Role Of Bone Marrow Stem Cells In The Recovery Of Acute Renal Tubular Necrosis In Mice

Role of bone marrow stem cells in the recovery of acute tubular necrosis in mice(Abstract)BACKGROUND:According to traditional theory of the recovery after acute tubular necrosis,reconstruction of renal tubule is dependent on residual epithelial cells next to the necrosis region. Undergoing the process of dedifferentiation,proliferation and redifferentiation, these cells can reestablish the injured tubule and its function. Along with the study of stem cells, some polypotential stem cells named adult stem cells have been found in adult tissue, which have the ability of multi-lineage differentiation, and this made them very important roles in tissue regeneration and recovery after injury. Adult stem cells are abundant in bone marrow, and some recent researches have found that bone marrow stem cells may differentiate into renal tubular epithelial cells and play a role in turnover of acute tubular necrosis, though there is still controversy about this issue.OBJECTIVE: We intend to demonstrate bone marrow stem cells can differentiate into renal rubular epithelial cells by an animal bone marrow transplantation model, discuss the role of bone marrow stem cells in the recovery of acute tubular necrosis, fertilize the theory of turnover in acute renal tubular necrosis. METHOD: Transgenic C57BL/6 mice labeled with green flouresent protein(GFP) as bone marrow donors, C57BL/6 mice without fluorescence label, recipients of bone marrow transplantation, were divided into seven groups: (1) Normal group: obtain physiological and renal histological data of normal C57BL/6 mice. (2) Glycerol i.m group: kidneys of mice obtained on day 3, day 7, day 14 and day 28 after acute tubular necrosis was induced by 50% glycerol, process of ATN in this model was observed. (3) Ischemia/Reperfusion group: cross clasp left renal pedicle for 30 minutes followed by reperfusion, right renal pedicle left untouched, kidneys obtained on day 3, day 7, day 14 and day 28 after the operation, histological change of both sides was observed. (4) Total Body Irradiation group: no bone marrow transplantation after lethally TBI, put to death in a week to observe effect of irradiation on the structure and functin of kidneys. (5) Bone Marrow Transplantion group: BMT after irradiation, sacrificed on day 56 and day 84 after transplantation, to observe the differentiation of bone marrow stem cells in the kidneys without injury. (6) BMT+Glycerol i.m group: Glycerol i.m on day 56 after bone marrow transplantation, to observe the role of bone marrow stem cells in the recovery of ATN. (7) BMT+IR group: unilateral IR operation carried out on day 56 after bone marrow transplantation, to observe differentiation of donor bone marrow stem cells in bilateral kidneys. Bone marrow reconstruction after transplantation proved by blood routine and flow cytometry of bone marrow cells; distribution and amount of green fluorescence in kidneys of recipient mice observed by fluorescence histochemistry,immunohistochemistry means. RESULT: Both glycerol i.m and single lateral ischemia-reperfusion injury result in acute tubular necrosis, and proximal tubule was the most sensitive to the injury. Significant difference in pathology of kidney was found between the two sides of the ischemia-reperfusion group. Biochemical results showed increase of BUN,SCr in glycerol group but no significant change in single lateral ischemia-reperfusion group; in our study, recovery process of tubule in both ATN models began on day 3 after induction and accomplished on day 28, similar result was seen in acute tubular necrosis models after bone marrow transplantation. Lethally total body irradiation made no significant change in renal histological structure and founction, green fluorescence was seen in renal tubular epithelium on day 56 and 84 after bone marrow transplantation, further prove of these cells locating in tubular epithelium was obtained by laser scanning confocal microscope, fluorescence histochemistry show these cells expressed renal tubular epithelium specific protein megalin,...