Biodistribution of biodegradable polymeric nano-carriers loaded with busulphan and designed for multimodal imaging

Engineered smart materials for RNA based molecular therapy to treat Glioblastoma

Glioblastoma (GBM) is an aggressive malignancy of the central nervous system (CNS) that remains incurable despite the multitude of improvements in cancer therapeutics. The conventional chemo and radiotherapy post-surgery have only been able to improve the prognosis slightly; however, the development of resistance and/or tumor recurrence is almost inevitable. There is a pressing need for adjuvant molecular therapies that can successfully and efficiently block tumor progression. During the last few decades, non-coding RNAs (ncRNAs) have emerged as key players in regulating various hallmarks of cancer including that of GBM. The levels of many ncRNAs are dysregulated in cancer, and ectopic modulation of their levels by delivering antagonists or overexpression constructs could serve as an attractive option for cancer therapy. The therapeutic potential of several types of ncRNAs, including miRNAs, lncRNAs, and circRNAs, has been validated in both in vitro and in vivo models of GBM. However, the delivery of these RNA-based therapeutics is highly challenging, especially to the tumors of the brain as the blood-brain barrier (BBB) poses as a major obstacle, among others. Also, since RNA is extremely fragile in nature, careful considerations must be met while designing a delivery agent. In this review we have shed light on how ncRNA therapy can overcome the limitations of its predecessor conventional therapy with an emphasis on smart nanomaterials that can aide in the safe and targeted delivery of nucleic acids to treat GBM. Additionally, critical gaps that currently exist for successful transition from viral to non-viral vector delivery systems have been identified. Finally, we have provided a perspective on the future directions, potential pathways, and target areas for achieving rapid clinical translation of, RNA-based macromolecular therapy to advance the effective treatment of GBM and other related diseases.

Nanoparticle biodistribution coefficients: A quantitative approach for understanding the tissue distribution of nanoparticles

The objective of this manuscript is to provide quantitative insights into the tissue distribution of nanoparticles. Published pharmacokinetics of nanoparticles in plasma, tumor and 13 different tissues of mice were collected from literature. A total of 2018 datasets were analyzed and biodistribution of graphene oxide, lipid, polymeric, silica, iron oxide and gold nanoparticles in different tissues was quantitatively characterized using Nanoparticle Biodistribution Coefficients (NBC). It was observed that typically after intravenous administration most of the nanoparticles are accumulated in the liver (NBC = 17.56 %ID/g) and spleen (NBC = 12.1 %ID/g), while other tissues received less than 5 %ID/g. NBC values for kidney, lungs, heart, bones, brain, stomach, intestine, pancreas, skin, muscle and tumor were found to be 3.1 %ID/g, 2.8 %ID/g, 1.8 %ID/g, 0.9 %ID/g, 0.3 %ID/g, 1.2 %ID/g, 1.8 %ID/g, 1.2 %ID/g, 1.0 %ID/g, 0.6 %ID/g and 3.4 %ID/g, respectively. Significant variability in nanoparticle distribution was observed in certain organs such as liver, spleen and lungs. A large fraction of this variability could be explained by accounting for the differences in nanoparticle physicochemical properties such as size and material. A critical overview of published nanoparticle physiologically-based pharmacokinetic (PBPK) models is provided, and limitations in our current knowledge about in vitro and in vivo pharmacokinetics of nanoparticles that restrict the development of robust PBPK models is also discussed. It is hypothesized that robust quantitative assessment of whole-body pharmacokinetics of nanoparticles and development of mathematical models that can predict their disposition can improve the probability of successful clinical translation of these modalities.

A near-infrared probe for detecting and interposing amyloid beta oligomerization in early Alzheimer's disease

BACKGROUND

The misfolding and deposition of amyloid beta (Aβ) in human brain is the main hallmark of Alzheimer's disease (AD) pathology. One of the drivers of Alzheimer´s pathogenesis is the production of soluble oligomeric Aβ, which could potentially serve as a biomarker of AD.

METHODS

Given that the diphenylalanine (FF) at the C-terminus of Aβ fragments plays a key role in inducing the AD pathology, based on the hydrophobic structure of FF, we synthesized a near-infrared BF2-dipyrrolmethane fluorescent imaging probe (NB) to detect both soluble and insoluble Aβ.

