Nanoplastic impact on bone microenvironment: A snapshot from murine bone cells

Maternal exposure to polystyrene nanoplastics during gestation and lactation impaired skeletal growth in progeny mice by inhibiting neutrophil extracellular trap formation

Microplastics and nanoplastics are widely distributed in the natural environment and shown to accumulate in living organisms. While their potential impact on human health has been investigated, significant uncertainties remain regarding their toxic effects and mechanisms of interaction with the human skeletal system. We examined the potential effects of polystyrene nanoplastics (PS-NPs, 100 nm) on skeletal health and the underlying molecular mechanisms using the human RAW264.7 and MC3T3-E1 cell lines as in-vitro models, along with a murine model. Maternal exposure to PS-NPs (10 mg/L) through drinking water during the prenatal and lactational periods led to an increase in osteoblasts, as well as a significant rise in bone mineral density (BMD) and bone content in offspring mice. Exposure to 100 mg/L PS-NPs resulted in a significant reduction in the thickness of the femoral growth plates. Multi-omics analysis revealed that both high (100 mg/L) and low (10 mg/L) maternal PS-NP exposure concentrations disrupted gene expression and metabolic regulation in the skeletal system of offspring mice. Regulatory analysis showed PS-NPs probably induced inflammation and abnormal immune infiltration levels by inhibiting the formation of neutrophil extracellular traps (NETs), especially in 100 mg/L exposure. In in-vitro tests, the PS-NPs dose-relatedly reduced the relative viability of RAW264.7 cells and promoted osteoclast differentiation, but did not affect MC3T3-E1 cells up to 500 mg/L. Our findings demonstrate that maternal exposure to PS-NPs has detrimental effects on skeletal development and function in progeny mice, providing new insights into their toxicological effects on the skeletal system.

Effects of micro- and nanoplastic exposure on macrophages: a review of molecular and cellular mechanisms

Micro- and nanoplastics (MNPs), pervasive environmental pollutants, contaminate water, soil, air, and the food chain and ultimately accumulate in living organisms. Macrophages are the main immune cells that gather around MNPs and engulf them through the process of phagocytosis. This internalization triggers M1 polarization and the secretion of inflammatory cytokines, including IL-1, IL-18, IL-12, TNF-α, and IFN-γ. Furthermore, MNPs damage mitochondria and lysosomes, causing overactivation of iNOS and excessive production of ROS. This results in cellular stress and induce apoptosis, necroptosis, and, in some cases, metosis in macrophages. The internalization of MNPs also increases the expression of receptors, involving CD36, SR-A, LOX-1, and the macrophage receptor with a collagenous structure (MARCO) while decreasing ABCA-1 and ABCG-1. MNPs in adipose tissue macrophages trigger proinflammatory cytokine secretion, causing adipogenesis, lipid accumulation, insulin resistance, and the secretion of inflammatory cytokines in adipocytes. Various factors influence the rate of MNP internalization by macrophages, including size, charge, and concentration, which affect internalization through passive diffusion. Receptor-mediated phagocytosis of MNPs occurs directly via receptors like T-cell immunoglobulin and mucin domain containing 4 (TIM-4) and MARCO. The attachment of biomolecules, including proteins, antibodies, opsonins, or microbes to MNPs (forming corona structures) promotes indirect receptor-mediated endocytosis, as macrophages possess receptors like TLRs and FcγRIII. MNPs also cause gut dysbiosis, a risk factor for proinflammatory microenvironment and M1 polarization. Here, we review the mechanisms and consequences of MNP macrophage exposure, which is linked to autoimmunity, inflammation, and cardiometabolic syndrome manifestations, including atherosclerosis and obesity, highlighting the immunotoxicity of MNPs.

Mitigating microplastic-induced organ Damage: Mechanistic insights from the microplastic-macrophage axes

We live in a world increasingly dominated by plastic, leading to the generation of microplastic particles that pose significant global health concerns. Microplastics can enter the body via ingestion, inhalation, and direct contact, accumulating in various tissues and potentially causing harm. Despite this, the specific cellular mechanisms and signaling pathways involved remain poorly understood. Macrophages are essential in absorbing, distributing, and eliminating microplastics, playing a key role in the body's defense mechanisms. Recent evidence highlights oxidative stress signaling as a key pathway in microplastic-induced macrophage dysfunction. The accumulation of microplastics generates reactive oxygen species (ROS), disrupting normal macrophage functions and exacerbating inflammation and organ damage. This review serves as the first comprehensive examination of the interplay between microplastics, macrophages, and oxidative stress. It discusses how oxidative stress mediates macrophage responses to microplastics and explores the interactions with gut microbiota. Additionally, it reviews the organ damage resulting from alterations in macrophage function mediated by microplastics and offers a novel perspective on the defense, assessment, and treatment of microplastic-induced harm from the viewpoint of macrophages.

