ИСТИНА

Neural crest descendants are retained in the adult tissues as multipotent progenitor cells, which could be involved in the regeneration. These cells express nestin, which is used by researchers as a marker protein allowing tracking neural crest descendants. The aim of this study was to analyze the localization and functions of nestin-expressing cells in adipose tissue in vivo and to investigate their possible role in regeneration. We used mice with expression the green fluorescent protein (GFP) driven by the regulatory elements of nestin promoter (nesGFP+). Using confocal microscopy we found groups, chains and single nesGFP+ cells within whole-mount adipose tissue fragments as well as thick sections of adipose tissue. These cells had small-sized bodies and very long and thin processes with synapse-like endings. Using immunofluorescent staining of adipose tissue samples we found that nesGFP+ cells localized in a close proximity to CD31-positive endothelium of medium-size blood vessels and within adipose tissue stroma between mature adipocytes. Part of these nesGFP+ cells also expressed NG2, alphaSMA and PDGFRbeta. To further characterize nesGFP+ cells we isolated them from adipose tissue within a population of mesenchymal stem/stromal cells (MSCs) according to a standard protocol. The proportion of nesGFP+ cells in total MSCs population was 5-10% at the passage 0 and only slightly declined to 2-3 passages. We analyzed the expression of markers characteristic for murine mesenchymal stromal and stem cells (CD34, PDGFRα, PDGFRβ, Sca-1, CD106, CD105, CD73, CD29, CD44, CD90, c-kit, Oct4, Nanog, SOX2, SSEA1) as well as CXCR4, NG2, alphaSMA and PPARgamma using immunofluorescence and flow cytometry. These cells were negative for leukocyte markers CD11b and CD45. Sorted nesGFP+ cells were able to give clones and differentiate in adipogenic, osteo- and chondrogenic directions. Thus, nestin-expressing cells in adipose tissue have the characteristics of stem cells. NesGFP+ cells are also capable of migrating in «scratch assay». Together morphology, tissue distribution and immunophenotype suggest that neural crest derived nestin-expressing cells in adipose tissue represent telocytes, which were previously found in various tissues as mediators of intercellular signaling process. This study was supported by RSF grant 14-15-00439. This study was performed using biomaterial collected and archived with a support of Russian Science Foundation (grant 14-50-00029).