Neural Ganglioside GD2+ Cells Define a Subpopulation of Mesenchymal Stem Cells in Adult Murine Bone Marrow

Abstract

Background/Aims: Due to the lack of specific markers, the isolation of pure mesenchymal stem cells (MSCs) from murine bone marrow remains an unsolved problem. The present study explored whether the neural ganglioside GD2 could serve as a single surface marker to uniquely distinguish murine bone marrow MSCs (mBM-MSCs) from other marrow elements. Methods: Immunocytochemistry and flow cytometry, in combination with quantitative RT-PCR, were used to identify the expression of GD2 on culture-expanded mBM-MSCs. GD2⁺ and GD2^- fractions from mBM-MSCs cultures were sorted by immunosorting. Flow cytometry was performed to further analyze the biomarkers of GD2-sorted and unsorted cells. Employing CFU-F assay and CCK-8 assay, we examined the clonogenic and proliferative capabilities of GD2-sorted and unsorted cells. Using oil red O and von Kossa staining assay, we also assessed the multi-lineage potential of GD2-sortedand unsorted cells. Results: We found that mBM-MSCs expressed a novel surface marker the neural ganglioside GD2. Importantly, mBM-MSCs were the only cells within bone marrow that expressed this marker. Further studies demonstrated that a homogenous population of MSCs could be obtained from bone marrow cultures in early passages by GD2 immunosorting. Compared to parental cells, GD2⁺-sorted cells not only possessed much higher clonogenic and proliferative capabilities but also had significantly stronger differentiation potential to adipocytes and osteoblasts. Furthermore, GD2⁺-sorted cells displayed enhanced expression of ES markers SSEA-1 and Nanog. Conclusion: Our observations provide the first demonstration that GD2 may serve as a maker for identification and purification of mBM-MSCs. Meanwhile, our study indicates that the cells selected by GD2 are a subpopulation of MSCs with features of primitive precursor cells.