Drug Delivery Mechanisms Research Articles

Impact of Patents on Pharmaceutical Companies and Public Health: Critical Study

This paper undertakes a review of available studies to provide a perspective on the role of Intellectual Property (IP) protection in developing health care innovations in India. The relevant literature in the context of India has followed two strands: some studies focus on the implications of the new IP regime on access to health care, while others explore the implications of IP on innovation in general and medical innovation in particular. 1.product innovations in drugs; 2.process innovations in pharmaceutical industry; 3.new drug delivery mechanisms, bio-enhancers that improve bio-availability/efficacy and dosage forms; 4.product innovations in medical equipment and devices; 5.innovations in the delivery of health services; and 6.Policy innovations to enhance access to health care. “It is not always possible to attribute all the aforementioned changes to the change in the IP regime as firms and governments strategically innovate for a variety of reasons. However, in this review, we focus on two types of “innovative responses” that may affect health care access and innovation, as these may be, at least partly, a response to the changes in the IP regime”: 1.Changes in innovation inputs and outputs, reviewing studies that capture implications of IP for changes in research and development (R&D), technology licensing/collaboration, patents, and other innovations at the firm level. 2.Institutional/policy innovations in the health care sector to provide better access to health care. For the purpose of this article, all policy experiments in this space are seen as ‘innovative’ even though these may not be globally ‘novel’. The following section provides a broad overview of the Indian pharmaceutical industry and health care provision in India. The “Changes in the IP regime and IP policy innovations” section briefly discusses the changes in IP policy in recent years to help appreciate other policy and health-related innovations. The subsequent three sections summarize the insights from the literature and available evidence on the two dimensions described earlier. The final section concludes the review.

Advances in Molecularly Imprinted Polymers as Drug Delivery Systems.

Despite the tremendous efforts made in the past decades, severe side/toxic effects and poor bioavailability still represent the main challenges that hinder the clinical translation of drug molecules. This has turned the attention of investigators towards drug delivery vehicles that provide a localized and controlled drug delivery. Molecularly imprinted polymers (MIPs) as novel and versatile drug delivery vehicles have been widely studied in recent years due to the advantages of selective recognition, enhanced drug loading, sustained release, and robustness in harsh conditions. This review highlights the design and development of strategies undertaken for MIPs used as drug delivery vehicles involving different drug delivery mechanisms, such as rate-programmed, stimuli-responsive and active targeting, published during the course of the past five years.

Mechanistic Insight into How PEGylation Reduces the Efficacy of pH-Sensitive Liposomes from Molecular Dynamics Simulations.

Liposome-based drug delivery systems composed of DOPE stabilized with cholesteryl hemisuccinate (CHMS) have been proposed as a drug delivery mechanism with pH-triggered release as the anionic form (CHSa) is protonated (CHS) at reduced pH; PEGylation is known to decrease this pH sensitivity. In this manuscript, we set out to use molecular dynamics (MD) simulations with a model with all-atom resolution to provide insight into why incorporation of poly(ethyleneglycol) (PEG) into DOPE–CHMS liposomes reduces their pH sensitivity; we also address two additional questions: (1) How CHSa stabilizes DOPE bilayers into a lamellar conformation at a physiological pH of 7.4? and (2) how the change from CHSa to CHS at acidic pH triggers the destabilization of DOPE bilayers? We found that (A) CHSa stabilizes the DOPE lipid membrane by increasing the hydrophilicity of the bilayer surface, (B) when CHSa changes to CHS by pH reduction, DOPE bilayers are destabilized due to a reduction in bilayer hydrophilicity and a reduction in the area per lipid, and (C) PEG stabilizes DOPE bilayers into the lamellar phase, thus reducing the pH sensitivity of the liposomes by increasing the area per lipid through penetration into the bilayer, which is our main focus.

