Impact of net charge, targeting ligand amount and mRNA modification on the uptake, intracellular routing and the transfection efficiency of mRNA lipopolyplexes in dendritic cells

Targeting mRNA formulations to achieve cell specificity is one of the challenges that must be tackled to mettle their therapeutic potential. Here, lipopolyplexes (LPR) bearing tri-mannose-lipid (TM) are used to target mannose receptor on dendritic cells. We investigated the impact of the net charge and percentage of TM units on the binding, uptake, transfection efficiency (TE) and RNA sensors activation. Binding and uptake capacities of naked and targeted LPR increase with the percent of cationic lipid, but the latter are 2-fold more up taken by the cells. Cationic LPR bearing 5 % and 10 % TM were localized in acidic compartments in contrast to naked LPR and 2.5 % TM-LPR. The drawback is the dramatic decrease of TE as the number of TM-units increases. Cationic LPR bearing 5 % and 10 % TM strongly induced NF-κB and PKR phosphorylation at 6 h. Conversely, mTOR is less activated in line with their low TE. Those side effects are overcome by using 5-methoxyuridine mRNA resulting in an improved TE due to non-phosphorylation of NF-κB and PKR and mTOR activation. Our results point out that targeting DC via mannose receptor triggers a higher uptake of cationic LPRs and fast routing to acidic compartments, and that efficient TE requires low number of TM units use or modified mRNA to escape RNA sensors activation to enhance the translation.

High-precision targeting and destruction of cancer-associated PDGFR-β+ stromal fibroblasts through self-assembling, protein-only nanoparticles

The need for more effective and precision medicines for cancer has pushed the exploration of new materials appropriate for drug delivery and imaging, and alternative receptors for targeting. Among the most promising strategies, finding suitable cell surface receptors and targeting agents for cancer-associated platelet derived growth factor receptor β (PDGFR-β)+ stromal fibroblasts is highly appealing. As a neglected target, this cell type mechanically and biologically supports the growth, progression, and infiltration of solid tumors in non-small cell lung, breast, pancreatic, and colorectal cancers. We have developed a family of PDGFR-β-targeted nanoparticles based on biofabricated, self-assembling proteins, upon hierarchical and iterative selective processes starting from four initial candidates. The modular protein PDGFD-GFP-H6 is well produced in recombinant bacteria, resulting in structurally robust oligomeric particles that selectively penetrates into PDGFR-β+ stromal fibroblasts in a dose-dependent manner, by means of the PDGFR-β ligand PDGFD. Upon in vivo administration, these GFP-carrying protein nanoparticles precisely accumulate in tumor tissues and enlighten them for IVIS observation. When GFP is replaced by a microbial toxin, selective tumor tissue destruction is observed associated with a significant reduction in tumor volume growth. The presented data validate the PDGFR-β/PDGFD pair as a promising toolbox for targeted drug delivery in the tumor microenvironment and oligomeric protein nanoparticles as a powerful instrument to mediate highly selective biosafe targeting in cancer through non-cancer cells. STATEMENT OF SIGNIFICANCE: We have developed a transversal platform for nanoparticle-based drug delivery into cancer-associated fibroblasts. This is based on the engineered modular protein PDGFD-GFP-H6 that spontaneously self-assemble and selectively penetrates into PDGFR-β+ stromal fibroblasts in a dose-dependent manner, by means of the PDGFR-β ligand PDGFD. In vivo, these protein nanoparticles accumulate in tumor and when incorporating a microbial toxin, they destroy tumor tissues with a significant reduction in tumor volume, in absence of side toxicities. The data presented here validate the PDGFR-β/PDGFD pair as a fully versatile toolbox for targeted drug delivery in the tumor microenvironment intended as a synergistic treatment.

Protein corona investigations of polyplexes with varying hydrophobicity - From method development to in vitro studies

In the field of non-viral drug delivery, polyplexes (PXs) represent an advanced investigated and highly promising tool for the delivery of nucleic acids. Upon encountering physiological fluids, they adsorb biological molecules to form a protein corona (PC), that influence PXs biodistribution, transfection efficiencies and targeting abilities. In an effort to understand protein - PX interactions and the effect of PX material on corona composition, we utilized cationic branched 10 kDa polyethyleneimine (b-PEI) and a hydrophobically modified nylon-3 polymer (NM0.2/CP0.8) within this study to develop appropriate methods for PC investigations. A centrifugation procedure for isolating hard corona - PX complexes (PCPXs) from soft corona proteins after incubating the PXs in fetal bovine serum (FBS) for PC formation was successfully optimized and the identification of proteins by a liquid chromatography-tandem mass spectrometry (LC-MS-MS) method clearly demonstrated that the PC composition is affected by the underlying PXs material. With regard to especially interesting functional proteins, which might be able to induce active targeting effects, several candidates could be detected on b-PEI and NM0.2/CP0.8 PXs. These results are of high interest to better understand how the design of PXs impacts the PC composition and subsequently PCPXs-cell interactions to enable precise adjustment of PXs for targeted drug delivery.

Therapeutic in vivo synthetic chemistry using an artificial metalloenzyme with glycosylated human serum albumin

The concept of "therapeutic in vivo synthetic chemistry" refers to chemical synthesis in living systems using new-to-nature reactions for the treatment or diagnosis of diseases. This review summarizes our development of therapeutic in vivo synthetic chemistry using glycan-modified human serum albumin (glycoHSA) and utilizing the selective glycan-targeting and metal protective effects of metal catalysts. The four artificial metalloenzymes with glycoHSA provided good cancer treatment results based on on-site drug synthesis and selective cell-tagging strategies. Thus, we propose that therapeutic in vivo synthetic chemistry using glycoHSA as a new modality of therapy or diagnosis is applicable to a wide range of diseases.

Bovine serum albumin-gold nanoclusters protein corona stabilized polystyrene nanoparticles as dual-color fluorescent nanoprobes for breast cancer detection

Breast cancer is the most prevalent malignancy and the first leading cause of cancer-related mortality among the female population worldwide. Approaches for precise and reliable detection of breast cancer cells, particularly in the nascent state, are desperately needed for elevating the survival rate of patients bearing the breast tumor. In this work, we successfully performed the sensitive, precise, and reliable breast cancer cell detection using facilely fabricated bovine serum albumin-gold nanocluster (BSA-AuNCs) protein corona stabilized, epithelial cell adhesion molecule (EpCAM) aptamer linked fluorescent polystyrene nanoparticle (PS NP), termed as PS-BSA-AuNCs-Apt. The rapidly adsorbed BSA-AuNCs hard protein corona without complicated covalent conjugation not only imparted excellent colloidal stability to the PS nanoparticles, but also offered numerous active anchors for the targeted EpCAM aptamers to locate. With the remarkable aid of the aptamers specifically targeting the EpCAM-positive breast cancer cells, the PS-BSA-AuNCs-Apt emitted strong and photostable dual-color fluorescent signals for precise and reliable cancer cell detection by overcoming the false signals. The specific identification potency of the PS-BSA-AuNCs-Apt system was further verified by successfully detecting the xenografted breast tumor tissue. Notably, to the best of our knowledge, the protein corona formed nanoprobes was exploited for direct tumor cell and tissue detection with high efficacy for the first time, demonstrating their promising potential in clinical tumor detection.

Recyclable cell-surface chemical tags for repetitive cancer targeting

Metabolic glycan labeling provides a facile yet powerful tool to install chemical tags to the cell membrane via metabolic glycoengineering processes of unnatural sugars. These cell-surface chemical tags can then mediate targeted conjugation of therapeutic agents via efficient chemistries, which has been extensively explored for cancer-targeted treatment. However, the commonly used in vivo chemistries such as azide-cyclooctyne and tetrazine-cyclooctene chemistries only allow for one-time use of cell-surface chemical tags, posing a challenge for long-term, continuous cell targeting. Here we show that cell-surface ketone groups can be recycled back to the cell membrane after covalent conjugation with hydrazide-bearing molecules, enabling repetitive targeting of hydrazide-bearing agents. Upon conjugation to ketone-labeled cancer cells via a pH-responsive hydrazone linkage, Alexa Fluor 488-hydrazide became internalized and entered endosomes/lysosomes where ketone-sugars can be released and recycled. The recycled ketone groups could then mediate targeted conjugation of Alexa Fluor 647-hydrazide. We also showed that doxorubicin-hydrazide can be targeted to ketone-labeled cancer cells for enhanced cancer cell killing. This study validates the recyclability of cell-surface chemical tags for repetitive targeting of cancer cells with the use of a reversible chemistry, which will greatly facilitate future development of potent cancer-targeted therapies based on metabolic glycan labeling.

Self-assembling protein nanocarrier for selective delivery of cytotoxic polypeptides to CXCR4+ head and neck squamous cell carcinoma tumors

Loco-regional recurrences and distant metastases represent the main cause of head and neck squamous cell carcinoma (HNSCC) mortality. The overexpression of chemokine receptor 4 (CXCR4) in HNSCC primary tumors associates with higher risk of developing loco-regional recurrences and distant metastases, thus making CXCR4 an ideal entry pathway for targeted drug delivery. In this context, our group has generated the self-assembling protein nanocarrier T22-GFP-H6, displaying multiple T22 peptidic ligands that specifically target CXCR4. This study aimed to validate T22-GFP-H6 as a suitable nanocarrier to selectively deliver cytotoxic agents to CXCR4⁺ tumors in a HNSCC model. Here we demonstrate that T22-GFP-H6 selectively internalizes in CXCR4⁺ HNSCC cells, achieving a high accumulation in CXCR4⁺ tumors in vivo, while showing negligible nanocarrier distribution in non-tumor bearing organs. Moreover, this T22-empowered nanocarrier can incorporate bacterial toxin domains to generate therapeutic nanotoxins that induce cell death in CXCR4-overexpressing tumors in the absence of histological alterations in normal organs. Altogether, these results show the potential use of this T22-empowered nanocarrier platform to incorporate polypeptidic domains of choice to selectively eliminate CXCR4⁺ cells in HNSCC. Remarkably, to our knowledge, this is the first study testing targeted protein-only nanoparticles in this cancer type, which may represent a novel treatment approach for HNSCC patients.

Targeting HER2 protein in individual cells using ICP-MS detection and its potential as prognostic and predictive breast cancer biomarker

The human epidermal growth factor receptor 2 (HER2) is a transmembrane protein that has become one of the most specific prognostic and predictive biomarker of breast cancer. Its early detection is key for optimizing the patient clinical outcome. This work is focused on the detection of HER2 in individual cells using an antibody containing lutetium (Lu) as reporter group that is monitored by introducing the individual cells into the inductively coupled plasma mass spectrometer (ICP-MS). This Lu-containing antibody probe is used to label different breast cancer cell lines considered HER2 negative (MDA-MB-231) and positive (SKBR-3 and BT-474). Optimizations regarding the amount of the probe necessary to ensure complete labelling reactions are conducted in the different cell models. Concentrations in the range of 0.006 fg Lu/cell and 0.030 fg Lu/cell could be found in the HER2 negative and HER2 positive cells, respectively. In addition, the selectivity of the labelling reaction is tested by using two different metal-containing antibody probes for HER2 (containing Lu) and for transferrin receptor 1 (containing Nd), respectively, within the same cell population. Finally, the methodology is applied to the targeting of HER2 positive cells in complex cell mixtures containing variable amounts of BT-474 and MDA-MB-231 cells. The obtained results showed the excellent capabilities of the proposed strategy to discriminate among cell populations. This finding could help for scoring HER2 positive tumors improving existing technologies.

Multifunctional antibody-conjugated coiled-coil protein nanoparticles for selective cell targeting

Nanostructures decorated with antibodies (Abs) are applied in bioimaging and therapeutics. However, most covalent conjugation strategies affect Abs functionality. In this study, we aimed to create protein-based nanoparticles to which intact Abs can be attached through tight, specific, and noncovalent interactions. Initially considered waste products, bacterial inclusion bodies (IBs) have been used in biotechnology and biomedicine. However, the amyloid-like nature of IBs limits their functionality and raises safety concerns. To bypass these obstacles, we have recently developed highly functional α-helix-rich IBs exploiting the natural self-assembly capacity of coiled-coil domains. We used this approach to create spherical, submicrometric, biocompatible and fluorescent protein nanoparticles capable of capturing Abs with high affinity. We showed that these IBs can be exploited for Ab-directed cell targeting. Simultaneous decoration of the nanoparticles with two different Abs in a controllable ratio enabled the construction of a bispecific antibody mimic that redirected T lymphocytes specifically to cancer cells. Overall, we describe an easy and cost-effective strategy to produce multivalent, traceable protein nanostructures with the potential to be used for biomedical applications. STATEMENT OF SIGNIFICANCE: Functional inclusion bodies (IBs) are promising platforms for biomedical and biotechnological applications. These nanoparticles are usually sustained by amyloid-like interactions, which imposes some limitations on their use. In this work, we exploit the natural coiled-coil self-assembly properties to create highly functional, nonamyloid, and fluorescent IBs capable of capturing antibodies. These protein-based nanoparticles are successfully used to specifically and simultaneously target two unrelated cell types and bring them close together, becoming a technology with potential application in bioimaging and immunotherapy.

Synthesis, structure and anticancer properties of new biotin- and morpholine-functionalized ruthenium and osmium half-sandwich complexes

Ruthenium (Ru) and osmium (Os) complexes are of sustained interest in cancer research and may be alternative to platinum-based therapy. We detail here three new series of ruthenium and osmium complexes, supported by physico-chemical characterizations, including time-dependent density functional theory, a combined experimental and computational study on the aquation reactions and the nature of the metal-arene bond. Cytotoxic profiles were then evaluated on several cancer cell lines although with limited success. Further investigations were, however, performed on the most active series using a genetic approach based on RNA interference and highlighted a potential multi-target mechanism of action through topoisomerase II, mitotic spindle, HDAC and DNMT inhibition.

Peptide conjugation enhances the cellular co-localization, but not endosomal escape, of modular poly(acrylamide-co-methacrylic acid) nanogels

Nanoparticles must recognize, adhere to, and/or traverse multiple barriers in sequence to achieve cytosolic drug delivery. New nanoparticles often exhibit a unique ability to cross a single barrier (i.e. the vasculature, cell membrane, or endosomal compartment), but fail to deliver an adequate dose to intracellular sites of action because they cannot traverse other biological barriers for which they were not optimized. Here, we developed poly(acrylamide-co-methacrylic acid) nanogels that were modified in a modular manner with bioactive peptides. This nanogel does not recognize target cells or disrupt endosomal vesicles in its unmodified state, but can incorporate peptides with molecular recognition or environmentally responsive properties. Nanogels were modified with up to 15 wt% peptide without significantly altering their size, surface charge, or stability in aqueous buffer. Nanogels modified with a colon cancer-targeting oligopeptide exhibited up to a 324% enhancement in co-localization with SW-48 colon cancer cells in vitro, while influencing nanogel uptake by fibroblasts and macrophages to a lesser extent. Nanogels modified with an endosome disrupting peptide failed to retain its native endosomolytic activity, when coupled either individually or in combination with the targeting peptide. Our results offer a proof-of-concept for modifying synthetic nanogels with a combination of peptides that address barriers to cytosolic delivery individually and in tandem. Our data further motivate the need to identify endosome disrupting moieties which retain their activity within poly(acidic) networks.

Clickable modular polysaccharide nanoparticles for selective cell-targeting

A therapeutic nanocarrier capable of cell targeting has the potential to reduce off-target effects of otherwise effective drugs. Nanoparticle surface modification can be tailored for specific cells, however multistep surface modification can prove slow and difficult for a variety of cell types. Here, we designed drug carrying polysaccharide based nanoparticles with a layered structure for clickable surface modification. The center of nanoparticle was composed of cationic macromer (e.g., poly-l-lysine) and anionic polysaccharide (e.g., heparin). Furthermore, a 'clickable' polysaccharide was installed on the surface of the nanoparticles to permit a wide range of bioconjugation via norbornene-tetrazine click chemistry. The utilities of these layered nanoparticles were demonstrated via enhanced protein sequestration, selective cell targeting (via PEGylation or altering polysaccharide coating), as well as loading and release of chemotherapeutic. The drug-loaded nanocarriers proved cytotoxic to J774A.1 monocytes and MOLM-14 leukemia cells.

