***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The efficacy of  post-percutaneous coronary intervention ( PCI )  intracoronary injection with bone marrow mesenchymal stem cells ( BMSCs ) in patients with acute myocardial infa rct ion ( AMI ) remains controversial . Here , 58 patients with AMI undergoing PCI  were r and omly divided into two groups : BMSC and control groups . Autologous BSMCs were then generated in vitro from the BMSC patients . After transplantation , left ventricular ejection fraction ( LVEF ) , left ventricular end-diastolic dimensions ( LVDd ) , and infa rct size ( IS ) were evaluated in both groups . LVEF , LVDd , and IS improved after BMSC transplantation but the changes were not significantly different from those in the controls . The number of adverse events and rehospitalization rates after 1 month were significantly higher in the control group than in the BMSC group . BMSC transplantation thus benefits patients by decreasing the number of adverse events and reducing the rehospitalization rate in the early stages following PCI BACKGROUND Fractional flow reserve ( FFR ) measured on catheterization is now widely used for the diagnosis of functional myocardial ischemia in patients with coronary artery disease ( CAD ) . FFR , however , is invasive and carries potential procedural complications . Therefore , the aim of this study was to compare the diagnostic capability in functionally significant stenosis identified on FFR , between cardiac magnetic resonance myocardial perfusion imaging ( CMR-MPI ) , single-photon emission computed tomography MPI ( SPECT-MPI ) , and dobutamine stress echocardiography ( DSE ) in patients with CAD . METHODS AND RESULTS A total of 25 patients who had at least 1 angiographic stenosis ≥50 % on coronary angiography was studied .  CMR-MPI , SPECT-MPI and DSE were done before FFR measurement . FFR was measured in all 3 major epicardial coronary arteries . Out of 71 vascular territories excluding 4 territories due to inadequate imaging , 29 ( 41 % ) had FFR < 0.80 . The sensitivity of CMR-MPI was significantly higher than that of SPECT-MPI and DSE ( P=0.02 and P=0.001 , respectively ) . The area under the receiver operating characteristic curve ( AUC ) for CMR-MPI ( AUC , 0.92 ) was significantly greater than for SPECT-MPI ( AUC , 0.73 ; P=0.006 ) and DSE ( AUC , 0.69 ; P<0.001 ) . CONCLUSIONS CMR-MPI performed well in the detection of functionally significant stenosis defined according to FFR , and had the highest diagnostic sensitivity among the 3 modalities tested in patients with CAD Rationale : Mesenchymal precursor cells ( MPCs ) are a specific Stro-3 + sub population of mesenchymal stem cells isolated from bone marrow . MPCs exert extensive cardioprotective effects , and are considered to be immune privileged . Objective : This study assessed the safety , feasibility , and efficacy of intracoronary delivery of allogeneic MPCs directly after acute myocardial infa rct ion in sheep . Methods and Results : Initially , intracoronary delivery conditions were optimized in 20 sheep . These conditions were applied in a r and omized study of 68 sheep with an anterior acute myocardial infa rct ion . Coronary flow was monitored during MPC infusion , and cardiac function was assessed using invasive hemodynamics and echocardiography at baseline and during 8 weeks follow-up . Coronary flow remained within thrombolysis in myocardial infa rct ion III definitions in all sheep during MPC infusion . Global left ventricular ejection fraction as measured by pressure – volume loop analysis deteriorated in controls to 40.7±2.6 % after 8 weeks . In contrast , MPC treatment  improved cardiac function to 52.8±0.7 % . Echocardiography revealed significant improvement of both global and regional cardiac functions . Infa rct size decreased by 40 % in treated sheep , whereas infa rct and border zone thickness were enhanced . Left ventricular adverse remodeling was abrogated by MPC therapy , result ing in a marked reduction of left ventricular volumes . Blood vessel density increased by > 50 % in the infa rct and border areas . Compensatory cardiomyocyte