BDNF and major depressive disorder: It has been shown to have protective effects on ischemic brain injury.23 Brain-derived neurotrophic factor levels have been associated with many neurological diseases, such as Alzheimer’s, schizophrenia, and depression.14,24 The neuroprotective and therapeutic effects of MSCs together with BDNF have been demonstrated in optic nerve damage25 and neuron ventral root damage,26 axonal growth,27 Huntington's disease,28 and multiple sclerosis.29