RESULTS

We found that NB not only binds Aβ, particularly oligomeric Aβ, but also interposes self-assembly of Aβ through π-π interaction between NB and FF.

CONCLUSION

This work holds great promise in the early detection of AD and may also provide an innovative approach to decelerate and even halt AD onset and progression.

Molecular homing and retention of muscle membrane stabilizing copolymers by non-invasive optical imaging in vivo

First-in-class membrane stabilizer Poloxamer 188 (P188) has been shown to confer membrane protection in an extensive range of clinical conditions; however, elements of the systemic distribution and localization of P188 at the organ, tissue, and muscle fiber levels in vivo have not yet been elucidated. Here we used non-invasive fluorescence imaging to directly visualize and track the distribution and localization of P188 in vivo. The results demonstrated that the Alx647 probe did not alter the fundamental properties of P188 to protect biological membranes. Distribution kinetics in mdx mice demonstrated that Alx647 did not interface with muscle membranes and had fast clearance kinetics. In contrast, the distribution kinetics for P188-Alx647 was significantly slower, indicating a dramatic depot and retention effect of P188. Results further demonstrated the significant retention of P188-Alx647 in the skeletal muscle of mdx mice, showing a significant genotype effect with a higher fluorescence signal in the mdx muscles over BL10 mice. High-resolution optical imaging provided direct evidence of P188 surrounding the sarcolemma of skeletal and cardiac muscle cells. Taken together, these findings provide direct evidence of muscle-disease-dependent molecular homing and retention of synthetic copolymers in striated muscles thereby facilitating advanced studies of copolymer-membrane association in health and disease.

Advances in biomarkers and techniques for pancreatic cancer diagnosis

Pancreatic cancer is the most lethal type of malignancy and is characterized by high invasiveness without severe symptoms. It is difficult to detect PC at an early stage because of the low diagnostic accuracy of existing routine methods, such as abdominal ultrasound, CT, MRI, and endoscopic ultrasound (EUS). Therefore, it is of value to develop new diagnostic techniques for early detection with high accuracy. In this review, we aim to highlight research progress on novel biomarkers, artificial intelligence, and nanomaterial applications on the diagnostic accuracy of pancreatic cancer.

In Vivo Distribution of Poly(ethylene glycol) Functionalized Iron Oxide Nanoclusters: An Ultrastructural Study

The in vivo distribution of 50 nm clusters of polyethylene glycol-conjugated superparamagnetic iron oxide nanoparticles (SPIONs-PEG) was conducted in this study. SPIONs-PEG were synthesized de novo, and their structure and paramagnetic behaviors were analyzed by specific methods (TEM, DLS, XRD, VSM). Wistar rats were treated with 10 mg Fe/kg body weight SPIONs-PEG and their organs and blood were examined at two intervals for short-term (15, 30, 60, 180 min) and long-term (6, 12, 24 h) exposure evaluation. Most exposed organs were investigated through light and transmission electron microscopy, and blood and urine samples were examined through fluorescence spectrophotometry. SPIONs-PEG clusters entered the bloodstream after intraperitoneal and intravenous administrations and ended up in the urine, with the highest clearance at 12 h. The skin and spleen were within normal histological parameters, while the liver, kidney, brain, and lungs showed signs of transient local anoxia or other transient pathological affections. This study shows that once internalized, the synthesized SPIONs-PEG disperse well through the bloodstream with minor to nil induced tissue damage, are biocompatible, have good clearance, and are suited for biomedical applications.

Multimodal Imaging of Pancreatic Ductal Adenocarcinoma Using Multifunctional Nanoparticles as Contrast Agents

