Hang T. Ta

Osteosarcoma treatment: state of the art

Osteosarcoma (OS) is a class of cancer originating from bone, mainly afflicting children or young adults. It is the second highest cause of cancer-related death in these age groups, mainly due to development of often fatal metastasis, usually in the lungs. Survival for these patients is poor despite the aggressive use of surgery, chemotherapy, and/or radiotherapy. Thus, new effective drugs and other forms of therapy are needed. This article reviews the biology and the state of the art management of OS. New experimental drugs and potential therapies targeting molecular pathways of OS are also discussed.

A chitosan-dipotassium orthophosphate hydrogel for the delivery of Doxorubicin in the treatment of osteosarcoma

The current management of primary osteosarcoma (OS) and its secondary metastasis is limited by the lack of an efficient drug delivery system. Here we report an in situ gelling chitosan/dipotassium orthophosphate hydrogel system designed to directly deliver the frontline chemotherapeutic agent (Doxorubicin) in a sustained time period to tumor sites. A significant reduction of both primary and secondary OS in a clinically relevant orthotopic model was measured when doxorubicin was administered with the hydrogel. This hydrogel delivery system also reduced cardiac and dermal toxicity of Doxorubicin in mice. The results obtained from this study demonstrate the potential application of a biodegradable hydrogel technology as an anti-cancer drug delivery system for successful chemotherapy.

A chitosan hydrogel delivery system for osteosarcoma gene therapy with pigment epithelium-derived factor combined with chemotherapy

Osteosarcoma (OS) is the most common type of malignant bone cancer, and the sixth most common type of cancer in children and young adults. Currently, gene therapy is being evaluated as a novel method for OS treatment. Here we report on an in situ gelling chitosan-based hydrogel system that sustains the release of a potential anti-cancer gene (pigment epithelium-derived factor) to the tumor site. A significant reduction of the primary OS in a clinically relevant orthotopic model was measured. The combination of plasmid treatment and chemotherapy together with the use of this delivery system led to the highest suppression of tumor growth without side effects. The results obtained from this study demonstrate the potential application of a biodegradable hydrogel technology as an anti-cancer drug delivery system for successful chemo-gene therapy.

Enzymatic Single-Chain Antibody Tagging A Universal Approach to Targeted Molecular Imaging and Cell Homing in Cardiovascular Disease

Rationale: Antibody-targeted delivery of imaging agents can enhance the sensitivity and accuracy of current imaging techniques. Similarly, homing of effector cells to disease sites increases the efficacy of regenerative cell therapy while reducing the number of cells required. Currently, targeting can be achieved via chemical conjugation to specific antibodies, which typically results in the loss of antibody functionality and in severe cell damage. An ideal conjugation technique should ensure retention of antigen-binding activity and functionality of the targeted biological component. Objective: To develop a biochemically robust, highly reproducible, and site-specific coupling method using the Staphylococcus aureus sortase A enzyme for the conjugation of a single-chain antibody (scFv) to nanoparticles and cells for molecular imaging and cell homing in cardiovascular diseases. This scFv specifically binds to activated platelets, which play a pivotal role in thrombosis, atherosclerosis, and inflammation. Methods and Results: The conjugation procedure involves chemical and enzyme-mediated coupling steps. The scFv was successfully conjugated to iron oxide particles (contrast agents for magnetic resonance imaging) and to model cells. Conjugation efficiency ranged between 50% and 70%, and bioactivity of the scFv after coupling was preserved. The targeting of scFv-coupled cells and nanoparticles to activated platelets was strong and specific as demonstrated in in vitro static adhesion assays, in a flow chamber system, in mouse intravital microscopy, and in in vivo magnetic resonance imaging of mouse carotid arteries. Conclusions: This unique biotechnological approach provides a versatile and broadly applicable tool for procuring targeted regenerative cell therapy and targeted molecular imaging in cardiovascular and inflammatory diseases and beyond.Rationale: Antibody-targeted delivery of imaging agents can enhance the sensitivity and accuracy of current imaging techniques. Similarly, homing of effector cells to disease sites increases the efficacy of regenerative cell therapy while reducing the number of cells required. Currently, targeting can be achieved via chemical conjugation to specific antibodies, which typically results in the loss of antibody functionality and in severe cell damage. An ideal conjugation technique should ensure retention of antigen-binding activity and functionality of the targeted biological component. Objective: To develop a biochemically robust, highly reproducible, and site-specific coupling method using the Staphylococcus aureus sortase A enzyme for the conjugation of a single-chain antibody (scFv) to nanoparticles and cells for molecular imaging and cell homing in cardiovascular diseases. This scFv specifically binds to activated platelets, which play a pivotal role in thrombosis, atherosclerosis, and inflammation. Methods and Results: The conjugation procedure involves chemical and enzyme-mediated coupling steps. The scFv was successfully conjugated to iron oxide particles (contrast agents for magnetic resonance imaging) and to model cells. Conjugation efficiency ranged between 50% and 70%, and bioactivity of the scFv after coupling was preserved. The targeting of scFv-coupled cells and nanoparticles to activated platelets was strong and specific as demonstrated in in vitro static adhesion assays, in a flow chamber system, in mouse intravital microscopy, and in in vivo magnetic resonance imaging of mouse carotid arteries. Conclusions: This unique biotechnological approach provides a versatile and broadly applicable tool for procuring targeted regenerative cell therapy and targeted molecular imaging in cardiovascular and inflammatory diseases and beyond. # Novelty and Significance {#article-title-36}

