[Gautam Mahajan]

Thanks everyone for your comment, we’ve reached the end of the AMA session. If you have any follow-up questions, feel free to add them here and I’ll try to answer them

[Gautam Mahajan]

Hey Daniel, It is great to see growing interest in immune system models on a chip. We modeled lymph node or lymphoid follicle (upto 3 weeks) using Emulate S1 chip and Zoe culture module. https://onlinelibrary.wiley.com/doi/10.1002/advs.202103241 show that primary human blood B- and T-lymphocytes autonomously assemble into ectopic LFs when cultured in a three-dimensional (3D) extracellular matrix gel within an organ-on-a-chip microfluidic device. To explore utility for vaccine testing, autologous monocyte-derived dendritic cells were integrated into LF Chips and when inoculated with commercial influenza vaccine, Plasma Cell formation and production of anti-hemagglutinin IgG were observed, as well as secretion of cytokines similar to those observed in vaccinated humans. Human LF chips demonstrated improved antibody responses to split virion influenza vaccination compared to 2D cultures, which were enhanced by addition of a squalene-in-water emulsion adjuvant. This demonstrates the ability of the human Lymphoid Follicle Chip as an alternative to animal testing and predict human relevant response to vaccination and immunotherapies.

https://emulatebio.com/modeling-human-immune-response-lymphoid-follicle-organ-chips/

https://wyss.harvard.edu/news/the-immune-system-is-very-complicated-but-now-its-on-a-chip/#:~:text=In%20addition%20to%20allowing%20researchers,in%20a%20dish%20and%20non%2D

 

[Gautam Mahajan]

Thanks Jackson! Great question… In this current configuration, the focus was to use commercially available cells. We screened a few vendors and used the cells expressing appropriate vaginal epithelial cell makers. In this study we used 2 different donors from Caucasian and Hispanic ethnicity. Both donors behaved similarly on the chip with some differences in forming strong barrier. Current efforts are towards incorporating additional donors..

[Gautam Mahajan]

Thanks Rebecca! Next step is incorporation of immune cells and mucus to better enable host-microbiome interactions..

[Gautam Mahajan]

Hi Ben, great questions…

1. There is no consensus yet if Vagina is hypoxic or not. The current methods of measuring comes with its own challenges such as tampon based sensors leading to influx of atmospheric air. So, keeping in mind the focus of the study we decided to go with the low O2 conditions provided by the consumption of O2 by cells and influx of O2 by episodic flow which was verified using COMSOL.

2. This is not something explored yet but will be great to add it in future work by current team at Wyss. I will provide this feedback to them.

[Gautam Mahajan]

Great questions..

1. Biggest challenge was to recapitulate out the dynamic microenvironment which vaginal epithelium experience. In this model after several iterations we developed and used the workflow of episodic flow in the epithelium compartment. This helped with growth of epithelium and bacteria.

2. Organ chip provides a great tool to recapitulate patient responses in vitro and offers attractive solution for personalized medicine testing. This commercially available chip and platform is cell agnostic and provides an opportunity to build your own model. And your approach of using patient cancer cells and tumor microenvironment will fit within the realms of organ chip.

[Gautam Mahajan]

Hi Asli, This is a very important question and thank you for asking this.

1. Current models are 2D monolayers, transwell models, bioreactor models. In the discussion section of the paper, we touched base on the limitation of these and especially why these models do not provide an attractive solution for host-microbiome interactions. And of course there are animal models which comes with its own challenges, the biggest one being differences in animal vs human microbiome.

2. It is known fact that current models can only sustain bacterial growth for <24 hours followed by overgrowth of this bacteria. Our dynamic chip helps bacteria to grow and provide in vivo like environment of multilayer epithelium, low O2 gradient and episodic flow.

[Gautam Mahajan]

Hi Anthony, Thank you! Great Question.. Current work was focused on utilizing the commercially available chip to support this host-microbiome interactions and therefore we used COMSOL as a tool. I would love to see sensor integration and verify the results. I am confident we will see similar results, a study in the past verified this approach https://www.nature.com/articles/s41551-019-0397-0

[Gautam Mahajan]

Hi Jane, this session is focused on answering question through this forum. Please submit any questions you have and I am more than happy to answer those.

[Gautam Mahajan]

Thank you everyone for submitting their questions.

Reply to @Sasha.. Great Questions:

1. The main focus of the paper is to model host-microbiome interactions and this model can be used to study infection and progression of STI for example gonorrhoea, chlamydia etc. I feel the workflow in the manuscript can be used for these applications with some optimization.

2. In figure 1, we showed that Vagina Chip is responsive to fluctuations to hormone levels. Although Menopause is a complex phenomenon, the chip can help recapitulate the changes to vaginal epithelium, stroma and microbes due to hormonal changes during menopause.