A feasible strategy of fabricating hybrid drugs encapsulated polymeric nanoparticles for the treatment of gastric cancer therapy

Chemotherapy of hybrid-drugs has become one of the widely used therapies for the prevention of cancers with promising clinical results. This study aimed to create compostable polymeric nanoparticles (PPNPs) for the codelivery of capsaicin (CAPS) and biotin (BT) and to examine the anticancer activity of the drug delivery mechanism (CAPS/BT@PPNPs) against in vitro and in vivo gastric cancer cells. Because of the insufficiency of double antitumor drugs BT and CAPS compressed in polymer-based bio-degradable nanoparticles, the encapsulation of BT and CAPS antitumor drugs co-loaded with polyethylene glycol and polylactidecoglycolide nanoparticles (PPNPs) is effective. Transmission electron microscopy (TEM) was utilized to investigate the structure of BT@PPNPs, CAPS@PPNPs, and BT/CAPS@PPNPs, as well as their shape and size. Human gastric carcinoma cell lines, such as SGC-791 and NCI-N87, were also induced to apoptosis in vitro by BT/CAPS@PPNPs. Morphologies and cell death were observed using bio-chemical staining methods, AO/EB (acridine orange/ethidium bromide) and Hoechst. Flow cytometry in dual staining was also used to confirm the mechanistic investigations of apoptosis. Overall, this dual drug delivery strategy suggests that BT/CAPS@PPNPs could be used as a new method to increase the efficacy of gastric therapeutics.

Sunitinib-Loaded Chondroitin Sulfate Hydrogels as a Novel Drug-Delivery Mechanism for the Treatment of Pancreatic Neuroendocrine Tumors.

Pancreatic neuroendocrine tumors (PanNETs) are increasingly common. Experts debate whether small tumors should be resected. Tumor destruction via injection of cytotoxic agents could offer a minimal invasive approach to this controversy. We hypothesize that a new drug delivery system comprising chondroitin sulfate (CS) hydrogels loaded with sunitinib (SUN) suppresses tumor growth in PanNET cells. Injectable hydrogels composed of CS modified with methacrylate groups (MA) were fabricated and loaded with SUN. Loading target was either 200 µg (SUN200-G) or 500 µg (SUN500-G) as well as sham hydrogel with no drug loading (SUN0-G). SUN release from hydrogels was monitored in vitro over time and cytotoxicity induced by the released SUN was evaluated using QGP-1 and BON1 PanNET cell lines. QGP-1 xenografts were developed in 35 mice and directly injected with 25 µL of either SUN200-G, SUN500-G, SUN0-G, 100 µL of Sunitinib Malate (SUN-inj), or given 40 mg/kg/day oral sunitinib (SUN-oral). SUN-loaded CSMA hydrogel retained complete in vitro cytotoxicity toward the QGP-1 PanNET and BON-1 PanNET cell lines for 21 days. Mouse xenograft models with QGP-1 PanNETs showed a significant delay in tumor growth in the SUN200/500-G, SUN-inj and SUN-oral groups compared with SUN0-G (p = 0.0014). SUN500-G hydrogels induced significantly more tumor necrosis than SUN0-G (p = 0.04). There was no difference in tumor growth delay between SUN200/500G, SUN-inj, and SUN-oral. This study demonstrates that CSMA hydrogels loaded with SUN suppress PanNETs growth. This drug delivery could approach represents a novel way to treat PanNETs and other neoplasms via intratumoral injection.

Niosomes as a Potential Drug Delivery System

A non-ionic vesicle dependent on surfactants is a niosome. Niosomes are mainly formed as an excipient by non-ionic surfactant and cholesterol incorporation. Various excipients can also be used. Niosomes have a greater penetrating potential than previous emulsion preparations. There are various methods of manufacturing niosomes like thin film hydration, microfluidization, sonication, bubble method to name a few. The fact that niosomes are amphiphillic molecules makes them a flexible carrier of drugs, as both hydrophilic and lipophillic drugs can be trapped. Applications of niosomes in the pharmaceutical industry are many, some of the most important ones being as cosmoceuticals, gene delivery carriers, carriers for vaccine delivery and also in medical imaging. The main object of this review the appliance of niosome technology is employed to treat variety of diseases, niosome have good opportunity in research and beneficial for researcher and pharma industries. As niosome is stable and economical, niosome seems to be a well-preferred drug delivery mechanism over liposome.