Particle generation, functionalization and sortase A–mediated modification with targeting of single-chain antibodies for diagnostic and therapeutic use

Antibody fusion to nonprotein materials such as contrast agents or radio-tracers, nano- or microparticles or small-molecule drugs is attracting major interest for molecular imaging and drug delivery. Nondirected bioconjugation techniques may impair antibody affinity, result in lower amounts of functional antibodies and generate multicomponent mixtures. We present a detailed protocol for the enzymatic bioconjugation of small recombinant antibodies to imaging particles, and we also describe the generation of and conjugation to a low-fouling capsule assembled for drug delivery from PEG and PVPON (poly(N-vinylpyrrolidone) by a layer-by-layer (LbL) technique. The single-chain variable fragment (scFv) is equipped with a short C-terminal LPETG tag and the fusion partners are functionalized with an N-terminal GGG nucleophilic group for sortase A conjugation. The LbL capsules are assembled through hydrogen bonding by depositing alkyne-modified poly(vinylpyrrolidone) and poly(methacrylic acid) layers on silica particles, followed by depositing alkyne-modified PEG. The generation of the antibodies and LbL capsules takes ∼1–2 weeks each. The conjugation and functional testing takes another 3–4 d.

Polymerization-Induced Self-Assembly (PISA) - Control over the Morphology of 19F-Containing Polymeric Nano-objects for Cell Uptake and Tracking

Fluorine-containing polymeric materials are receiving increasing attention as imaging probes in fluorine-19 magnetic resonance imaging (19F MRI), for example to enable quantitative in vivo detection of cells. Here we describe the one-pot polymerization synthesis of 19F-containing functional poly(oligo(ethylene glycol) methyl ether methacrylate-co-2,2,2-trifluoroethyl acrylate-b-poly(styrene-co-3-vinylbenzaldehyde) (poly(OEGA-co-TFEA)-b-poly(St-co-VBA)) copolymers as a new class of fluorinated MRI agent. A range of nanoparticle morphologies, including spheres, worm-like particles, and vesicles were formed as a consequence of polymerization-induced self-assembly (PISA). It was found that the extent of cell uptake strongly depends on the morphology of the nano-objects, with preferable uptake for worm-like particles compared to spherical nanoparticles and vesicles. All the nano-objects have a single resonance in the 19F NMR spectrum with relatively short MRI relaxation times, which were independent of the morphology of the nano-objects. These results confirm that these polymeric nano-objects of varied morphologies are promising as 19F MRI imaging agents for use in tracking of cells and selective MRI.

Self-confirming molecular imaging of activated platelets via iron oxide nanoparticles displaying unique dual MRI contrast

Magnetic resonance imaging (MRI) has been used as a powerful and indispensable tool in medical research and clinical diagnosis due to its high spatial resolution and non-limited penetration depth. The simultaneous use of positive and negative MRI imaging that employs the same contrast agents will significantly improve the detection accuracy. Here we report for the first time the development of multimodal iron oxide nanoparticles for targeted MRI of thrombosis using a combination of chemical and biological techniques.

Signalling pathways regulating galactosaminoglycan synthesis and structure in vascular smooth muscle: implications for lipoprotein binding and atherosclerosis

&NA; Atherosclerosis commences with the trapping of low density lipoproteins (LDLs) in blood vessels by modified proteoglycans (PGs) with hyperelongated glycosaminoglycan (GAG) chains. GAG chain synthesis and growth factor mediated hyperelongation regulates the composition and size of PGs in a manner that would cause low density lipoprotein (LDLs) retention in vessel wall. Galactosaminoglycans are a class of GAGs, commonly observed on PGs. Multiple enzymes are involved in galactosaminoglycan biosynthesis. Galactosaminoglycan synthesis is regulated by various signalling pathways which are amenable to pharmacological manipulation to treat atherosclerosis. Receptor mediated signalling pathways including protein tyrosine kinase receptors (PTKRs), serine/threonine kinase receptors (S/TKRs) and G‐protein coupled receptors (GPCRs) pathways regulate galactosaminoglycan synthesizing enzyme expression. Increased expression of these enzymes modify galactosaminoglycan chain structure by making them hyperelongated. This review focuses on the signalling pathways regulating the expression of genes involved in galactosaminoglycan synthesis and modification. Furthermore, there are multiple other processes for inhibiting the interactions between LDL and galactosaminoglycans such as peptide mimetics of ApoB100 and anti‐galactosaminoglycan antibodies and the therapeutic potential of these strategies is also addressed.

