In vitro toxicity of fine and coarse particulate matter on the skin, ocular and lung microphysiological cell-culture systems.

Particulate matter (PM) has been associated with adverse effects on human health, causing allergies, skin and eye irritation and corrosion, respiratory tract irritation, headaches, bronchoconstriction, cardiopulmonary diseases such as asthma, chronic obstructive pulmonary disease (COPD), lung cancer, reproductive problems, premature deaths, and epigenetic changes that lead to a wide variety of cancers, among other health conditions. The air quality in the Medellín - Colombia presents fluctuations that oscillate between the maximum permissible levels established at the national level and by the WHO, which represents a latent risk to people's health. Although important efforts have been made to quantify the different levels of pollution and administrative measures have been established to mitigate air pollution, little research work has been done to establish the relationship between these levels of pollutants and the effects on biological systems. The objective of the present research was to make a morphological and chemical characterization of particulate matter (PM) captured with a commercial air filter and a electrospun nanofiber membrane and evaluate the cytotoxicity of the each PM extracts in monolayer and co-culture models which recreate microphysiological systems of lung, skin and cornea and propose the possible cellular interactions that lead the cytotoxic response of the chemical compounds found in particulate matter in cities. The morphology and elemental chemical characterization were done with scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM - EDS). For the polycyclic aromatic hydrocarbons detection was made with a chromatographic method accoupled to mass spectrometer. Finally, the cytotoxicity was made in monolayers of A549, HEK001, and SIRC cell lines and microphysiological systems consisting of two-cell layer construct to resemble the interaction between fibroblast and epithelial cells that comprises naturally the corneal, skin and lung tissue. We performed three different cocultures models with BALB/3T3 clone A31 as a feeder layer, using porous Transwell® inserts in the in-contact and non-contact way. Monolayer and co-culture models were exposed to coarse and fine PM (1, 2, and 5 mg/mL) and the cell viability was evaluated at 24 h using an MTT assay. The electrospun nanofibers membranes demonstrates higher efficiency to capture PM with different sizes and high concentration of polycyclic aromatic hydrocarbons, heavy metals, and other chemical compounds responsible of many human diseases. Cytotoxic effects of MP were observed in all models at higher concentration; however, models exposed to fine PM exhibited a significant reduction in cell viability compared to those exposed to coarse PM. In addition, multilayer models are more resistant to PM exposure than monolayer models. Furthermore, the study indicated that, depending on the seeding strategy, different results might be observed: the non-contact model showed higher resistance to PM exposure than in-contact for SIRC and HEK001, but A549 monolayers showed the highest viability response. This study demonstrates the usefulness of applying co-culture models to assess environmental pollutant toxicity, in addition to being a potential alternative method to animal testing for risk assessment.

Detección del daño genotóxico agudo y crónico en una población de laboratoristas ocupacionalmente expuestos / Detection of acute and chronic genotoxic damage in an occupationally-exposed population

En el ámbito mundial se ha encontrado una fuerte relación entre la exposición a agentes genotóxicos y la incidencia de cáncer y problemas reproductivos, en personal ocupacionalmente expuesto. En el presente trabajo se evaluó, en personal vinculado a los laboratorios de la Universidad Nacional de Colombia, sede Medellín, el efecto de la exposición a agentes potencialmente genotóxicos, mediante las pruebas de intercambio de cromátides hermanas (ICH) y la electroforesis en gel de células individuales (prueba cometa). Se logró estandarizar herramientas metodológicas que permitieran cuantificar el daño producido por la exposición a agentes potencialmente genotóxicos e implementarlas en programas de monitorización para propósitos de salud ocupacional. La evaluación se realizó en dos poblaciones, una expuesta y una control, mediante el uso de muestras pareadas; para el apareamiento se eligieron individuos de la misma edad, género y hábitos. La prueba cometa mostró daño agudo en la población expuesta, mientras que la prueba de ICH no reveló daño crónico. De otro lado, se encontró que el índice de ICH en las dos poblaciones evaluadas no varió con los hábitos ni con el género, pero sí con la edad. Lo anterior muestra la utilidad de la prueba cometa para medir las exposiciones agudas y la del ICH como una excelente prueba para cuantificar las exposiciones crónicas; estas pruebas son imprescindibles como parte de la batería utilizada en estudios de Monitorización genotóxica. Mediante este estudio se adecuó la infraestructura y se capacitó al personal para llevar a cabo monitorizaciones sobre genotoxicidad con propósitos de salud ocupacional y con el ánimo de extender este servicio tanto a la comunidad universitaria como a los sectores público y privado

Worldwide studies in people occupationally exposed to genotoxic agents have shown a strong correlation of the exposition with cancer incidence and reproductive dysfunctions. This research evaluated, in laboratory personnel at the Universidad Nacional, Medellín, Colombia, the effect of exposition to potentially genotoxic agents, by means of sister chromatids interchange tests (SCI) and electrophoresis in single cells gel (comet assay). Standardization of methodological tools to quantify the damage produced by exposition to potentially genotoxic agents was achieved, in order to implement them in occupational health monitoring programs. Evaluation was carried out in two populations, exposed and control, using paired samples. Age, sex and habits were used as criterions for pairing. Comet assay showed punctual damage in the exposed population, while SCI test did not reveal chronic damage. On the other hand, neither habits nor sex showed relation with SCI index, but age did. The usefulness of the comet assay to measure the effect of punctual expositions, and that of SCI as an excellent test to quantify the effect of chronic expositions, makes them indispensable as part of the battery used in genotoxic monitoring studies. As part of the benefits of this research, infrastructure was adapted and some personnel was qualified to carry out occupational health genotoxic monitoring, with the aim of extending this service to the University community and to the private and public sectors