Drug delivery to central nervous pathologies is compromised by the blood-brain barrier (BBB). A clinically explored strategy to promote drug delivery across the BBB is sonopermeation, which relies on the combined use of ultrasound (US) and microbubbles (MB) to induce temporally and spatially controlled opening of the BBB. We developed an advanced in vitro BBB model to study the impact of sonopermeation on the delivery of the prototypic polymeric drug carrier pHPMA as a larger molecule and the small molecule antiviral drug ribavirin. This was done under standard and under inflammatory conditions, employing both untargeted and RGD peptide-coated MB. The BBB model is based on human cerebral capillary endothelial cells and human placental pericytes, which are co-cultivated in transwell inserts and which present with proper transendothelial electrical resistance (TEER). Sonopermeation induced a significant decrease in TEER values and facilitated the trans-BBB delivery of fluorescently labeled pHPMA (Atto488-pHPMA). To study drug delivery under inflamed endothelial conditions, which are typical for e.g. tumors, neurodegenerative diseases and CNS infections, tumor necrosis factor (TNF) was employed to induce inflammation in the BBB model. RGD-coated MB bound to and permeabilized the inflamed endothelium-pericyte co-culture model, and potently improved Atto488-pHPMA and ribavirin delivery. Taken together, our work combines in vitro BBB bioengineering with MB-mediated drug delivery enhancement, thereby providing a framework for future studies on optimization of US-mediated drug delivery to the brain.

• Keywords
• Blood-brain barrier, Drug delivery, Microbubbles, Sonopermeation, Ultrasound,
• MeSH
• Antiviral Agents administration & dosage   chemistry   pharmacology   pharmacokinetics   MeSH
• Endothelial Cells * drug effects   metabolism   MeSH
• Blood-Brain Barrier * metabolism   MeSH
• Coculture Techniques * MeSH
• Drug Delivery Systems methods   MeSH
• Humans MeSH
• Microbubbles * MeSH
• Oligopeptides * chemistry   administration & dosage   pharmacokinetics   MeSH
• Pericytes * metabolism   drug effects   MeSH
• Polymers chemistry   administration & dosage   MeSH
• Ribavirin administration & dosage   chemistry   pharmacokinetics   MeSH
• Ultrasonic Waves MeSH
• Inflammation drug therapy   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Antiviral Agents MeSH
• arginyl-glycyl-aspartic acid MeSH Browser
• Oligopeptides * MeSH
• Polymers MeSH
• Ribavirin MeSH

Rationale: The blood-brain barrier (BBB) is a major obstacle for drug delivery to the brain. Sonopermeation, which relies on the combination of ultrasound and microbubbles, has emerged as a powerful tool to permeate the BBB, enabling the extravasation of drugs and drug delivery systems (DDS) to and into the central nervous system (CNS). When aiming to improve the treatment of high medical need brain disorders, it is important to systematically study nanomedicine translocation across the sonopermeated BBB. To this end, we here employed multimodal and multiscale optical imaging to investigate the impact of DDS size on brain accumulation, extravasation and penetration upon sonopermeation. Methods: Two prototypic DDS, i.e. 10 nm-sized pHPMA polymers and 100 nm-sized PEGylated liposomes, were labeled with fluorophores and intravenously injected in healthy CD-1 nude mice. Upon sonopermeation, computed tomography-fluorescence molecular tomography, fluorescence reflectance imaging, fluorescence microscopy, confocal microscopy and stimulated emission depletion nanoscopy were used to study the effect of DDS size on their translocation across the BBB. Results: Sonopermeation treatment enabled safe and efficient opening of the BBB, which was confirmed by staining extravasated endogenous IgG. No micro-hemorrhages, edema and necrosis were detected in H&E stainings. Multimodal and multiscale optical imaging showed that sonopermeation promoted the accumulation of nanocarriers in mouse brains, and that 10 nm-sized polymeric DDS accumulated more strongly and penetrated deeper into the brain than 100 nm-sized liposomes. Conclusions: BBB opening via sonopermeation enables safe and efficient delivery of nanomedicine formulations to and into the brain. When looking at accumulation and penetration (and when neglecting issues such as drug loading capacity and therapeutic efficacy) smaller-sized DDS are found to be more suitable for drug delivery across the BBB than larger-sized DDS. These findings are valuable for better understanding and further developing nanomedicine-based strategies for the treatment of CNS disorders.

