Introduction: The main goal in tissue engineering is to design and create a structure similar to the natural structure of a tissue in a living organism, in order to repair tissue damage and lesions. The urethra, as one of the main organs in the urinary system, is an elastic, hollow tube with an inner wall lined with urethral cells that directs urine out of the bladder. urethra diseases can be caused by early conditions such as cancer, fistulas and congenital problems such as hypospadias and epispadias or swelling, infection, injury and injuries caused by surgery. One of the most common urinary tract problems is urethral stricture. More than 300 methods have been proposed and used to treat this disease, but in most of these methods, the reversibility of duct stenosis is very high.
In recent years, rapid advances in tissue engineering and regenerative medicine have created a new approach to urethral reconstruction and have offered promising treatment options. In this method, an alternative tissue with the same function as the original tissue is prepared in vitro or in vivo.
Polymers play an important role in tissue engineering as scaffolds, and as biological materials, they can mimic the extracellular matrix (ECM) and improve the biological behavior of cells. Scaffolds are made using natural and synthetic polymers that are biocompatible and biodegradable for urethra tissue engineering applications. Polymer selection for designing of scaffold is very important in urethra tissue engineering. Scaffolding should be able to control and mimic the structure and function of urethral tissue. The polymer used, in addition to biocompatibility and biodegradability, must also have the properties of a natural, elastic and impermeable duct to urine. Polymers used in urethra tissue engineering studies can be divided into two groups: synthetic and natural. Synthetic polymers used in tissue engineering must be compatible with the body, degradable and absorbable, and easily converted to various three-dimensional matrix structures. Natural base polymers can easily interact with biological systems and improve cellular behavior such as migration, adhesion, proliferation and differentiation.
Methods: In this study, the method of library collection, search in various texts and authoritative scientific articles has been used.
Results: A wide range of polymer scaffolds have been used to date in tissue engineering. The ideal scaffold should be biocompatible, enhance cell interaction and tissue growth, and have good mechanical and physical properties. The scaffold used to repair the urethra must be impermeable to water to prevent urine from leaking into the growing tissue. In addition, the scaffold needs to be flexible so that the urethra does not become rigid. The advantage of scaffolds containing synthetic polymers is that the structure and mechanical properties and biodegradability can be changed according to the conditions. For example, PGA degraded significantly faster than PLA. Mixing these materials in different proportions produces scaffolds whose destruction different from week to year. One of the disadvantages of these scaffolds is the lack of ECM proteins. Synthetic polymers have better mechanical properties than natural polymers, but if used alone in the scaffolding structure, inflammation and stenosis will occur in the duct. The most important advantage of using natural polymers is that they cause fewer inflammatory reactions. In natural polymers, cell differentiation, signaling and cell adhesion are better but have low mechanical strength, and some, such as collagen and silk fibroin, have high degradation rates.
Conclusion: According to studies and work done in this field, choosing the suitable polymer to regenerate the urethra is still challenging, but it seems that using a combination of polymers with different properties is a more appropriate option.