Regenerative Medicine in Urology: Urethral Reconstruction

Organ regeneration has different aspects including tissue engineering,stem cells and colonizing. Tissue engineering is the main part ofregenerative medicine, in which cell transplantation rules, material sciences and tissue engineering are applied to develop biologicsubstitutes to reproduce and maintain natural organ functions. Tissueengineering strategies can be categorized in 2 main parts: cellular andacellular matrix. Acellular tissue matrix has been reproduced by scaffoldproduction or by eliminating cell content of tissue by mechanicalor chemical manipulation in order to produce collagen-rich matrix.The cells then will be implanted on matrix and gradually reproducenew matrix. This new matrix tends to replace the extracellular matrix(ECM). The other ways to use cells for therapeutic goals are injection,hydrogels transporting or even solely. These cells can directly or afterproliferation on a scaffold be implanted into recipient. This will result inleast complications of functional and structural nature of cells. The bestautologous cells are the cells obtained by a biopsy and then isolationand proliferation of cells in a medium and finally implanting them inrecipient. However, this process can result in inflammatory responses butthe lethal side effects of immunosuppressant drugs is prevented. In themajority of patients with significant organ failure it is impossible to obtainsufficient healthy cells through a biopsy, in these cases stem cells whichare purified from other sources as embryonic, bone marrow and adiposetissue cells are a valuable alternative. Nowadays, a significant advancein tissue engineering in the field of genitourinary (GU) system has beenachieved. The most significant advancements are obtained in the Urethraland Bladder regeneration. Various strategies have been projected overthe years for the regeneration of urethral tissue. Woven meshes of PGAwithout cells and with cells have been utilized to regenerate urethras invarious animal models. Naturally derived collagen-based materials (e.g.,bladder-derived acellular submucosa, acellular urethral submucosa, andcollagen gels) have also been examined experimentally in various animalmodels in terms of urethral reconstruction. The bladder submucosamatrix proved to be an appropriate graft for the repair of urethral defectsin rabbits. The neourethras showed a normal urothelial luminal liningand organized muscle bundles. These findings were clinically validatedin a series of patients with a history of failed hypospadias reconstructionwherein the urethral defects were repaired with human bladder acellularcollagen matrices.

کلیدواژه ها:

Regenerative medicine ، Urology ، Urethral reconstruction