Tissue engineering for the replacement of organ function in the genitourinary system

Abstract

Acquired and congenital abnormalities may lead to genitourinary organ damage or loss, requiring eventual reconstruction. Tissue engineering follows the principles of cell transplantation, materials science, and engineering toward the development of biological substitutes that would restore and maintain normal function. Tissue engineering may involve matrices alone, wherein the body's natural ability to regenerate is used to orient or direct new tissue growth, or the use of matrices with cells. Both synthetic and natural biodegradable materials have been used, either alone or as cell delivery vehicles. Tissue engineering has been applied experimentally for the reconstitution of several urologic tissues and organs, including bladder, ureter, urethra, kidney, testis, and genitalia. Fetal applications have also been explored. Recently, several tissue engineering technologies have been used clinically including the use of cells as bulking agents for the treatment of vesicoureteral reflux and incontinence and urethral replacement. Recent progress suggests that engineered genitourinary tissues may have clinical applicability in the future.

Integration of collagen matrices into the urethra when implanted as onlay graft

“…Thus, a large number of techniques have been used in the attempt to restore the anatomy of the organ, aiming to achieve adequate micturition and, in the cases of male patients, to enable forward ejaculation with an adequate amount of spermatozoids (1-5,7). All techniques used to date have a high rate of complications and, when such patients undergo several procedures, which is quite usual, the use of flaps or grafts is almost always necessary (5)(6)(7)14,15).…”

“…A decellularized matrix, either natural or synthetic, may serve as a pattern for implantation of individual cells previously obtained by harvesting a full fragment from the very organ. The different cell layers are separated by using different techniques, expanded "in vitro", and then seeded in the matrix before reimplantation (5). The different researchers that use cell-seeded matrices describe the process of matrix incorporation into the new urethra, however, not observing the manner in which this incorporation actually takes place in the early phases of tissue repair.…”

“…Urethral reconstruction is frequently used in the treatment of both congenital and acquired anomalies (1)(2)(3)(4)(5)(6). When the urethra needs to be repaired or reconstructed, either partially or totally, different surgical approaches can be used such as anastomosis of the urethral stumps, flaps or grafts.…”

“…Although such techniques are still largely employed, in several occasions adverse effects such as fistulas, stenosis, infections, stone formation, graft contracture or diverticula formation may appear. In addition to morbidity at the donor site, there is tissue scarcity when such patients undergo a number of surgical interventions (1,2,(4)(5)(6)(7)(8)(9)(10)(11)(12).…”

Epithelial-Differentiated Adipose-Derived Stem Cells Seeded Bladder Acellular Matrix Grafts for Urethral Reconstruction: An Animal Model

“…1,2 For solving the problem, studies have been performed to find an ideal substitution material for urethroplasty using tissue engineering technology. [3][4][5][6] Composite materials seeded by autologous epithelium have been tried in preclinical studies. [7][8][9] But in vitro cellular senescence, however, prevents their clinical use.…”