Add C++ Class to CLR Project with Visual Forms

I create some classes with methods including WinApi, c++11 thread, mutex. Now I'am doing some UI to this methods in VS CLR Project where I add Form. After adding this classes .h and .cpp received errors that thread in CLR project doesnt supported. Adding System::Threading form .Net( I gues that is .net ) and include Mutex in class recieved to me error that it is non-managed class, but if I make it so (for example:public ref class ...) then the class will no longer work at all.