Translocation of mineralo-organic nanoparticles from blood to urine: a new mechanism for the formation of kidney stones?

A Luminol-Based Self-Illuminating Nanocage as a Reactive Oxygen Species Amplifier to Enhance Deep Tumor Penetration and Synergistic Therapy

The dense extracellular matrix (ECM) in tumor tissues resists drug diffusion into tumors and leads to a poor prognosis. To address this problem, glucose oxidase (GOx)-modified ferritin loaded with luminol-curcumin was fabricated. Once delivered to the tumor, this luminol-based self-illuminating nanocage could actively convert glucose to reactive oxygen species (ROS) to achieve starvation therapy. Then, excessive ROS were transmitted to luminol, thereby emitting 425 nm blue-violet light. Momentarily, light was further absorbed by curcumin and ROS production was amplified. Abundant ROS helps break down the ECM network to penetrate deep into tumors. In addition, ROS produced after cell internalization can induce apoptosis of tumor cells by decreasing the mitochondrial membrane potential and can promote ferroptosis by consuming reduced glutathione. Effective penetration and multiple pathways inducing tumor cell death contributed to the efficient antitumor effect (tumor inhibition rate of GOx-modified ferritin loaded with luminol-curcumin: 71.73%). This study developed a glucose-driven self-illuminating nanocage for active tumor penetration via ROS-mediated destruction of the ECM and provided the synergetic mechanism of apoptosis and ferroptosis.

Association between aortic calcification and the presence of kidney stones: calcium oxalate calculi in focus

PURPOSE

The current research is aimed at analyzing the relationship between kidney stone (KS) and abdominal aortic calcification (AAC) and the relationship between KS components and AAC.

METHODS

This is a retrospective, case-control study. Kidney stone formers (KSFs) were treated at the Department of Urology, West China Hospital, Sichuan University for urological calculus disease from January 2014 to January 2020. Matched non-stone formers (non-SFs) were drawn from the same hospital for routine health examination from January 2018 to February 2019. Research-related information was collected and reviewed retrospectively from the hospital's computerized records. AAC were evaluated using available results of computed tomography imaging and abdominal vascular ultrasound. The relationships of AAC between KSFs and non-SFs were compared. The composition of renal calculi was analyzed by Fourier-transform infrared spectrophotometer. KSFs were divided into AAC groups and non-AAC based on AAC. The relationship of the composition of renal calculi between AAC and non-AAC were compared. The independent-sample t test, the chi-squared test and binary logistics regression were performed.

RESULTS

Altogether, 4516 people were included, with 1027 KSFs and 3489 non-SFs. There were no significant differences in the laboratory parameters between KSFs and non-SFs. The association between the presence of AAC and KS was significant in multivariable model 2 [adjusting hypertension, diabetes mellitus, fasting blood glucose, uric acid, serum triglyceride (TG), serum calcium, and urine pH] (OR 5.756, 95% CI 4.616-7.177, p < 0.001). The result of KSFs showed that calcium oxalate calculi (CaOx) was significantly associated with AAC in multivariable model 3 (adjusting age, hypertension, diabetes mellitus, drinking history, smoking history, and TG) (OR 1.351, 95% CI 1.002-1.822, p = 0.048).

CONCLUSIONS

The current study pioneered the revelation of the relationship between CaOx and AAC. Through an elimination of the confounding factors, the study demonstrated that KS and AAC were connected.

Ectopic calcification and formation of mineralo-organic particles in arteries of diabetic subjects

Vascular calcification occurs in various diseases including atherosclerosis, chronic kidney disease and type 2 diabetes but the mechanism underlying mineral deposition remains incompletely understood. Here we examined lower limb arteries of type 2 diabetes subjects for the presence of ectopic calcification and mineral particles using histology, electron microscopy and spectroscopy analyses. While arteries of healthy controls showed no calcification following von Kossa staining, arteries from 83% of diabetic individuals examined (19/23) revealed microscopic mineral deposits, mainly within the tunica media. Mineralo-organic particles containing calcium phosphate and proteins such as albumin, fetuin-A and apolipoprotein-A1 were detected in calcified arteries. Ectopic calcification and mineralo-organic particles were observed in a majority of diabetic patients and predominantly in arteries showing hyperplasia. While a low number of subjects was examined and information about disease severity and patient characteristics is lacking, these calcifications and mineralo-organic particles may represent signs of tissue dysfunction.