• Keywords
• Blood-brain barrier, Drug delivery, Microbubbles, Nanomedicine, Ultrasound,
• MeSH
• Fluorescent Dyes administration & dosage   MeSH
• Blood-Brain Barrier diagnostic imaging   metabolism   MeSH
• Drug Delivery Systems methods   MeSH
• Liposomes administration & dosage   MeSH
• Microbubbles MeSH
• Brain diagnostic imaging   MeSH
• Mice, Nude MeSH
• Mice MeSH
• Nanomedicine methods   MeSH
• Brain Diseases drug therapy   MeSH
• Optical Imaging methods   MeSH
• Ultrasonography methods   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Fluorescent Dyes MeSH
• Liposomes MeSH

Tumors are characterized by leaky blood vessels, and by an abnormal and heterogeneous vascular network. These pathophysiological characteristics contribute to the enhanced permeability and retention (EPR) effect, which is one of the key rationales for developing tumor-targeted drug delivery systems. Vessel abnormality and heterogeneity, however, which typically result from excessive pro-angiogenic signaling, can also hinder efficient drug delivery to and into tumors. Using histidine-rich glycoprotein (HRG) knockout and wild type mice, and HRG-overexpressing and normal t241 fibrosarcoma cells, we evaluated the effect of genetically induced and macrophage-mediated vascular normalization on the tumor accumulation and penetration of 10-20 nm-sized polymeric drug carriers based on poly(N-(2-hydroxypropyl)methacrylamide). Multimodal and multiscale optical imaging was employed to show that normalizing the tumor vasculature improves the accumulation of fluorophore-labeled polymers in tumors, and promotes their penetration out of tumor blood vessels deep into the interstitium.

• Keywords
• Drug delivery, EPR, HRG, Nanomedicine, Tumor targeting, Vascular normalization, pHPMA,
• MeSH
• Histidine-Rich Glycoprotein MeSH
• Polymethacrylic Acids metabolism   pharmacokinetics   MeSH
• Drug Delivery Systems methods   MeSH
• Mice, Inbred C57BL MeSH
• Mice, Knockout MeSH
• Mice MeSH
• Cell Line, Tumor MeSH
• Neoplasms blood supply   genetics   metabolism   MeSH
• Drug Carriers metabolism   pharmacokinetics   MeSH
• Permeability MeSH
• Proteins genetics   metabolism   MeSH
• Tissue Distribution MeSH
• Up-Regulation MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Duxon MeSH Browser
• Histidine-Rich Glycoprotein MeSH
• Polymethacrylic Acids MeSH
• Drug Carriers MeSH
• Proteins MeSH

PURPOSE: Two different monoclonal antibody-targeted HPMA copolymer-doxorubicin conjugates, classic and starlike, were synthesized to be used for site-specific cancer therapy. The anti-mouse Thy-1.2 (IgG3) and two anti-human CD71/A (IgG1) and CD71/B (IgG2a) monoclonal antibodies were used as targeting structures. METHODS: Their binding and cytotoxic activity in vitro, body distribution, and anticancer activity in vivo were evaluated. RESULTS: The results of flow cytometric analysis showed comparable binding of classic and starlike conjugates to the target cells. The in vitro cytotoxic effect was 10-fold higher if cancer cells were exposed to the starlike conjugate compared to the classic one. Biodistribution studies showed that the starlike conjugate remained in a relatively high concentration in blood, whereas the classic conjugate was found in a 6.5-times lower amount. In contrast to the low antitumor activity of free doxorubicin and nontargeted HPMA copolymer-doxorubicin conjugate, both anti-Thy-1.2 targeted conjugates (classic and starlike) cured all mice bearing T-cell lymphoma EL4. On the other hand, starlike conjugates containing anti-CD71/A or anti-CD71/B monoclonals as targeting structures were more effective against human colorectal cancer SW 620 than the classic one. CONCLUSIONS: We have shown that the starlike conjugates are more effective systems for targeted drug delivery and cancer treatment than classic conjugates.

• MeSH
• Cell Division drug effects   MeSH
• Doxorubicin chemistry   pharmacokinetics   pharmacology   MeSH
• Colorectal Neoplasms drug therapy   MeSH
• Humans MeSH
• Lymphoma, T-Cell drug therapy   MeSH
• Methacrylates chemistry   pharmacology   MeSH
• Molecular Structure MeSH
• Antibodies, Monoclonal chemistry   metabolism   MeSH
• Mice, Inbred BALB C MeSH
• Mice, Inbred C57BL MeSH
• Mice MeSH
• Cell Line, Tumor MeSH
• Prodrugs chemistry   pharmacology   MeSH
• Antibiotics, Antineoplastic chemistry   pharmacokinetics   pharmacology   MeSH
• In Vitro Techniques MeSH
• Tissue Distribution MeSH
• Neoplasm Transplantation MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Doxorubicin MeSH
• hydroxypropyl methacrylate MeSH Browser
• Methacrylates MeSH
• Antibodies, Monoclonal MeSH
• Prodrugs MeSH
• Antibiotics, Antineoplastic MeSH