Late diagnosis and refractory behavior toward current treatment protocols make pancreatic ductal adenocarcinoma (PDAC) one of the most difficult cancer forms to treat. The imaging-based approach plays an important role to identify potentially curable PDAC patients in high-risk groups at the early stage. In the present study, we developed a core-shell structured gold nanorod (AuNR) as a contrast agent for multimodal imaging and investigated its application for PDAC diagnosis. The composite nanoparticles composed of a AuNR core inside a layer of mesoporous silica that was then coated with a gadolinium oxide carbonate shell (AuNR-SiO₂-Gd) are designed to be used in magnetic resonance imaging (MRI), X-ray computed tomography (CT), and photoacoustic imaging (PAI). A phantom study with the AuNR-SiO₂-Gd NPs demonstrated higher MRI contrast compared to Gadovist and higher X-ray attenuation than Visipaque. A strong, stable, and broad wavelength range signal with a peak at 800 nm was observed in PAI. The AuNR-SiO₂-Gd NPs showed significant contrast enhancement under PAI/MRI/CT in both the liver and spleen of control mice after intravenous administration. The utility in PDAC was studied in a genetically engineered mouse model carrying Kras and p53 mutations, which develops spontaneous tumors and keeps the desmoplasia and hypovascularity feature of PDAC in patients. The AuNR-SiO₂-Gd NPs were highly accumulated in the surrounding soft tissues but were sparsely distributed throughout the tumor due to dense stroma infiltration and poor tumor vascularization. Hence, a negative contrast within the tumor area in CT/PAI and a positive contrast in MRI were observed. In conclusion, AuNR-SiO₂-Gd NPs have good potential to be developed as a multimodal contrast agent for PDAC, which might improve early diagnosis and benefit the clinical outcome for PDAC patients.

Systemically Delivered Magnetic Hyperthermia for Prostate Cancer Treatment

Herein, we report a novel therapy for prostate cancer based on systemically delivered magnetic hyperthermia. Conventional magnetic hyperthermia is a form of thermal therapy where magnetic nanoparticles delivered to cancer sites via intratumoral administration produce heat in the presence of an alternating magnetic field (AMF). To employ this therapy for prostate cancer tumors that are challenging to inject intratumorally, we designed novel nanoclusters with enhanced heating efficiency that reach prostate cancer tumors after systemic administration and generate desirable intratumoral temperatures upon exposure to an AMF. Our nanoclusters are based on hydrophobic iron oxide nanoparticles doped with zinc and manganese. To overcome the challenges associated with the poor water solubility of the synthesized nanoparticles, the solvent evaporation approach was employed to encapsulate and cluster them within the hydrophobic core of PEG-PCL (methoxy poly(ethylene glycol)-b-poly(ε-caprolactone))-based polymeric nanoparticles. Animal studies demonstrated that, following intravenous injection into mice bearing prostate cancer grafts, the nanoclusters efficiently accumulated in cancer tumors within several hours and increased the intratumoral temperature above 42 °C upon exposure to an AMF. Finally, the systemically delivered magnetic hyperthermia significantly inhibited prostate cancer growth and did not exhibit any signs of toxicity.

Folate Receptor α-Modified Nanoparticles for Targeting of the Central Nervous System

Effective and timely delivery of therapeutic agents from the systemic circulation to the central nervous system (CNS) is often precluded by the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB). A new pathway of folate uptake mediated by folate receptor alpha (FRα, molecular weight of 28.29 kg mol^-1) occurring in various epithelial cells of the CNS (e.g., choroid plexus) was described. Aiming to investigate this mechanism for the delivery of nanomedicines to the CNS, in this work, we initially produced nanoparticles (NPs) made of a highly hydrophobic poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-b-PCL) block copolymer functionalized with an amine moiety in the edge of the PEG block by a simple nanoprecipitation method. Hydrophilic PEG blocks migrated to the NP surface during formation, exposing primary amine groups that were used to conjugate the targeting ligand, FRα. The size of the NPs was in the 58-98 nm range and standard deviation (S.D., a measure of the size population peak width) of 26-41 nm, as measured by dynamic light scattering (DLS). The FRα conjugation yield ranged between 50% and 75% (determined indirectly by the bicinchoninic acid protein assay). Pristine and FRα-modified NPs showed good compatibility with primary human choroid plexus epithelial cells (HCPEpiCs). The uptake of FRα-conjugated NPs by HCPEpiCs was qualitatively evaluated in vitro using inverted optical fluorescence and confocal microscopy. FRα-modified NPs were internalized by HCPEpiCs to a greater extent than the unmodified counterparts. Then, their permeability was characterized in standard and inverted HCPEpiC monolayers. In both cases, NPs surface modified with the FRα and complexed to folic acid (FA) showed significantly higher apparent permeability coefficient (P_app) values than the pristine ones. Finally, the biodistribution of unmodified and FRα-FA-modified NPs following intravenous (i.v.) administration was compared in ICR mice. Results indicated that conjugation of the FRα-FA complex to the NP surface promotes higher accumulation in the brain, highlighting the promise of FRα-FA-modified NPs to serve as a platform for the targeting of active molecules to the CNS from the systemic circulation.

