Which of the following is NOT true about astrocytes?

A) They can wall off an injury site to prevent spread of inflammation.
B) They can prevent toxic substances from entering brain tissue.
C) They can release chemicals that promote formation of synapses.
D) They can aid in the regeneration of injured neurons.

Astrocytes, a type of glial cell in the brain, do not directly aid in the regeneration of injured neurons. Their primary roles include supporting neurons, forming the blood-brain barrier, and contributing to the repair and scarring process after central nervous system injury, but they do not facilitate neuronal regeneration.