Nanoemulgel- A revolutionary approach for local gel oriented formulation

In previous years, incredible efforts have been made for different techniques of drug discovery, a variety of drug molecules available today have contributed to the resolution of the numerous health care system challenges. Unfortunately because of their restricted clinical use, more than half of such drugs have either been classified in BSC (biopharmaceutical classification system) class II / IV, or both are excluded from the development process. A nanotechnological theory acknowledges great anticipation and it is observed that lipoid processing is appropriate for the development of these drugs. From numerous nanolipoidal formulations Nanoemulsion based gel i.e. Nanoemulgel, has been considered to be an appropriate strategy for effective drug delivery across topical route. Nanoemulgel exists in two systems in which nanoemulsion containing drug is integrated in a gel base. Lipophilic drugs can be instantly integrated, and because of the finely dispersed oil droplets in the gel form, the skin absorption co-efficient of the incorporated drugs can be increased in numerous stages. At the same time, it can be more precisely targeted to the site of action and can prevent first pass metabolism and alleviate the patient from gastric/ systemic incompatibilities. The nanoemulgel drug delivery mechanism is a formulation-related technology designed to enhance drug absorption and lipophilic drug therapeutic profile. A significant growth in nanoemulgel has been noted in recent years owing to the high toleration of the formulation to the patients, due to their non-greasy, convenient spreadability, easy applicability, strong therapeutic and safety feature. Even after having few drawbacks, the formulation of nanoemulgel may in future be recognized as key and effective targets for the topical delivery of lipophilic drugs. Keywords: Nanolipoidal delivery, Nanoemulgel, Lipophilic drug, Human skin, etc.

Modern World Applications for Nano-Bio Materials: Tissue Engineering and COVID-19.

Over the past years, biomaterials-based nano cues with multi-functional characteristics have been engineered with high interest. The ease in fine tunability with maintained compliance makes an array of nano-bio materials supreme candidates for the biomedical sector of the modern world. Moreover, the multi-functional dimensions of nano-bio elements also help to maintain or even improve the patients’ life quality most securely by lowering or diminishing the adverse effects of in practice therapeutic modalities. Therefore, engineering highly efficient, reliable, compatible, and recyclable biomaterials-based novel corrective cues with multipurpose applications is essential and a core demand to tackle many human health-related challenges, e.g., the current COVID-19 pandemic. Moreover, robust engineering design and properly exploited nano-bio materials deliver wide-ranging openings for experimentation in the field of interdisciplinary and multidisciplinary scientific research. In this context, herein, it is reviewed the applications and potential on tissue engineering and therapeutics of COVID-19 of several biomaterials. Following a brief introduction is a discussion of the drug delivery routes and mechanisms of biomaterials-based nano cues with suitable examples. The second half of the review focuses on the mainstream applications changing the dynamics of 21st century materials. In the end, current challenges and recommendations are given for a healthy and foreseeable future.

Amphiphilic Core Cross-Linked Star Polymers for the Delivery of Hydrophilic Drugs from Hydrophobic Matrices.

