Basic Science and Pathogenesis

Background: Cardiovascular disease causes vascular dementia and contributes to most clinical dementia. This is embodied in the concept of vascular contributions to cognitive impairment and dementia (VCID). The potent endogenous peptide endothelin-1 (ET1) causes small artery vasoconstriction and fibrosis. ET1 is implicated in microvascular disease and in VCID. There are few experimental animal models relevant to VCID [Hainsworth et al. 2017]. Pigs are higher mammals with a gyrencephalic brain and extensive subcortical white matter.

Method: We engineered domestic pigs carrying additional copies of the ET1-encoding gene EDN1 under a Tet-ON promotor, by lentiviral injection into blastocysts. We induced transgene expression for up to 8 days using oral doxycycline in young adults.

Result: We studied ET1-overexpressing (n = 6, 3F/3M, mean±SD age 184±61 days) and control animals (n = 5, 3F/2M, 149±41 days). Following doxycycline treatment we observed a wide range of transgene expression at mRNA level. Antibody labelling indicated a spectrum of ET1 abundance in brain and heart tissue. Heart weight was 460±106 g in ET1-overexpressing pigs and 394±25 g in controls. Brain weight: 104±14.4 g in ET1-overexpressing, 101±9.0 in controls. We will report phenotypes relevant to inflammation and blood vessel fibrosis.

Conclusion: Adult-onset EDN1 induction in domestic pigs produces ET1 overexpression that is well-tolerated to 8 days. Reference: Hainsworth AH, et al. (2017) BMC Med.15(1):16. Translational models for vascular cognitive impairment: a review including larger species.