Enzymatic Single-Chain Antibody Tagging

Rationale: Antibody-targeted delivery of imaging agents can enhance the sensitivity and accuracy of current imaging techniques. Similarly, homing of effector cells to disease sites increases the efficacy of regenerative cell therapy while reducing the number of cells required. Currently, targeting can be achieved via chemical conjugation to specific antibodies, which typically results in the loss of antibody functionality and in severe cell damage. An ideal conjugation technique should ensure retention of antigen-binding activity and functionality of the targeted biological component. Objective: To develop a biochemically robust, highly reproducible, and site-specific coupling method using the Staphylococcus aureus sortase A enzyme for the conjugation of a single-chain antibody (scFv) to nanoparticles and cells for molecular imaging and cell homing in cardiovascular diseases. This scFv specifically binds to activated platelets, which play a pivotal role in thrombosis, atherosclerosis, and inflammation. Methods and Results: The conjugation procedure involves chemical and enzyme-mediated coupling steps. The scFv was successfully conjugated to iron oxide particles (contrast agents for magnetic resonance imaging) and to model cells. Conjugation efficiency ranged between 50% and 70%, and bioactivity of the scFv after coupling was preserved. The targeting of scFv-coupled cells and nanoparticles to activated platelets was strong and specific as demonstrated in in vitro static adhesion assays, in a flow chamber system, in mouse intravital microscopy, and in in vivo magnetic resonance imaging of mouse carotid arteries. Conclusions: This unique biotechnological approach provides a versatile and broadly applicable tool for procuring targeted regenerative cell therapy and targeted molecular imaging in cardiovascular and inflammatory diseases and beyond.Rationale: Antibody-targeted delivery of imaging agents can enhance the sensitivity and accuracy of current imaging techniques. Similarly, homing of effector cells to disease sites increases the efficacy of regenerative cell therapy while reducing the number of cells required. Currently, targeting can be achieved via chemical conjugation to specific antibodies, which typically results in the loss of antibody functionality and in severe cell damage. An ideal conjugation technique should ensure retention of antigen-binding activity and functionality of the targeted biological component. Objective: To develop a biochemically robust, highly reproducible, and site-specific coupling method using the Staphylococcus aureus sortase A enzyme for the conjugation of a single-chain antibody (scFv) to nanoparticles and cells for molecular imaging and cell homing in cardiovascular diseases. This scFv specifically binds to activated platelets, which play a pivotal role in thrombosis, atherosclerosis, and inflammation. Methods and Results: The conjugation procedure involves chemical and enzyme-mediated coupling steps. The scFv was successfully conjugated to iron oxide particles (contrast agents for magnetic resonance imaging) and to model cells. Conjugation efficiency ranged between 50% and 70%, and bioactivity of the scFv after coupling was preserved. The targeting of scFv-coupled cells and nanoparticles to activated platelets was strong and specific as demonstrated in in vitro static adhesion assays, in a flow chamber system, in mouse intravital microscopy, and in in vivo magnetic resonance imaging of mouse carotid arteries. Conclusions: This unique biotechnological approach provides a versatile and broadly applicable tool for procuring targeted regenerative cell therapy and targeted molecular imaging in cardiovascular and inflammatory diseases and beyond. # Novelty and Significance {#article-title-36}

Novel iron oxide–cerium oxide core–shell nanoparticles as a potential theranostic material for ROS related inflammatory diseases

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are key signaling molecules that play an important role in the inflammation and progression of many diseases such as cardiovascular disease, especially atherosclerosis. ROS are in particular a significant factor in the development of rheumatoid arthritis and other autoimmune diseases such as allergies. In this study, novel Fe3O4/CeO2 core-shell theranostic nanoparticles capable of reacting with ROS and of being detected by MRI were synthesized and thoroughly characterized. In vitro studies, such as measurement of cell uptake, magnetic resonance imaging, toxicity and ROS scavenging, were conducted. The results indicate that the novel Fe3O4/CeO2 theranostic nanoparticles are effective for scavenging ROS and show excellent magnetic resonance (MR) imaging performance. These theranostic nanomaterials, therefore, show great potential for the treatment and diagnosis of ROS-related inflammatory diseases.