Nanobacteria are mineralo fetuin complexes

Synergistic effect of doxycycline and aqueous extract of irradiated khella on structure of nanobacteria isolated from kidney stones: In vitro and in vivo studies

Kidney stones have been associated with an increased risk of chronic kidney diseases, end-stage renal failure. This study is devoted to isolate nanobacteria from patients with active urolithiasis and investigate the in vitro and in vivo antinanobacterial activity of some antibiotics alone or in combination with extracts of irradiated herbs from certain medicinal plants. Nanobacteria were detected using scanning (SEM) and transmission (TEM) electron microscopy, protein electrophoresis (SDS-PAGE) and DNA profile. The antimicrobial susceptibility of some biofilm-producing nanobacterial isolates was evaluated. The effect of medicinal plant extracts on growth was tested. A combination treatment between the most potent extracts and antibiotics was tested on biofilm production, protein profile, release of 260 nm absorbing material, protein content, and ultrastructure of the strongest biofilm producers. In vivo study of nanobacteria and its treatment by the most potent agents was evaluated on male rats. Renal function was measured in serum; histological examination and oxidative stress parameters were determined in kidney tissues. Results showed that streptomycin, trimethoprim/sulfamethoxazole, doxycycline, and water extracts of irradiated khella at 6 kGy had antinanobacterial activity. Meanwhile, the synergistic effect of the aqueous extract of irradiated Khella and doxycycline showed higher inhibition activity on microbial growth and biofilm production. They affected dramatically the strength of its cell membrane and subsequently its ultrastructure. Moreover, these results are confirmed by ameliorations in renal function and histological alterations. It could be concluded that the combination of DO and an aqueous extract of irradiated khella has an antinephrotoxic effect against nanobacteria-induced renal toxicity.

Calciprotein Particles: Balancing Mineral Homeostasis and Vascular Pathology

[Figure: see text].

Femtoplankton: What's New?

Since the discovery of high abundances of virus-like particles in aquatic environment, emergence of new analytical methods in microscopy and molecular biology has allowed significant advances in the characterization of the femtoplankton, i.e., floating entities filterable on a 0.2 µm pore size filter. The successive evidences in the last decade (2010-2020) of high abundances of biomimetic mineral-organic particles, extracellular vesicles, CPR/DPANN (Candidate phyla radiation/Diapherotrites, Parvarchaeota, Aenigmarchaeota, Nanoarchaeota and Nanohaloarchaeota), and very recently of aster-like nanoparticles (ALNs), show that aquatic ecosystems form a huge reservoir of unidentified and overlooked femtoplankton entities. The purpose of this review is to highlight this unsuspected diversity. Herein, we focus on the origin, composition and the ecological potentials of organic femtoplankton entities. Particular emphasis is given to the most recently discovered ALNs. All the entities described are displayed in an evolutionary context along a continuum of complexity, from minerals to cell-like living entities.

Mud in the blood: the role of protein-mineral complexes and extracellular vesicles in biomineralisation and calcification

Protein-mineral interaction is known to regulate biomineral stability and morphology. We hypothesise that fluid phases produce highly dynamic protein-mineral complexes involved in physiology and pathology of biomineralisation. Here, we specifically focus on calciprotein particles, complexes of vertebrate mineral-binding proteins and calcium phosphate present in the systemic circulation and abundant in extracellular fluids - hence the designation of the ensuing protein-mineral complexes as "mud in the blood". These complexes exist amongst other extracellular particles that we collectively refer to as "the particle zoo".

Waiting for Aπαταω: 250 Years Later

Scientific articles have been traditionally written from single points of view. In contrast, new knowledge is derived strictly from a dialectical process, through interbreeding of partially disparate perspectives. Dialogues, therefore, present a more veritable form for representing the process behind knowledge creation. They are also less prone to dogmatically disseminate ideas than monologues, alongside raising awareness of the necessity for discussion and challenging of differing points of view, through which knowledge evolves. Here we celebrate 250 years since the discovery of the chemical identity of the inorganic component of bone in 1769 by Johan Gottlieb Gahn through one such imaginary dialogue between two seasoned researchers and aficionados of this material. We provide the statistics on ups and downs in the popularity of this material throughout the history and also discuss important achievements and challenges associated with it. The shadow of Samuel Beckett's Waiting for Godot is cast over the dialogue, acting as its frequent reference point and the guide. With this dialogue presented in the format of a play, we provide hope that conversational or dramaturgical compositions of scientific articles - albeit virtually prohibited from the scientific literature of the day - may become more pervasive in the future.

Discovery of High Abundances of Aster-Like Nanoparticles in Pelagic Environments: Characterization and Dynamics

This study reports the discovery of Aster-Like Nanoparticles (ALNs) in pelagic environments. ALNs are pleomorphic, with three dominant morphotypes which do not fit into any previously defined environmental entities [i.e., ultramicro-prokaryotes, controversed nanobes, and non-living particles (biomimetic mineralo-organic particles, natural nanoparticles or viruses)] of similar size. Elemental composition and selected-area electron diffraction patterns suggested that the organic nature of ALNs may prevail over the possibility of crystal structures. Likewise, recorded changes in ALN numbers in the absence of cells are at odds with an affiliation to until now described viral particles. ALN abundances showed marked seasonal dynamics in the lakewater, with maximal values (up to 9.0 ± 0.5 × 10⁷ particles·mL⁻¹) reaching eight times those obtained for prokaryotes, and representing up to about 40% of the abundances of virus-like particles. We conclude that (i) aquatic ecosystems are reservoirs of novel, abundant, and dynamic aster-like nanoparticles, (ii) not all virus-like particles observed in aquatic systems are necessarily viruses, and (iii) there may be several types of other ultra-small particles in natural waters that are currently unknown but potentially ecologically important.

Clinical implications of fetuin-A

Fetuin-A, also termed alpha2-Heremans-Schmid glycoprotein, is a 46kDa hepatocyte derived protein (hepatokine) and serves multifaceted functions.

