BackgroundA key requirements for therapy utilizing the tissue engineering methodologies is use of techniques which have the capability to yield a high number of cells, from small tissue biopsy in a relatively short time. Up to date there was no optimal methods of isolation and expansion of urinary bladder smooth muscle cells (UB-SMCs). The aim of this study was to compare isolation and expansion techniques of UB-SMCs to select the most repeatable and efficient one.MethodFive protocols of porcine UB- SMCs isolation including enzymatic and explant techniques and three expansion techniques were compared. Isolation effectiveness was evaluated using trypan blue assay. Cell phenotype was confirmed by immunofluorescence staining. Proliferation rate was analyzed using MTT and X- Celligence system. Cellular senescence was assessed measuring β-galactosidase activity.ResultsEnzymatic methods using collagenase with dispase (method I) or collagenase only (method III) allowed to isolate much larger number of cells than the methods using trypsin with collagenase (method II) and collagenase after digestion with trypsin (method IV). The success rate of establishment of primary culture was the highest when the isolated cells were cultured in the Smooth muscle Growth Medium-2 (SmGM-2). Expression of the smooth muscle markers- alpha smooth muscle actin and smoothelin was the highest for cells isolated by enzymatic method I and cultured in SmGM-2. There was no significant signs of cell senescence until the 8th passage.ConclusionThe most efficient method of establishment of porcine UB-SMCs culture is enzymatic digestion of urinary bladder tissue with collagenase and dispase and culture of isolated cells in SmGM-2. This method was up to 10 times more efficient than other methods used for isolation and culture of UB-SMCs. This is an easy and consistent method for obtaining high numbers of urinary bladder smooth muscle cells.

Cell-based therapy, as practiced today, is a safe but ineffective method for SUI treatment. The key to an optimal therapeutic outcome in SUI is accurate diagnosis combined with targeted therapy. Targeted therapy in SUI should be based on cell implantation to restore and regenerate the damaged urethral sphincter and/or the construction of a neo-pubourethral ligament utilizing tissue engineering methodologies.

Many experimental approaches have been conducted in order to isolate urothelial cells from bladder tissue biopsies, but each method described has utilized different protocols and sources of bladder tissue. In this study, we compared the different methods of urothelial cell isolation available in literature together with standardized methods in order to obtain more unified results. Five methods for primary porcine urothelial culture establishment were compared: tissue explants and four enzymatic methods utilizing collagenase II, dispase II, combination of dispase II and trypsin, and trypsin alone. The average number of isolated cells, cell morphology, success of established culture, average number of cells from the first passage, expression of p63 and pancytokeratin and the characterization of urothelial cell growth, and aging were analyzed during the in vitro culture. The method utilizing dispase II was the most efficient and reproducible method for the isolation and culture of porcine urothelial cells when compared to the other tested methods. Urothelial cells obtained by this method grew considerably well and the cultures were established with high efficiency, which enabled us in obtaining a large quantity of cells with normal morphology. Contamination with fibroblasts in this method was the lowest. The utilization of a proper method for urothelial cell isolation is a critical step in the urinary tract regeneration when using tissue engineering techniques. In summary, this study demonstrated that by utilizing the described method with dispase II, a suitable number of cells was achieved, proving the method useful for tissue regeneration.

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