Assessing the Impact of Nanoplastics in Biological Systems: Systematic Review of In Vitro Animal Studies

Nanoplastic (NP) pollution has emerged as a growing concern due to its potential impact on human health, although its adverse effects on different organ systems are not yet fully understood. This systematic scoping review, conducted in accordance with international guidelines, aimed to map the current evidence on the biological effects of NPs. In vitro animal studies assessing cellular damage caused by exposure to any type of NP were searched on PubMed, Web of Science, and Scopus. Data on primary outcomes related to genotoxicity and cytotoxicity (cell viability, oxidative stress, inflammation, DNA and cytoplasmic damage, apoptosis) were extracted from the included studies, and overall reporting quality was assessed. A total of 108 articles published between 2018 and 2024, mostly by China (54%), Spain (14%), and Italy (9%), were included. Polystyrene (PS) was the most frequently studied polymer (85%). NP sizes in solution ranged from 15 to 531 nm, with a higher prevalence in the 40-100 nm range (38%). The overall quality of studies was rated as moderate (60%), with many lacking essential details about cell culture conditions (e.g., pH of the medium, passage number, substances used). A higher frequency of negative effects from NP exposure was observed in respiratory cell lines, while immune, digestive, and hepatic cell lines showed greater resistance. Nervous, urinary, and connective tissue systems were impacted by NPs. Positively charged and smaller PS particles were consistently associated with higher toxicity across all systems. In summary, this review highlights the multifactorial nature of NP toxicity, influenced by size, surface charge, and polymer type. It also reveals a significant knowledge gap, stemming from the predominant use of immortalized monocultures exposed to commercially available PS NPs, the limited use of environmentally relevant particles, and the underutilization of advanced experimental models (e.g., organ-on-chip systems) that better mimic physiological conditions.

Potential Biological Impacts of Microplastics and Nanoplastics on Farm Animals: Global Perspectives with Insights from Bangladesh

Microplastics (MPs) and nanoplastics (NPs), formed through the degradation of larger plastic materials, are emerging pollutants of significant concern. While their impact on aquatic ecosystems is well documented, their effects on terrestrial, especially farm animals remain underexplored. This review assesses the potential threats of MPs and NPs to Bangladesh's livestock sector by analyzing the results of experimental models and environmental studies. In Bangladesh, MPs and NPs have been detected in agricultural soils, air, water bodies, and aquatic organisms, indicating possible entry into animal systems through contaminated feed, water, and inhalation. Once internalized, these particles may trigger oxidative stress, inflammation, and tissue damage, impairing vital biological systems. Documented health consequences include reduced fertility, hematotoxicity, gut microbiota imbalance, gut-brain axis disruption, skeletal disorders, and metabolic dysfunction. Additionally, MPs and NPs can induce genomic changes, including altered gene expression and DNA hypomethylation, intensifying physiological damage and reducing productivity. Therefore, managing plastic contamination is vital in protecting animal health, ensuring food safety, and preserving human well-being around the globe, especially in vulnerable regions like Bangladesh. Given the critical role of livestock and poultry in ensuring food security and public health, the findings highlight an urgent need for comprehensive research and mitigation strategies.

Effects of microplastics on the immune system: How much should we worry?

Plastics are everywhere. It is widely recognized that they represent a global problem, the extent of which is yet to be defined. Humans are broadly exposed to plastics, whose effects and consequences are poorly characterized so far. The main route of exposure is via alimentary and respiratory intake. Plastics pollutions may come from both: water and food contamination itself, and their packaging. The smaller sizes (i.e. microplastics <150 µm - MPs) are considered to be the most pervasive of living organisms and, therefore, potentially the most harmful. As humans occupy one of the apex positions of the food chain, we are exposed to bioaccumulation and biomagnification effects of MPs. In fact, MPs are commonly found in human stools and blood. However, there are no data available yet on their ability to accumulate and to produce detrimental consequences on biological systems. Even though the effects of plastics pollution are poorly studied in mammals, including humans, they appear to have inflammatory effects, which is rather concerning as many etiologies of disease are based on a pro-inflammatory status.

