The protective value of neuron-derived
conditioned medium (NCM) in
cerebral ischemia and the underlying mechanism(s) responsible for NCM-mediated brain protection against
cerebral ischemia were investigated in the study. NCM was first collected from the neuronal culture growing under the in vitro ischemic condition (
glucose-,
oxygen- and serum-deprivation or GOSD) for 2, 4 or 6 h. Through the focal
cerebral ischemia (bilateral CCAO/unilateral MCAO) animal model, we discovered that
ischemia/reperfusion (I/R)-induced
brain infarction was significantly reduced by NCM, given directly into the cistern magna at the end of 90 min of CCAO/MCAO. Immunoblocking and chemical blocking strategies were applied in the in vitro ischemic studies to show that NCM supplement could protect microglia, astrocytes and neurons from GOSD-induced cell death, in a
growth factor (TGFβ1, NT-3 and
GDNF) and p-ERK dependent manner. Brain injection with TGFβ1, NT3,
GDNF and ERK agonist (DADS) alone or in combination, therefore also significantly decreased the
infarct volume of ischemic brain. Moreover, NCM could inhibit ROS but stimulate IL-1β release from GOSD-treated microglia and limit the infiltration of IL-β-positive microglia into the core area of ischemic brain, revealing the
anti-oxidant and anti-inflammatory activities of NCM. In overall, NCM-mediated brain protection against
cerebral ischemia has been demonstrated for the first time in S.D. rats, due to its anti-apoptotic,
anti-oxidant and potentially anti-
glutamate activities (NCM-induced IL-1β can inhibit the
glutamate-mediated neurotoxicity) and restriction upon the infiltration of inflammatory microglia into the core area of ischemic brain. The therapeutic potentials of NCM, TGFβ1,
GDNF, NT-3 and DADS in the control of
cerebral ischemia in human therefore have been suggested and require further investigation.