ECM) scaffolds may provide an attractive alternative for urologists. ECMs are decellularised, biodegradable membranes that have shown promise for repairing defective urinary tract segments in vitro and in vivo by inducing a host-derived tissue remodelling response after implantation. In urology, porcine small intestinal submucosa (SIS) and porcine urinary bladder matrix (UBM) are commonly selected as ECMs for tissue regeneration. Both ECMs support ingrowth of native tissue and differentiation of multi-layered urothelial and smooth muscle cells layers while providing mechanical support in vivo. In their native acellular state, ECM scaffolds can repair small urinary tract defects. Larger urinary tract segments can be repaired when ECMs are manipulated by seeding them with various cell types prior to in vivo implantation. In the present review, we evaluate and summarise the clinical potential of tissue engineered ECMs in reconstructive urology with emphasis on their long-term outcomes in urological clinical trials.

Tubular Compressed Collagen Scaffolds for Ureteral Tissue Engineering in a Flow Bioreactor System

Ureteral replacement by tissue engineering might become necessary following tissue loss after excessive ureteral trauma, after retroperitoneal cancer, or even after failed reconstructive surgery. This need has driven innovation in the design of novel scaffolds and specific cell culture techniques for urinary tract reconstruction. In this study, compressed tubular collagen scaffolds were evaluated, addressing the physical and biological characterization of acellular and cellular collagen tubes in a new flow bioreactor system, imitating the physiological pressure, peristalsis, and flow conditions of the human ureter. Collagen tubes, containing primary human smooth muscle and urothelial cells, were evaluated regarding their change in gene and protein expression under dynamic culture conditions. A maximum intraluminal pressure of 22.43 ± 0.2 cm H2O was observed in acellular tubes, resulting in a mean wall shear stress of 4 dynes/cm(2) in the tubular constructs. Dynamic conditions directed the differentiation of both cell types into their mature forms. This was confirmed by their gene expression of smooth muscle alpha-actin, smoothelin, collagen type I and III, elastin, laminin type 1 and 5, cytokeratin 8, and uroplakin 2. In addition, smooth muscle cell alignment predominantly perpendicular to the flow direction was observed, comparable to the cell orientation in native ureteral tissue. These results revealed that coculturing human smooth muscle and urothelial cells in compressed collagen tubes under human ureteral flow-mimicking conditions could lead to cell-engineered biomaterials that might ultimately be translated into clinical applications.

Application of bladder acellular matrix in urinary bladder regeneration: the state of the art and future directions

Construction of the urinary bladder de novo using tissue engineering technologies is the “holy grail” of reconstructive urology. The search for the ideal biomaterial for urinary bladder reconstruction has been ongoing for decades. One of the most promising biomaterials for this purpose seems to be bladder acellular matrix (BAM). In this review we determine the most important factors, which may affect biological and physical properties of BAM and its regeneration potential in tissue engineered urinary bladder. We also point out the directions in modification of BAM, which include incorporation of exogenous growth factors into the BAM structure. Finally, we discuss the results of the urinary bladder regeneration with cell seeded BAM.