G1-APOL1 bone marrow chimeric B6 mice and rejection of fully MHC mismatched heterotopic Heart Transplants (BALBc-to-B6 model)

G1-mice demonstrated greater CD8+T-cell graft infiltration and reduced survival in a mismatched heart transplant model following sensitization. Single-cell transcriptomics of graft infiltrating TCMs showed enrichment of T-cell receptor (TCR) response pathways including calcium signaling. Overall design: To evaluate APOL1-RVs in an allotransplantation model, we generated bone marrow chimeric mice from G0- and G1-BAC-Tg (in a B6/45.2 background) in B6/45.1 hosts. B6/45.2 chimerism was confirmed at 4 weeks in B6/45.1 hosts (both H-2b). Bacterial artificial chromosome transgenic mice (BAC-Tg) show physiologic expression of APOL1 gene and each mouse line expresses only that respective variant, Co-stimulation blockade with CTLA4-Ig (methods) was provided and the mice were monitored for rejection till 28 days. To study G1-CD8+T-cell subsets, we evaluated the single-cell transcriptome of graft infiltrating T-cells from the BALBc/J cardiac allografts harvested from chimeric G1- or -G0 recipients at 4-weeks (N=3 each). We flow-sorted live CD3+ cells from allografts and performed single-cell RNA sequencing using a hashtagging approach to multiplex the 6 samples during sequencing (n~17000 total cells).