Effects of nanoplastics and compound pollutants containing nanoplastics on plants, microorganisms and rhizosphere systems: A review

Nanoplastics (NPs) are the most widespread and least detectable type of plastic pollutant due to their extremely small particle size. The root system of plants has become an important pathway for NPs to enter the food chain from the natural environment. By combining with heavy metals or organic pollutants, NPs can exhibit greater biological toxicity compared to single pollutants. Although many studies have focused on the phytotoxicity and microbial toxicity of NPs separately, to the best of our knowledge, no review summarizes the toxicity of NPs from the perspective of the plant rhizosphere system with a combination of pollutants. By summarizing samples from 2015 to 2025, this review highlights that NPs can affect photosynthesis, gene transcription, and enzyme activity in both plants and microorganisms. NPs with large particle size can also disrupt the chemical balance of the rhizosphere environment and intensify competition for nutrients between plants and microorganisms, ultimately affecting the geochemical cycle. NPs of different particle sizes and concentrations can poison various biological structures, from surface layers to genetic material. In compound pollutants, where NPs combine with other contaminants, they can further disrupt elemental cycles in plants, reduce microbial community diversity, and increase the accumulation of other pollutants in the rhizosphere system compared to single pollutants. These findings provide new insights into the biotoxicity of NPs and the degradation of compound pollutants containing NPs. In addition, combined with the research results of this review, some research prospects on the relationship between NPs and rhizosphere systems are given.

ROS-responsive hydrogel for bone regeneration: Controlled dimethyl fumarate release to reduce inflammation and enhance osteogenesis

Large bone defects, often arising from trauma or infection, pose a considerable therapeutic challenge due to their limited capacity for spontaneous healing, thus requiring bone graft materials for effective reparative procedures. The persistence of inflammation and elevated levels of reactive oxygen species (ROS) within these defect sites significantly impede bone regeneration process. Addressing this, an injectable hydrogel system with ROS-responsive functionality is developed, specifically tailored to the high ROS microenvironment characteristic of bone defects. This system incorporates hyaluronic acid functionalized with dopamine to introduce catechol moieties, and employs 4-formylphenylboronic acid as a crosslinking agent to form a dynamic hydrogel matrix (HAC) with carboxymethyl chitosan. The HAC hydrogel serves as a carrier for dimethyl fumarate (DMF), a compound with established anti-inflammatory and antioxidant effects, enabling its controlled release in response to ROS levels. Herein, we investigated the physicochemical properties of DMF loaded hydrogel (DHAC) by microstructure observation, in vitro degradation assay, self-healing test, injectability experiments, DMF drug release assay. Meanwhile, we systematically investigated its effects on inflammation, intracellular ROS, and osteogenesis. Consequently, the DHAC significantly reduced pro-inflammatory cytokines secreted by RAW264.7 cells and scavenged intracellular ROS in MC3T3 cells. This effect was accompanied by an augmentation in the osteogenic potential of MC3T3 cells and a promotion in the repair of cranial defects in rats. The DHAC, which exhibits anti-inflammatory, antioxidant, and osteogenic activity, hold great potential as an effective strategy for the management of large bone defects. STATEMENT OF SIGNIFICANCE: Here, a novel dimethyl fumarate-loaded ROS-responsive hydrogel system was developed for effective treatment of large bone defects. Our findings demonstrated that the hydrogel not only promotes bone regeneration but also controls inflammation, addressing two critical challenges in bone healing. Comprehensive evaluations show significant improvements in bone formation and reduction of pro-inflammatory cytokines in animal models. Additionally, the hydrogel exhibits excellent reactive oxygen species scavenging ability, effectively modulating oxidative stress in the bone defect microenvironment. Findings suggest the hydrogel system may serve as a promising therapeutic strategy for clinical management of critical-sized bone defects.

