PURIFICATION, CHARACTERIZATION AND CULTURE OF ENSHEATHING CELLS FROM HUMAN OLFACTORY MUCOSA BIOPSIES

Among all the possible sources of mesenchymal stem cells, adipose tissue and olfactory mucosa have raised great interest and have become some of the most investigated sources. Adipose tissue-derived mesenchymal stem cells and the fat itself as a source of human adipose derived stem cells, represent one of the major fields of research in regenerative medicine. A great advantage is represented by the minimal invasive and high accessibility to adipose tissue and its ready availability. In the present study, hADSCs were isolated from the adipose tissue donated by several patient and have been investigated and characterized through different technical approaches, such as flow cytometry and immunocytochemistry. These hADSCs reproducibly fulfill the general definition of MSCs by both phenotypic and differentiation capabilities criteria, showing also the expression of neural markers, as observed by confocal microscope analysis. Lipoaspirated adipose tissue showed positivity to ß-tubulin III that was also maintained in lipoaspirate-derived hADSCs. A population of stem cells retaining typical characteristics of surface markers of classical adipose tissue stem cells and MSC was obtained when adipose tissue was subjected to culture in vitro, either by processing through centrifugation or by direct plating without enzymatic digestion with collagenase. Flow cytometry analyses showed that hADSCs expressed classical mesenchymal markers such as CD44, CD73, CD90, CD105 and CD166, while endothelial (CD31, CD34, CD144, CD146) and hematopoietic (CD45, CD133) markers were much less represented. Also the ability to give rise to tissue of mesenchymal origins, such as osteoblastic and adipogenic lineages, were present in hADSCs. In addition, the immunofluorescence staining indicated the expression of neural stem markers in hADSCs which consequently co-expressed nestin, β-tubulin III and glial GFAP. We have also characterized human olfactory ensheathing stem cells. Olfactory mucosa is specialized tissue inside the nasal cavity involved in olfactory perception and capable of lifelong regeneration throughout adulthood. Multipotent stem cells obtained from it offer the possibility of promoting regeneration and reconstruction in regenerative medicine, being readily accessible with minimal invasive techniques, capable of expansion in vitro and retaining broadly potent differentiative capacity as stem cell progenitors. Among the several members of the olfactory mucosa, Olfactory Ensheathing Cells (OECs) are well known to be useful in repairing the nervous system. By following our method, cells can be easily isolated and maintained in TCM, and their cultivation in large flasks allowed obtaining rich cultures of OECs in 2 weeks. Cell cycle analysis showed that the majority of cells are in G0/G1 phase, while just a lesser part is in S/G2 phase. In our growth conditions, no chromosomal abnormalities were observed also at high culture passage (p14). Live morphology of obtained cells showed a fibroblast-like phenotype and the immunohistochemical analyses showed the expression of beta-Tubulin III, Vimentin, Nestin, Glial Fibrillary Acidic Protein and Microtubule-Associated Protein 2. By FACS analysis we demonstrated that OECs are positive to typical surface mesenchymal markers (CD44, CD73, CD90, CD105, CD146 and CD166). As expected, some endothelial (CD31, CD34) and hematopoietic (CD45) markers were very few represented, while some others (CD56, CD144, CD146, CD133) are partially found. These cells also express genes that constitute the core circuitry of self-renewal such as SOX2, NANOG and OCT4 and the stemness marker CD133. OECs incubated with serum-free medium, normally used for the formation of neurospheres, spontaneously formed large spheroids reaching a mean diameter of 100 μm in 10 days of culture. Immunofluorescence of specific proteins showed that spheres were positive to markers such as Nestin, Vimentin, TUJ-1, MAP2 and GFAP. In conclusion, our method allows the quickly and easily hADSCs and hOESCs isolation from human adipose tissue and nasal biopsies. The obtained cells can be cultured without altering their mesenchymal properties, suggesting the pluripotency nature of these cells and that they are a reliable source for regenerative medicine.