Biochemical transformation of calciprotein particles in uraemia

Calciprotein particles (CPP) have emerged as nanoscale mediators of phosphate-induced toxicity in Chronic Kidney Disease (CKD). Uraemia favors ripening of the particle mineral content from the amorphous (CPP-I) to the crystalline state (CPP-II) but the pathophysiological significance of this transformation is uncertain. Clinical studies suggest an association between CPP ripening and inflammation, vascular dysfunction and mortality. Although ripening has been modelled in vitro, it is unknown whether particles synthesised in serum resemble their in vivo counterparts. Here we show that in vitro formation and ripening of CPP in uraemic serum is characterised by extensive physiochemical rearrangements involving the accretion of mineral, loss of surface charge and transformation of the mineral phase from a spherical arrangement of diffuse domains of amorphous calcium phosphate to densely-packed lamellar aggregates of crystalline hydroxyapatite. These physiochemical changes were paralleled by enrichment with small soluble apolipoproteins, complement factors and the binding of fatty acids. In comparison, endogenous CPP represent a highly heterogeneous mixture of particles with characteristics mostly intermediate to synthetic CPP-I and CPP-II, but are also uniquely enriched for carbonate-substituted apatite, DNA fragments, small RNA and microbe-derived components. Pathway analysis of protein enrichment predicted the activation of cell death and pro-inflammatory processes by endogenous CPP and synthetic CPP-II alike. This comprehensive characterisation validates the use of CPP-II generated in uraemic serum as in vitro equivalents of their endogenous counterparts and provides insight into the nature and pathological significance of CPP in CKD, which may act as vehicles for various bioactive ligands.

Calcifying nanoparticles induce cytotoxicity mediated by ROS-JNK signaling pathways

Calcifying nanoparticles (CNPs) play an important role in kidney stone formation, but the mechanism(s) are unclear. CNPs were isolated and cultured from midstream urine of patients with kidney stones. CNP morphology and characteristics were examined by electron microscopy and electrophoresis analysis. Chemical composition was analyzed using energy-dispersive X-ray microanalysis and Western blotting. Human renal proximal convoluted tubule cell (HK-2) cultures were exposed to CNPs for 0, 12 and 72 h, and production of reactive oxygen species (ROS), mitochondrial membrane potential and apoptosis levels were evaluated. CNPs isolated from patients showed classical morphology, the size range of CNPs were 15-500 nm and negative charge; they were found to contain fetuin-A. Exposure of HK-2 cells to CNPs induced ROS production, decreased mitochondrial membrane potential and decreased cell viability. Transmission electron microscopy showed that CNPs can enter the cell by phagocytosis, and micrographs revealed signs of apoptosis and autophagy. CNPs increased the proportion of apoptotic cells, down-regulated Bcl-2 expression and up-regulated Bax expression. CNPs also up-regulated expression of LC3-B, Beclin-1and p-JNK.CNPs are phagocytosed by HK-2 cells, leading to autophagy, apoptosis and ROS production, in part through activation of JNK signaling pathways. ROS and JNK pathways may contribute to CNP-induced cell injury and kidney stone formation.

Novel assessments of systemic calcification propensity

PURPOSE OF REVIEW

Blood is a biological fluid, which controls the precipitation of calcium and phosphate and transports mineral debris. This review presents and discusses the current concepts and novel assessment methods of systemic calcification propensity in blood.

RECENT FINDINGS

Calcium and phosphate combine with calcification-inhibiting proteins, mainly fetuin-A, to form amorphous calcium phosphate-containing primary calciprotein particles (CPPs). These nanosized mineral-protein clusters undergo spontaneous transformation to secondary CPP, which contain crystalline calcium phosphate. Two recently developed methods assess complementary aspects of the calcification propensity of serum. The CPP-fetuin-A method determines the amount of sedimentable fetuin-A, whereas the T50-Test determines the transformation time point T50 from amorphous to crystalline CPPs in artificially supersaturated serum.Clinical studies in renal patients have already demonstrated close associations of the CPP-fetuin-A method with all-cause mortality, severity of coronary calcification and aortic stiffness, and of the T50-Test with cardiovascular and all-cause mortality, renal graft failure and aortic stiffening.

SUMMARY

Systemic calcification propensity can be assessed by two novel methods providing complementary information about the status and performance of the humoral calcification-regulating system in serum. These tests may help guide better patient care in the future with the use of more individualized therapies.

Calciprotein particles as potential etiologic agents of idiopathic preterm birth

Preterm birth (PTB) is a leading cause of neonatal morbidity and mortality and is often preceded by preterm premature rupture of the membranes (PPROM) without an identifiable cause. Pathological calcification, the deposition of hydroxyapatite (HA) in nonskeletal tissues, has been implicated in degenerative diseases including atherosclerosis and aneurism rupture. Among pathogenic mechanisms, the aberrant aggregation of HA into calciprotein particles (CPPs) and the HA-induced differentiation of mesenchymal cells into osteoblasts (ectopic osteogenesis) have been implicated. We explored the hypothesis that CPPs form in human amniotic fluid (AF), deposit in fetal membranes, and are linked mechanistically to pathogenic pathways favoring PTB. We demonstrated that fetal membranes from women with idiopathic PPROM frequently show evidence of ectopic calcification and expression of osteoblastic differentiation markers. Concentrations of fetuin-A, an endogenous inhibitor of ectopic calcification, were decreased in AF of idiopathic PPROM cases, which reflected their reduced functional capacity to inhibit calcification. Using long-term cultures of sterile AF, we demonstrated coaggregation of HA with endogenous proteins, including fetuin-A. The fetuin-HA aggregates exhibited progressive growth in vitro in a pattern similar to CPPs. When applied to amniochorion explants, AF-derived CPPs induced structural and functional pathological effects recapitulating those noted for PPROM. Our results demonstrate that disruption of protein-mineral homeostasis in AF stimulates the formation and deposition of CPPs, which may represent etiologic agents of idiopathic PPROM. Therapeutic or dietary interventions aimed at maintaining the balance between endogenous HA formation and fetuin reserve in pregnant women may therefore have a role in preventing PTB.

