Culture of human nasal olfactory stem cells and their extracellular vesicles as advanced therapy medicinal products

Abstract: The olfactory ecto-mesenchymal stem cell (OE-MSC) are mesenchymal stem cells originating from the lamina propria of the nasal mucosa. They have neurogenic and immune-modulatory properties and showed therapeutic potential in animal models of spinal cord trauma, hearing loss, Parkinsons disease, amnesia, and peripheral nerve injury. In this paper we designed a protocol that meet the requirements set by human health agencies to manufacture these stem cells for clinical applications. Once purified, OE-MSCs can be used per se or expanded in order to get the extracellular vesicles (EV) they secrete. A protocol for the extraction of these vesicles was validated and the EV from the OE-MSC were functionally tested on an in vitro model. Nasal mucosa biopsies from three donors were used to validate the manufacturing process of clinical grade OE-MSC. All stages were performed by expert staff of the cell therapy laboratory according to aseptic handling manipulations, requiring grade A laminar airflow. Enzymatic digestion provides more rapidly a high number of cells and is less likely to be contaminated. Foetal calf serum was replaced with human platelet lysate and allowed stronger cell proliferation, with the optimal percentage of platelet lysate being 10%. Cultivated OE-MSCs are sterile, highly proliferative (percentage of CFU-F progenitors was 15,5%) and their maintenance does not induce chromosomal rearrangement (karyotyping and chromosomal microarray analysis were normal). These cells express the usual phenotypic markers of OE-MSC. Purification of the EVs was performed with ultracentrifugation and size exclusion chromatography. Purified vesicles expressed the recognized markers of EVs (Minimal Information for Studies of Extracellular Vesicles (MISEV) guidelines) and promoted cell differentiation and neurite elongation in a model of neuroblastoma Neuro2a cell line. We developed a safer and more efficient manufacturing process for clinical-grade olfactory stem cells, these cells can now be used in humans. A phase I clinical trial will begin soon. An efficient protocol for the purification of the OE-MSC EVs have been validated. These EVs exert neurogenic properties in vitro. More studies are needed to understand the exact mechanisms of action of these EVs and prove their efficacy and safety in animal models.