The delivery of hydrophilic drugs from hydrophobic polymers is a long-standing challenge in the biomaterials field due to the limited solubility of the therapeutic agent within the polymer matrix. In this work, we develop a drug delivery mechanism that enables the impregnation and subsequent elution of hydrophilic drugs from a hydrophobic polymer material. This was achieved by synthesizing core cross-linked star polymer amphiphiles with hydrophilic cores and hydrophobic coronas. While significant work has been done to create nanocarriers for hydrophilic drugs, this work is distinct from previous work in that it designs amphiphilic and core cross-linked particles for controlled release from hydrophobic matrices. Ultraviolet-mediated atom transfer radical polymerization was used to synthesize the poly(ethylene glycol) (PEG)-based hydrophilic cores of the star polymers, and hydrophobic coronas of poly(caprolactone) (PCL) were then built onto the stars using ring-opening polymerization. We illustrated the cytocompatibility of PCL loaded with these star polymers through human endothelial cell adhesion and proliferation for up to 7 days, with star loadings of up to 40 wt %. We demonstrated successful loading of the hydrophilic drug heparin into the star polymer core, achieving a loading efficiency and content of 50 and 5%, respectively. Finally, the heparin-loaded star polymers were incorporated into a PCL matrix and sustained release of heparin was illustrated for over 40 days. These results support the use of core cross-linked star polymer amphiphiles for the delivery of hydrophilic drugs from hydrophobic polymer matrices. These materials were developed for application as drug-eluting and biodegradable coronary artery stents, but this flexible drug delivery platform could have impact in a broad range of medical applications.

Measurement of Peristaltic Forces Exerted by Living Intestine on Robotic Capsule

Using robotic capsules for assessing gut health has been an emerging field since the early 2000s with researchers attempting to perform diagnosis, monitoring, and therapeutic functions inside the gut. The knowledge of peristaltic forces inside the intestine are crucial for designing the actuation mechanism of robotic capsules, however, the impact of peristalsis on a capsule has not yet been quantified. In this work, an analytical model is presented to study the peristaltic movement of the small intestine. For the first time, finite element simulations were conducted in COMSOL multiphysics to generate intestinal peristaltic forces, and analyze their impact on a robotic capsule. A capsule prototype (30 × φ12 mm) was developed to measure the peristaltic forces from living intestinal tissue, while an embedded system was used simultaneously to record the live data from the capsule-intestine interaction. In in vitro experiments, the intestine applied an average axial force of 226 mN and contraction cycles of 9 times/min, while the capsule prototype experienced maximum radial force of 180 mN. A specialized in vitro setup is developed to keep fresh ex vivo intestine samples alive for up to 6 h, while the capsule prototype measured the intestinal forces from the living tissue. This in vitro experimental setup provided an excellent model for the in vivo environment in terms of generating peristaltic movements, hence this force analysis will help in developing efficient prototypes for locomotion, anchoring, localization, biopsy, drug delivery, and sampling mechanisms for robotic capsules.

Drug-Eluting Medical Textiles: From Fiber Production and Textile Fabrication to Drug Loading and Delivery.

Drug-eluting medical textiles have recently gained great attention to be used in different applications due to their cost effectiveness and unique physical and chemical properties. Using various fiber production and textile fabrication technologies, fibrous constructs with the required properties for the target drug delivery systems can be designed and fabricated. This review summarizes the current advances in the fabrication of drug-eluting medical textiles. Different fiber production methods such as melt-, wet-, and electro-spinning, and textile fabrication techniques such as knitting and weaving are explained. Moreover, various loading processes of bioactive agents to obtain drug-loaded fibrous structures with required physicochemical and morphological properties, drug delivery mechanisms, and drug release kinetics are discussed. Finally, the current applications of drug-eluting fibrous systems in wound care, tissue engineering, and transdermal drug delivery are highlighted.

Transient and Efficient Vascular Permeability Window for Adjuvant Drug Delivery Triggered by Microbeam Radiation.

