Homing of Transplanted Stem Cells in Marrow Ablated Mice - Implications in Cell Mediated Tissue Repair
Filip Stanislav
Department of Oncology and Radiotherapy
Charles University in Prague
Medical Faculty in Hradec Králové
Prague, Czech Republic
Abstract:
Cell mobilization, vascular circulation and homing represent key sequential processes of cell-mediated tissue repair elicited in response to wounding or pathology resulting from disease. Processes involved in cell-mediated tissue repair have been extensively studied, but many unknown factors influence this vital process. We undertook this study to evaluate if organ ablation influences cell-mediated repair by altering the kinetics and destiny of mobilized cells.
We utilized ROSA mice as donor for bone marrow cell transplantation mice were used as recipients to assess the influence of splenectomy on changes in the circulation and homing of transplanted stem cells throughout the body. Splenectomy was performed in recipients 14 days before irradiation (9 Gy from a 60Co source), used to ablate endogenous bone marrow cells. Suspension of 5x104 lin-/CD117+ (lacZ+) bone marrow cells were transplanted by i.v. injection into recipients 3 hours after irradiation in splenectomised and non-splenectomised animals. Analysis of cell circulation and homing was carried out on day 8, 12 and 30 after transplantation of donor cells. Examination of restoration of hematopoesis revealed that in splenectomised mice, reparation of lymphopoesis occurred before myelopoesis. RT-PCR analysis demonstrated that by day 30 after transplantation in splenectomised mice, transplanted lacZ+ cells occupied the thymus and the mucosa-associated lymphoid tissue of the gastrointestinal tract, namely the small intestine. Changes in distribution of transplanted cells between the thymus and the bone marrow were documented by flow cytometric analysis of CD45+/CD117+/Sca-1+ cells. Our results demonstrate that splenectomy markedly alters cellular repair processes by its influence on the distribution and homing of engrafted stem cells. Similar alterations may result from ablation of other organs. Thus, tissue repair effected by stem cells is a complex and multifaceted process that is influenced by both soluble factors, cellular mobilization and organ integrity.
This work was supported by grant MZO 00179906 and MSMT 0021620820 of the Czech Republic.
Keywords: Hematopoetic stem cells, splenectomy, in vivo homing, tissue regeneration
