You can backup using normal methods. Restore is to restore to vCenter and then import back to vCloud Director. If you are restoring only the VMDKs, you might be able to power off existing VMs and restore the VMDKs as a direct replacement.
I recently presented at a vMUG conference and saw two compaines there had vCloud Aware backup Solutions.
Zerto Zerto: Data Replication and Disaster Recovery for Virtual IT and Cloud
Veeam: Veeam Backup & Replication Cloud Edition for VMware and Hyper-V