Animal Nose-only Exposure Method and Cell in Vitro Exposure Method

Assisting in the Study of the Effects of Air Pollution on Human Health

Background

Air pollution is like a silent killer, causing approximately 3.7 million deaths worldwide each year, accounting for 6.7% of all deaths worldwide. Deaths related to air pollution are mostly caused by respiratory diseases such as lung cancer and respiratory infections. According to the emission rate/formation source of pollutants, air pollutants can be divided into primary and secondary. Primary air pollutants are pollutants directly emitted into the atmosphere, such as industrial and biogenic processes; secondary air pollutants are pollutants formed in the atmosphere.

Regarding chemical composition, air pollution is a mixture of gases and particulate matter (PM). Gas and PM can react under atmospheric influence and cause different toxicity over time. It is estimated that up to 87% of the world's population lives in areas 2.5 (PM<2.5) that exceed the World Health Organization's (WHO) air quality guidelines for PM, causing an estimated 2.9 million deaths annually. The gases in the atmosphere are also at harmful levels. For example, ozone is estimated to cause 217000 deaths annually.

Although the general public will be affected by air pollution, vulnerable groups such as the elderly, pregnant women, children, and those with some existing diseases may face a higher risk of related incidence rates and mortality. For example, in patients aged 65 and above, increased levels of outdoor ozone, sulfur dioxide, and carbon monoxide are associated with a higher risk of cardiovascular-related hospitalization. Asthma patients can also worsen their condition due to air pollutants. Other social factors, such as health disparities, including malnutrition, low socio-economic status, and race, can also exacerbate the impact of air pollutants on them.

Objective

Faced with the limitations of in vivo research, people urgently need to find new evaluation methods to measure the toxicity of air pollution more accurately. Cell in vitro models and experimental animal models are two excellent alternative methods that have emerged, which can evaluate the toxicity of the testing environment more efficiently.

Cell in Vitro Exposure System

(A) The exposure chamber includes a porous plate culture dish with an undirected internal circulation flow.

(B) The vertical flow system, including the porous plate culture dish, has nozzles that directly guide the airflow above the cells.

(C) Horizontal flow system - airflow passes through a cell culture chamber below the flow path.

In Vitro Models Evaluation

Types of toxicity endpoints associated with air pollution exposure can be evaluated by in vitro models. The general in vitro exposure conditions conducted at the air-liquid interface and various types of toxic reactions can be measured. After exposure to pollutants, changes in cell viability, gene, protein, and epigenome levels all occurred.

Animal Models Evaluation

A more effective method of in vitro exposure is to study the toxic reactions of experimental animals to air pollutants. These designs allow the use of exposure generation systems and experimental devices similar to in vitro experiments to evaluate rodents exposed to air pollutants. These methods can improve the credibility of in vitro data.

By taking animal experiments, the toxicological effects of exposure to air pollutants can be evaluated in a more controllable environment. Rats and mice are the most common models, and other animals, such as non-human primates, dogs, and rabbits, are also used to evaluate the toxicity of air pollution. Acute, subchronic, and chronic study designs can be used to expose animals to air pollutants. Acute design can include, for example, one-day, two-day, or daily exposure, spanning 5-7 days per week, less than 14 days. The subchronic design includes similar daily exposure but should be maintained for 90-180 days. The span of chronic design ranges from 180 days to two years. Many types of toxicological outcomes can be observed from animal studies, including overall mortality and abnormalities and effects on organ, tissue, and molecular levels.

Conclusion

In summary, according to current scientific research, the combination of animal nose-only exposure and cell in vitro exposure is an efficient experimental method that researchers can use to study the medium—and long-term effects of various pollutants on the human body.

The animal nose-only exposure system and cell in vitro exposure system (ALI), which Tow-Int Tech independently developed, can assist and accelerate research in this area.

Solutions and applications

Tow-Int Tech Small Animal Nose-only Exposure System

The Tow-Int Tech Small Animal Nose-only Exposure System is suitable for conducting nose-only administration and inhalation exposure experiments on mice, rats, guinea pigs, and other experimental animals. The system has good airtightness and uniform exposure concentration, making it suitable for nose-only inhalation toxicity experiments using inhalable substances such as liquid, dust, nanoparticle aerosols, and smoke. The system can ensure consistency in the inhalation dose of the same experimental group of animals, realize online concentration detection of aerosols and real-time online sampling, and adopt a high-precision control system to ensure the uniformity and stability of contamination.

Animal exposure systems can test various substances, including drugs, air pollutants, PM2.5, organic matter, industrial hygiene, agricultural chemicals, etc. Multiple gas contamination experiments can be conducted, including acute and chronic contamination, hypobaric, hyperbaric, hypoxia, and hyperoxia.

Tow-Int Tech ALI Cell in Vitro Exposure System

Tow-Int Tech ALI Cell in Vitro Exposure System (gas-liquid interface culture exposure): Cells are cultured at the ALI gas-liquid interface using Transwell membrane technology and then exposed to inhalable substances for contamination by the exposure system. Due to the exposure of the cell surface to the contaminated substance and the membrane substrate being in the culture medium, this method simulates the process of inhalable substances entering the human body.

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Reference:

New Approach Methods to Evaluate Health Risks of Air Pollutants: Critical Design Considerations for In Vitro Exposure Testing