Introduction
The potential for modern reconstructive urology treatments to improve the quality of life and restore urinary tract function is progressively becoming a reality. The second half of the 20th century saw significant growth in the methods used to reconstruct the urinary tract because of general advancements in technology and a more profound knowledge of the anatomy and histology of the urinary tract.
What Is Tissue Engineering?
Tissue engineering is one of the methods used in reconstructive medicine. It is based on the concepts of materials science (the properties of the materials used), engineering, and cell transplantation to create biological replacements that can sustain and restore normal function. In general, there are two types of tissue engineering strategies. The first involves using acellular scaffolds, which rely on the natural ability of the body to regenerate, effectively coordinate, and direct the formation of new tissue, and the second involves using scaffolds that have been seeded with cells.
Acellular scaffolds are synthetic materials that are used to deliver drugs. Usually, acellular scaffolds are made by creating synthetic scaffolds or mechanically and chemically removing cells from tissues to create acellular, collagen-rich matrices. After implantation, these matrices break down progressively and are replaced by proteins called Extracellular Matrix (ECM) released by the developing cells. Cells can also be injected for medical treatments, either alone or in combination with carriers like hydrogels.
What Is Reconstructive Urology?
Reconstructive urology is a challenging specialization of modern urology. Any surgical procedure that enhances an individual's capacity to use their urinary system is a part of reconstructive urology. It includes both reproductive and urogenital functions. Urinary reconstruction is particularly challenging due to the complexity of the cases, the need for a microsurgical approach, and the continual exposure to urine. Practical results are still inadequate because of poor healing, extensive scarring, and repeated fibrosis. Novel methods like tissue engineering technology-based solutions are gradually being studied for better, more successful outcomes.
How Is Tissue Engineering Used in Reconstructive Urology?
Tissue engineering is one approach that shows promise for overcoming most challenges in restorative urology. In addition, no special surgeries are required to get a bioengineered graft for the affected patient. This reduces the possibility of adverse reactions after harvesting, as seen in the oral mucosa. A significant advantage is the practically unlimited amount of biomaterial that can be converted into a functional graft of any size. In addition, using stem cells and biomaterials together positively impacts growth factors. Tissue engineering typically combines several methods, for example, implanting matrices containing cells into the body to encourage the development of functional tissue.
What Is the Role of Cells in Urogenital Tissue Engineering?
In most cases, donor tissue is divided into individual cells before imploding into the host. They are grown in culture conditions, placed on a support matrix, and then reimplanted following expansion when used for tissue engineering. The transplanted tissue could be autologous (obtained from the same source), allogeneic (obtained from sources that are not genetically similar), or heterologous (an entirely different source).
The source of the cells needed for regeneration is a frequent subject of concern. The idea behind creating synthetic tissue constructs is to take normal or almost normal cells from the organ that has to be replaced and grow them in a lab setting until enough is available for the selected implantation method. It has been established that genetically normal progenitor cells are the starting points for developing new cells and are found in both healthy and diseased tissue. They are rewired to give rise to normal tissue regardless of whether they are found in healthy or diseased tissues. As a result, research into the stem cell theory and its function in healthy tissue regeneration is still in progress.
What Are the Materials Used for Tissue Engineering?
Many types of biomaterials were used in the clinical research of tissue engineering. Scaffolds from tissues that were decellularized were the most frequently used. The Small Intestine Submucosa (SIS) was the first material widely employed in preclinical experiments. A large number of experiments used non-seeded SIS scaffolds. The regenerated urethra comprised circular smooth muscle layers, connective tissue, and differentiated epithelium. A patch of SIS implanted using the onlay approach for partial restoration of the urethra yielded satisfactory results. However, when done without stem cell seeding, SIS has limited effectiveness for full circumferential substitutional urethroplasty (a surgical procedure to repair the urethra).
Bladder Acellular Matrix (BAM) is another material promising for urethral repair. It is usually obtained from pig or leporine bladders. BAM scaffolds with cell seeding and tubular scaffolds were used in several preclinical experiments. Another attempt used a combination of autologous urethral tissue and the acellular Bladder Submucosa Matrix (BSM). Grated urethral tissue connected to BSM using fibrin glue was seeded into the scaffold. In comparison to reconstruction with BSM alone, the experiment produced favorable findings.
What Are the Current Challenges in Reconstructive Urology?
There are three main areas of difficulty faced by reconstructive urology at present. The primary and most important task is achieving optimal oncologic results. Finding the best functional outcomes is the second challenge. Lowering morbidity is the third key consideration in reconstructive surgery. Newly developed reconstructive materials must meet these conditions. It makes sense that tissue-engineered materials or materials that require no harvesting would be utilized, given the reconstructive materials that are currently in use.
What Are Injectable Therapies?
Urine must flow in just one direction for the urinary system to operate correctly. Flow dynamics control this mechanism. A problem with the ureter's valve-like structure as it passes through the bladder wall has been identified as vesicoureteral reflux. A weakness in the bladder's ability to resist urine leakage is the cause of urinary incontinence. Despite being two distinct conditions, both can be managed with bulking agent injections to restrict urine flow in an undesirable manner.
Biocompatible and biodegradable substances are ideal for injection. Treatment for vesicoureteral reflux with Deflux has shown promise recently. Collagen is undoubtedly a famous bulking agent for urine incontinence patients. Adults with stress incontinence caused by intrinsic sphincter deficit and children with vesicoureteral reflux can benefit from autologous chondrocytes grown in tissue culture and injected cystoscopically.
Conclusion
Reconstructive urology unquestionably requires sophisticated therapeutic techniques that use recent biotechnological advancements to increase the efficacy of present treatments. Modern reconstructive urology development trajectory perfectly aligns with tissue engineering, which focuses on manipulating cells and biomaterials. However, the method is very rarely used in urology. This is probably due to ineffective translational research and occasional skepticism among clinicians regarding tissue engineering applied outside the experimental field.
