الفهرس 
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Abstract
The kidney is capable of regeneration following injury, particularly following acute insults. Emerging evidence suggests a role for cells of renal origin in the repair and replacement of damaged renal cells in tubular and glomerular diseases.
CD24+CD133+ progenitors in the parietal epithelium of urinary pole of Bowman’s capsule are bipotent resident renal stem cells which can initiate the replacement and regeneration of both injured glomerular and tubular cells of different portions of the nephron. There are also papillary interstitial cells which are involved in renal repair especially renal tubules.
Bowman’s capsule progenitors could be subclassified. CD133+CD24+PDX− cells displayed the potential to regenerate podocytes and tubular cells. By contrast, CD133+CD24+PDX+ cells did not induce improvement of glomerular function and rarely generated podocytes suggesting that these cells display a very limited engraftment capacity. CD133−CD24−PDX+ cells did not engraft within injured human kidneys at all which is consistent with their nature of terminally differentiated cells.
Some studies have suggested that cells from bone marrow might possess a surprising degree of plasticity and could differentiate into cell types of multiple organs of the body. It has been confirmed that bone marrow-derived stem cells (BMSC) have a role in maintenance and repair of renal tubules, mesangium and endothelium.
MSC can protect against both chemical and ischaemia reperfusion injury. MSC can repair the injured kidney through variable mechanisms including homing of MSC to the injured kidney, Paracrine/Endocrine mechanism and action of MSCs on endogenous renal stem cells. It remains uncertain whether MSCs engraftment represents a transdifferentiation or cell fusion process.
HSC can contribute to the regeneration of renal tubular epithelial cells especially after ischemia reperfusion injury (I/R) where HSC can differentiate into renal tubular cells. HSCs also contributed to direct regeneration of tubules after HgCl2 induced cute tubular injury.
Bone marrow-derived cells have the potential to differentiate into glomerular mesangial cells. Circulating endothelial progenitor cells (EPC) may contribute to glomerular capillary repair.
Other types of stem cells have been used for improving kidney regeneration. For example, ES and iPS cells have a potency to differentiate into mature renal cells; however, iPS cells have a tendency to remain undifferentiated with less sensitivity to renal differentiation compared with ES cells. In addition, (hAFSC) were used for treatment of ATN.
Regeneration of parenchymal cells after acute injury is activated by a number of renotropic factors and some important genes.
Stem cells can be used also for generation of a new kidney in cases of chronic renal failure (CRF). There are attempts to establish whole kidney de novo via metanephroi transplantation or to establish self kidney from autologous mesenchymal stem cells. Kidney regeneration may also be applied for treatment of hereditary renal diseases.
The development of approaches for renal repair in human using stem cells continues to face some barriers. However, regenerative medicine for renal diseases provides significant hope for patients with renal disease who are dependent on dialysis for the rest of their lives.