Reduction of Nanoparticle Load in Cells by Mitosis but Not Exocytosis

The long-term fate of biomedically relevant nanoparticles (NPs) at the single cell level after uptake is not fully understood yet. We report that lysosomal exocytosis of NPs is not a mechanism to reduce the particle load. Biopersistent NPs such as nonporous silica and gold remain in cells for a prolonged time. The only reduction of the intracellular NP number is observed via cell division, e.g., mitosis. Additionally, NP distribution after cell division is observed to be asymmetrical, likely due to the inhomogeneous location and distribution of the NP-loaded intracellular vesicles in the mother cells. These findings are important for biomedical and hazard studies as the NP load per cell can vary significantly. Furthermore, we highlight the possibility of biopersistent NP accumulation over time within the mononuclear phagocyte system.

Advantages and Limitations of Current Techniques for Analyzing the Biodistribution of Nanoparticles

Nanomedicines are typically submicrometer-sized carrier materials (nanoparticles) encapsulating therapeutic and/or imaging compounds that are used for the prevention, diagnosis and treatment of diseases. They are increasingly being used to overcome biological barriers in the body to improve the way we deliver compounds to specific tissues and organs. Nanomedicine technology aims to improve the balance between the efficacy and the toxicity of therapeutic compounds. Nanoparticles, one of the key technologies of nanomedicine, can exhibit a combination of physical, chemical and biological characteristics that determine their in vivo behavior. A key component in the translational assessment of nanomedicines is determining the biodistribution of the nanoparticles following in vivo administration in animals and humans. There are a range of techniques available for evaluating nanoparticle biodistribution, including histology, electron microscopy, liquid scintillation counting (LSC), indirectly measuring drug concentrations, in vivo optical imaging, computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine imaging. Each technique has its own advantages and limitations, as well as capabilities for assessing real-time, whole-organ and cellular accumulation. This review will address the principles and methodology of each technique and their advantages and limitations for evaluating in vivo biodistribution of nanoparticles.

Magnetic polymeric nanoassemblies for magnetic resonance imaging-combined cancer theranostics

Cancer has become one of the primary causes of death worldwide. Current cancer-therapy schemes are progressing relatively slowly in terms of reducing mortality, prolonging survival, time and enhancing cure rate, owing to the enormous obstacles of cancer pathophysiology. Therefore, specific diagnosis and therapy for malignant tumors are becoming more and more crucial and urgent, especially for early cancer diagnosis and cancer-targeted therapy. Derived theranostics that combine several functions into one "package" could further overcome undesirable differences in biodistribution and selectivity between distinct imaging and therapeutic agents. In this article, we discuss a chief clinical diagnosis tool - MRI - focusing on recent progress in magnetic agents or systems in multifunctional polymer nanoassemblies for combing cancer theranostics. We describe abundant polymeric MRI-contrast agents integrated with chemotherapy, gene therapy, thermotherapy, and radiotherapy, as well as other developing directions.

Intermittent time-set technique controlling the temperature of magnetic-hyperthermia-ablation for tumor therapy

Magnetic-hyperthermia-ablation is considered as an effective and minimally invasive technology for tumor therapy.

Biodistribution of arctigenin-loaded nanoparticles designed for multimodal imaging

BACKGROUND

Tracking targets of natural products is one of the most challenging issues in fields ranging from pharmacognosy to biomedicine. It is widely recognized that the biocompatible nanoparticle (NP) could function as a "key" that opens the target "lock".

RESULTS

We report a functionalized poly-lysine NP technique that can monitor the target protein of arctigenin (ATG) in vivo non-invasively. The NPs were synthesized, and their morphologies and surface chemical properties were characterized by transmission electron microscopy (TEM), laser particle size analysis and atomic force microscopy (AFM). In addition, we studied the localization of ATG at the level of the cell and the whole animal (zebrafish and mice). We demonstrated that fluorescent NPs could be ideal carriers in the development of a feasible method for target identification. The distributions of the target proteins were found to be consistent with the pharmacological action of ATG at the cellular and whole-organism levels.

CONCLUSIONS

The results indicated that functionalized poly-lysine NPs could be valuable in the multimodal imaging of arctigenin.