Kidney diseases are among the most expensive and most debilitating diseases. Total costs are in excess of $50 billion a year, with $30 billion spent on people with end-stage renal disease including hemodialysis and kidney transplantation. People with kidney diseases have diminished quality of life, and substantial amounts of their time are devoted to medical treatment. Not surprisingly, researchers are aggressively pursuing novel therapies to treat kidney diseases before they result in end-stage renal disease. Stem cells and exosomes are among the most exciting and the most promising research topics in this area.
Most cells release tiny packets called extracellular vesicles. The most notable extracellular vesicles are exosomes. While small, exosomes are filled with high concentrations of potentially helpful substances such as RNA, DNA, and proteins. While most cells release exosomes, researchers are particularly interested in exosomes released by stem cells. It is within these exosomes that stem cells pass along the substances that make stem cells helpful in tissue repair and regeneration.
Zhang and coauthors reviewed the recent advances that have been made using exosomes to treat kidney diseases. Most of the work has focused on acute kidney injury or AKI. Acute kidney injury can lead to chronic kidney disease and kidney failure. Thus, if one could stop AKI, they could potentially reduce the risk of chronic kidney disease.
Many different research groups have shown the power of exosomes and other extracellular vesicles in treating acute kidney injury. Exosomes taken from mesenchymal stem cells protected kidney cells from cell death and fibrosis and helped them repair themselves. The same was true of exosomes derived human umbilical cord stem cells. Even stem cells taken from human liver cells were able to improve kidney function after injury. There are many other examples.
Gatti et al. reported that extracellular vesicles derived from human adult mesenchymal stem cells could protect against acute kidney injury, but, most impressively, also halted the progression of AKI to chronic kidney disease. This finding has important implications for people who suffer from serious acute kidney illnesses, such as kidney ischemia. It means that—if confirmed in human studies—stem cell-derived extracellular vesicles can help treat kidney disease in the short term and reduce the risk of that illness becoming a chronic, debilitating problem.
Further research is needed in this field but, initial results confirmed by many laboratories have created well-founded enthusiasm for the future.
Reference: Zhang, W. et al. (2016). Extracellular vesicles in diagnosis and therapy of kidney diseases. American Journal of Physiology – Renal Physiology. 2016, Nov 1; 311(5): F844-F851.