Bladder: Major Pathologies

Stress Urinary Incontinence

Stress incontinence is a common medical condition that affects over 200 million people in the world. It is defined as involuntary leakage of urine with exertive actions such as coughing or sneezing that increase intra-abdominal pressure. This happens when the muscular internal or external sphincter of the bladder outlet tract, their blood supply, or their nerve supply are damaged. Current studies are comparing the use of mesenchymal and embryonic stem cells in the treatment of stress urinary incontinence versus the traditional surgical treatment. While the use of embryonic stem cells is still ethically controversial, mesenchymal stem cells from adult sources are currently being utilized. These mesenchymal stem cells can come from skeletal muscle, adipose tissue, or bone marrow. These stem cells can differentiate into a variety of tissue types and are classified as multipotent stem cells. The idea behind the use of stem cells is to regrow urethral sphincter muscle and nerve tissue by implanting the stem cells directly into the area and releasing certain factors that induce [Page 93]differentiation of the stem cells into the desired tissue type. These factors include basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF), neuregulin, and forskolin. From the current studies that have been done, the use of stem cells in treating stress urinary incontinence has demonstrated good short-term outcomes in both clinical improvement and cure rate of stress urinary incontinence. However, further studies are needed to determine overall efficacy and long-term outcomes of stem cell therapy. Using multipotent mesenchymal stem cells to restore the function of the bladder sphincter can lead to proper urinary continence and lack of leakage from the bladder into the urethra.

Neurogenic Bladder

The bladder’s ability to store and eliminate urine is controlled by a complex network of neural pathways. When there is dysfunction in these pathways, a condition termed neurogenic bladder occurs. The symptoms of neurogenic bladder are urinary incontinence, urinary retention, urinary frequency, and urinary tract infections. Neurogenic bladder can be a result of spinal cord injury, as many neural pathways involve the lower levels of the spinal cord. Current therapy includes electrical stimulation, chemotherapy, and surgery, but these methods have significant adverse side effects. There are currently studies examining the use of stem cells in regenerating the spinal cord lesions that result in neurogenic bladder. Stem cells are induced to differentiate into neuronal progenitor cells and are injected directly at the site of spinal cord injury. The L4-L5 spinal cord levels are specifically what affect bladder function and injection of neuronal progenitor cells into those levels has led to improvement of neurogenic bladder from spinal cord injury in animal models. However, more research needs to be done to evaluate the efficacy of this treatment in humans with neurogenic bladder. The ability of stem cells to differentiate into a variety of different tissues, including neural tissue, can theoretically lead to the proper innervation of the bladder and restoration of the bladder’s function and continence.

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