Induction of apoptosis and autophagy by calcifying nanoparticles in human bladder cancer cells

Calcifying nanoparticles have been linked to various types of human disease, but how they contribute to disease processes is unclear. Here, we examined whether and how calcifying nanoparticles isolated from patients with kidney stones are cytotoxic to human bladder cancer cells. Calcifying nanoparticles were isolated from midstream urine of patients with renal calcium oxalate stones and examined by electron microscopy. Human bladder cancer cells (EJ cells) were cultured in the presence of calcifying nanoparticles or nanohydroxyapatites for 12 and 72 h and examined for toxicity using the Cell Counting Kit-8, for autophagy using transmission electron microscopy and confocal microscopy, and for apoptosis using fluorescence microscopy, transmission electron microscopy, and flow cytometry. Changes in protein expression were analyzed by Western blotting. The results showed that the size and shape of the isolated calcifying nanoparticles were as expected. Calcifying nanoparticles were cytotoxic to EJ cells, more so than nanohydroxyapatites, and this was due, at least in part, to the production of intracellular reactive oxygen species. Transmission electron microscopy showed that calcifying nanoparticles were packaged into vesicles and autolysosomes. Calcifying nanoparticles induced greater autophagy and apoptosis than nanohydroxyapatites. Our findings demonstrate that calcifying nanoparticles can trigger bladder cancer cell injury by boosting reactive oxygen species production and stimulating autophagy and apoptosis.

Pleomorphic Structures in Human Blood Are Red Blood Cell-Derived Microparticles, Not Bacteria

Background

Red blood cell (RBC) transfusions are a common, life-saving therapy for many patients, but they have also been associated with poor clinical outcomes. We identified unusual, pleomorphic structures in human RBC transfusion units by negative-stain electron microscopy that appeared identical to those previously reported to be bacteria in healthy human blood samples. The presence of viable, replicating bacteria in stored blood could explain poor outcomes in transfusion recipients and have major implications for transfusion medicine. Here, we investigated the possibility that these structures were bacteria.

Results

Flow cytometry, miRNA analysis, protein analysis, and additional electron microscopy studies strongly indicated that the pleomorphic structures in the supernatant of stored RBCs were RBC-derived microparticles (RMPs). Bacterial 16S rDNA PCR amplified from these samples were sequenced and was found to be highly similar to species that are known to commonly contaminate laboratory reagents.

Conclusions

These studies suggest that pleomorphic structures identified in human blood are RMPs and not bacteria, and they provide an example in which laboratory contaminants may can mislead investigators.

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

Recent studies indicate that mineralo-organic nanoparticles form in various human body fluids, including blood and urine. These nanoparticles may form within renal tubules and increase in size in supersaturated urine, eventually leading to the formation of kidney stones. Here, we present observations suggesting that mineralo-organic nanoparticles found in blood may induce kidney stone formation via an alternative mechanism in which the particles translocate through endothelial and renal epithelial cells to reach urine. We propose that this alternative mechanism of kidney stone formation and the study of mineralo-organic nanoparticles in general may provide novel strategies for the early detection and treatment of ectopic calcifications and kidney stones.

Formation and characteristics of biomimetic mineralo-organic particles in natural surface water

Recent studies have shown that nanoparticles exist in environmental water but the formation, characteristics and fate of such particles remain incompletely understood. We show here that surface water obtained from various sources (ocean, hot springs, and soil) produces mineralo-organic particles that gradually increase in size and number during incubation. Seawater produces mineralo-organic particles following several cycles of filtration and incubation, indicating that this water possesses high particle-seeding potential. Electron microscopy observations reveal round, bacteria-like mineral particles with diameters of 20 to 800 nm, which may coalesce and aggregate to form mineralized biofilm-like structures. Chemical analysis of the particles shows the presence of a wide range of chemical elements that form mixed mineral phases dominated by calcium and iron sulfates, silicon and aluminum oxides, sodium carbonate, and iron sulfide. Proteomic analysis indicates that the particles bind to proteins of bacterial, plant and animal origins. When observed under dark-field microscopy, mineral particles derived from soil-water show biomimetic morphologies, including large, round structures similar to cells undergoing division. These findings have important implications not only for the recognition of biosignatures and fossils of small microorganisms in the environment but also for the geochemical cycling of elements, ions and organic matter in surface water.

Apoptosis-mediated endothelial toxicity but not direct calcification or functional changes in anti-calcification proteins defines pathogenic effects of calcium phosphate bions

Calcium phosphate bions (CPB) are biomimetic mineralo-organic nanoparticles which represent a physiological mechanism regulating the function, transport and disposal of calcium and phosphorus in the human body. We hypothesised that CPB may be pathogenic entities and even a cause of cardiovascular calcification. Here we revealed that CPB isolated from calcified atherosclerotic plaques and artificially synthesised CPB are morphologically and chemically indistinguishable entities. Their formation is accelerated along with the increase in calcium salts-phosphates/serum concentration ratio. Experiments in vitro and in vivo showed that pathogenic effects of CPB are defined by apoptosis-mediated endothelial toxicity but not by direct tissue calcification or functional changes in anti-calcification proteins. Since the factors underlying the formation of CPB and their pathogenic mechanism closely resemble those responsible for atherosclerosis development, further research in this direction may help us to uncover triggers of this disease.

