Nicotinamide-loaded Peptoid Nanotubes for Energy Regeneration in Acute Brain Injury

Abstract

Acute brain injuries such as perinatal asphyxia, stroke, and traumatic brain injury result in ischemia, oxidative stress, excitotoxicity, and inflammation, leading to a depletion of ATP, the brains cellular energy store. Nicotinamide adenine dinucleotide (NAD+), a key regulator of cellular homeostasis, is crucial for energy regeneration and DNA repair in post-injury recovery. However, the therapeutic benefits of NAD+ and its precursors, such as nicotinamide (NAM), are limited by the complexity of their metabolic pathways and challenges in effective cell-specific intracellular delivery. Therefore, cellular delivery strategies are needed to capture the potential of an NAD+-regenerating therapeutic approach. In this study, we introduce a nanopeptoid delivery strategy to replenish cellular redox state and energy production in the acutely injured brain. By self-assembling peptoids into tubular structures, we created biocompatible NAM-conjugated peptoid nanotubes (NAM-PNTs) that vary in tubular length. NAM-PNTs demonstrated significant therapeutic benefits by enhancing cell viability and replenishing intracellular ATP levels within 24 hours of treatment in oxygen-glucose deprived (OGD) BV-2 cells. In organotypic brain slices, NAM-PNT treatment promoted glial proliferation, reduced pro-inflammatory cytokine levels, and increased anti-inflammatory cytokines after OGD, an ex vivo model of hypoxia-ischemia. A single systemic dose of NAM-PNTs also reduced brain tissue loss and improved neuropathology after hypoxia-ischemia in term-equivalent rats. These findings highlight the strong therapeutic potential of NAM-PNTs for cell-specific targeted delivery and energy restoration in the acutely injured neonatal brain. In the neonatal brain injury field, this is the first demonstration of a novel nanoparticle platform development from first principles design and synthesis to in vitro screening and then demonstration of efficacy in vivo.