ABSTRACT
There is growing evidence about the role of mesenchymal stem cells (MSCs) as cancer stem cells in many sarcomas. Nevertheless, little is still known about the cellular and molecular mechanisms underlying MSCs transformation. We aimed at investigating the role of p53 and p21, two important regulators of the cell cycle progression and apoptosis normally involved in protection against tumorigenesis. Mesenchymal stem cells from wild-type, p21(-/-)p53(+/+), and p21(-/-)p53(+/-) mice were cultured in vitro and analyzed for the appearance of tumoral transformation properties after low, medium, and high number of passages both in vitro and in vivo. Wild-type or p21(-/-)p53(+/+) MSCs did not show any sign of tumoral transformation. Indeed, after short-term in vitro culture, wild-type MSCs became senescent, and p21(-/-)p53(+/+) MSCs showed an elevated spontaneous apoptosis rate. Conversely, MSCs carrying a mutation in one allele of the p53 gene (p21(-/-)p53(+/-) MSCs) completely lost p53 expression after in vitro long-term culture. Loss of p53 was accompanied by a significant increase in the growth rate, gain of karyotypic instability, loss of p16 expression, and lack of senescence response. Finally, these cells were able to form fibrosarcomas partially differentiated into different mesenchymal lineages when injected in immunodeficient mice both after subcutaneous and intrafemoral injection. These findings show that MSCs are very sensitive to mutations in genes involved in cell cycle control and that these deficiencies can be at the origin of some mesodermic tumors.
Subject(s)
Cell Transformation, Neoplastic/genetics , Cyclin-Dependent Kinase Inhibitor p21/deficiency , Mesenchymal Stem Cells/pathology , Neoplastic Stem Cells/pathology , Tumor Suppressor Protein p53/genetics , Animals , Blotting, Western , Cell Transformation, Neoplastic/metabolism , Cellular Senescence/genetics , Cyclin-Dependent Kinase Inhibitor p16/genetics , Cyclin-Dependent Kinase Inhibitor p16/metabolism , Cyclin-Dependent Kinase Inhibitor p21/genetics , Flow Cytometry , Mesenchymal Stem Cells/metabolism , Mice , Mice, Mutant Strains , Mutation , Neoplastic Stem Cells/metabolismABSTRACT
Direct intrathymic injection is a common procedure used in several types of experimental protocols in the mouse. Currently available approaches involve major surgical procedures that expose the thoracic cavity, resulting in an increased risk of poor recovery and postsurgical complications. The authors sought to refine this surgery to reduce animal pain and distress without compromising overall efficiency of the technique. Using a minimally invasive method that does not expose the thoracic cavity, the authors gave accurately placed intrathymic injections, as confirmed by analyses with a reporter dye. They describe this new approach for intrathymic injection in mice that reduces complications associated with lengthy periods of anesthesia and thoracic cavity exposure.
Subject(s)
Injections/veterinary , Mice/surgery , Minimally Invasive Surgical Procedures/veterinary , Thymus Gland/surgery , Animals , Female , Injections/methods , Mice, Inbred C57BL , Minimally Invasive Surgical Procedures/methods , Specific Pathogen-Free OrganismsABSTRACT
The distribution of GM mice between facilities has raised new problems because of variable microbiological quality. One of the most important management issues concerns the methods of reporting laboratory animal health surveillance results. The authors evaluated the format and content of 380 health reports of mice received from 55 institutions in Europe and North America. Their results suggest that a standardized rodent health form would facilitate the management of laboratory mouse distribution and infection control.
