Researchers at Johns Hopkins University recently published an article in PNAS describing how neurons actually "hand-off" their used up mitochondria to astrocytes for degradation and disposal. This may have a large impact for many neurological disorders, as commented on by Science Daily:
But the implications of the results go beyond the optic nerve head, Marsh-Armstrong says, as a buildup of "garbage" inside cells causes neurodegenerative diseases such as Parkinson's, Alzheimer's and ALS. "By showing that this type of alternative disposal happens, we've opened up the door for others to investigate whether similar processes might be happening with other cell types and cellular parts other than mitochondria," he says.