Background to the NRP Discovery using a phenotypic brain tissue screen to monitor neuronal migration
It has been never shown before that postnatal thalamic tissue (diencephalon) derived from rodents when actually put into tissue culture can be “coaxed” into producing migrating neural cell chains that travel to its target tissue, the neocortical formation.
A purified cell culture supernatant harvested from metabolising rat hippocampal cells was capable of exactly doing the aforementioned phenotypic “behaviour”. Neuronal thalamic cells were migrating alongside freshly formed extracellular matrix between 24 - 48 hrs after contact with the purified protein fraction (deriving from brain cell culture supernatant) towards the cortical entity that was fixed on a coverslip opposite the thalamic tissue (see diagram below). Specialised biochemical fractionation of the metabolized cell nutrients (including peptides) led to the discovery of a neuronal proliferation and migration-inducing activity.
The rat peptide responsible for initiating neural migration was purified to homogeneity and named Neural Regeneration Peptide-1 (NRP-1). NRP-1 is a fragment of a secreted small protein named dermcidin.
Identification of the lead compound NRP2945:
A homologue sequence to rat NRP-1 was found within the human protein CAPS-2 and further bioinformatics approaches were undertaken to find the shortest human peptide sequence to provoke bioactivities necessary for neural regeneration. These activities include the upregulation of one cell cycle of committed stem cells, chemoattraction, promotion of neuronal survival from excitotoxic and oxidative stress conditions and promotion of final neural differentiation.
Kinetics and overall mechanistic effects of the lead:
NRP2945 has been constructed in such a manner that shelf-life stability as well as metabolic stability is sufficiently enhanced so that NRP2945 is crossing the blood brain barrier, after entering the blood stream, in order to initiate gene expression necessary for neuronal survival and repair. Endogenous enhancement of gene expression facilitating repair is driving the NRP2945 kinetics towards a long-term effect of NRP2945 bolus injections. This strategy enables to extend re-dosing (re-application of NRP2945) to 48 hours.