Cheah, E. | bioRxiv Science

bioRxiv2024

3D printed microtissue cassettes enabling high throughput proton radiobiological assays

Uncertainties on proton relative biological effectiveness (RBE) across the spread out of Bragg peak (SOBP) (typically assumed to be 1.1) may lead to suboptimal treatment plan and unwarranted toxicity to organs-at-risk. Herein, we report a reliable analytical method to determine the proton RBE along the SOBP and distal fall-off region. The 3D microtissue cassette enables the high throughput assessment of biological assays including clonogenic assay and {gamma}-H2AX assay following a single proton irradiation. Clonogenic assay shows the RBE of 1.6 (10% cellular survival) which is consistent with the deter-mined RBE of 1.58 using the {gamma}-H2AX assay. Besides, we also show that the high spatial resolution of the cassette can distinguish the minute but significant foci changes (number, area) in response to small proton radiation dose fraction. The results validate the reliability of our setup in addressing critical proton radiobiological questions.

bioengineering↗

bioRxiv2024

A pumpless and tubeless microfluidic device enables extended in vitro development of Cryptosporidium parvum

The enteric parasite Cryptosporidium remains a treatment challenge for drinking water utilities globally due to its resistance to chlorine disinfection. However, the lack of an in vitro culture system for Cryptosporidium that is both cost-effective and reliable remains a key bottleneck in Cryptosporidium research. Here we report that the microfluidic culture of HCT-8 cells under fluid shear stress enables the extended development of Cryptosporidium parvum. Specifically, the growth of C. parvum in a user-friendly pumpless microfluidic device was assessed using immunofluorescence assays, scanning electron microscopy and quantitative PCR, which revealed that development peaked at six days post-infection but continued for ten days in total. Oocysts produced within the microfluidic device were infective to fresh HCT-8 monolayers, however these oocysts were only present at low levels. We anticipate that such microfluidic approaches will facilitate a wide range of in vitro studies on Cryptosporidium and may have the potential to be further developed as a routine infectivity assessment tool for the water industry.

microbiology↗