Viruses Occur Incorporated in Biogenic High-Mg Calcite from Hypersaline Microbial Mats

Using three different microscopy techniques (epifluorescence, electronic and atomic force microscopy), we showed that high-Mg calcite grains in calcifying microbial mats from the hypersaline lake "La Salada de Chiprana", Spain, contain viruses with a diameter of 50-80 nm. Energy-dispersive X-ray spectrometer analysis revealed that they contain nitrogen and phosphorus in a molar ratio of ~9, which is typical for viruses. Nucleic acid staining revealed that they contain DNA or RNA. As characteristic for hypersaline environments, the concentrations of free and attached viruses were high (>10(10) viruses per g of mat). In addition, we showed that acid treatment (dissolution of calcite) resulted in release of viruses into suspension and estimated that there were ~15 × 10(9) viruses per g of calcite. We suggest that virus-mineral interactions are one of the possible ways for the formation of nano-sized structures often described as "nanobacteria" and that viruses may play a role in initiating calcification.

A story told by a single nanoparticle in the body fluid: demonstration of dissolution-reprecipitation of nanocrystals in a biological system

AIM

Analysis of the chemical composition of mineral particles found in the body is critical to understand the formation and effects of these entities in vivo. Yet, the possibility that biological fluids may modulate particle composition over time has not been examined. Materials & methods: Mineralo-organic nanoparticles similar to the ones that spontaneously form in human tissues were analyzed using electron microscopy, spectroscopy and proteomic analyses. 

RESULTS

 We show that the mineralo-organic nanoparticles assimilate various ions and minerals during incubation in ionic solutions simulating body fluids. The particles undergo dissolution-reprecipitation reactions that affect the final protein composition of the particles.

CONCLUSION

The reactions occurring at the mineral-water interface therefore modulate the ionic and organic composition of mineral nanoparticles formed in biological fluids, producing changes that may alter the effects of mineral particles and stones in vivo.

Nanobacteria in the pathogenesis of urolithiasis: Myth or reality?

Stone formation in the urinary tract is a common phenomenon with associated morbidity. The exact physicochemical factors responsible for stone formation are not clearly known. Over the past decade considerable interest has been generated in defining the role of nanobacteria in urinary stone formation. A review of the available literature has been carried out to give insights into their nature and outline their role in stone formation. The two aspects of nanobacteria that need to be considered include its biological nature and the other merely as mineralo-protein complexes. Though the current literature favors the concept of mineralo-protein particles, further research is needed to clearly define their nature. Whether living or nonliving, these apatite forming nanoparticles appear to play role in kidney stone formation.

Cytotoxicity induced by nanobacteria and nanohydroxyapatites in human choriocarcinoma cells

We explored the cytotoxic effects of nanobacteria (NB) and nanohydroxyapatites (nHAPs) against human choriocarcinoma cells (JAR) and the mechanisms of action underlying their cytotoxicity. JAR cells were co-cultured with NB and nHAPs for 48 h, and ultrastructural changes were more readily induced by NB than nHAPs. Autophagy in the plasma of JAR cells were observed in the NB group. The rate of apoptosis induced by NB was higher than that for nHAPs. The expression of Bax and FasR proteins in the NB group was stronger than that for the nHAP group. NB probably resulted in autophagic formation. Apoptosis was possibly activated via FasL binding to the FasR signaling pathway.

Comparison of polymerase chain reaction and immunologic methods for the detection of nanobacterial infection in type-III prostatitis

OBJECTIVE

To compare the results of polymerase chain reaction (PCR) and immunologic methods for the detection of nanobacteria (NB) in the expressed prostatic secretions (EPSs) of patients with type-III prostatitis.

METHODS

In total, 150 patients with type-III prostatitis for whom conventional clinical treatment had failed were selected from September 2009 to April 2010. The EPS of each patient was divided into 3 parts, which were used for PCR analysis, indirect immunofluorescence staining (IIFS), and culture and subsequent indirect immunofluorescence staining (CIIFS).

RESULTS

PCR analysis has a higher sensitivity than IIFS for the detection of NB in EPSs. Of 83 CIIFS-positive EPS samples, 79 (95.2%) were positive by PCR. Of 67 EPS samples that were negative by CIIFS, 60 (89.6%) were negative by PCR. The sensitivity of PCR for the detection of NB compared with the CIIFS method was 95.2%, with a specificity of 89.6%. The positive predictive value was 91.9%, and the negative predictive value was 93.8%. A comparative evaluation showed no statistically significant difference between PCR and CIIFS in the detection of NB in EPSs. A strong agreement in the positive and the negative results obtained by PCR and CIIFS for NB detection was found for all EPS samples.

CONCLUSION

PCR analysis has a higher sensitivity than IIFS for NB detection in type-III prostatitis. PCR can detect nanobacterial infection in type-III prostatitis equally well as CIIFS and offers significant advantages for the rapid, simple, and economical detection of nanobacterial infection in type-III prostatitis.

Calcifying nanoparticles promote mineralization in vascular smooth muscle cells: implications for atherosclerosis

Background

Nano-sized complexes of calcium phosphate mineral and proteins (calcifying nanoparticles [CNPs]) serve as mineral chaperones. Thus, CNPs may be both a result and cause of soft tissue calcification processes. This study determined if CNPs could augment calcification of arterial vascular smooth muscle cells in vitro.

Methods

CNPs 210 nm in diameter were propagated in vitro from human serum. Porcine aortic smooth muscle cells were cultured for up to 28 days in medium in the absence (control) or presence of 2 mM phosphate ([P] positive calcification control) or after a single 3-day exposure to CNPs. Transmission electron-microscopy was used to characterize CNPs and to examine their cellular uptake. Calcium deposits were visualized by light microscopy and von Kossa staining and were quantified by colorimetry. Cell viability was quantified by confocal microscopy of live-/dead-stained cells and apoptosis was examined concurrently by fluorescent labeling of exposed phosphatidylserine.

Results

CNPs, as well as smaller calcium crystals, were observed by transmission electron-microscopy on day 3 in CNP-treated but not P-treated cells. By day 28, calcium deposits were visible in similar amounts within multicellular nodules of both CNP- and P-treated cells. Apoptosis increased with cell density under all treatments. CNP treatment augmented the density of apoptotic bodies and cellular debris in association with mineralized multicellular nodules.

