Simply ensure that all of the matrices are stored in one cell array C, and then all you need to do is use a comma-separated list with vertcat:
M = vertcat(C{:})
MATLAB code can be so neat, simple, and efficient when people take care to design their data well!
Whatever you do, avoid magically creating/loading/acessing lots of separate variable names: this is a design decision that some beginners use to force themselves to write slow, complex, buggy, obfuscated code. Read more here:
