Targeting tumors with cyclic RGD-conjugated lipid nanoparticles loaded with an IR780 NIR dye: In vitro and in vivo evaluation

Unlocking the Therapeutic Applicability of LNP-mRNA: Chemistry, Formulation, and Clinical Strategies

Messenger RNA (mRNA) has emerged as an innovative therapeutic modality, offering promising avenues for the prevention and treatment of a variety of diseases. The tremendous success of mRNA vaccines in effectively combatting coronavirus disease 2019 (COVID-19) evidences the unlimited medical and therapeutic potential of mRNA technology. Overcoming challenges related to mRNA stability, immunogenicity, and precision targeting has been made possible by recent advancements in lipid nanoparticles (LNPs). This review summarizes state-of-the-art LNP-mRNA-based therapeutics, including their structure, material compositions, design guidelines, and screening principles. Additionally, we highlight current preclinical and clinical trends in LNP-mRNA therapeutics in a broad range of treatments in ophthalmological conditions, cancer immunotherapy, gene editing, and rare-disease medicine. Particular attention is given to the translation and evolution of LNP-mRNA vaccines into a broader spectrum of therapeutics. We explore concerns in the aspects of inadequate extrahepatic targeting efficacy, elevated doses, safety concerns, and challenges of large-scale production procedures. This discussion may offer insights and perspectives on near- and long-term clinical development prospects for LNP-mRNA therapeutics.

Lipid Nanoparticle (LNP) Enables mRNA Delivery for Cancer Therapy

Messenger RNA (mRNA) has received great attention in the prevention and treatment of various diseases due to the success of coronavirus disease 2019 (COVID-19) mRNA vaccines (Comirnaty and Spikevax). To meet the therapeutic purpose, it is required that mRNA must enter the target cells and express sufficient proteins. Therefore, the development of effective delivery systems is necessary and crucial. Lipid nanoparticle (LNP) represents a remarkable vehicle that has indeed accelerated mRNA applications in humans, as several mRNA-based therapies have already been approved or are in clinical trials. In this review, the focus is on mRNA-LNP-mediated anticancer therapy. It summarizes the main development strategies of mRNA-LNP formulations, discusses representative therapeutic approaches in cancer, and points out current challenges and possible future directions of this research field. It is hoped that these delivered messages can help further improve the application of mRNA-LNP technology in cancer therapy.

Targeting endothelial permeability in the EPR effect

The characteristics of the primary tumor blood vessels and the tumor microenvironment drive the enhanced permeability and retention (EPR) effect, which confers an advantage towards enhanced delivery of anti-cancer nanomedicine and has shown beneficial effects in preclinical models. Increased vascular permeability is a landmark feature of the tumor vessels and an important driver of the EPR. The main focus of this review is the endothelial regulation of vascular permeability. We discuss current challenges of targeting vascular permeability towards clinical translation and summarize the structural components and mechanisms of endothelial permeability, the principal mediators and signaling players, the targeted approaches that have been used and their outcomes to date. We also critically discuss the effects of the tumor-infiltrating immune cells, their interplay with the tumor vessels and the impact of immune responses on nanomedicine delivery, the impact of anti-angiogenic and tumor-stroma targeting approaches, and desirable nanoparticle design approaches for greater translational benefit.

Gold Half-Shell-Coated Paclitaxel-Loaded PLGA Nanoparticles for the Targeted Chemo-Photothermal Treatment of Cancer

Conventional cancer therapies suffer from nonspecificity, drug resistance, and a poor bioavailability, which trigger severe side effects. To overcome these disadvantages, in this study, we designed and evaluated the in vitro potential of paclitaxel-loaded, PLGA-gold, half-shell nanoparticles (PTX-PLGA/Au-HS NPs) conjugated with cyclo(Arg-Gly-Asp-Phe-Lys) (cyRGDfk) as a targeted chemo-photothermal therapy system in HeLa and MDA-MB-231 cancer cells. A TEM analysis confirmed the successful gold half-shell structure formation. High-performance liquid chromatography showed an encapsulation efficiency of the paclitaxel inside nanoparticles of more than 90%. In the release study, an initial burst release of about 20% in the first 24 h was observed, followed by a sustained drug release for a period as long as 10 days, reaching values of about 92% and 49% for NPs with and without near infrared laser irradiation. In in vitro cell internalization studies, targeted nanoparticles showed a higher accumulation than nontargeted nanoparticles, possibly through a specific interaction of the cyRGDfk with their homologous receptors, the ανβ3 y ανβ5 integrins on the cell surface. Compared with chemotherapy or photothermal treatment alone, the combined treatment demonstrated a synergistic effect, reducing the cell viability to 23% for the HeLa cells and 31% for the MDA-MB-231 cells. Thus, our results indicate that these multifuncional nanoparticles can be considered to be a promising targeted chemo-photothermal therapy system against cancer.

Synthesis of Novel Carborane-Containing Derivatives of RGD Peptide

Short peptides containing the Arg-Gly-Asp (RGD) fragment can selectively bind to integrins on the surface of tumor cells and are attractive transport molecules for the targeted delivery of therapeutic and diagnostic agents to tumors (for example, glioblastoma). We have demonstrated the possibility of obtaining the N- and C-protected RGD peptide containing 3-amino-closo-carborane and a glutaric acid residue as a linker fragment. The resulting carboranyl derivatives of the protected RGD peptide are of interest as starting compounds in the synthesis of unprotected or selectively protected peptides, as well as building blocks for preparation of boron-containing derivatives of the RGD peptide of a more complex structure.

Protein corona: Friend or foe? Co-opting serum proteins for nanoparticle delivery

For systemically delivered nanoparticles to reach target tissues, they must first circulate long enough to reach the target and extravasate there. A challenge is that the particles end up engaging with serum proteins and undergo immune cell recognition and premature clearance. The serum protein binding, also known as protein corona formation, is difficult to prevent, even with artificial protection via "stealth" coating. Protein corona may be problematic as it can interfere with the interaction of targeting ligands with tissue-specific receptors and abrogate the so-called active targeting process, hence, the efficiency of drug delivery. However, recent studies show that serum protein binding to circulating nanoparticles may be actively exploited to enhance their downstream delivery. This review summarizes known issues of protein corona and traditional strategies to control the corona, such as avoiding or overriding its formation, as well as emerging efforts to enhance drug delivery to target organs via nanoparticles. It concludes with a discussion of prevailing challenges in exploiting protein corona for nanoparticle development.

An assessment of in-vitro and in-vivo evaluation methods for theranostic nanomaterials

Nanoparticles (NPs) as nanocarriers have emerged as novel and promising theranostic agents. The term theranostics revealed the properties of NPs capable of diagnosing the disease at an early stage and/or treating the disease. Such NPs are usually developed employing a surface engineering approach. The theranostic agents comprise NPs loaded with a drug/diagnostic agent that delivers it precisely to the target site. Theranostics is a field with promising results in enhancing therapeutic efficacy facilitated through higher payload at the targeted tissue, reduced dose, and dose-dependent side effects. However, controversies in terms of toxicity and size-dependent properties have often surfaced for NPs. Thus, a stringent in-vitro and in-vivo evaluation is required to develop safe and non-toxic NPs as theranostic agents. The review also focuses on the various entry points of NPs in the human system and their outcomes, including toxicity. It elaborates the evaluation criteria to ensure the safe use of NPs for diagnostic and therapeutic purposes.

IR780-based nanomaterials for cancer imaging and therapy

IR780, a small molecule with a strong optical property and excellent photoconversion efficiency following near infrared (NIR) irradiation, has attracted increasing attention in the field of cancer treatment and imaging. This review is focused on different IR780-based nanoplatforms and the application of IR780-based nanomaterials for cancer bioimaging and therapy. Thus, this review summarizes the overall aspects of IR780-based nanomaterials that positively impact cancer biomedical applications.

Antibody conjugated lipid nanoparticles as a targeted drug delivery system for hydrophobic pharmaceuticals

Cancer remains a significant health issue worldwide. The most common group of chemotherapeutic agents are small-molecule drugs, which often are associated with toxic side-effects and non-specific delivery, leading to limited therapeutic effect. This paper describes the development of a targeted drug delivery system based on lipid nanoparticles for cancer therapy. The lipid nanoparticles consist of a lipid core conjugated to an albumin stealth coating and targeting antibodies through thiol chemistry synthesized utilizing a one-step method. Applying the developed method, lipid nanoparticles with diameters down to 87 nm, capable of encapsulating small molecule compounds were synthesized. Cellular uptake studies of the lipid nanoparticles loaded with the model drug Nile red demonstrated that stealth-coating reduced non-specific cell uptake by up to a 1000-fold compared to free drug. Moreover, antibody-conjugation led to a significant cellular retargeting. Finally, it was shown that the lipid nanoparticles undergo cellular uptake through the endocytic pathway. The lipid nanoparticles are simple to synthesize, stabile in serum and have the potential to be versatile targeted towards receptors selectively expressed by diseased cells using antibodies. Thus, the system may reduce the toxic side-effects of cancer drugs while improving their delivery to cancer cells, increasing the therapeutic effect.

Dye-Loaded Nanoemulsions: Biomimetic Fluorescent Nanocarriers for Bioimaging and Nanomedicine

Lipid nanoemulsions (NEs), owing to their controllable size (20 to 500 nm), stability and biocompatibility, are now frequently used in various fields, such as food, cosmetics, pharmaceuticals, drug delivery, and even as nanoreactors for chemical synthesis. Moreover, being composed of components generally recognized as safe (GRAS), they can be considered as "green" nanoparticles that mimic closely lipoproteins and intracellular lipid droplets. Therefore, they attracted attention as carriers of drugs and fluorescent dyes for both bioimaging and studying the fate of nanoemulsions in cells and small animals. In this review, the composition of dye-loaded NEs, methods for their preparation, and emerging biological applications are described. The design of bright fluorescent NEs with high dye loading and minimal aggregation-caused quenching (ACQ) is focused on. Common issues including dye leakage and NEs stability are discussed, highlighting advanced techniques for their characterization, such as Förster resonance energy transfer (FRET) and fluorescence correlation spectroscopy (FCS). Attempts to functionalize NEs surface are also discussed. Thereafter, biological applications for bioimaging and single-particle tracking in cells and small animals as well as biomedical applications for photodynamic therapy are described. Finally, challenges and future perspectives of fluorescent NEs are discussed.

Formulation of Folate-Modified Raltitrexed-Loaded Nanoparticles for Colorectal Cancer Theranostics

Multifunctional nanoparticles (NPs) that enable the imaging of drug delivery and facilitate cancer cell uptake are potentially powerful tools in tailoring oncologic treatments. Here we report the development of a layer-by-layer (LbL) formulation of folic acid (FA) and folate antimetabolites that have been well-established for enhanced tumor uptake and as potent chemotherapeutics, respectively. To investigate the uptake of LbL coated NPs, we deposited raltitrexed (RTX) or combined RTX-FA on fluorescent polystyrene NPs. The performance of these NP formulations was evaluated with CT26 murine colorectal cancer (CRC) cells in vitro and in vivo to examine both uptake and cytotoxicity against CRC. Fluorescence microscopy and flow cytometry indicated an increased accumulation of the coated NP formulations versus bare NPs. Ex vivo near-infrared (NIR) fluorescence imaging of major organs suggested the majority of NPs accumulated in the liver, which is typical of a majority of NP formulations. Imaging of the CRC tumors alone showed a higher average fluorescence from NPs accumulated in animals treated with the coated NPs, with the majority of RTX NP-treated animals showing the consistently-highest mean tumoral accumulation. Overall, these results contribute to the development of LbL formulations in CRC theranostic applications.

IR780-based light-responsive nanocomplexes combining phase transition for enhancing multimodal imaging-guided photothermal therapy

Near-infrared (NIR) light-triggered photothermal therapy (PTT) has been widely applied for treating cancer. The combination of nanotechnology and NIR has shown great promise for promoting the efficacy of PTT. However, PTT alone could not completely ablate the tumors and easily causes tumor recurrence. To overcome this challenge, many studies have been performed to enhance PTT, including combining chemical therapy and radiotherapy, both of which have side effects on the body. To reduce the side effects and enhance PTT, a new infrared IR780-based nanocomplex combining liquid fluorocarbon perfluoropentane (PFP) has been synthesized for enhancing multimodal imaging-guided PTT. Under NIR irradiation, the size changes of PFP-loaded nanobubbles transforming into microbubbles allow ultrasound (US) imaging, showing boundaries and internal information of tumors. The breakup process and cascade reaction of phase transition can improve intratumoral permeation and retention of nanoparticles in nonmicrovascular tissue and damage the cell membranes of tumors, further enhancing PTT to kill tumor cells. The strong absorption in the NIR field of IR780-loaded NPs allows not only photoacoustic (PA) imaging but also NIR fluorescence (NIRF) imaging, which provides more anatomical information about tumors. This nanocomplex exhibits good biocompatibility and nontoxicity, strong PA/US/NIRF imaging contrast, excellent liquid-gas transition and a photothermal effect. This finding provides a new method to enhance multimodal imaging-guided cancer nanotheranostics.

Towards more accurate bioimaging of drug nanocarriers: turning aggregation-caused quenching into a useful tool

One of the current challenges in the monitoring of drug nanocarriers lies in the difficulties in discriminating the carrier-bound signals from the bulk signals of probes. Environment-responsive probes that enable signal switching are making steps towards a solution to this problem. Aggregation-caused quenching (ACQ), a phenomenon generally regarded as unfavorable in bioimaging, has turned out to be a promising characteristic for achieving environment-responsiveness and eliminating free-probe interference. So-called ACQ probes emit fluorescence when dispersed molecularly within the carrier matrix but quench immediately and absolutely once they are released into the ambient aqueous environment upon the degradation of the nanocarriers. Therefore, the fluorescence observed represents integral nanocarriers. Based on this rationale, the in vivo fates of various nanocarriers have been explored using live imaging equipment, with very interesting findings revealing the role of the particles. The current applications are however restricted to nanocarriers with highly hydrophobic matrices (lipid or polyester nanoparticles) or with a hydrophobic core-hydrophilic shell structure (micelles). The ACQ-based bioimaging strategy is emerging as a promising tool to achieve more accurate bioimaging of drug nanocarriers. This review article provides an overview of the ACQ phenomenon and the rationale for and examples of applications, as well as the limitations of the ACQ-based strategy, with a focus on improving the accuracy of bioimaging of nanoparticles.

Cyclic RGD-conjugated Pluronic® blending system for active, targeted drug delivery

BACKGROUND

Blending micellar systems of different types of polymers has been proposed as an efficient approach for tailor-made drug formulations. The lamellar structure of hydrophobic polymers may provide a high drug loading capacity, and hydrophilic polymers may provide good colloidal stability.

METHODS

In this study, the anticancer model drug docetaxel was loaded onto a nanosized blending micellar system with two pluronics (L121/F127). To achieve increased antitumor activity, the cyclic arginine-glycine-aspartic acid tripeptide (cRGD) as an active tumor targeting ligand was conjugated to the blending system.

RESULTS

The docetaxel-loaded Pluronic blending system exhibited a higher drug loading capacity than that of F127 and showed high colloidal stability with a spherical structure. cRGD conjugates demonstrated enhanced drug cellular uptake and anticancer activity against αvβ3 integrin-overexpressing U87MG cancer cells. In vivo animal imaging also revealed that the prepared cRGD-conjugated nanoparticles effectively accumulated at the targeted tumor site through an active and passive targeting strategy.

CONCLUSION

Accordingly, the prepared nanosized system shows potential as a tailor-made, active targeting, nanomedicinal platform for anticancer therapy. We believe that this novel nanoplatform will provide insights for advancement of tumor therapy.

Bakhiet A, Khan A, A. Khan H. Recent Trends in Biomedical Applications of Nanomaterials

In recent years, there have been enormous developments in utilizing the potential of nanotechnology in different fields including biomedical sciences. The most remarkable biomedical applications of nanoparticles (NPs) are in the diagnosis and treatment of various diseases. Functionalization of NPs renders them unique properties so that they can be used as contrast agent for dual or triple modal imaging. The design and synthesis of new generation NPs aiming at targeted drug delivery has revolutionized the safe and effective therapies for complex and difficult to treat diseases. The theranostic NPs possess the dual capabilities for disease diagnosis and treatment. This review highlights the biomedical applications of NPs based on recent reports published in this area of research.

A Lipophilic IR-780 Dye-Encapsulated Zwitterionic Polymer-Lipid Micellar Nanoparticle for Enhanced Photothermal Therapy and NIR-Based Fluorescence Imaging in a Cervical Tumor Mouse Model

To prolong blood circulation and avoid the triggering of immune responses, nanoparticles in the bloodstream require conjugation with polyethylene glycol (PEG). However, PEGylation hinders the interaction between the nanoparticles and the tumor cells and therefore limits the applications of PEGylated nanoparticles for therapeutic drug delivery. To overcome this limitation, zwitterionic materials can be used to enhance the systemic blood circulation and tumor-specific delivery of hydrophobic agents such as IR-780 iodide dye for photothermal therapy. Herein, we developed micellar nanoparticles using the amphiphilic homopolymer poly(12-(methacryloyloxy)dodecyl phosphorylcholine) (PCB-lipid) synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization. The PCB-lipid can self-assemble into micelles and encapsulate IR-780 dye (PCB-lipid–IR-780). Our results demonstrated that PCB-lipid–IR-780 nanoparticle (NP) exhibited low cytotoxicity and remarkable photothermal cytotoxicity to cervical cancer cells (TC-1) upon near-infrared (NIR) laser irradiation. The biodistribution of PCB-lipid–IR-780 showed higher accumulation of PCB-lipid–IR-780 than that of free IR-780 in the TC-1 tumor. Furthermore, following NIR laser irradiation of the tumor region, the PCB-lipid–IR-780 accumulated in the tumor facilitated enhanced tumor ablation and subsequent tumor regression in the TC-1 xenograft model. Hence, these zwitterionic polymer-lipid hybrid micellar nanoparticles show great potential for cancer theranostics and might be beneficial for clinical applications.

The effects of surface charge on the intra-tumor penetration of drug delivery vehicles with tumor progression

Tumor progression determines the penetrating ability of drug delivery vehicles with different surface charges.

Biocompatible nanoparticles containing hydrophobic nickel-bis(dithiolene) complexes for NIR-mediated doxorubicin release and photothermal therapy

Nickel-bis(dithiolene) containing NPs: controlled release of Dox and photothermal therapy under NIR Irradiation.