Applying Condensational Growth for Direct Exposure of Human Small Airway Epithelial Cells to Flame-Generated Soot
SHUBHAM SUNIL SHARMA, Dhruv Mitroo, Durgesh N. Das, Paul Hamilton, Joseph V. Puthussery, Rajan K. Chakrabarty, Benjamin Kumfer, Washington University in St. Louis
Abstract Number: 435
Working Group: Health-Related Aerosols
Abstract
Soot emitted from combustion sources such as wildfires and activities such as driving, cooking, and open waste incineration has been shown to cause adverse heath effects in various mammalian cells. Physicochemical properties such as particle size, morphology, surface area, surface reactivity, and PAHs content vary by source and influence toxicity in cells. Preserving these properties during in vitro studies is crucial for accurately assessing their impact on cell health. Traditional cell exposure by addition of suspension of particles in cell media is challenging due to colloidal instability and difficulty in preserving the original size distribution and morphology. To overcome this challenge, methods to directly deposit aerosols onto the cells such as electrostatic deposition and impaction through condensational growth have been used to by different research groups but, to the best of our knowledge, the application of condensational growth with deposition has not yet been explored with soot aerosol. Exposure through condensational growth better simulates the mechanism of real-life exposure by mimicking the warm and humid air pathway to lungs. However, the condensational growth of particles is sensitive to the number concentration and the temperature gradients in the growth tube. In the work here, a parametric study using a Spot SamplerTM (Handix Scientific Inc.) is performed to optimize the number concentration and growth tube temperatures and an exposure system is developed that directly exposes primary Human Small Airway Epithelial Cells (HSAEC) growing in a standard multi-well culture plate to the flame-generated soot aerosol with controlled dosage. The effect of operating parameters on cell exposure is presented for both premixed and non-premixed flame generated soot. The study also compares an initial biological response observed between direct exposure using condensational growth and exposure through processing of particles collected on a filter. The combined system provides an unique platform for assessing toxicity using exposure through condensational growth of soot, and for elucidating the particle properties most relevant to health outcomes.