ABSTRACT
Mesenchymal stem cells (MSC) are the ideal adult stem cells in cell/gene therapy and tissue engineering for their features of easily-handling, highly proliferative capacity in vitro, low immunogenicity and immunomodulatory ability. MSC, as a kind of cellular drug, have been utilized in a phase III clinical trial to treat refractory graft-versus-host disease (GVHD). However, the essences of MSC in culture remain elusive so far. Whether the cells expanded in vitro are stem cells per se, and if not, why expanded MSC maintain their multiple differentiation ability? And are the MSC cultivated in vitro homogeneous and if not, what the heterogeneity stands for? Focusing on the heterogeneity of MSC in culture in vitro, the above questions are briefly discussed in this review.
Subject(s)
Humans , Cell Differentiation , Cell Proliferation , Cells, Cultured , Mesenchymal Stem Cells , Cell BiologyABSTRACT
Objective To investigate the exposure dose levels of patient body surface and main sensitive organs from routine medical X-ray diagnosis so as to offer a basic data of guidance levels in radiological diagnosis practice. Methods To measure the skin surface exposure doses of the irradiation field and the main sensitive organs of patients by thermoluminescent dosimeter moreover to estimate the main sensitive organs exposure doses using tissue percentage depths formula. Results The exposure dose of chest fluoroscopy was 30 times that of fluorography. The exposure dose(12.41 mGy/time) of barium meal examination in alimentary canal was the highest in all examination. The dose of thyroid(0.210 mGy/time) was the highest when getting the chest fluoroscopy the dose of ovary was the highest when getting barium meal(0.390 mGy/time) and lumbar fluoroscopy(0.168 mGy/time) in all of sensitive organs dose. Conclusion Chest fluorography will give the patients a lower dose exposure of X-ray compared with fluoroscopy.