Therapeutic potential of mesenchymal stem cells-derived exosomes on experimentally induced neurodegeneration in olfactory bulb of adult male albino rat: histological, physiological and biochemical studies

Neurodegeneration (ND) is a major medical problem in elderly. Olfactory bulb represents an early-vulnerable brain area to ND. Mesenchymal stem cells-derived exosomes are currently evaluated as a possible therapeutic agent for several diseases. This study aimed to assess exosomes-therapeutic potential on ND-induced olfactory bulb changes. Forty-five adult male albino rats were equally categorized into three groups: control (I), ND (II), and exosomes treated (III). ND was induced in groups II and III using aluminum chloride, then group III rats received a single intravenous injection of 200 µg exosomes. Buried food test was conducted to assess sense of olfaction. Blood was collected to assess serum malondialdehyde (MDA) and total antioxidant capacity (TAC) levels. Olfactory bulb specimens were prepared for histological and immunohistochemical (GFAP & synaptophysin) studies. ND group displayed a highly significant increase in buried food test time and MDA level, along with decrease in TAC level. Marked histological changes were observed affecting nerve cells, synapses, neuropil and bulb vasculature with a highly significant increase in GFAP area percentage and decrease in that of synaptophysin. Treatment with exosomes in group III markedly ameliorated these changes. These results reflected that MSCs-derived exosomes had a remarkable therapeutic potential against ND-induced changes in olfactory bulb.