Novel stem cell technologies are powerful tools to understand the impact of human factors on Plasmodium falciparum malaria

Plasmodium falciparum parasites have a complex life cycle, but the most clinically relevant stage of the disease is the invasion of erythrocytes and the proliferation of the parasite in the blood. The influence of human genetic traits on malaria has been known for a long time, however understanding the role of the proteins involved is hampered by the anuclear nature of erythrocytes that makes them inaccessible to genetic tools. Here we overcome this limitation using stem cells to generate erythroid cells with an in-vitro differentiation protocol and assess parasite invasion with an adaptation of flow cytometry to detect parasite hemozoin. We combine this strategy with reprogramming of patient cells to Induced Pluripotent Stem Cells and genome editing to understand the role of key genes and human traits in malaria infection. We show that deletion of basigin ablates invasion while deletion of ATP2B4 has a minor effect and that erythroid cells from reprogrammed patient-derived HbBart α-thalassemia samples poorly support infection. The possibility to obtain patient-secific and genetically modifed erythoid cells offers an unparalleled opportunity to study the role of human genes and polymorphisms in malaria allowing preservation of the genomic background to demonstrate their function and understand their mechanisms.

Abstract 4887: Direct mutational consequences of CRISPR-cas9 gene-edited DNA repair genes

Cancer whole-genome sequencing has revealed characteristic mutational signatures associated with defective DNA repair that underpin human genetic diseases. To define the direct mutagenic effects of DNA repair deficiency at the genome-wide level, we investigate mutational signatures generated by CRISPR-Cas9-based knockouts of 42 genes involved in DNA repair/replication using a human-induced pluripotent stem cell line. Knockouts (Δ) of nine DNA repair genes reveal substitution/indel mutational signatures. Notably, dissection of signatures of defective mismatch repair (MMR) uncovers gene-specific characteristics including distinguishing features of ΔMLH1, ΔMSH2, and ΔMSH6 from ΔPMS2. This gene-specificity is also exhibited by hIPSCs derived from patients with autosomal recessive Constitutional Mismatch Repair Deficiency (CMMRD) that carry biallelic germline mutations of MMR genes. Furthermore, gene-specificity manifests in whole genome sequenced primary human cancers. Additionally, detailed analyses reveal putative sources of endogenous DNA damage that contribute to MMR signatures, including guanine oxidation, errors of DNA polymerases and reversed template slippage or double slippage. Finally, we find that using all mutational signatures of MMR-deficiency as identified in this study results in improved sensitivity and specificity in classifying MMR-deficient tumors, critical for accurate patient stratification for therapeutic intervention.

Citation Format: Xueqing Zou, Gene Koh, Scott Nanda, Andrea Degasperi, Katie Urgo, Wendy Bushell, Chukwuma Agu, Vanesa Perez-Alonso, Daniel Rueda, Julia Foreman, Rebecca Harris, Josef Jiricny, Bill Skarnes, Serena Nik-Zainal. Direct mutational consequences of CRISPR-cas9 gene-edited DNA repair genes [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4887.

Sustaining global partnerships for simulation integration: lessons from the field

AIM

A reciprocal partnership between two World Health Organization Collaborating Centers in the Americas region aimed to strengthen nursing and midwifery education through innovative integration of high-fidelity simulation.

METHODS/IMPLEMENTATION

Immersion of a visiting scholar in six-week training within a North American nursing school (host) solidified simulation champion designation, upon return at the home institution. Next, two expert nursing faculty implemented a train-the-trainer simulation course on-site. Following evaluation and virtual debriefing, a midwifery faculty visited the host institution for second-round training.

CONCLUSION

This ongoing program targets faculty development needs through a strong academic partnership, built upon global awareness and sustainable engagement.