Conclusion

Exogenous CNPs are taken up by aortic smooth muscle cells in vitro and potentiate accumulation of smooth-muscle-derived apoptotic bodies at sites of mineralization. Thus, CNPs may accelerate vascular calcification.

Renal struvite stones--pathogenesis, microbiology, and management strategies

Infection stones-which account for 10-15% of all urinary calculi-are thought to form in the presence of urease-producing bacteria. These calculi can cause significant morbidity and mortality if left untreated or treated inadequately; optimal treatment involves complete stone eradication in conjunction with antibiotic therapy. The three key principles of treating struvite stones are: removal of all stone fragments, the use of antibiotics to treat the infection, and prevention of recurrence. Several methods to remove stone fragments have been described in the literature, including the use of urease inhibitors, acidification therapy, dissolution therapy, extracorporeal shockwave lithotripsy, ureteroscopy, percutaneous nephrolithotomy (PCNL), and anatrophic nephrolithotomy. PCNL is considered to be the gold-standard approach to treating struvite calculi, but adjuncts might be used when deemed necessary. When selecting antibiotics to treat infection, it is necessary to acquire a stone culture or, at the very least, urine culture from the renal pelvis at time of surgery, as midstream urine cultures do not always reflect the causative organism.

Of nanobacteria, nanoparticles, biofilms and their role in health and disease: facts, fancy and future

Nanobacteria have been at the center of a major scientific controversy in recent years owing to claims that they represent not only the smallest living microorganisms on earth but also new emerging pathogens associated with several human diseases. We and others have carefully examined these claims and concluded that nanobacteria are in fact nonliving mineralo-organic nanoparticles (NPs) that form spontaneously in body fluids. We have shown that these mineral particles possess intriguing biomimetic properties that include the formation of cell- and tissue-like morphologies and the possibility to grow, proliferate and propagate by subculture. Similar mineral NPs (bions) have now been found in both physiological and pathological calcification processes and they appear to represent precursors of physiological calcification cycles, which may at times go awry in disease conditions. Furthermore, by functioning at the nanoscale, these mineralo-organic NPs or bions may shed light on the fate of nanomaterials in the body, from both nanotoxicological and nanopathological perspectives.

Cytotoxicity and apoptosis induced by nanobacteria in human breast cancer cells

Background

The existing evidence that nanobacteria (NB) are closely associated with human disease is overwhelming. However, their potential toxicity against cancer cells has not yet been reported. The objective of this study was to investigate the cytotoxic effects of NB and nanohydroxyapatites (nHAPs) against human breast cancer cells and to elucidate the mechanisms of action underlying their cytotoxicity.

Methodology/principal findings

NB were isolated from calcified placental tissue, and nHAPs were artificially synthesized. The viability of the MDA-MB-231 human breast cancer cell line was tested by using the Kit-8 cell counting kit assay. Apoptosis was examined by transmission electron microscopy and flow cytometry. The endocytosis of NB and nHAPs by MDA-MB-231 cells was initially confirmed by microscopy. Although both NB and nHAPs significantly decreased MDA-MB-231 cell viability and increased the population of apoptotic cells, NB were more potent than nHAPs. After 72 hours, NB also caused ultrastructural changes typical of apoptosis, such as chromatin condensation, nuclear fragmentation, nuclear dissolution, mitochondrial swelling, and the formation of apoptotic bodies.

Conclusion/significance

In MDA-MB-231 human breast cancer cells, NB and nHAPs exerted cytotoxic effects that were associated with the induction of apoptosis. The effects exerted by NB were more potent than those induced by nHAPs. NB cytotoxicity probably emerged from toxic metabolites or protein components, rather than merely the hydroxyapatite shells. NB divided during culturing, and similar to cells undergoing binary fission, many NB particles were observed in culture by transmission electron microscopy, suggesting they are live microorganisms.

Clinical implications of calcifying nanoparticles in dental diseases: a critical review

BACKGROUND

Unknown cell-culture contaminants were described by Kajander and Ciftçioğlu in 1998. These contaminants were called nanobacteria initially and later calcifying nanoparticles (CNPs). Their exact nature is unclear and controversial. CNPs have unique and unusual characteristics, which preclude placing them into any established evolutionary branch of life.

AIM

The aim of this systematic review was to assess published data concerning CNPs since 1998 in general and in relation to dental diseases in particular.

MATERIALS AND METHODS

The National Library of Medicine (PubMed) and Society of Photographic Instrumentation Engineers (SPIE) electronic and manual searches were conducted. Nanobacteria and calcifying nanoparticles were used as keywords. The search yielded 135 full-length papers. Further screening of the titles and abstracts that followed the review criteria resulted in 43 papers that met the study aim.

CONCLUSION

The review showed that the existence of nanobacteria is still controversial. Some investigators have described a possible involvement of CNPs in pulpal and salivary gland calcifications, as well as the possible therapeutic use of CNPs in the treatment of cracked and/or eroded teeth.

A phosphate-centric paradigm for pathophysiology and therapy of chronic kidney disease

Extracellular phosphate is toxic to the cell at high concentrations. When the phosphate level is increased in the blood by impaired urinary phosphate excretion, premature aging ensues. When the phosphate level is increased in the urine by dietary phosphate overload, this may lead to kidney damage (tubular injury and interstitial fibrosis). Extracellular phosphate exerts its cytotoxicity when it forms insoluble nanoparticles with calcium and fetuin-A, referred to as calciprotein particles (CPPs). CPPs are highly bioactive ligands that can induce various cellular responses, including osteogenic transformation of vascular smooth muscle cells and cell death in vascular endothelium and renal tubular epithelium. CPPs are detected in the blood of animal models and patients with chronic kidney disease (CKD) and associated with adaptation of the endocrine axes mediated by fibroblast growth factor-23 (FGF23) and Klotho that regulate mineral metabolism and aging. These observations have raised the possibility that CPPs may contribute to the pathophysiology of CKD. This notion, if validated, is expected to provide new diagnostic and therapeutic targets for CKD.

