Genetically engineered mesenchymal stem cells as a nitric oxide reservoir for acute kidney injury therapy.

Animals are made up of cells of different types, with each type of cell specializing on a specific role. But for the body to work properly, the different types of cells must be able to coordinate with each other to respond to internal and external stimuli. This can be achieved through signaling molecules, that is, molecules released by a cell that can elicit a specific response in other cells. There are many types of different molecules, including hormones and signaling proteins. Gases can also be potent signaling molecules, participating in various biological processes. Nitric oxide (NO) is a gas signaling molecule that can freely diffuse through the membranes of cells and has roles in blood vessel constriction and other disease processes, making it a promising therapeutic agent. Unfortunately, using artificial carriers to deliver nitric oxide to the organs and tissues where it is needed can lead to issues, including immune reactions to the carrier and long-term toxicity. One way to avoid these effects is by using cells to deliver nitric oxide to the right place. Huang, Qian, Liu et al. have used mesenchymal stem cells ­ which usually develop to form connective tissues such as bone and muscle ­ to develop a cell-based NO-delivery system. The researchers genetically modified the mesenchymal stem cells to produce a compound called ß-GAL^H363A. On its own ß-GAL^H363A does not do much, but in its presence, a non-toxic, non-reactive compound developed by Huang, Qian, Liu et al., called MGP, can drive the release of NO from cells. To confirm the usefulness of their cells as a delivery system, Huang, Qian, Liu et al. transplanted some of the genetically modified mesenchymal stem cells into the kidneys of mice, and then showed that when these mice were given MGP, the levels of NO increased in the kidneys but not in other organs. This result confirms that the cell-based delivery system provides spatial and temporal control of the production of NO. These findings demonstrate a new delivery system for therapies using gas molecules, which can be controlled spatiotemporally in mice. In the future, these types of systems could be used in the clinic for long-term treatment of conditions where artificial carriers could lead to complications.