I'm not aware of anyone with MS having benefited from injecting mice with anything! For a start, mice DON'T have MS. A disorder which mimics it can be artificially induced in the laboratory, but that doesn't mean it's the same thing. And secondly, mice are - well, mice - not people. Although both are mammals, the fact that something is effective in mice with an MS-like condition doesn't mean the same is true for humans with real MS. It also doesn't mean it would be safe or without side-effects for humans, even if it did show some promise.
So, I'd be very cautious about adopting anything into daily living, simply because it has "shown promise in mice".
Having said that, I DO take an Omega 3 supplement, because research suggests it may be beneficial for MS - but my decision to take it is not linked specifically to the mouse studies - which I didn't even know about.
If you prefer to avoid supplements, it's easy to Google which foods are rich in Omega 3.