Bions: a family of biomimetic mineralo-organic complexes derived from biological fluids

Mineralo-organic nanoparticles form spontaneously in human body fluids when the concentrations of calcium and phosphate ions exceed saturation. We have shown previously that these mineralo-organic nanoparticles possess biomimetic properties and can reproduce the whole phenomenology of the so-called nanobacteria-mineralized entities initially described as the smallest microorganisms on earth. Here, we examine the possibility that various charged elements and ions may form mineral nanoparticles with similar properties in biological fluids. Remarkably, all the elements tested, including sodium, magnesium, aluminum, calcium, manganese, iron, cobalt, nickel, copper, zinc, strontium, and barium form mineralo-organic particles with bacteria-like morphologies and other complex shapes following precipitation with phosphate in body fluids. Upon formation, these mineralo-organic particles, which we term bions, invariably accumulate carbonate apatite during incubation in biological fluids; yet, the particles also incorporate additional elements and thus reflect the ionic milieu in which they form. Bions initially harbor an amorphous mineral phase that gradually converts to crystals in culture. Our results show that serum produces a dual inhibition-seeding effect on bion formation. Using a comprehensive proteomic analysis, we identify a wide range of proteins that bind to these mineral particles during incubation in medium containing serum. The two main binding proteins identified, albumin and fetuin-A, act as both inhibitors and seeders of bions in culture. Notably, bions possess several biomimetic properties, including the possibility to increase in size and number and to be sub-cultured in fresh culture medium. Based on these results, we propose that bions represent biological, mineralo-organic particles that may form in the body under both physiological and pathological homeostasis conditions. These mineralo-organic particles may be part of a physiological cycle that regulates the function, transport and disposal of elements and minerals in the human body.

Ectopic calcification: importance of common nanoparticle scaffolds containing oxidized acidic lipids

The term nanobacteria, sometimes referred to as nanobacteria-like particles (NLPs), is presently recognized as a misnomer for inert calcified nanoparticles. However, misinterpretation of its propagation as a living organism still continues. Ultrastructural and elemental analyses, combining immuno-electron microscopy with an original NLP isolate (P-17) derived from urinary stones, and an IgM monoclonal antibody (CL-15) raised against P-17 have now revealed that, oxidized lipids with acidified functional groups were key elements in NLP propagation. Lamellar structures composed of acidic/oxidized lipids provided structural scaffolds for carbonate apatite crystals. During in vitro culture, lipid peroxidation induced by γ-irradiation of FBS was a major cause of accelerated NLP propagation. In pathological tissue samples from hyperlipidemic atherosclerosis-prone mice, CL-15 co-localized with fatty plaques, macrophage infiltrates and osteocalcin staining of aortic valve lesions. These observations indicate that naturally occurring NLP composed of mineralo-oxidized lipids complexes are generated as by-products rather than etiological agents of chronic inflammation.

FROM THE CLINICAL EDITOR

The term "nanobacteria-like particles (NLPs)" is presently recognized as a misnomer for inert calcified nanoparticles as opposed to living organisms. This study convincingly demonstrates that naturally occurring NLPs composed of mineralo-oxidized lipid complexes are generated as by-products rather than etiological agents of chronic inflammation.

Membrane vesicles nucleate mineralo-organic nanoparticles and induce carbonate apatite precipitation in human body fluids

Recent studies indicate that membrane vesicles (MVs) secreted by various cells are associated with human diseases, including arthritis, atherosclerosis, cancer, and chronic kidney disease. The possibility that MVs may induce the formation of mineralo-organic nanoparticles (NPs) and ectopic calcification has not been investigated so far. Here, we isolated MVs ranging in size between 20 and 400 nm from human serum and FBS using ultracentrifugation and sucrose gradient centrifugation. The MV preparations consisted of phospholipid-bound vesicles containing the serum proteins albumin, fetuin-A, and apolipoprotein A1; the mineralization-associated enzyme alkaline phosphatase; and the exosome proteins TNFR1 and CD63. Notably, we observed that MVs induced mineral precipitation following inoculation and incubation in cell culture medium. The mineral precipitates consisted of round, mineralo-organic NPs containing carbonate hydroxyapatite, similar to previous descriptions of the so-called nanobacteria. Annexin V-immunogold staining revealed that the calcium-binding lipid phosphatidylserine (PS) was exposed on the external surface of serum MVs. Treatment of MVs with an anti-PS antibody significantly decreased their mineral seeding activity, suggesting that PS may provide nucleating sites for calcium phosphate deposition on the vesicles. These results indicate that MVs may represent nucleating agents that induce the formation of mineral NPs in body fluids. Given that mineralo-organic NPs represent precursors of calcification in vivo, our results suggest that MVs may initiate ectopic calcification in the human body.

Physicochemical and biological properties of biomimetic mineralo-protein nanoparticles formed spontaneously in biological fluids

Recent studies indicate that mineral nanoparticles (NPs) form spontaneously in human body fluids. These biological NPs represent mineral precursors that are associated with ectopic calcifications seen in various human diseases. However, the parameters that control the formation of mineral NPs and their possible effects on human cells remain poorly understood. Here a nanomaterial approach to study the formation of biomimetic calcium phosphate NPs comparable to their physiological counterparts is described. Particle sizing using dynamic light scattering reveals that serum and ion concentrations within the physiological range yield NPs below 100 nm in diameter. While the particles are phagocytosed by macrophages in a size-independent manner, only large particles or NP aggregates in the micrometer range induce cellular responses that include production of mitochondrial reactive oxygen species, caspase-1 activation, and secretion of interleukin-1β (IL-1β). A comprehensive proteomic analysis reveals that the particle-bound proteins are similar in terms of their identity and number, regardless of particle size, suggesting that protein adsorption is independent of particle size and curvature. In conclusion, the conditions underlying the formation of mineralo-protein particles are similar to the ones that form in vivo. While mineral NPs do not activate immune cells, they may become pro-inflammatory and contribute to pathological processes once they aggregate and form larger mineral particles.

