Spatially resolved transcriptional analysis of brains from mice flown on the RR-3 mission

The Rodent Research-3 (RR-3) mission was sponsored by the pharmaceutical company Eli Lilly and Co. and the Center for the Advancement of Science in Space to study the effectiveness of a potential countermeasure for the loss of muscle and bone mass that occurs during spaceflight. Twenty BALB/c 18-weeks old female mice (ten controls and ten treated) were flown to the ISS and housed in the Rodent Habitat for 39-42 days. Twenty mice of similar age and matching sex and strain were used for ground controls housed in identical hardware and matching ISS environmental conditions. Basal controls were housed in standard vivarium cages. Spaceflight ground controls and basal groups had blood collected then were euthanized had one hind limb removed and finally whole carcasses were stored at -80 C until dissection. All mice in this data set received only the control/sham injection. Brain samples from three flight and three ground control animal groups were cut in half between hemispheres. One hemisphere of each brain was used for generating spatially resolved transcriptional profiling data. Hemispheres were cryosectioned so that 2 consecutive sections from the hippocampus of each brain was placed on Visium Gene Expression arrays. Samples were fixed stained with Hematoxylin and Eosin and imaged. Imaging was followed by tissue permeabilization to release mRNA molecules from cells for capture onto the array surface. Subsequently following the 10XGenomics Visium Gene Expression protocol Spatial Transcriptomics RNA-seq libraries were prepared and sequenced.