Intravital microscopy reveals a novel mechanism of nanoparticles excretion in kidney

Developing nanocarriers that accumulate in targeted organs and are harmlessly eliminated still remains a big challenge. Nanoparticles (NP) biodistribution is governed by their size, composition, surface charge and coverage. The current thinking in bionanotechnology is that renal clearance is limited by glomerular basement membrane pore size (≈6 nm), although there is a growing evidence that NP exceeding the threshold can also be excreted with urine. Here we compare biodistribution of PEGylated 140 nm iron oxide cubes and clusters with a special focus on renal accumulation and excretion. Atomic emission spectroscopy, fluorescent microscopy and magnetic resonance imaging revealed rapid and transient accumulation of magnetic NP in kidney. Using intravital microscopy we tracked in real time NP translocation from peritubular capillaries to basal compartment of tubular cells and subsequent excretion to the lumen within 60 min after systemic administration. Transmission electron microscopy revealed persistence of intact full-sized NP in urine 2 h post injection. The results suggest that translocation through peritubular endothelium to tubular epithelial cells is an alternative mechanism of renal clearance enabling excretion of NP above glomerular cut-off size.

Comprehensive organic profiling of biological particles derived from blood

Mineral nanoparticles form in physiological and pathological processes occurring in the human body. The calcium phosphate mineral phase of the particles has affinity for proteins and lipids, but the complete profiling of the organic molecules that bind to the particles has not been described in detail. We report here a comprehensive analysis of organic components found in mineralo-organic particles derived from body fluids. Based on biological staining, fluorescent tagging, proteomics and metabolomics, our results indicate that the mineral particles bind to proteins, amino acids, carbohydrates, polysaccharides, phospholipids, fatty acids, DNA and low molecular weight metabolites. These results can be used to study the formation and effects of mineralo-organic particles in biological fluids.

Mineralo-organic nanoparticles in health and disease: an overview of recent findings

We observed earlier that mineralo-organic nanoparticles form in human body fluids when the concentrations of calcium, carbonate and phosphate exceed saturation. The particles have been shown to represent mineral precursors in developing bones and teeth as well as in ectopic calcification and kidney stones. Recent studies suggest that the mineral particles may also be involved in other physiological processes, including immune tolerance against the gut microbiota and food antigens. We review here the involvement of mineralo-organic nanoparticles in physiological and pathological processes and discuss recent findings that reveal novel and unexpected roles for these particles in the human body.

Pleomorphic bacteria-like structures in human blood represent non-living membrane vesicles and protein particles

Although human blood is believed to be a sterile environment, recent studies suggest that pleomorphic bacteria exist in the blood of healthy humans. These studies have led to the development of "live-blood analysis," a technique used by alternative medicine practitioners to diagnose various human conditions, including allergies, cancer, cardiovascular disease and septicemia. We show here that bacteria-like vesicles and refringent particles form in healthy human blood observed under dark-field microscopy. These structures gradually increase in number during incubation and show morphologies reminiscent of cells undergoing division. Based on lipid analysis and Western blotting, we show that the bacteria-like entities consist of membrane vesicles containing serum and exosome proteins, including albumin, fetuin-A, apolipoprotein-A1, alkaline phosphatase, TNFR1 and CD63. In contrast, the refringent particles represent protein aggregates that contain several blood proteins. 16S rDNA PCR analysis reveals the presence of bacterial DNA in incubated blood samples but also in negative controls, indicating that the amplified sequences represent contaminants. These results suggest that the bacteria-like vesicles and refringent particles observed in human blood represent non-living membrane vesicles and protein aggregates derived from blood. The phenomena observed during live-blood analysis are therefore consistent with time-dependent decay of cells and body fluids during incubation ex vivo.

Kidney stone nano-structure - Is there an opportunity for nanomedicine development?

BACKGROUND

Kidney stone analysis techniques are well-established in the field of materials characterization and provide information for the chemical composition and structure of a sample. Nanomedicine, on the other hand, is a field with an increasing rate of scientific research, a big budget and increasingly developing market. The key scientific question is if there is a possibility for the development of a nanomedicine to treat kidney stones.

MAJOR CONCLUSIONS

The main calculi characterization techniques such as X-ray Diffraction and Fourier Transform Infrared Spectroscopy can provide information about the composition of a kidney stone but not for its nanostructure. On the other hand, Small Angle X-ray Scattering and Nitrogen Porosimetry can show the nanostructural parameters of the calculi. The combination of the previously described parameters can be used for the development of nano-drugs for the treatment of urolithiasis, while no such nano-drugs exist yet.

GENERAL SIGNIFICANCE

In this study, we focus on the most well-known techniques for kidney stone analysis, the urolithiasis management and the search for possible nanomedicine for the treatment of kidney stone disease. We combine the results from five different analysis techniques in order to represent a three dimensional model and we propose a hypothetical nano-drug with gold nanoparticles. This article is part of a Special Issue entitled "Recent Advances in Bionanomaterials" Guest Editor: Dr. Marie-Louise Saboungi and Dr. Samuel D. Bader.