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Updated: Sep 17, 2025
Production of Humanized Mouse via Thymic Renal Capsule Grafting, CD34+ Cells Injection, and Cytokine Delivery
Published on: September 27, 2021
Development and characterization of a fully humanized ACE2 mouse model
Chunyu Ge1, Amr R Salem1, Amany Elsharkawy2
1Vascular Biology Center, Medical College of Georgia at Augusta University, Augusta, GA, 30912, USA.
Background:
Many humanized angiotensin-converting enzyme 2 (ACE2) mouse models of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection do not replicate human ACE2 protein expression and thus exhibit pathology infrequently observed in humans. To address this limitation, we designed and characterized a fully humanized ACE2 (hACE2) mouse by replacing all exons/introns of the mouse Ace2 locus with human DNA comprising the entire ACE2 gene and an upstream long noncoding RNA (LncRNA).
Results:
Compared to the popular Keratin18 ACE2 (KRT18-ACE2, K18) mouse model of SARS-CoV-2 infection, hACE2 mice displayed a similar tissue expression profile of ACE2 as that seen in human tissues. Further, hACE2 mice showed comparable blood pressure, angiotensin II metabolism, and renal cortical transcriptome as wild-type mice. Intranasal infection of K18 mice with the beta variant of SARS-CoV-2 resulted in high viral replication and inflammation of the lung and brain, weight loss, and compassionate euthanasia five days post-infection (PI). Similarly infected hACE2 mice displayed viral replication and inflammation in the lung (but not in brain), sustained weight, and 100% survival up to 12 days PI, with clear evidence of acquired immunity. CRISPR-mediated disruption of the upstream LncRNA caused minimal effects on ACE2 mRNA and protein.
Conclusions:
The hACE2 model offers a more accurate approach to studying mechanisms underlying tissue-restricted expression of ACE2, elucidating noncoding sequence variants and an upstream LncRNA, and defining pathways relevant to human disease and associated co-morbidities.