Targeting and sensing of some cancer cells using folate bioreceptor functionalized nitrogen-doped graphene quantum dots

In recent years, study of folate receptor (FR) expression related to targeting, drug delivery and counting of tumoral cells have been followed. In this work, a fast and simple strategy was reported to determine the FR expressed cancer cells based on the selective bonding of the folic acid/folate (FA) to the FR-positive tumor cells. The folate decorated Nitrogen-doped graphene quantum dots (N-GQDs) were utilized as selective targeting of the MKN 45 cells. Fluorescent microscopy imaging investigations revealed that the produced FA conjugated N-GQDs could specifically attach to the target FR-positive tumor cells. Due to the fluorescence emission of N-GQDs, the developed cytosensor is free from attaching any fluorescent ligand i.e. Rhodamine B to capture the florescence microscopy images and also flow cytometry analysis. The fabricated cytosensor possesses a dynamic range from 100 to 7.0 × 10⁴ cell·mL^-1 with high selectivity. Furthermore, the cytosensor also could visualized the MCF 7 and HT 29 cells where the dynamic ranges were 100 to 1.0 × 10⁴ and 500 to 4.0 × 10⁴ cells·mL^-1, respectively. In vitro toxicity tests has shown low toxicity of the synthesized N-GQDs where the minimum viability is 68%. The proposed FA-N-GQDs based cytosensor provides a novel platform for detection of MKN 45, HT 29 and MCF 7 cancer cell lines which could be used in multi-channel cancer diagnosis biodevice.

Towards targeted cancer therapy: Aptamer or oncolytic virus?

Cancer is a leading cause of global mortality. Whilst anticancer awareness programs have increased significantly over the years, scientific research into the development of efficient and specific drugs to target cancerous cells for enhanced therapeutic effects has not received much clinical success. Chemotherapeutic agents are incapable of acting specifically on cancerous cells, thus causing low therapeutic effects accompanied by toxicity to surrounding normal tissues. The search for smart, highly specific and efficient cancer treatments and delivery systems continues to be a significant research endeavor. Targeted cancer therapy is an evolving treatment approach with great promise in enhancing the efficacy of cancer therapies via the delivery of therapeutic agents specifically to and into desired tumor cells using viral or non-viral targeting elements. Viral oncotherapy is an advanced cancer therapy based on the use of oncolytic viruses (OV) as elements to specifically target, replicate and kill malignant cancer cells selectively without affecting surrounding healthy cells. Aptamers, on the other hand, are non-viral targeting elements that are single-stranded nucleic acids with high specificity, selectivity and binding affinity towards their cognate targets. Aptamers have emerged as a new class of bioaffinity targeting elements can be generated and molecularly engineered to selectively bind to diverse targets including proteins, cells and tissues. This article discusses, comparatively, the potentials and impacts of both viral and aptamer-mediated targeted cancer therapies in advancing conventional drug delivery systems through enhanced target specificity, therapeutic payload, bioavailability of the therapeutic agents at the target sites whilst minimizing systemic cytotoxicity. This article emphasizes on effective site-directed targeting mechanisms and efficacy issues that impact on clinical applications.

Genetically engineering encapsulin protein cage nanoparticle as a SCC-7 cell targeting optical nanoprobe

BACKGROUND

Protein cage nanoparticles are promising nanoplatform candidates for efficient delivery systems of diagnostics and/or therapeutics because of their uniform size and structure as well as high biocompatibility and biodegradability. Encapsulin protein cage nanoparticle is used to develop a cell-specific targeting optical nanoprobe.

