Exosomes with Engineered Brain Derived Neurotrophic Factor on Their Surfaces Can Proliferate Menstrual Blood Derived Mesenchymal Stem Cells: Targeted Delivery for a Protein Drug.

Despite the efficacy of brain derived neurotrophic factor (BDNF) in neuro-regenerative medicine, it can't pass the blood-brain barrier. Recently, exosomes have been harnessed for targeted delivery of therapeutics into brain. Given these facts, an engineered exosome capable of BDNF expression on the surface would be an amenable tool for drug delivery. The BDNF gene was cloned into a plex-lamp lentiviral vector and virus particles were packaged using the Torano method. HEK293T cells were transduced by the purified viruses to produce and purify recombinant exosomes displaying the fusion protein on their surfaces. Western blot, Zeta sizer, TEM, and ELISA methods were used for exosome characterization. The effect of engineered exosomes on menstrual blood-derived mesenchymal stem cells (Mens-MSCs) proliferation was evaluated by cell counting assay, MTT assay, and qPCR on the bcl2 and nestin genes. Approximately, 1.8 × 10 TdU/ml of the viral particles was purified from the transfected cells and transduced into the HEK293T. Western blot and ELISA methods confirmed the surface display of the LAMP-BDNF fusion. TEM graphs and Zeta sizer results confirmed the morphology and the size of purified exosomes. Treatment of Mens-MSCs with the targeted exosomes augmented the expression level of bcl2 and nestin genes, increased the cell proliferation, and elevated the cell number. Chimeric BDNF on the exosome surface could retain its biological activity and elevate the expression of bcl2 and nestin genes. Moreover, these exosomes are capable of elevating the Mens-MSCs proliferation.