The invention relates to a neuroprotective composition derived from mesenchymal stem cells, especially a neuroprotective composition derived from the primary culture of dental pulp mesenchymal stem cells. Processes of preparing the neuroprotective composition are claimed comprising culturing mesenchymal stem cells (MSCs) in a serum free basal culture medium for at least 3 hours to obtain a cell culture, and processing the cell culture to obtain an aqueous fraction (i.e. to produce the mesenchymal stem cell conditioned medium) with a molecular weight of no more than about 5 kDa as the neuroprotective composition. The process can use ultra-filtration or tangential flow filtration (TFF) with a molecular weight cut-off of 5 kDa to collect a filtrate passing through the filter membrane. The MSCs can be dental pulp stem cells. Compositions obtained from the aforementioned method are also claimed, along with the medical use of the compositions in the treatment of neurological diseases associated with neuronal damage, including subarachnoid haemorrhage and Parkinson’s disease.