The first idea that came in my mind is : use a mechanism which will put your datas in tables. Follow the next steps:
1.Think the structure of a 90 degrees rounded table. That means, instead of having, i.e., columns id,name,birthdate,address etc. , you will have columns id,recordid,propid,value, and records:1,1,1,'1'/2,1,2,'Marius Zaharia'/3,1,3,'1969-09-11' etc. You will have a rather difficult mission to extract normal records from this table, but this structure has a great advantage: it's very flexible; you can store practically everything here. You need it because you don't know the dimension of data.
2. Create a custom class containing the properties useful for you. The class will have to save programmatically the array(s) on the disk (in the table you created before) and to load them back in the same way, when you need them. This solution takes some time, but your datas will be safe and, as I said before, it is very flexible and independent of the data structure.