Simple SummaryOne of the major challenges in the pharmacological treatment of solid tumours is ensuring that therapeutic concentrations of the agent reach and penetrate the tumour tissue. This is hampered by physiological barriers imposed by the aberrant and abnormal vessel structures of the tumours and high intratumoural pressure. We show that compound penetration into tumour tissue can be greatly enhanced by irradiating the tumour with an arrangement of discrete, synchrotron generated parallel X-rays in a range of 25–50 μm in width. This irradiation geometry induces a transient increase in vessel permeability in a time-dependent manner with a maximum between 45 min and 2 h after irradiation. The latter phenomenon was fully characterized in a vascular model of the developing chick embryo and termed “permeability window”. The reported methodology could be considered as a potent and unique drug delivery system for combined tumour treatment. This will help to create new, more efficient treatment strategies against cancer and other vascular diseases.Background: Microbeam Radiation Therapy (MRT) induces a transient vascular permeability window, which offers a novel drug-delivery system for the preferential accumulation of therapeutic compounds in tumors. MRT is a preclinical cancer treatment modality that spatially fractionates synchrotron X-rays into micrometer-wide planar microbeams which can induce transient vascular permeability, especially in the immature tumor vessels, without compromising vascular perfusion. Here, we characterized this phenomenon using Chicken Chorioallantoic Membrane (CAM) and demonstrated its therapeutic potential in human glioblastoma xenografts in mice. Methods: the developing CAM was exposed to planar-microbeams of 75 Gy peak dose with Synchrotron X-rays. Similarly, mice harboring human glioblastoma xenografts were exposed to peak microbeam doses of 150 Gy, followed by treatment with Cisplatin. Tumor progression was documented by Magnetic Resonance Imaging (MRI) and caliper measurements. Results: CAM exposed to MRT exhibited vascular permeability, beginning 15 min post-irradiation, reaching its peak from 45 min to 2 h, and ending by 4 h. We have deemed this period the “permeability window”. Morphological analysis showed partially fragmented endothelial walls as the cause of the increased transport of FITC-Dextran into the surrounding tissue and the extravasation of 100 nm microspheres (representing the upper range of nanoparticles). In the human glioblastoma xenografts, MRI measurements showed that the combined treatment dramatically reduced the tumor size by 2.75-fold and 5.25-fold, respectively, compared to MRT or Cisplatin alone. Conclusions: MRT provides a novel mechanism for drug delivery by increasing vascular transpermeability while preserving vessel integrity. This permeability window increases the therapeutic index of currently available chemotherapeutics and could be combined with other therapeutic agents such as Nanoparticles/Antibodies/etc.

Synergic fabrication of combination therapy of Irinotecan and 5-Fluorouracil encapsulated polymeric nanoparticles for the treatment of gastric cancer therapy

A novel combination therapy for the treatment of gastric cancers has been established using two or more medications with a wide range of mode of actions. The effectiveness of this hybrid drug delivery mechanism involving irinotecan (SN-38) and 5-fluorouracil (5FU) was improved based on their potent anti-tumor capacity, which increased the anticancer property of gastric cells through stabilizing the tumor microenvironment. The encapsulation of SN-38 and 5FU anticancer drugs co-loaded in polyethylene glycol (PEG) and polylactide-co-glycolide (PLGA) nanoparticles (NPs) are incompetent owing to the inadequacy of the dual anticancer drugs SN-38 and 5FU encapsulated in polymeric biodegradable nanoparticles. Transmission microscopy (TEM) was used to examine the morphology of SN-38@NPs, 5FU@NPs, and SN-38-5FU@NPs, and the structure and size of these nanoparticles. Furthermore, the stability of these nanoparticles was assessed using dynamic light scattering (DLS). SN-38-5FU@NPs also induced in vitro apoptosis of human gastric cells, such as NCI-N87 and SGC-791. Morphological shifts and cell death were detected using various biochemical staining, such as Calcein+/PI and Hoechst staining. Additionally, the mechanistic investigation of cell death was verified using flow cytometry in Annex V-FITC. Altogether, this dual drug delivery approach indicates that SN-38-5FU@NPs might be used as a potential tool to improve the effectiveness of gastric cancer therapy.

