Adult stem cells can be used in urinary tract regeneration, especially hair follicle and bone marrow mesenchymal stem cells. These stem cell populations show high plasticity potential and can differentiate into urothelium and muscle layer in vitro under defined culture conditions.
The urinary system involves the kidney, ureter, bladder, and urethra. The upper urinary tract is made up of the kidneys while the other structures are the components of the lower urinary tract. Urine that is formed in the kidney drains into the renal pelvis, ureter, and bladder. Finally, urine stored in the bladder is excreted through the urethra. Among the whole urinary system, the kidney is the core organ to reabsorb water and concentrate urine.
Urine concentration and dilution mainly proceed in the kidney by regulating water excretion and reabsorption. During water excretion and reabsorption, water permeability in the proximal tubules, descending limbs of Henle, late distal tubules and collecting ducts is very important. In contrast, those segments (such as ascending limbs of Henle) of the nephrons that are continuously impermeable to water are also necessary to establish an osmotic gradient from renal cortex to inner medulla. Antidiuretic hormone (ADH) regulates the urine concentration by changing the water permeability of late distal tubules and collecting ducts. The water permeability in certain segments of renal tubules, collecting ducts and vasa recta is mediated by water channel aquaporins (AQPs) in the plasma membrane of epithelium and endothelium.
Stem cells can undergo self-renewal and multidirectional differentiation. There are several potential sources of stem cells for the treatment of stress urinary incontinence, like bone marrow stromal stem cells, muscle-derived stem cells, and adipose-derived stem cells. Stem cells injection therapy increased leak point pressure and urethral muscle strip contractility in experimental models of stress urinary incontinence.
Kidney disease and its related complications are an important issue of public health worldwide. Broadly defined, kidney regeneration includes both renal repair and regrowth of partial or whole nephron in kidney disease. Stem cells including BMDCs, autologous adipose-derived mesenchymal stem cells (ADMStem cells), embryonic stem (ES) cells, induced pluripotent stem (iPS) cells, and renal stem/progenitor cells all play roles in the repair of damaged renal tissue.
Fig.1 The application of reprogramming to the kidney. (Takaori, 2014)
Utilizing stem cells to regenerate has been researched in bladder disorders, female and SUI, and BOO. Tissue engineering techniques have been tried to overcome the limitations associated with the conventional use of bowel to augment and repair bladders with decreased bladder capacity or compliance. Regenerative bladder replacement has involved the use of scaffolds that are either acellular or seeded with stem cells. These scaffolds are degradable, biocompatible materials that promote tissue development. Research into the use of stem cells for female SUI is close to reaching clinical maturity with autologous muscle-derived cells used to augment urethral sphincter function in women with an intrinsic sphincteric deficiency (ISD).
The rapidly growing research in the use of stem cells is thought to promote progress in urinary system therapy, and its identification shows the way forward for future research. Research of stem cells recently focus on:
Reference
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