No abstract

Prime editing is a recently reported genome editing tool using a nickase-cas9 fused to a reverse transcriptase that directly synthesizes the desired edit at the target site. Here, we explore the use of prime editing in human organoids. Common TP53 mutations can be correctly modeled in human adult stem cell–derived colonic organoids with efficiencies up to 25% and up to 97% in hepatocyte organoids. Next, we functionally repaired the cystic fibrosis CFTR-F508del mutation and compared prime editing to CRISPR/Cas9–mediated homology-directed repair and adenine base editing on the CFTR-R785* mutation. Whole-genome sequencing of prime editing–repaired organoids revealed no detectable off-target effects. Despite encountering varying editing efficiencies and undesired mutations at the target site, these results underline the broad applicability of prime editing for modeling oncogenic mutations and showcase the potential clinical application of this technique, pending further optimization.

Altogether, these results indicate that R560S is a class II mutation. However, unlike F508del, it cannot be rescued by any of the CFTR modulators tested.

CFTR-dependent intestinal epithelial ion transport properties can be measured in rectal organoid-derived monolayers of subjects and correlate with donor-matched ICM and rectal organoid swelling.

Cholera is a potentially fatal bacterial infection that affects a large number of people in developing countries. It is caused by the cholera toxin (CT), an AB5 toxin secreted by Vibrio cholera. The toxin comprises a toxic A-subunit and a pentameric B-subunit that bind to the intestinal cell surface. Several monovalent and multivalent inhibitors of the toxin have been synthesized but are too complicated and expensive for practical use in developing countries. Meta-nitrophenyl α-galactoside (MNPG) is a known promising ligand for CT, and here mono- and multivalent compounds based on MNPG were synthesized. We present the synthesis of MNPG in greatly improved yields and its use while linked to a multivalent scaffold. We used economical polymers as multivalent scaffolds, namely, polyacrylamide, dextran, and hyperbranched polyglycerols (hPGs). Copper-catalyzed alkyne azide cycloaddition reaction (CuAAC) produced the inhibitors that were tested in an ELISA-type assay and an intestinal organoid swelling inhibition assay. The inhibitory properties varied widely depending on the type of polymer, and the most potent conjugates showed IC50 values in the nanomolar range.

Background: Pharmacotherapies for people with cystic fibrosis (pwCF) who have premature termination codons (PTCs) in the cystic fibrosis transmembrane conductance regulator ( CFTR ) gene are under development. Thus far, clinical studies focused on compounds that induce translational readthrough (RT) at the mRNA PTC location. Recent studies using primary airway cells showed that PTC functional restoration can be achieved through combining compounds with multiple mode-of-actions. Here, we assessed induction of CFTR function in PTC-containing intestinal organoids using compounds targeting RT, nonsense mRNA mediated decay (NMD) and CFTR protein modulation. Methods: Rescue of PTC CFTR protein was assessed by forskolin-induced swelling of 12 intestinal organoid cultures carrying distinct PTC mutations. Effects of compounds on mRNA CFTR level was assessed by RT-qPCRs. Results: Whilst response varied between donors, significant rescue of CFTR function was achieved for most donors with the quintuple combination of a commercially available pharmacological equivalent of the RT compound (ELX-02disulfate or ELX-02ds), NMD inhibitor SMG1i, correctors VX-445 and VX-661 and potentiator VX-770. The quintuple combination of pharmacotherapies reached swelling quantities higher than the mean swelling of three VX-809/VX-770-rescued F508del/F508del organoid cultures, indicating level of rescue is of clinical relevance as VX-770/VX-809-mediated F508del/F508del rescue in organoids correlate with substantial improvement of clinical outcome. Conclusions: Whilst variation in efficacy was observed between genotypes as well as within genotypes, the data suggests that strong pharmacological rescue of PTC requires a combination of drugs that target RT, NMD and protein function.

Thermoresponsive receptors for the recognition unit of the cholera toxin (CTB) can recognise the protein with nanomolar affinity. An increase in temperature can drastically reduce their avidity, enabling on-demand release of CTB.

a b s t r a c tSignificant progress has been made in the development of CFTR modulator therapy; however, current CFTR modulator therapies are only available for a minority of the CF-patient population. Additionally, heterogeneity in in vivo modulator response has been reported among individuals carrying homozygous F508del-CFTR, adding to the desire for an optimal prediction of response-to-therapy on an individual level. In the last decade, a lot of progress has been made in the development of primary cell cultures into 3D patient-derived disease models. The advantage of these models is that the endogenous CFTR function is affected by the patient's mutation as well as other genetic or environmental factors. In this review we focus on intestinal organoids as in vitro model for CF, enabling for CF disease classification, drug development and treatment optimization in a personalized manner, taking into account rare CFTR mutations and clinical heterogeneity among individuals with CF.