hypertrophy was reduced in border and remote segments , accompanied by reduced collagen deposition and apoptosis . No microinfa rct ions in remote myocardial segments or histological abnormalities in unrelated organs were found . Conclusions : Intracoronary infusion of allogeneic MPCs is safe , feasible , and markedly effective in a large animal model of acute myocardial infa rct ion BACKGROUND Pilot trials suggest that the intracoronary administration of autologous progenitor cells may improve left ventricular function  after acute myocardial infa rct ion . METHODS In a multicenter trial , we r and omly assigned 204 patients with acute myocardial infa rct ion to receive an intracoronary infusion of progenitor cells derived from bone marrow ( BMC ) or placebo medium into the infa rct artery 3 to 7 days after successful reperfusion therapy . RESULTS At 4 months , the absolute improvement in the global left ventricular ejection fraction ( LVEF ) was significantly greater in the BMC group than in the placebo group ( mean [ + /-SD ] increase , 5.5+/-7.3 % vs. 3.0+/-6.5 % ; P=0.01 ) . Patients with a baseline LVEF at or below the median value of 48.9 % derived the most benefit ( absolute improvement in LVEF , 5.0 % ; 95 % confidence interval , 2.0 to 8.1 ) . At 1 year , intracoronary infusion of BMC was associated with a reduction in the prespecified combined clinical end point of death , recurrence of myocardial infa rct ion , and any revascularization procedure ( P=0.01 ) . CONCLUSIONS Intracoronary administration of BMC is associated with improved recovery of left ventricular contractile function in patients with acute myocardial infa rct ion . Large-scale studies are warranted to examine the potential effects of progenitor-cell administration on morbidity and mortality Background The use of adult stem cells is limited by the quality and quantity of host stem cells . It has been demonstrated that Wharton ’s jelly – derived mesenchymal stem cells ( WJMSCs ) , a primitive stromal population , could integrate into ischemic cardiac tissues and significantly improve heart function . In this r and omized , controlled trial , our aim was to assess the safety and efficacy of intracoronary WJMSCs in patients with ST-elevation acute myocardial infa rct ion ( AMI ) . Methods In a multicenter trial , 116 patients with acute ST-elevation MI were r and omly assigned to receive an intracoronary infusion of WJMSCs or placebo into the infa rct artery at five to seven days after successful reperfusion therapy . The primary endpoint of safety : the incidence of adverse events ( AEs ) within 18 months , was monitored and quantified . The endpoint of efficacy : the absolute changes in myocardial viability and perfusion of the infa rct ed region from baseline to four months , global left ventricular ejection fraction ( LVEF ) from baseline to 18 months were measured using F-18-fluorodeoxyglucose positron emission computed tomography ( F-18-FDG-PET ) and 99mTc-sestamibi single-photon emission computed tomography ( 99mTc-SPECT ) , and two-dimensional echocardiography , respectively . Results During 18 months follow-up , AEs rates and laboratory tests including tumor , immune , and hematologic indexes were not different between the two groups . The absolute increase in the myocardial viability ( PET ) and perfusion within the infa rct ed territory ( SPECT ) was significantly greater in the WJMSC group [ 6.9 ± 0.6 % ( 95 % CI , 5.7 to 8.2 ) ] and [ 7.1 ± 0.8 % ( 95 % CI , 5.4 to 8.8 ) than in the placebo group [ 3.3 ± 0.7 % ( 95 % CI , 1.8 to 4.7 ) , P < 0.0001 ] and 3.9 ± 0.6(95 % CI , 2.8 to 5.0 ) , P = 0.002 ] at four months . The absolute increase in the LVEF at 18 months in the WJMSC group was significantly greater than that in the placebo group [ 7.8 ± 0.9 ( 6.0 to approximately 9.7 ) vs. 2.8 ± 1.2 ( 0.4 to approximately 5.1 ) , P = 0.001 ] . Concomitantly , the absolute decreases in LV end-systolic volumes and end-diastolic volumes at 18 months in the WJMSC group were significantly greater than those in the placebo group ( P = 0.0004 , P = 0.004 , respectively ) . Conclusions Intracoronary infusion of WJMSCs is