Pathogenic Prion Protein Isoforms Are Not Present in Cerebral Organoids Generated from Asymptomatic Donors Carrying the E200K Mutation Associated with Familial Prion Disease

Abstract

Cerebral organoids (COs) are a self-organizing three-dimensional brain tissue mimicking the human cerebral cortex. COs are a promising new system for modelling pathological features of neurological disorders, including prion diseases. COs expressing normal prion protein (PrPC) are susceptible to prion infection when exposed to the disease isoforms of PrP (PrPD). This causes the COs to develop aspects of prion disease pathology considered hallmarks of disease, including the production of detergent-insoluble, protease-resistant misfolded PrPD species capable of seeding the production of more misfolded species. To determine whether COs can model aspects of familial prion diseases, we produced COs from donor fibroblasts carrying the E200K mutation, the most common cause of human familial prion disease. The mature E200K COs were assessed for the hallmarks of prion disease. We found that up to 12 months post-differentiation, E200K COs harbored no PrPD as confirmed by the absence of detergent-insoluble, protease-resistant, and seeding-active PrP species. Our results suggest that the presence of the E200K mutation within the prion gene is insufficient to cause disease in neuronal tissue. Therefore, other factors, such as further genetic modifiers or aging processes, may influence the onset of misfolding.

Neuronal excitatory-to-inhibitory balance is altered in cerebral organoid models of genetic neurological diseases

“…While we have previously shown that COs can model infectious prion disease, we and others also found that COs generated from donors with the E200K mutation within the prion protein gene ( PRNP ) that causes genetic CJD do not show any parameters of disease [ 6 , 19 ]. To investigate whether the PRNP E200K mutation can influence electrophysiological functions of the CO cultures and contrast this with the trisomy 21-causing AD and LRRK2 G2019S -causing PD mutations, organoids at 3–4 and 6–10 months post differentiation were monitored for electrophysiological aberrations and for changes in their synaptic receptors.…”

Cerebral organoids as a new model for prion disease

“…It is believed that interactions between host genetics and cellular environment trigger the conversion of PrP to PrP Sc [16][17][18]. Our group has previously found that hCOs produced from asymptomatic donors carrying the PrP gene (PRNP) E200K mutation do not develop any signs of PrD up to 12 months post-differentiation [16].…”

“…However, using hCOs, treatment can be tested against any subtype in large numbers. Additionally, iPSCs can be derived from skin samples making patient-specific COs easily obtainable for personalized testing [16]. Furthermore, PRNP mutations introduced through CRISPR/Cas-9 technology can generate larger numbers of individual iPSC cell lines than can be obtained from donors with the advantage of isotype controls.…”

From Cell Culture to Organoids-Model Systems for Investigating Prion Strain Characteristics

“…Foliaki et al, prepared organoids from the fibroblasts of 2 people carrying the E200K CJD mutation, which is the most common familial prion disease mutation. Despite a line of transgenic mouse model with this mutation developing disease at about 5-6 months old [ 117 ], neither organoid showed any sign of PrP seeding activity or pathology after culturing for 12 months [ 118 ]. Again, this illustrates the difference between transgenic mice and humans, and also the need to identify methods of inducing or accelerating familial prion disease in organoids.…”