Do you get any error messages?
You are overwriting the handle of your edit box, thus you use the wrong handle when you try to update it:
handles.edit1 = edit1; % this should throw an error unless you have an edit1 function somewhere
edit1=handles.edit1; %this would be okayish, but not necessary
I am not aware of any cell2str function. Here is a small example what might work:
handles.MyData{1}=123;
handles.edit1=uicontrol('style','edit');
set(handles.edit1,'callback',{@edit1_cb,handles})
function edit1_cb(hObj,~,handles)
set(handles.edit1,'string',num2str(handles.MyData{1}))
%set(hObj,'string',num2str(handles.MyData{1})) %this would work aswell
end
