Conditioned medium obtained from mesenchymal stem cells attenuates focal cerebral ischemia reperfusion injury through activation of ERK1/ ERK2-BDNF signaling pathway

Previous studies have shown that conditioned medium (CM) obtained from mesenchymal stem cells (MSCs) might exert neuroprotective effects against focal cerebral ischemia reperfusion (I/R) injury. This study was conducted to investigate if CM obtained from MSCs gives rise to neuroprotection by targeting neurogenesis. To induce focal cerebral ischemia in rats, middle cerebral artery (MCA) was occluded for 1 h and the amniotic mesenchymal stem cells-conditioned medium (AMSC-CM) at the dose of 0.5 mu l was administered 30 min after reperfusion by stereotactic intracerebral infusion. The animals were randomly divided into three groups: sham operated animals received all procedures except occlusion of MCA (sham, n = 12), I/R group only received occlusion of MCA (MCAO, n = 17), treatment group received MCAO + 0.5 mu l of AMSC-CM (MCAO + AMSC-CM, n = 17). The expression of Phospho-ERK1/ERK2, BDNF, VEGF and NGF were determined using immunohistochemical assay. Neuronal loss and DNA fragmentation were evaluated by Nissl and TUNEL assay, respectively. Our results demonstrated that the expression of Phospho-ERK1/ERK2 and BDNF, VEGF and NGF significantly decreased in MCAO rats and was reversed by AMSC-CM. Likewise, AMSC-CM markedly reduced neuronal loss and DNA fragmentation at 24 h after reperfusion. In sum, our study showed that AMSC-CM administration at the onset of reperfusion led to neuroprotection by activating neuronal ERK1/ERK2-BDNF signaling pathway, neurogenesis, angiogenesis as well as suppression of apoptosis.