Development and pre-clinical evaluation of recombinant human myelin basic protein nano therapeutic vaccine in experimental autoimmune encephalomyelitis mice animal model

Recombinant human myelin basic protein (rhMBP) was previously produced in the milk of transgenic cows. In this study the activity of rhMBP as a therapeutic vaccine against multiple sclerosis (MS) was investigated using experimental autoimmune encephalomyelitis (EAE) animal model. The rhMBP was tested in its free form and when formulated into controlled released poly(ε-caprolactone) nanoparticles (NPs). Following optimization of NP formulation, spherical, rough-surfaced rhMBP NPs (294±21 nm, -18.6±8.40 mV) with entrapment efficiency of 99.86±1.7%, release pattern 5.5±0.12% and 48.4±5.30% over 1 h and 3 days, respectively were obtained. Results indicated that rhMBP was both loaded into and electrostatically adsorbed onto the surface of NPs. Subcutaneous administration of free and rhMBP NPs (100µg/mice) for 8 days before EAE-induction reduced the average behavioral score of mice from 2.1±0.34 to 1.38±0.20 and 1.11±0.18 for free and rhMBP NPs, respectively. Mice brains of EAE-induced group showed focal gliosis where astrocytosis replaced the encephalomalitic areas. Focal deep eosinophilic plagues were formed in cerebrum of mice pretreated with free rhMBP. On the other hand, mice pretreated with rhMBP NPs showed only mild histological alterations. Luxol fast blue/periodic acid-Schiff’s stain of mice brains in EAE-induced group indicated complete demyelination, whereas groups pretreated with free or rhMBP NPs displayed preservation of myelin sheath, with the latter group showing better protection. Analysis of inflammatory cytokines in mice brains revealed that pretreatment with free or rhMBP NPs significantly protected against induced inflammation where IFN-γ levels decreased from 115.46±7.20 in case of EAE-induced mice to 53.08±2.23 and 41.20±2.01pg/g, while the IL-10 levels were elevated from 14.80±0.92 to 31.10±2.02 and 41.12±2.11pg/g, respectively. In conclusion: i) rhMBP ameliorated EAE symptoms in mice animal model, ii) nanoformulation significantly enhanced the efficacy of rhMBP as a therapeutic vaccine and iii) clinical investigations are required in order to demonstrate the activity of rhMBP NPs as a therapeutic vaccine for Multiple Sclerosis.