Magnetic tri-bead microrobot assisted near-infrared triggered combined photothermal and chemotherapy of cancer cells

Magnetic micro/nanorobots attracted much attention in biomedical fields because of their precise movement, manipulation, and targeting abilities. However, there is a lack of research on intelligent micro/nanorobots with stimuli-responsive drug delivery mechanisms for cancer therapy. To address this issue, we developed a type of strong covalently bound tri-bead drug delivery microrobots with NIR photothermal response azobenzene molecules attached to their carboxylic surface groups. The tri-bead microrobots are magnetic and showed good cytocompatibility even when their concentration is up to 200 µg/mL. In vitro photothermal experiments demonstrated fast NIR-responsive photothermal property; the microrobots were heated to 50 °C in 4 min, which triggered a significant increase in drug release. Motion control of the microrobots inside a microchannel demonstrated the feasibility of targeted therapy on tumor cells. Finally, experiments with lung cancer cells demonstrated the effectiveness of targeted chemo-photothermal therapy and were validated by cell viability assays. These results indicated that tri-bead microrobots have excellent potential for targeted chemo-photothermal therapy for lung cancer cell treatment.

Ultrasound-responsive polymer-based drug delivery systems.

Ultrasound-responsive polymeric materials have received a tremendous amount of attention from scientists for several decades. Compared to other stimuli-responsive materials (such as UV-, thermal-, and pH-responsive materials), these smart materials are more applicable since they allow more efficient drug delivery and targeted treatment by fairly non-invasive means. This review describes the recent advances of such ultrasound-responsive polymer-based drug delivery systems and illustrates various applications. More specifically, the mechanism of ultrasound-induced drug delivery, typical formulations, and biomedical applications (tumor therapy, disruption of blood–brain barrier, fighting infectious diseases, transdermal drug delivery, and enhanced thrombolysis) are summarized. Finally, a perspective on the future research directions for the development of ultrasound-responsive polymeric materials to facilitate a clinical translation is given.Graphical abstract

The optimum implementation of long-acting injectable cabotegravir–rilpivirine in sub-Saharan Africa

The optimum implementation of long-acting injectable cabotegravir–rilpivirine in sub-Saharan Africa

Novel approaches in development of cell penetrating peptides

Therapeutic cargos which are impermeable to the cell can be delivered by cell penetrating peptides (CPPs). CPP-cargo complexes accumulate by endocytosis inside the cells but they fail to reach the cytosolic space properly as they are often trapped in the endocytic organelles. Here the CPP mediated endosomal escape and some strategies used to increase endosomal escape of CPP-cargo conjugates are discussed with evidence. Potential benefits can be obtained by peptides such as reduction in side effects, biocompatibility, easier synthesis and can be obtained at lower administered doses. The particular peptide known as cell penetrating peptides are able to translocate themselves across membrane with the carrier drugs with different mechanisms. This is of prime importance in drug delivery systems as they have capability to cross physiological membranes. This review describes various mechanisms for effective drug delivery and associated challenges

Novel engineering: Biomimicking erythrocyte as a revolutionary platform for drugs and vaccines delivery

Over the years, extensive studies on erythrocytes, also known as red blood cells (RBCs), as a mechanism for drug delivery, have been explored mainly because the cell itself is the most abundant and has astonishing properties such as a long life span of 100–120 days, low immunogenicity, good biocompatibility, and flexibility. There are various types of RBC-based systems for drug delivery, including those that are genetically engineered, non-genetically engineered RBCs, as well as employing erythrocyte as nanocarriers for drug loading. Although promising, these systems are still in an early development stage. In this review, we aimed to highlight the development of biomimicking RBC-based drug and vaccine delivery systems, as well as the loading methods with illustrative examples. Drug-erythrocyte associations will also be discussed and highlighted in this review.We have highlighted the possibility of exploiting erythrocytes for the sustained delivery of drugs and vaccines, encapsulation of these biological agents within the erythrocyte or coupling to the surface of carrier erythrocytes, and provided insights on genetically- and non-genetically engineered erythrocytes-based strategies.Erythrocytes have been known as effective cellular carriers for therapeutic moieties for several years. Herein, we outline various loading methods that can be used to reap the benefits of these natural carriers. It has been shown that drugs and vaccines can be delivered via erythrocytes but it is important to select appropriate methods for increasing the drug encapsulated or conjugated on the surface of the erythrocyte membrane. The outlined examples will guide the selection of the most effective method as well as the impact of using erythrocytes as delivery systems for drugs and vaccines.

