| Beside the hematopoietic stem cells (HSCs), there are also mesenchymal stem cells (MSCs) or bone marrow stromal cells (BMSCs), multipotent adult progenitor cells (MAPCs) and progenitor of endothelial cells (PEs) in the bone marrow. So the bone marrow stem cells have been considered to be mixture of several sub-population of stem cells. The term "bone marrow derived-stem cells (BMDSCs)" has been therefore used to indicate such special population of stem cells from bone marrow in some articles recently. BMDSCs can migrate into several organs and differentiate into blood lineages, skeletal muscle, cardiac muscle, and pulmonary and liver epithelium in vivo. There is however a certain dispute on whether BMDSCs can migrate into the normal brain and further differentiate into the neural glia and/or neurons now. Because injury may increase the SP differentiation in other tissues, the question may be raised for that whether neural injury would also induce donor BMDSCs to differentiate into neural-like cells in injuried brain tissue. To answer this question, the mouse Y chromosome was used ascell marker for tracing the donor BMDSCs in the present study. A brain injury model was made with iridectomy knife hi the right cortex of female mice with lethally irradiation and then they accepted an intravenous transplantation of the male bone marrow from age-matched males. Fluorescence in situ hybridization (FISH) was performed on the brain tissue sections to detect grafted cells in the injuried brain tissue. In addition, the same animal models were made in Sprague-Dawley female rats, and the GFP labeled male BMDSCs was injected into the tail vein at 24 hours after brain injury. Fluorescence Immunohistochemistry was performed on brain tissue sections to characterize with GFP-labeled BMDSCs which have migrated from blood circulation and resided in the injuried brain tissue.Section I The labeling and application of a RNA probe from Ychromosome sequence in the mouseObjective To RNA probe from the mouse Y chromosome sequence waslabeled and was used to test its efficiency for the detecting Y chromosomepositive cells in peripheral blood smear and brain sections in mice.Method A RNA probe was labeled from pY353/B, a repeat sequence ofmouse Y chromosome. As controlled by the C57BL/6 female mouse, theperipheral blood smear and brain sections of the C57BL/6 male mice weredetected with in situ hybridization and fluorescence in situ hybridization(FISH).Result The Y chromosome positive cells were found on all of white cells inthe peripheral blood smear and 85.67% cells in brain tissue sections of malemice, but not in the female.Conclusion The high sensitivity and specificity for detecting of Ychromosome positive cells in peripheral blood smear and brain tissue sectionsof mice is proved by a RNA probe (from Y chromosome sequence) in situhybridization and Fluorescence in situ hybridization (FISH).Key words: Y chromosome, in situ hybridization, Fluorescence in situhybridization (FISH), Bone marrow-derived stem cells (BMDSCs)Section II The possibility for migration of bone marrow-derived stemcells to the injured brain tissue in the mouseObjective To investigate whether BMDSCs could migrate into the injuriedbrain tissue.Method A cohort of lethally irradiated C57BL/6 female mice received wholeBMT of age-matched male donors. At 2 months after BMT, a brain injurymodel was made with iridectomy knife in the right cortex of female mice.The animals were sacrificed at the 1 2 4 and 6 weeks after brain injury.Fluorescence in situ hybridization (FISH) for the Y chromosome wasperformed on the peripheral blood smear and fresh brain tissue sections.Result At 2 months after BMT, Y chromosome positive cells were found onall of white cells in the peripheral blood smear of female BMT recipients; at6 weeks after brain injury, Y chromosome positive cells were found insignificant numbers at injury sites.Conclusion The blood-lineage chimaeric mouse has successfully been madein...
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