Biological Effects of Micro-/Nano-Plastics in Macrophages

The environmental impact of plastics is worsened by their inadequate end-of-life disposal, leading to the ubiquitous presence of micro- (MPs) and nanosized (NPs) plastic particles. MPs and NPs are thus widely present in water and air and inevitably enter the food chain, with inhalation and ingestion as the main exposure routes for humans. Many recent studies have demonstrated that MPs and NPs gain access to several body compartments, where they are taken up by cells, increase the production of reactive oxygen species, and lead to inflammatory changes. In most tissues, resident macrophages engage in the first approach to foreign materials, and this interaction largely affects the subsequent fate of the material and the possible pathological outcomes. On the other hand, macrophages are the main organizers and controllers of both inflammatory responses and tissue repair. Here, we aim to summarize the available information on the interaction of macrophages with MPs and NPs. Particular attention will be devoted to the consequences of this interaction on macrophage viability and functions, as well as to possible implications in pathology.

The Effects of Microplastics on Musculoskeletal Disorder; A Narrative Review

PURPOSE OF REVIEW

The physical health impacts of microplastics have received increasing attention in recent years. However, limited data impedes a full understanding of the internal exposure to microplastics, especially concerning the musculoskeletal system. The purpose of this review is to summarize the recent literature regarding the effects of microplastics on the musculoskeletal system.

RECENT FINDINGS

Microplastics have been shown to cause abnormal endochondral ossification and disrupt the normal function of pre-osteoblasts, osteocyte-like cells, and pre-osteoclasts through gene mutations, endoplasmic reticulum stress induction, and reduced autophagosome formation in bone growth areas. Although there are few reports on their effects on muscle, it has been noted that microplastics inhibit energy and lipid metabolism, decrease type I muscle fiber density, impair muscle angiogenesis, cause muscle atrophy, and increase lipid deposition. Only a few recent studies have shown that microplastics interfere with the normal function of bone growth-related cells and reduce muscle mass and quality. This review underscores the need for further research into other parts of the musculoskeletal system and studies using human tissues at the disease level.

Neutrophils inhibit bone formation by directly contacting osteoblasts and suppressing osteogenic differentiation

Neutrophils have been extensively studied for their critical roles in supporting immune defense mechanisms, initiating bone regeneration, and promoting angiogenesis. Nonetheless, the influence of neutrophils on physiological conditions, particularly in the context of bone development, remains incompletely understood. In this study, we examined the effects of non-inflammatory neutrophils on bone physiology by depleting Ly6G+ neutrophils and inducing neutropenia through myelosuppression. Our results demonstrated a notable increase in bone mass and a decrease in the bone marrow cavity upon depletion of the neutrophils. These effects were attributed to the direct interaction between neutrophils and osteoblasts, independent of reduced secretion of typical inflammatory cytokines or diminished osteoclast differentiation. This observation suggests a non-inflammatory function of neutrophils within the endosteal microenvironment, where they regulate osteogenic differentiation to preserve optimal bone mass, shape healthy three-dimensional bone trabecular structures, and create ample space for hematopoietic niche development.

Cinobufagin Suppresses Lipid Peroxidation and Inflammation in Osteoporotic Mice by Promoting the Delivery of miR-3102-5p by Macrophage-Derived Exosomes

BACKGROUND

Cinobufagin, the primary active compound in toad venom, is commonly used for anti-tumor, anti-inflammatory, and analgesic purposes. However, its specific bone-protective effects remain uncertain. This research aims to ascertain the bone-protective properties of cinobufagin and investigate underlying mechanisms.

METHODS

Mice were ovariectomized to establish an osteoporosis model, followed by intraperitoneal injections of cinobufagin and cinobufagin-treated RAW.264.7-derived exosomes for therapy. MicroCT, HE staining, and TRAP staining were employed to evaluate bone mass and therapeutic outcomes, while mRNA sequencing and immunoblotting were utilized to assess markers of bone metabolism, inflammation, and lipid peroxidation. Osteoblast and osteoclast precursor cells were differentiated to observe the impact of cinobufagin-treated exosomes derived from RAW264.7 cells on bone metabolism. Exosomes characteristics were studied using transmission electron microscopy and particle size analysis, and miRNA binding targets in exosomes were determined by luciferase reporting.