Efficacy and Safety of 1% Progesterone Gel to the Forehead for Ocular Chronic Graft-versus-Host Disease

There is no Food and Drug Administration-approved treatments for ocular chronic graft-versus-host disease (oGVHD) to date, and current therapeutic options are limited. Forehead application of 1% progesterone gel provides corneal antinociception in preclinical models, suggesting it may be useful in alleviating ocular irritations. This study was conducted to evaluate the efficacy and safety of 1% progesterone gel in treating moderate to severe symptomatic oGVHD. Thirty-three patients with oGVHD following allogeneic stem cell transplantation were enrolled in this single-center, sponsor-initiated, prospective exploratory randomized double-masked placebo-controlled phase II clinical trial. The inclusion criteria included a National Institutes of Health consensus score of ≥2, moderate to severe ocular discomfort level, and receipt of a stable immunosuppression regimen. Twenty-one of the 22 patients in the progesterone arm and all 11 patients in the placebo arm completed the course of twice-daily forehead drug application for 10 weeks. The changes from baseline of self-reported ocular symptom scores and physician-recorded cornea fluorescein staining scores were analyzed using mixed-model repeated-measures regression model in an intention-to-treat population. The 33 patients included 12 women and 21 men, with a median age of 66 years (range, 24 to 75 years). At 10 weeks, there was a significant reduction in ocular symptoms from baseline in the progesterone group compared with the placebo group in symptom frequency (-30.7 versus -2.2; P < .001) and severity (-19.8 versus +1.6; P=.005). At 10 weeks, there was also greater reduction of cornea fluorescein staining centrally (-1.2 versus +.1; P=.001) and inferiorly (-1.4 versus -0.2; P=.005). No difference was noted in superior cornea staining. There were no severe adverse events in the progesterone group. Foreheadapplicationof 1% progesterone gelsignificantlyimproved ocular signs and symptoms within 10 weeks. It appears to be a safe and effective new therapy for oGVHD, and a novel mechanism for neuroaxis drug delivery. A multicenter phase III clinical trial is planned for further validation.

The Preparation of Chicken Ex Ovo Embryos and Chorioallantoic Membrane Vessels as In Vivo Model for Contrast-Enhanced Ultrasound Imaging and Microbubble-Mediated Drug Delivery Studies.

The chicken embryo and the blood-vessel rich chorioallantoic membrane (CAM) is a valuable in vivo model to investigate biomedical processes, new ultrasound pulsing schemes, or novel transducers for contrast-enhanced ultrasound imaging and microbubble-mediated drug delivery. The reasons for this are the accessibility of the embryo and vessel network of the CAM as well as the low costs of the model. An important step to get access to the embryo and CAM vessels is to take the egg content out of the eggshell. In this protocol, three methods for taking the content out of the eggshell between day 5 and8 of incubation are described thus allowing the embryos to develop inside the eggshell up to these days. The described methods only require simple tools and equipment and yield a higher survival success rate of 90% for 5-day, 75% for 6-day, 50% for 7-day, and 60% for 8-day old incubated eggs in comparison to ex ovo cultured embryos (~50%). The protocol also describes how to inject cavitation nuclei, such as microbubbles, into the CAM vascular system, how to separate the membrane containing the embryo and CAM from the rest of the egg content for optically transparent studies, and how to use the chicken embryo and CAM in a variety of short-term ultrasound experiments. The in vivochicken embryo and CAM model is extremely relevant to investigate novel imaging protocols, ultrasound contrast agents, and ultrasound pulsing schemes for contrast-enhanced ultrasound imaging, and to unravel the mechanisms of ultrasound-mediated drug delivery.