Identifying Exosomes as a Messenger Unit During Heterochronic Parabiosis for Amelioration of Huntington’s Disease

Abstract

<jats:title>Abstract</jats:title> <jats:p><jats:bold>Background:</jats:bold>Huntington’s disease (HD) starts its pathology long before clinical manifestation, however, there is no therapy to cure it completely and only a few studies have been reported for delaying the progression of HD. We demonstrated the blood sharing effect by heterochronic parabiosis in HD and explored the underlying mechanism for transferring positive factors in the young blood serum.A shared blood circulation by heterochronic parabiosis has improved behavioral performance and HD pathology through mediation of mitochondria dysfunction and cell death. Furthermore, the messenger unit for the effective components in young blood is identified for the first time to the best of our knowledge.<jats:bold>Methods:</jats:bold>R6/2 mice were surgically connected with young wild-type mice (n=13), old wild-type mice (n=8), or R6/2 mice (n=6) to examine the effect of heterochronic parabiosis.Parabionts composed of 5- to 6-week-old transgenic and wild-type mice were observed for 6 weeks in a single cage. The <jats:italic>in vitro </jats:italic>cellular model of HD cells were treated by the 200 μg/mlblood serum of the young or old mice, and by the exosomes isolated from thereof. The<jats:italic>in vitro </jats:italic>cellular model of HD were developed by differentiating neural stem cells cultured from SVZ of the brain.<jats:bold>Results:</jats:bold>After the heterochronic parabiosis, the weight loss and survival of HD mice was improved, and also, mutant Huntingtin aggregation (EM48 p&lt;0.005), improvement of mitochondria dysfunction (PGC-1a p&lt;0.05, p-CREB/CREB p&lt;0.005), cell death (p53 p&lt;0.05, Bax p&lt;0.05, Cleaved-caspase3 p&lt;0.05),and cognition (DCX p&lt;0.5) showed a near complete restoration. In addition, treatment of exosomes from young blood serum to the<jats:italic>in vitro </jats:italic>cellular model of HD improved mutant Huntingtin aggregation (EM48 p&lt;0.05), mitochondria biogenesis (p-CREB/CREB p&lt;0.005), cell death (p53 p&lt;0.05, Bax p&lt;0.005, Cleaved-caspase3 p&lt;0.05, Bcl-2 p&lt;0.05), and cell proliferation (WST-1 p&lt;0.005).<jats:bold>Conclusions:</jats:bold>We found that the overall pathology of HD is improved by the shared blood circulation through heterochronic parabiosis, furthermore, we demonstrated that the exosomes are messengers for transferring positive factors,showing the potential of exosomes from young bloodfor the amelioration of HD.</jats:p>