We know that age-related changes in the cellular microenvironment are at least as important as changes within stem cells when it comes to declining regenerative capacity with aging. Can we do anything about that with the biotechnologies of today? Perhaps so: "When human umbilical cord blood cells (UCBC) were injected into aged laboratory animals, researchers [found] improvements in the microenvironment of the hippocampus region of the animals' brains and a subsequent rejuvenation of neural stem/progenitor cells. ... In the brain, there are two stem cell pools, one of which resides in the hippocampus. As in other stem cell pools, the stem cells in the brain lose their capacity to generate new cells. A potent stressor of stem cell proliferation is inflammation ... We think that UCBCs may have a similar potential to reduce inflammation and to restore some of the lost capacity of stem/progenitor cells to proliferate and differentiate into neurons ... Our results raise the possibility that a cell therapy could be an effective approach to improving the microenvironment of the aged brain and restoring some lost capacity."