Nuclei from liquid nitrogen frozen organs were isolated using the Nuclei Extraction Buffer (Miltenyi) according to manufacturer's instructions. For snRNA-sequencing, nuclei of 1 replicate per time point (BL6xCAST females) were incubated with DRAQ7 for 5 min before sorting, staining the DNA of nuclei. Sorting the DRAQ7-positive population ensured a debris-free nuclei suspension, which was again assessed on the Countess™ II FL Automated Cell Counter equipped with the DAPI EVOS light cube. Single-nucleus libraries were generated using the Chromium Next GEM Single Cell 3ʹ Reagent Kit v3.1 (10X Genomics) with a target of 10,000 nuclei per sample.