safe and effective in patients with AMI , providing clinical ly relevant therapy within a favorable time window . This study encourages additional clinical trials to determine whether WJMSCs may serve as a novel alternative to BMSCs for cardiac stem cell-based therapy . Trial registration Clinical Trials NCT01291329 ( 02/05/2011 ) Recent studies suggest that the intracoronary administration of bone marrow (BM)-derived mesenchymal stem cells ( MSCs ) may improve left ventricular function in patients with acute myocardial infa rct ion ( AMI ) . However , there is still argumentative for the safety and efficacy of MSCs in the AMI setting . We thus performed a r and omized pilot study to investigate the safety and efficacy of MSCs in patients with AMI . Eighty patients with AMI after successful reperfusion therapy were r and omly assigned and received an intracoronary administration of autologous BM-derived MSCs into the infa rct related artery at 1 month . During follow-up period , 58 patients completed the trial . The primary endpoint was changes in left ventricular ejection fraction ( LVEF ) by single-photon emission computed tomography ( SPECT ) at 6 month . We also evaluated treatment-related adverse events . The absolute improvement in the LVEF by SPECT at 6 month was greater in the BM-derived MSCs group than in the control group ( 5.9%±8.5 % vs 1.6%±7.0 % ; P=0.037 ) . There was no treatment-related toxicity during intracoronary administration of MSCs . No significant adverse cardiovascular events occurred during follow-up . In conclusion , the intracoronary infusion of human BM-derived MSCs at 1 month is tolerable and safe with modest improvement in LVEF at 6-month follow-up by SPECT . ( Clinical Trials.gov registration number : NCT01392105 BACKGROUND There are only few data on long-term effectiveness of the stem cell therapy . AIM We studied the time course of global and regional left ventricular function in patients with acute myocardial infa rct ion within 1 year after the autologous mononuclear bone marrow cell transplantation .  METHODS Sixty patients with a first acute myocardial infa rct ion , who had been r and omized into 3 groups , completed a 12-month protocol . Two groups were intracoronarily given bone marrow cells in either higher ( 10(8 ) cells , HD group , n=20 ) or lower ( 10(7 ) cells , LD group , n=20 ) doses . Twenty patients without cell transplantation  served as a control ( C ) group . Doppler tissue imaging and the gated technetium-99 m sestamibi single photon emission computed tomography were performed before cell transplantation and at 3 , 6 , and 12 months later . RESULTS The baseline peak systolic velocities of longitudinal contraction of the infa rct ed wall ( S(infa rct ) ) of 5.2 cm/s , 4.6 cm/s , and 4.4 cm/s in C , LD , and HD groups increased by 0.0 cm/s , 0.3 cm/s ( p = NS vs. C group ) , and by 0.7 cm/s ( p<0.05 vs. C group ) , respectively , at 3 months . At 12 months , however , the corresponding changes from baseline values of 0.1 cm/s , 0.2 cm/s , and 0.6 cm/s did not differ significantly ( all p = NS ) . In contrast , the post-transplant improvements in the left ventricular ejection fraction by 6 % , 7 % , and 7 % at months 3 , 6 , and 12 , respectively , were preserved in HD group patients during the whole 12-month follow-up and remained significantly better as compared to controls . CONCLUSIONS In our study , the autologous mononuclear bone marrow cell transplantation provided sustained improvement in global left ventricular systolic function in patients with acute myocardial infa rct ion . However , when evaluating regional systolic function of the infa rct ed wall , the short-term benefit was partially lost during the 12-month follow-up Objectives : Intracoronary cell transplantation during catheter balloon inflations may be associated with 
    Output:
    
Conclusions Transplantation time and injected cell dose are key factors that determine the therapeutic effect of stem cell therapy .
The injection of no more than 107 MSCs within 1 week for AMI after percutaneous coronary intervention might improve left ventricular systolic function .