Chiara Brombin

Base and prime editors (BEs and PEs) may provide more precise genetic engineering than nuclease-based approaches because they bypass the dependence on DNA double-strand breaks. However, little is known about their cellular responses and genotoxicity. Here, we compared state-of-the-art BEs and PEs and Cas9 in human hematopoietic stem and progenitor cells with respect to editing efficiency, cytotoxicity, transcriptomic changes and on-target and genome-wide genotoxicity. BEs and PEs induced detrimental transcriptional responses that reduced editing efficiency and hematopoietic repopulation in xenotransplants and also generated DNA double-strand breaks and genotoxic byproducts, including deletions and translocations, at a lower frequency than Cas9. These effects were strongest for cytidine BEs due to suboptimal inhibition of base excision repair and were mitigated by tailoring delivery timing and editor expression through optimized mRNA design. However, BEs altered the mutational landscape of hematopoietic stem and progenitor cells across the genome by increasing the load and relative proportions of nucleotide variants. These findings raise concerns about the genotoxicity of BEs and PEs and warrant further investigation in view of their clinical application.

BACKGROUND: There is increasing interest in the psychobiological mechanisms of resilience and psychological well-being. It is conceivable that activation of such mechanisms in the school setting may entail long-term benefits, both in terms of the developmental process and of prevention of distress. This study wants to apply and test the efficacy of a school-based intervention protocol derived from well-being therapy (WBT) compared to cognitive-behavioral strategies. METHODS: School interventions were performed in a population of 111 students randomly assigned to: (a) a protocol using theories and techniques derived from cognitive-behavioral therapy; (b) a protocol derived from WBT. Assessment before and after interventions was performed using two self-rating scales: Kellner's Symptom Questionnaire and Ryff's Psychological Well-Being Scales. RESULTS: Both school-based interventions resulted in a comparable improvement in symptoms and psychological well-being. CONCLUSIONS: This new well-being-enhancing strategy could play an important role in the prevention of psychological distress in school settings and in promoting optimal human functioning among children.