mice where the M2 response is impaired (discussed in a later section) that lesion size was increased relative to young animals with a more functional M2 response [70]. The M2 microglia observed during traumatic brain injury do seem to possess beneficial phenotypes that can mitigate damage associated with traumatic brain injury. For example, M2 cells recruited around sites of intracranial hemorrhage after traumatic brain injury expressed the receptor CD163, which functions in hemoglobin scavenging [39,40,77].
