hematopoietic stem - cell transplantation ( hsct ) is an important therapeutic option for many malignant and nonmalignant disorders . since the first report of bone marrow ( bm ) transplantation
, steady - state bm ( ss - bm ) has been the only stem - cell source for hsct . in recent years , granulocyte colony - stimulating factor ( g - csf)-mobilized peripheral blood stem - cells ( g - pbsc ) have become an alternative stem - cell source .
g - pbsc is even preferred in adults receiving human leucocyte antigen ( hla)-identical sibling transplantation .
although g - pbsc are enriched in progenitor cells as compared to ss - bm , which allows a faster engraftment , the use of g - pbsc will increase the incidence of chronic graft - versus - host disease ( cgvhd ) . to take advantage of g - pbsc while decrease the risk of cgvhd ,
recently , g - bm has been an attractive option for hla - haploidentical / mismatched donor transplantation .
however , g - bm does not seem to be considered an alternative to ss - bm in hla - identical hsct due to nonsignificant improvement in survivals , although its feasibleness , safety , well - engraftment and limited incidence of gvhd have been demonstrated .
the conclusions from previous studies on hla - identical transplantation with g - bm might be limited due to the number of patients , underlying diseases , disease status at the time of transplantation , g - csf schedules , conditioning regimens , and gvhd prophylaxis . in this study
, we conducted a retrospective nonrandomized controlled study to evaluate the clinical outcomes of g - bm , ss - bm , and g - pbsc in hla - identical sibling hsct in our center .
the results suggested that g - bm was an excellent stem - cell source in hla - identical sibling hsct .
a total of 226 early stage myeloid leukemia patients , including de novo acute myelogenous leukemia ( aml ) ( complete remission 1 [ cr1 ] ) and chronic myelogenous leukemia ( cml ) ( chronic phase 1 [ cp1 ] ) , with hla - identical sibling donor , were enrolled in this study ( march 2004march 2009 ) .
the main clinical characteristics of patients at the time of hsct were listed in table 1 .
43 , 60 , and 123 patients were enrolled in the g - bm , ss - bm , and g - pbsc groups , respectively .
patient characteristics ss - bm : steady - state bone marrow ; g - pbsc : g - peripheral blood stem cell ; g - bm : g - csf - primed bone marrow ; aml : acute myelocytic leukemia ; cml : chronic myelocytic leukemia ; tbi : total body irradiation .
this study was approved by the ethics committee of the affiliated hospital of academy of military medical sciences .
informed consents were obtained from all patients , donors , or their legal guardians . in the g - pbsc group , donors received g - csf at 8.0 g kg d divided in two subcutaneous injections for 5 consecutive days ( day 3 to day + 1 ) , and pbsc was harvested on day 0 and day + 1 . in the g - bm group , donors received g - csf at 5.0 g kg d by a single subcutaneous injection for 3 consecutive days ( day 3 to day 1 ) , and g - bm was harvested on day 0 . in the ss - bm group , bm
bms was harvested from donors based on a target volume of 20 ml / kg .
the median total nucleated cells infused into recipients were 4.2  10/kg ( g - bm , range : 2.2  10 8.1  10/kg ) , 7.7  10/kg ( g - pbsc , range : 1.8  10 22.7  10/kg ) , and 2.5  10/kg ( ss - bm , range : 1.8  104.4  10/kg ) of recipient weight , respectively . plasma or red cell depletion of the grafts was performed if any abo incompatibility was presented before infusions .
all recipients received the standard preparative regimen involving cyclophosphamide ( 60 mgkgd  2 , day 4 , day 3 ) and total body irradiation ( tbi ) ( 5 gy / day  2 , day 2 , day 1 ) .
the gvhd prophylaxis included cyclosporin a ( csa ) and the short - term methotrexate ( mtx ) .
neutrophil recovery was defined as having occurred after the first of 3 days with an absolute neutrophil count > 500/l after the post - transplant nadir .
platelet recovery was defined as the first of 7 consecutive days with a platelet count > 50,000/l without platelet transfusions .
transplant - related mortality ( trm ) was defined as death from any cause except relapse .
leukemia - free survival ( lfs ) was defined as the time interval from transplantation to the first event ( either relapse or death ) .
the cumulative incidence curves of gvhd , trm , lfs , and os were plotted using the kaplan  meier method , and the long - rank test was used for independence comparison between variables . for all analysis , p <
a total of 226 early stage myeloid leukemia patients , including de novo acute myelogenous leukemia ( aml ) ( complete remission 1 [ cr1 ] ) and chronic myelogenous leukemia ( cml ) ( chronic phase 1 [ cp1 ] ) , with hla - identical sibling donor , were enrolled in this study ( march 2004march 2009 ) .
the main clinical characteristics of patients at the time of hsct were listed in table 1 .
