The inability of the neurons to regenerate has encouraged thescientists to search for a method to replace damaged or dead nerve cells.Parkinson disease (PD) is the most common neurodegenerative disorder,affecting 2% of individuals over age 65 and 4-5% over 85 years, and it iscaused by the loss of dopaminergic (DA) neurons. There is no effectivetreatment for PD and the disease progression cannot be counteracted, aswell as over time the side effects of medications appear. Therefore, nervecell replacement is an important therapeutic option for PD. The aim of this study was to explore the in-vitro ability of humanMSCs derived from peripheral blood, after their mobilization from bonemarrow, to differentiate into DA neurons. Peripheral blood mononuclear cells (MNCs) were obtained from 10healthy donors undergoing stem cell mobilization for stem celltransplantation after confirmed verbal consent. The age of the donorsranged from 25 to 35 years. They were 8 males and 2 females. Thedonors were subcutaneously injected with Granulocyte-colonystimulating factor (G-CSF) in a single daily dose of 10 μg/kg for 5 days.Then collection of MNCs by apheresis was done on the fifth day one hourafter injection of the last dose. Total leucocytic counts were done before and after mobilization.Culture and separation of MSCs were done. Cell viability test was doneafter culture, and immunophenotyping of CD44 cells was done beforeand after culture. Differentiation of MSCs into neural lineage was doneusing nerve growth factor, while differentiation into DA neurons wasdone after using ascorbic acid. Immunostaining was done using antineurofilament (NF) and anti tyrosine hydroxylase (TH) antibodies. Colonies of MSCs were detected by the inverted microscope 3 daysafter culture and they increased markedly after 7 days. Culturedspecimens immunostained with anti NF and anti TH antibodies showedscattered immunopositive cells (brown deposits). The percentage of cellsstained for NF was 15.38±3.84, while the percentage of cells stained forTH was 5.94±0.65.