Accelerated growth plate mineralization and foreshortened proximal limb bones in fetuin-A knockout mice

The plasma protein fetuin-A/alpha2-HS-glycoprotein (genetic symbol Ahsg) is a systemic inhibitor of extraskeletal mineralization, which is best underscored by the excessive mineral deposition found in various tissues of fetuin-A deficient mice on the calcification-prone genetic background DBA/2. Fetuin-A is known to accumulate in the bone matrix thus an effect of fetuin-A on skeletal mineralization is expected. We examined the bones of fetuin-A deficient mice maintained on a C57BL/6 genetic background to avoid bone disease secondary to renal calcification. Here, we show that fetuin-A deficient mice display normal trabecular bone mass in the spine, but increased cortical thickness in the femur. Bone material properties, as well as mineral and collagen characteristics of cortical bone were unaffected by the absence of fetuin-A. In contrast, the long bones especially proximal limb bones were severely stunted in fetuin-A deficient mice compared to wildtype littermates, resulting in increased biomechanical stability of fetuin-A deficient femora in three-point-bending tests. Elevated backscattered electron signal intensities reflected an increased mineral content in the growth plates of fetuin-A deficient long bones, corroborating its physiological role as an inhibitor of excessive mineralization in the growth plate cartilage matrix - a site of vigorous physiological mineralization. We show that in the case of fetuin-A deficiency, active mineralization inhibition is a necessity for proper long bone growth.

Aortic valve-derived calcifyng nanoparticles: no evidence of life

INTRODUCTION AND OBJECTIVES

Calcifying nanoparticles, also known as "nanobacteria," are very small bacteria-like structures (0.1-0.5 μm) with the ability to facilitate the precipitation and growth of calcium phosphate in pathological conditions and have been associated with aortic valve calcification. The status of nanobacteria is controversial; some have proposed that they are a new class of living organism while others describe calcifying nanoparticles as mineralo-fetuin complexes. The objective of the present study is to elucidate if calcifying nanoparticles are living entities, based on whether or not they have metabolic activity, a characteristic of life, irrespective of their composition.

METHODS

Calcifying nanoparticles were grown from 6 different valves randomly chosen among 84 consecutively explanted aortic valves, as described in the literature. The (1)H-NMR spectra were acquired from calcifying nanoparticles culture media to assess metabolic changes and the presence of 16sRNA in the culture media was investigated by real-time polymerase chain reaction.

RESULTS

After 6 weeks in culture, calcifying nanoparticles could be seen clearly attached to the surface of culture flasks. All samples were negative for 16sRNA, discarding the presence of known bacteria. (1)H-NMR spectra showed no difference between calcifying nanoparticles and 6-week-old sterile culture media maintained under the same conditions.

CONCLUSIONS

Our results show that calcifying nanoparticles cannot be considered as living organisms.

Hemoglobin aggregates studied under static and dynamic conditions involving the formation of nanobacteria-like structures

Laser light scattering and scanning electron microscopy (SEM) are used to study hemoglobin in the aqueous phase. The impact that salts [NaCl, Ca₃(PO₄)₂] and iron oxide nanoparticles have on the hemoglobin size are also studied. The first set of experiments examined hemoglobin aggregates in the aqueous phases in the presence of salts and nanoparticles. Aqueous phase samples were then dehydrated and examined using SEM. The resulting structures resemble those observed in nanobacteria studies conducted in other labs. This study demonstrates that aggregates of hemoglobin and various salts found in a physiological environment can produce structures that resemble nanobacteria.

The role of calcifying nanoparticles in biology and medicine

Calcifying nanoparticles (CNPs) (nanobacteria, nanobacteria-like particles, nanobes) were discovered over 25 years ago; nevertheless, their nature is still obscure. To date, nobody has been successful in credibly determining whether they are the smallest self-replicating life form on Earth, or whether they represent mineralo-protein complexes without any relation to living organisms. Proponents of both theories have a number of arguments in favor of the validity of their hypotheses. However, after epistemological analysis carried out in this review, all arguments used by proponents of the theory about the physicochemical model of CNP formation may be refuted on the basis of the performed investigations, and therefore published data suggest a biological nature of CNPs. The only obstacle to establish CNPs as living organisms is the absence of a fairly accurately sequenced genome at the present time. Moreover, it is clear that CNPs play an important role in etiopathogenesis of many diseases, and this association is independent from their nature. Consequently, emergence of CNPs in an organism is a pathological, not a physiological, process. The classification and new directions of further investigations devoted to the role of CNPs in biology and medicine are proposed.

Are We from Outer Space?

The biological record suggests that life on Earth arose as soon as conditions were favorable, which indicates that life either originated quickly, or arrived from elsewhere to seed Earth. Experimental research under the theme of “astrobiology” has produced data that some view as strong evidence for the second possibility, known as the panspermia hypothesis. While it is not unreasonable to consider the possibility that Earth’s life originated elsewhere and potentially much earlier, we conclude that the current literature offers no definitive evidence to support this hypothesis.

Chladni’s view, that they fall from the skies, pronounced in 1795, was ridiculed by the learned men of the times. (Rachel, 1881)

Evidence of life on Mars, even if only in the distant past, would finally answer the age-old question of whether living beings on Earth are alone in the universe. The magnitude of such a discovery is illustrated by President Bill Clinton’s appearance at a 1996 press conference to announce that proof had been found at last. A meteorite chipped from the surface of the Red Planet some 15 million years ago appeared to contain the fossil remains of tiny life-forms that indicated life had once existed on Mars. (Young and Martel, 2010)

Calcium-based nanoparticles accelerate skin wound healing

Introduction

Nanoparticles (NPs) are small entities that consist of a hydroxyapatite core, which can bind ions, proteins, and other organic molecules from the surrounding environment. These small conglomerations can influence environmental calcium levels and have the potential to modulate calcium homeostasis in vivo. Nanoparticles have been associated with various calcium-mediated disease processes, such as atherosclerosis and kidney stone formation. We hypothesized that nanoparticles could have an effect on other calcium-regulated processes, such as wound healing. In the present study, we synthesized pH-sensitive calcium-based nanoparticles and investigated their ability to enhance cutaneous wound repair.

