Stem cells in bone marrow are considered as an ideal sources of seed cells with the advantage of being isolation and easy proliferated in vitro,which is a prerequisite for the autotransplantation. Studies show that the cells can differentiate into neurons. However,this opinion challenges the traditional conception of cell differentiation and therefore the dispute arises. Here we review the results of research on dedifferentiation of bone marrow cells.

Objective To explore the relationship between the fall of postprandial blood pressure and superior mesenteric artery (SMA) blood flow in elderly patients aged 80 years and over.Methods The study included 25 inpatients aged 80 years and over with postprandial hypotension (PPH group) and 27 age matched cases without PPH (control group).The changes in blood pressure and the hemodynamics of SMA at fasting stage and 2 hour after meal were observed.The differences between the two groups were compared.Results The incidence of abnormal glucose metabolism (including diabetes and impaired glucose tolerance) was significantly higher in PPH group than in control group [[92.0％ (23 cases) vs.40.7％ (11 cases), P＜0.05].There were no significant differences in other clinical data between the two groups (all P＞0.05).The blood pressure in two groups at different time points was decreased after meal significantly as compared with that at fasting stage (all P＞0.05).The maximal fall of postprandial systolic blood pressure and diastolic blood pressure was significantly increased in PPH group as compared with in control group [(31.3± 14.8)mmHg(1 mmHg=0.133 kPa) vs.(6.9±16.5) mmHg, (13.1±6.6) mmHg vs.(9.0±3.9)mmHg, both P＜0.05].The postprandial SMA blood flow at different time points was significantly increased after meal as compared with that at fasting stage in two groups (all P＞0.05).The maximal increase of postprandial SMA blood flow was larger in PPH group than in control group [(550.5±149.5) ml/min vs.(312.8±241.4) ml/min, P＜0.05].The maximal fall of postprandial systolic blood pressure was positively associated with the maximal increase of postprandial SMA blood flow (r=0.352, P=0.025).Conclusions The fall of postprandial blood pressure is associated with the increase of the SMA blood flow.Postprandial increase in splanchnic perfusion is one of the mechanisms for the formation of PPH.