Characterization of Engineered Dental Pulp Stem Cell Derived Exosomes

Retinal ischemia is a leading cause for impaired vision and retinal degradation. The traditional therapies focus on preventing the disease advancement and use intravitreal injections (anti- Vascular Endothelial Growth Factor (VEGF)), eye drops or laser treatment. Though effective in treating the symptoms, the underlying issue remains unaddressed. Stem cell therapy using mesenchymal stem cells (MSCs) has been evaluated as an experimental treatment option. Although traditionally isolated from the bone marrow, in this regard, dental pulp derived MSCs (DPSCs) can be ideal cells owing to their neural crest origin. However, drawbacks such as aberrant differentiation, dosage, cellular attachment and survival rates have hampered translational feasibility. On the other hand, MSC derived exosomes have been shown to be the principal agents of MSC paracrine function. In this study we genetically modified the DPSCs for exosome-specific expression of miR424 and tested DPSC derived Exosomes and engineered DPSC Exosomes to treat R28 retinal cells. The results indicated Exosomes being endocytosed by retinal cells in vitro in a dose, temperature dependent and saturable manner. Also, the uptake of Exosomes by retinal cells significantly increased retinal neuronal cell proliferation. When treated with Exosomes in simulated ischemic conditions (oxygen-glucose deprivation), control and engineered exosomes reduced cell death. Finally, we determined that both naïve and engineered exosomes can bind to extracellular matrix proteins such as type I collagen, fibronectin and the vitreous humor of the eye indicating that they can be delivered site-specifically, tethered to biomaterials. Overall, this study highlights the potential of DPSC-Exosomes in neuroprotection and regenerative therapy for ischemic retinal disorders and provides an insight into their applicability for tissue engineering and regenerative medicine in general.