It has been discovered that compositions comprising magnetically heatable entities (MHEs), therapeutic agents and optional carriers such as hydrogels can be piloted from an injection point in a blood vessel to a specific location of the blood-brain barrier (BBB) using for example, a magnetic resonance imaging (MRI) device for propelling, steering and tracking of MHEs. Once the MHEs have reached their target location at or near the desired blood vessel of the BBB, an alternating magnetic field causes the MHEs to controllably heat up, thereby reversibly increasing the permeability of the BBB and allowing the therapeutic (or cytotoxic) agent to enter brain tissue.
