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Environmental pollution arising from plastic waste is a major global concern. Plastic macroparticles, microparticles, and nanoparticles have the potential to affect marine ecosystems and human health. It is generally accepted that microplastic particles are not harmful or at best minimal to human health. However direct contact with microplastic particles may have possible adverse effect in cellular level. Primary polystyrene (PS) particles were the focus of this study, and we investigated the potential impacts of these microplastics on human health at the cellular level. We determined that PS particles were potential immune stimulants that induced cytokine and chemokine production in a sizedependent and concentration-dependent manner. Microplastic particles can be divided into two categories, primary and secondary. Plastic particles less than 5 mm in diameter are considered microplastics 1. Although local and national governments in North America took action in 2015 to regulate the manufacture of microbeads, microplastic particles are still produced in other parts of the world 2. Primary microplastic particles are intentionally manufactured at the microscale and are key ingredients in scrubs 3 , handwashing soaps 4 , cleansers 5 , toothpastes 6 , and biomedical products 7. Primary microplastic particles, particularly those between 1 and 5 µm in diameter, are spherical and often made of polypropylene (PP), polystyrene (PS), or polyethylene (PE). Unlike primary microplastic particles, secondary microplastic particles are generated through the fragmentation of plastic litter 8-10. Plastic debris is the primary source of secondary microplastic particles found in the ocean and soil, because the debris breaks down into mesoparticles and macroparticles. Ultraviolet (UV) radiation from the sun and physical forces degrade these particles into plastic microparticles and nanoparticles 11,12. A recent study investigated the fragmentation of PS coffee cup lids, disposable plates, and PS foams irradiated with simulated UV light to determine the degradation mechanism 13. Seafood is also a potential source of particulate plastic contaminants 14-18. Anthropogenic debris, including plastic particles and fibers, was found in over 20% of individual shellfish and the gastrointestinal (GI) tracts of fish in a 2015 study 19. The ingestion of microplastics by fish and shellfish has been demonstrated in several studies 16,18,20. Food, food containers, everyday products (personal care products), biomedical products, and drinking water are not the main sources of particulate plastic contaminants. However, they may be continuous sources of plastic particles 21-24. For example, one study found microplastic fragments in all types of returnable and single-use plastic bottles 24. Other examples include facial scrubs that are commonly used for exfoliation. It is estimated that 1.1 million women in the UK use these scrubs every day. A typical amount for daily use is 5 mL, which contains between 4,594 and 94,500 microplastic particles 4,5. Additio...

Animal cell culture technology for therapeutic protein production has shown significant improvement over the last few decades. Chinese hamster ovary (CHO) cells have been widely adapted for the production of biopharmaceutical drugs. In the biopharmaceutical industry, it is crucial to develop cell culture media and culturing conditions to achieve the highest productivity and quality. However, CHO cells are significantly affected by apoptosis in the bioreactors, resulting in a substantial decrease in product quantity and quality. Thus, to overcome the obstacle of apoptosis in CHO cell culture, it is critical to develop a novel method that does not have minimal concern of safety or cost. Herein, we showed for the first time that exosomes, which are nano-sized extracellular vesicles, derived from CHO cells inhibited apoptosis in CHO cell culture when supplemented to the culture medium. Flow cytometric and microscopic analyses revealed that substantial amounts of exosomes were delivered to CHO cells. Higher cell viability after staurosporine treatment was observed by exosome supplementation (67.3%) as compared to control (41.1%). Furthermore, exosomes prevented the mitochondrial membrane potential loss and caspase-3 activation, meaning that the exosomes enhanced cellular activities under pro-apoptotic condition. As the exosomes supplements are derived from CHO cells themselves, it is not only beneficial for the biopharmaceutical productivity of CHO cell culture to inhibit apoptosis, but also from a regulatory standpoint to diminish any safety concerns. Thus, we conclude that the method developed in this research may contribute to the biopharmaceutical industry where minimizing apoptosis in CHO cell culture is beneficial.

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Plastic is produced, used, and accumulated exponentially. Humans can take it through the food chain, and microplastics can be potentially toxic to humans. In this study, we analyzed the surface patterns of microplastics and their effects on humans using polyvinyl chloride (PVC) and acrylonitrile butadiene styrene (ABS). The surface analysis of these microplastics will be used as a standardized measurement method for microplastic detection and will be used as an indicator of the impact of environmental pollution caused by microplastics on humans. We have used a statistical method to analyze the shape of the milled microplastics and estimated the local curvature for each plastic type and found that PVC microplastics have a more rugged shape than the ABS microplastics. We also analyzed the toxicity of PVC and ABS microplastics. Larger PVC tended to induce the release of interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α). Smaller ABS induced the release of IL-6 at high concentrations. However, larger ABS tended to induce the release of TNF-α at all concentrations. Thus, we concluded that microplastics can induce immune responses.

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BackgroundMicroplastics,plastics thathave gradually and randomly decomposed into small fragmentsafter exposure to physical and biological external stress,are emerging as a significant environmental threat. They are normally categorized into the following three types: particles, fibers, and random-shape fragments brokendown from bulk plastics. Here, we have demonstrated the in vitro toxicity of microplastics of two different shapes. To minimize the chemical effect, polyethylene (PE),which has abasic chemical polymer structure,was used. PE microplastics withtwo different shapes were prepared,high-density PE (HDPE) microbeads and randomly ground low-density PE (LDPE) from bulk pellets.ResultsTo quantify the randomness of the microplastic shape, the edge patterns of the generated PE microplasticswere converted into numerical values and analyzed using a statistical method. A10-fold difference in curvature value was observed between PE particles and ground PE microfragments. We found that the higher concentration and rough structure were associated with the toxicity of plastics toward immune- or non-immune cells, pro-inflammatory cytokinerelease, and hemolysis, even though PE is buoyant onto medium. The smooth PE particles did not exhibit severe cytotoxicity at any of the tested concentrations, but induced immune and hemolysis responses at high concentrations. ConclusionWhen comparing the toxicity of two different shapes of PE microplastics, we confirmed by statistical analysis that random-shape plastics with sharp edges and higher curvature differences may adversely affect human cells.