Anti-NRG1 monoclonal antibody, clone 8E6

ObjectivesPeripheral nerve injuries are a common occurrence, resulting in considerable patient suffering; it also represents a major economic burden on society. To improve treatment options following peripheral nerve injuries, scientists aim to find a way to promote Schwann cell (SC) myelination to help nerves to carry out their functions effectively. In this study, we investigated myelination ability of SCs, regulated by co-culture with adipose-derived stem cells (ASCs) or low-intensity pulsed ultrasound (LIPUS), and synergistic effects of combined treatments. Materials and methodsSchwann cells were co-cultured with or without ASCs, and either left untreated or treated with LIPUS for 10min/d for 1, 4 or 7days. Effects of LIPUS and ASC co-culture on pro-myelination indicators of SCs were analysed by real-time PCR (RT-PCR), Western blotting and immunofluorescence staining (IF). ResultsOur results indicate that ASC-SC co-culture and LIPUS, together or individually, promoted mRNA levels of epidermal growth factor receptor 3 (EGFR3/ErbB3), neuregulin1 (NRG1), early growth response protein 2 (Egr2/Krox20) and myelin basic protein (MBP), with corresponding increases in protein levels of ErbB3, NRG1 and Krox20. Interestingly, combination of ASC-SC co-culture and LIPUS displayed the most remarkable effects. ConclusionWe demonstrated that ASCs upregulated pro-myelination indicators of SCs by indirect contact (through co-culture) and that effects could be potentiated by LIPUS. We conclude that LIPUS, as a mechanical stress, may have potential in nerve regeneration with potential clinical relevance.

ErbB4 is a transmembrane receptor tyrosine kinase that binds to neuregulins to activate signaling. Proteolytic cleavage of ErbB4 results in release of soluble fragments of ErbB4 into the interstitial fluid. Disruption of the neuregulin-ErbB4 pathway has been suggested to be involved in the pathogenesis of amyotrophic lateral sclerosis (ALS). This study assesses whether soluble proteolytic fragments of the ErbB4 ectodomain (ecto-ErbB4) can be detected in cerebrospinal fluid (CSF) and plasma, and if the levels are altered in ALS. Immunoprecipitation combined with mass spectrometry or western blotting analyses confirmed the presence of ecto-ErbB4 in human CSF. Several anti-ErbB4-reactive bands, including a 55 kDa fragment, were detected in CSF. The bands were generated in the presence of neuregulin-1 (Nrg1) and were absent in plasma from ErbB4 knockout mice. Ecto-ErbB4 levels were decreased in CSF from ALS patients (n = 20) and ALS with concomitant frontotemporal dementia patients (n = 10), compared to age-matched controls (n = 13). A similar decrease was found for the short ecto-ErbB4 fragments in plasma of the same subjects. Likewise, the 55-kDa ecto-ErbB4 fragments were decreased in the plasma of the two transgenic mouse models of ALS (SOD1(G93A) and TDP-43(A315T)). Intracellular ErbB4 fragments were decreased in the frontal cortex from SOD1(G93A) mice, indicating a reduction in Nrg-dependent induction of ErbB4 proteolytic processing, and suggesting impaired signaling. Accordingly, overexpression of Nrg1 induced by an adeno-associated viral vector increased the levels of the ecto-ErbB4 fragment in the SOD1(G93A) mice. We conclude that the determination of circulating ecto-ErbB4 fragments could be a tool to evaluate the impairment of the ErbB4 pathway and may be a useful biomarker in ALS.