The mesenchymal stem cell ( MSC ) is an important component of the hematopoietic microenvironment .In the process of stem cell transplantation (SCT), MSC can restore the hematopoietic microenvironment , improve the capacity of hematopoiet-ic reconstitution, reduce the incidence of graft versus host disease (GVHD).MSC has been widely used in hematopoietic stem cell transplantation, immune therapy, tissue engineering and many other fields .The distribution and colonization of MSC in vivo directly af-fect the effectiveness of transplantation .Improving the homing and engraftment of MSC may obtain a better therapeutic effect .Further research on the mechanism and influential factors of MSC homing may lead to the development of therapies and promote clinical applica -tions of MSC.This paper reviews the recent progress in homing mechanism of MSC .

To establish the experts consensus on the management of delirium in critically ill patients.A special committee was set up by 15 experts from the Chinese Critical Hypothermia-Sedation Therapy Study Group.Each statement was assessed based on the GRADE (Grading of Recommendations Assessment,Development,and Evaluation) principle.Then the Delphi method was adopted by 36 experts to reassess all the statements.(1) Delirium is not only a mental change,but also a clinical syndrome with multiple pathophysiological changes.(2) Delirium is a form of disturbance of consciousness and a manifestation of abnormal brain function.(3) Pain is a common cause of delirium in critically ill patients.Analgesia can reduce the occurrence and development of delirium.(4) Anxiety or depression are important factors for delirium in critically ill patients.(5) The correlation between sedative and analgesic drugs and delirium is uncertain.(6) Pay attention to the relationship between delirium and withdrawal reactions.(7) Pay attention to the relationship between delirium and drug dependence/ withdrawal reactions.(8) Sleep disruption can induce delirium.(9) We should be vigilant against potential risk factors for persistent or recurrent delirium.(10) Critically illness related delirium can affect the diagnosis and treatment of primary diseases,and can also be alleviated with the improvement of primary diseases.(11) Acute change of consciousness and attention deficit are necessary for delirium diagnosis.(12) The combined assessment of confusion assessment method for the intensive care unit and intensive care delirium screening checklist can improve the sensitivity of delirium,especially subclinical delirium.(13) Early identification and intervention of subclinical delirium can reduce its risk of clinical delirium.(14) Daily assessment is helpful for early detection of delirium.(15) Hopoactive delirium and mixed delirium are common and should be emphasized.(16) Delirium may be accompanied by changes in electroencephalogram.Bedside electroencephalogram monitoring should be used in the ICU if conditions warrant.(17) Pay attention to differential diagnosis of delirium and dementia/depression.(18) Pay attention to the role of rapid delirium screening method in delirium management.(19) Assessment of the severity of delirium is an essential part of the diagnosis of delirium.(20) The key to the management of delirium is etiological treatment.(21) Improving environmental factors and making patient comfort can help reduce delirium.(22) Early exercise can reduce the incidence of delirium and shorten the duration of delirium.(23) Communication with patients should be emphasized and strengthened.Family members participation can help reduce the incidence of delirium and promote the recovery of delirium.(24) Pay attention to the role of sleep management in the prevention and treatment of delirium.(25) Dexmedetomidine can shorten the duration of hyperactive delirium or prevent delirium.(26) When using antipsychotics to treat delirium,we should be alert to its effect on the heart rhythm.(27) Delirium management should pay attention to brain functional exercise.(28) Compared with non-critically illness related delirium,the relief of critically illness related delirium will not accomplished at one stroke.(29) Multiple management strategies such as ABCDEF,eCASH and ESCAPE are helpful to prevent and treat delirium and improve the prognosis of critically ill patients.(30) Shortening the duration of delirium can reduce the occurrence of long-term cognitive impairment.(31) Multidisciplinary cooperation and continuous quality improvement can improve delirium management.Consensus can promote delirium management in critically ill patients,optimize analgesia and sedation therapy,and even affect prognosis.

Objective: The aim of this study was to investigate the effect of co-culture with AEC (amniotic epithelial cell) on the biological characteristics of AMSC (amniotic mesenchymal stem cell), and to investigate the roles of SDF-1/CXCR4 axis in the homing and migration of AMSC. Methods: AMSC andAEC were isolated from human amnion, and then cultured, amplified and identified, respectively. TheAMSC were divided into three groups:AEC co-cultured group, serum-free cultured group and serum cultured group.After culture for 24 h, 48 h, and 72 h, the proliferation viability ofAMSC was measured by CCK-8 assay and trypan blue staining; the expression of CXCR4 mRNAwas analyzed by flow cytometry and Real-time RT-PCR, and the migration ability ofAMSC in vitro was observed by migration assay. Results: Cell viability (48 h and 72 h) and survival rate in the co-culture and serum groups were higher than those in the serum-free group (all P<0.05). The mRNA and protein expressions of CXCR4 in AMSC of the co-culture and serum-free groups were significantly higher than those of the serum group (P<0.05). The migration ability of AMSC in the co-culture and serumfree groups, which increase with the SDF-1 (stromal cell derived factor-1) concentration gradient, were higher than that in the serum group (P<0.05). Conclusion: AMSC co-cultured with AEC still have the basic biological characteristics of MSC, and showed good growth activity. Co-culture withAEC can up-regulate CXCR4 onAMSC surfaces and enhance the migration ability ofAMSC in vitro.