RESULTS

FcBPs are genetically inserted and successfully displayed on the surface of encapsulin to form FcBP-encapsulin. Selectively binding of FcBP-encapsulin to SCC-7 is visualized with fluorescent microscopy.

CONCLUSIONS

Encapsulin protein cage nanoparticle is robust enough to maintain their structure at high temperature and easily acquires multifunctions on demand through the combination of genetic and chemical modifications.

Echographic imaging of tumoral cells through novel nanosystems for image diagnosis

Since the recognition of disease molecular basis, it has become clear that the keystone moments of medical practice, namely early diagnosis, appropriate therapeutic treatment and patient follow-up, must be approached at a molecular level. These objectives will be in the near future more effectively achievable thanks to the impressive developments in nanotechnologies and their applications to the biomedical field, starting-up the nanomedicine era. The continuous advances in the development of biocompatible smart nanomaterials, in particular, will be crucial in several aspects of medicine. In fact, the possibility of manufacturing nanoparticle contrast agents that can be selectively targeted to specific pathological cells has extended molecular imaging applications to non-ionizing techniques and, at the same time, has made reachable the perspective of combining highly accurate diagnoses and personalized therapies in a single theranostic intervention. Main developing applications of nanosized theranostic agents include targeted molecular imaging, controlled drug release, therapeutic monitoring, guidance of radiation-based treatments and surgical interventions. Here we will review the most recent findings in nanoparticles contrast agents and their applications in the field of cancer molecular imaging employing non-ionizing techniques and disease-specific contrast agents, with special focus on recent findings on those nanomaterials particularly promising for ultrasound molecular imaging and simultaneous treatment of cancer.

Targeting and activation of antigen-specific B-cells by calcium phosphate nanoparticles loaded with protein antigen

Cross-linking of the B-cell receptors of an antigen-specific B-cell is the initial signal for B-cell activation, proliferation, and differentiation into antibody secreting plasma cells. Since multivalent particulate structures are efficient activators of antigen-specific B-cells, we developed biodegradable calcium phosphate nanoparticles displaying protein antigens on their surface and explored the efficacy of the B-cell activation after exposure to these nanoparticles. The calcium phosphate nanoparticles were functionalized with the model antigen Hen Egg Lysozyme (HEL) to take advantage of a HEL-specific B-cell receptor transgenic mouse model. The nanoparticles were characterized by scanning electron microscopy and dynamic light scattering. The functionalized calcium phosphate nanoparticles were preferentially bound and internalized by HEL-specific B-cells. Co-cultivation of HEL-specific B-cells with the functionalized nanoparticles also increased surface expression of B-cell activation markers. Functionalized nanoparticles were able to effectively cross-link B-cell receptors at the surface of antigen-matched B-cells and were 100-fold more efficient in the activation of B-cells than soluble HEL. Thus, calcium phosphate nanoparticles coated with protein antigens are promising vaccine candidates for induction humoral immunity.

FRET-based and other fluorescent proteinase probes

The continuous detection of enzyme activities and their application in medical diagnostics is one of the challenges in the translational sciences. Proteinases represent one of the largest groups of enzymes in the human genome and many diseases are based on malfunctions of proteolytic activity. Fluorescent sensors may shed light on regular and irregular proteinase activity in vitro and in vivo and provide a deeper insight into the function of these enzymes and their role in pathophysiological processes. The focus of this review is on Förster resonance energy transfer (FRET)-based proteinase sensors and reporters because these probes are most likely to provide quantitative data. The medical relevance of proteinases are discussed using lung diseases as a prominent example. Probe design and probe targeting are described and fluorescent probe development for disease-relevant proteinases, including matrix-metalloproteinases, cathepsins, caspases, and other selected proteinases, is reviewed.

Small-Molecule End-Groups of Linear Polymer Determine Cell-type Gene-Delivery Efficacy

End-modified polymers are promising for the nonviral delivery of genes to cancer cells, immune cells, and human stem cells and point to polymer end-groups as regulators for cell-type specificity. A library of polymers has been synthesized and, although some polymers are strong transfection agents overall, for each cell type, a particular polymer is most effective.