Methods and compositions for targeting agents into and across the blood-barrier and other endothelial cell microvascular barriers

A method of delivering a therapeutic agent into and across an EC of a microvascular blood-CNS barrier in a subject, comprising administering to a DT-sensitive subject with (i) a CNS disease or disorder or (ii) a peripheral disease or disorder with CNS involvement, a composition comprising:

• (a) a therapeutic agent;
• and
• (b) a pharmaceutically acceptable carrier,
• wherein the therapeutic agent is encapsulated in a nanocontainer to which is linked a DTR-binding targeting molecule selected from the group consisting of:
• (i) a non-toxic portion of DT polypeptide chain;
• (ii) all or a portion of DT B chain;
• and
• (iii) all or a portion of a non-toxic DT mutant CRM197,
• wherein an effective barrier-entering and barrier-crossing amount of said therapeutic agent enters and crosses the EC microvascular blood CNS barrier.

A method of delivering a therapeutic agent into and across an EC of a microvascular blood-CNS barrier in a subject with a microvascular disorder, which comprises:

• (A) inducing immunological tolerance or unresponsiveness to a DTR-binding targeting molecule by administering to a DT-sensitive subject in need thereof an effective amount of:
• (i) free CRM197 or a fragment thereof;
• or
• (ii) DT B chain or a fragment thereof, and
• (B) administering to the subject a therapeutic agent with a pharmaceutically acceptable carrier, which therapeutic agent or carrier is conjugated to a targeting molecule as a conjugate that specifically binds to DTR, wherein the targeting molecule is selected from the group consisting of (i) a non-toxic portion of DT polypeptide chain;
• (ii) all or a portion of DT B chain;
• and (iii) all or a portion of a non-toxic DT mutant CRM197,
• wherein an effective barrier-entering and barrier-crossing amount of said conjugate enters and crosses the EC microvascular barrier.