Methods

Different populations of nanoparticles were synthesized on collagen-coated plates under various growth conditions. Bilateral dorsal cutaneous wounds were made on 8-week-old female Balb/c mice. Nanoparticles were then either administered intravenously or applied topically to the wound bed. The rate of wound closure was quantified. Intravenously injected nanoparticles were tracked using a FLAG detection system. The effect of nanoparticles on fibroblast contraction and proliferation was assessed.

Results

A population of pH-sensitive calcium-based nanoparticles was identified. When intravenously administered, these nanoparticles acutely increased the rate of wound healing. Intravenously administered nanoparticles were localized to the wound site, as evidenced by FLAG staining. Nanoparticles increased fibroblast calcium uptake in vitro and caused contracture of a fibroblast populated collagen lattice in a dose-dependent manner. Nanoparticles also increased the rate of fibroblast proliferation.

Conclusion

Intravenously administered, calcium-based nanoparticles can acutely decrease open wound size via contracture. We hypothesize that their contraction effect is mediated by the release of ionized calcium into the wound bed, which occurs when the pH-sensitive nanoparticles disintegrate in the acidic wound microenvironment. This is the first study to demonstrate that calcium-based nanoparticles can have a therapeutic benefit, which has important implications for the treatment of wounds.

A red herring in vascular calcification: 'nanobacteria' are protein-mineral complexes involved in biomineralization

Biomineralization at pathological extraosseous sites (i.e. vasculature and soft tissues) is associated with increased morbidity and mortality. So-called 'nanobacteria' have been described as pathogenic agents causing many diseases including calcification. Initially, their appearance, and having a content consisting of nucleic acids plus proteins and properties of growing structures, suggested that they were living organisms. However, it could be demonstrated that the so-called nanobacteria were in fact mineralizing nanoparticles that contain mineral and non-mineral compounds, that these particles bind to charged molecules and that supersaturation enables in vitro growth of these nanoparticles. Recent data indicate that nanoparticles consisting of protein-mineral complexes can be seen both in vitro and in vivo as precursors of matrix calcification.

Fetuin-A regulation of calcified matrix metabolism

The final step of biomineralization is a chemical precipitation reaction that occurs spontaneously in supersaturated or metastable salt solutions. Genetic programs direct precursor cells into a mineralization-competent state in physiological bone formation (osteogenesis) and in pathological mineralization (ectopic mineralization or calcification). Therefore, all tissues not meant to mineralize must be actively protected against chance precipitation of mineral. Fetuin-A is a liver-derived blood protein that acts as a potent inhibitor of ectopic mineralization. Monomeric fetuin-A protein binds small clusters of calcium and phosphate. This interaction results in the formation of prenucleation cluster-laden fetuin-A monomers, calciprotein monomers, and considerably larger aggregates of protein and mineral calciprotein particles. Both monomeric and aggregate forms of fetuin-A mineral accrue acidic plasma protein including albumin, thus stabilizing supersaturated and metastable mineral ion solutions as colloids. Hence, fetuin-A is a mineral carrier protein and a systemic inhibitor of pathological mineralization complementing local inhibitors that act in a cell-restricted or tissue-restricted fashion. Fetuin-A deficiency is associated with soft tissue calcification in mice and humans.

Serum-derived nanoparticles: de novo generation and growth in vitro, and internalization by mammalian cells in culture

AIM

While nanoparticles (NPs) have been shown to form spontaneously in body fluids such as serum, the possible implications of these NPs for cell cultures that use supporting media containing serum remain unclear. To understand the de novo formation of NPs, we delineated their growth characteristics, chemical composition and interaction with cells in culture.

MATERIALS & METHODS

Serum-derived particles were analyzed using a combination of dynamic light scattering, turbidity measurements, spectroscopic techniques and optical/electron microscopies.

RESULTS

NPs were found in serum and in serum-containing medium and they increased in size and number during incubation. The mineral particles, consisting mainly of calcium carbonate phosphate bound to organics such as proteins, underwent an amorphous-to-crystalline transformation with time. Serum-derived particles were internalized by the cells tested, eventually reaching lysosomal compartments.

CONCLUSION

The spontaneous formation of serum-derived NPs and their internalization by cells may have overlooked effects on cultured cells in vitro as well as potential pathophysiological consequences in vivo.

Detection and isolation of nanobacteria-like particles from urinary stones: long-withheld data

OBJECTIVES

To report our experimental results on detection and isolation of nanobacteria-like particles (NLP) from urinary stone samples.

METHODS

From March 2001 to August 2003, 47 urinary stone samples from Japanese patients and 18 from Paraguayan patients were collected and used for compositional analysis, direct survey of NLP by scanning electron microscopy (SEM) and their cultural isolation. For the isolation, culturing was carried out using strict aseptic techniques. Dulbecco's modified Eagle medium with 10% gamma-irradiated fetal bovine serum was used based on the original method described by Kajander and Ciftçioglu.

RESULTS

Positive NLP detection rates for Japanese and Paraguayan patient samples were 61.7% (29/47) and 66.7% (12/18), respectively. Positive NLP isolation rates for Japanese patient samples were 20.6% (7/34) and 20.0% (2/10) for Paraguayan patient samples. In the initial isolation, markedly different periods of incubation time were needed for each of the nine cases (6-220 days; median 36 days). Positive detection and isolation were obtained in stone samples with or without calcium phosphate. Growth modes and morphogenesis of NLP were divided into two phases; rod-shaped NLP was detected mainly as a floating form growing in culture medium and spherical NLP with a characteristic apatite shell was detected as an attached form growing on the surface of culture dishes.

CONCLUSIONS

Lifeless calcifying nanoparticles can be isolated from various human urinary stones, cultured in cell culture mediums and show two characteristic growth phases.