RESULTS

In ovariectomized mice, cinobufagin and cinobufagin-treated exosomes from RAW264.7 cells increased trabecular bone density and mass in the femur, while also decreasing inflammation and lipid peroxidation. The effect was reversed by an exosomes inhibitor. In vitro experiments revealed that cinobufagin-treated exosomes from RAW264.7 cells enhanced osteogenic and suppressed osteoclast differentiation, possibly linked to Upregulated miR-3102-5p in RAW-derived exosomes. MiR-3102-5p targets the 3'UTR region of alox15, thereby suppressing its expression and reducing the lipid peroxidation process in osteoblasts.

CONCLUSION

Overall, this study clarified cinobufagin's bone-protective effects and revealed that cinobufagin can enhance the delivery of miR-3102-5p targeting alox15 through macrophage-derived exosomes, demonstrating anti-lipid peroxidation and anti-inflammatory effects.

Polystyrene nanoplastics mediate skeletal toxicity through oxidative stress and the BMP pathway in zebrafish (Danio rerio)

The widespread presence of micro(nano)plastics (MNPs) has generated public concern. Studies have indicated that MNPs can accumulate in mammalian bones; however, research on the skeletal toxicity and underlying molecular mechanisms of MNPs in aquatic organisms remains limited. We subjected zebrafish embryos to three varying levels (1, 10, 100 μg/mL) of polystyrene nanoplastics (PSNPs) exposure over a period of 7 days in our research. The results revealed that PSNPs significantly reduced the body length and hatching rate of zebrafish, leading to skeletal deformities. mRNA level analysis showed significant upregulation of sp7, sparc, and smad1 genes transcription by PSNPs. Moreover, PSNPs markedly downregulated the mRNA levels associated with runx2a, bmp2a, and bmp4. Further investigations demonstrated that PSNPs dramatically increased ROS levels in zebrafish larvae, with significant downregulation of transcription levels of sod1 and cat genes, resulting in a sharp increase in transcription levels of apoptosis-related regulatory genes bcl-2 and bax. Furthermore, PSNPs led to a marked rise in Caspase 3 activity in zebrafish larvae, suggesting the initiation of apoptosis. PSNPs also notably inhibited alkaline phosphatase (AKP) activity. Compared to a 4-day exposure, a 7-day exposure to PSNPs intensified abnormalities across multiple indicators. In summary, our research indicates that PSNPs cause significant oxidative stress in zebrafish larvae, resulting in apoptosis. Moreover, PSNPs disrupt the transcription of genes related to skeletal development through the bone morphogenetic protein (BMP) pathway, further disrupting skeletal development processes and ultimately resulting in skeletal deformities in zebrafish larvae. This study provides new insights into the skeletal toxicity of MNPs.

Impact of polystyrene nanoplastics on apoptosis and inflammation in zebrafish larvae: Insights from reactive oxygen species perspective

In recent years, there has been a growing focus on the toxicity and mortality induced by nanoplastics (NPs) in aquatic organisms. However, studies investigating mechanisms underlying oxidative stress (OS), apoptosis, and inflammation induced by NPs in fish remain limited. This study observed that polystyrene NPs (PS-NPs) were accumulated into zebrafish larvae and zebrafish embryonic fibroblast (ZF4 cells), accompanied by the occurrence of pathological damage both at the cellular and tissue-organ level. Additionally, the transcriptional up-regulation of NADPH oxidases (NOXs) and subsequent excessive generation of reactive oxygen species (ROS) resulted in notable changes in the relative mRNA and protein expression levels associated with antioxidant oxidase systems in larvae. Furthermore, the study identified the impact of NPs on mitochondrial ultrastructural, resulting in mitochondrial depolarization and downregulation of mRNA expression related to the electron transport chain due to excessive ROS generation. Short-term exposure to NPs also triggered apoptosis and inflammation in zebrafish larvae, evident from significant up-regulation in mRNA expressions of proapoptotic factors and NF-κB proinflammatory signaling pathway, as well as increased transcription and protein levels of pro-inflammatory factors in larvae. Inhibition of intracellular excessive ROS effectively reduced the induction of apoptosis, NF-κB P65 nuclear migration levels, and cytokine secretion, underscoring OS as a pivotal factor throughout the process of apoptosis and inflammatory responses induced by NPs. This research significantly advances our comprehension of biological effects and underlying mechanisms of NPs in freshwater fish.