Dental pulp derived mesenchymal stem cells and its conditioned medium: a novel therapeutic approach for ALS

Abstract

Amyotrophic Lateral Sclerosis (ALS), also classified as a subtype of Motor Neuron Disease (MND), is the most common and stronger degenerative disorder that provokes progressive loss of motor neurons. It is also characterized by a neuroinflammatory condition due to astrocyte and microglia activation. The outcome of both events is the complete motor function degeneration with subsequent lethality. ALS is affecting more than 400,000 people worldwide and is usually misdiagnosed with other neurodegenerative diseases (e.g. Parkinson's disease). There is no cure for ALS and the preventive treatment only expand the lifetime of the patient for 3 months. Currently, there are several cell-based clinical trials on phase I/II for ALS using undifferentiated stem cells, like Mesenchymal Stem Cell (MSCs) lineage, with almost no success. MSCs are non-hematopoietic and show multi-lineage differentiation potential (e.g. osteocytes, adipocytes and chondrocytes). They can be isolated from different tissues, such as adipose and umbilical cord blood and tissue, and then expanded ex vivo without interfering on their functionality. Given that, MSCs differentiation can be a great strategy for autologous and allogeneic cell-based therapies for the treatment of neurodegenerative diseases. Furthermore, it is widely accepted from many diseased animal models that MSCs' positive outcome might be due to their paracrine effect caused by the secretion of biomolecular factors, like microvesicles. Enriched on cytokines, miRNA and mRNA, microvesicles are responsible for an activation effect on many cell types and can be obtained from MSCs' conditioned medium. In addition to the paracrine mechanism of action of MSCs, differentiation of this cell type into neuronal/glial lineages is drawing great attention. An optimal source of MSCs for differentiation into neuronal lineage is the dental pulp, due to its neural crest origin and its expression of specific neuronal markers under undifferentiated conditions. Therefore, the purpose of this study is to combine 1. The in vivo role of transplanted DP-MSCs into C9ORF72 ALS mouse model, 2. The use of conditioned medium to provide neurotrophic support and to reduce inflammatory levels by modulating glial cells' activation status in vivo and 3. Detail-in-depth analysis about the effect of hexameric C9ORF72 repeats at the level of motor neurons and gliosis (mainly microglia cells). Efficiency and success of transplantation will be determined based on behavioral and immunohistochemistry assays. The combination of the DP-MSC transplantation with infusion of conditioned medium from MSCs is here presented as a novel therapeutic mechanism to improve the scenarium of motor neuron degeneration and to reduce the inflammation observed in ALS disease. (AU)