43 , 60 , and 123 patients were enrolled in the g - bm , ss - bm , and g - pbsc groups , respectively .
patient characteristics ss - bm : steady - state bone marrow ; g - pbsc : g - peripheral blood stem cell ; g - bm : g - csf - primed bone marrow ; aml : acute myelocytic leukemia ; cml : chronic myelocytic leukemia ; tbi : total body irradiation .
this study was approved by the ethics committee of the affiliated hospital of academy of military medical sciences .
in the g - pbsc group , donors received g - csf at 8.0 g kg d divided in two subcutaneous injections for 5 consecutive days ( day 3 to day + 1 ) , and pbsc was harvested on day 0 and day + 1 . in the g - bm group , donors received g - csf at 5.0 g kg d by a single subcutaneous injection for 3 consecutive days ( day 3 to day 1 ) , and g - bm was harvested on day 0 . in the ss - bm group ,
bms was harvested from donors based on a target volume of 20 ml / kg .
the median total nucleated cells infused into recipients were 4.2  10/kg ( g - bm , range : 2.2  10 8.1  10/kg ) , 7.7  10/kg ( g - pbsc , range : 1.8  10 22.7  10/kg ) , and 2.5 
10/kg ( ss - bm , range : 1.8  104.4  10/kg ) of recipient weight , respectively .
plasma or red cell depletion of the grafts was performed if any abo incompatibility was presented before infusions .
all recipients received the standard preparative regimen involving cyclophosphamide ( 60 mgkgd  2 , day 4 , day 3 ) and total body irradiation ( tbi ) ( 5 gy / day  2 , day 2 , day 1 ) .
the gvhd prophylaxis included cyclosporin a ( csa ) and the short - term methotrexate ( mtx ) .
neutrophil recovery was defined as having occurred after the first of 3 days with an absolute neutrophil count > 500/l after the post - transplant nadir .
platelet recovery was defined as the first of 7 consecutive days with a platelet count > 50,000/l without platelet transfusions .
transplant - related mortality ( trm ) was defined as death from any cause except relapse .
leukemia - free survival ( lfs ) was defined as the time interval from transplantation to the first event ( either relapse or death ) . overall survival ( os ) was calculated from the time of transplantation to death .
the cumulative incidence curves of gvhd , trm , lfs , and os were plotted using the kaplan  meier method , and the long - rank test was used for independence comparison between variables . for all analysis , p < 0.05 was considered as statistically significant .
the median time to neutrophil recovery was 15 days ( range , 1126 ) , 17 days ( range , 1331 ) , and 25 days ( range , 1563 ) in the g - pbsc group , the g - bm group , and the ss - bm group , respectively [ figure 1a ] .
the median time to platelet recovery were 22 days ( range , 12176 ) , 32 days ( range , 15365 ) , and 47 days ( range , 21200 ) in the g - pbsc group , the g - bm group , and the ss - bm group , respectively [ figure 1b ] .
the time to neutrophils and platelet engraftment was significantly different among all groups ( g - pbsc vs. g - bm , g - pbsc vs. ss - bm , g - bm vs. ss - bm ) ( p < 0.05 ) .
iv agvhd were ( 30.4  7.0)% , ( 26.7  5.9)% , and ( 36.2  4.4)% in the g - bm , ss - bm , and g - pbsc group , respectively [ figure 2a ] .
there was no significant difference on incidence of agvhd among these groups ( p > 0.05 ) .
iv agvhd in the g - bm group ( [ 4.7  3.2]% ) was significantly lower than that in the ss - bm group ( [ 17.5  5.0]% , p < 0.05 ) .
iv agvhd in the g - pbsc group compared to ss - bm , although it was not statistically significant ( [ 16.4  3.4]% vs. [ 17.5  5.0]% , p = 0.058 ) [ figure 2b ] .
the cumulative incidence in the g - bm group was similar to that in the ss - bm group ( [ 28.4  7.8]% vs. [ 34.0  6.9]% , p > 0.01 ) , while there was significant differences between the g - bm and g - pbsc group ( [ 28.4  7.80]% vs. [ 64.4  5.1]% , p < 0.05 ) , and between the ss - bm and g - pbsc group ( [ 34.0  6.9]% vs. [ 64.4  5.1]% , p < 0.05 ) [ figure 2c ] .
similar patterns were observed when the cumulative incidences of extensive cgvhd were analyzed ( g - bm vs. g - pbsc : [ 11.8  5.6]% vs. [ 42.7  5.1]% , p <
0.05 ; g - bm vs. ss - bm : [ 11.8  5.6]% vs. [ 21.7  6.1]% , p < 0.05 ) [ figure 2d ] .
the os rate in the g - bm group and the g - pbsc group were ( 76.3  6.6)% and ( 70.3  4.6)% , respectively . both were significantly higher than the ss - bm group ( [ 45.1  6.6]% , p < 0.05 ) [ figure 3a ] .
the incidences of lfs in the g - bm and g - pbsc were ( 68.7  7.2)% and ( 68.9  4.7)% , both were significantly higher than that in the ss - bm group ( [ 45.3  6.6]% , p < 0.05 ) [ figure 3b ] .
the cumulative incidence of trm in the ss - bm group was ( 41.2  6.7)% , which was significantly higher than that in the g - pbsc and the g - bm groups ( [ 19.0  3.9]% , p < 0.05 ; [ 12.0  5.0]% , p < 0.05 ) [ figure 3c ] .
however , there were no significant differences in leukemia relapse rates between any two groups ( g - bm , [ 23.9  7.0]% ; g - pbsc , [ 20.3  4.4]% ; ss - bm , [ 24.0  7.0]% ) ( p > 0.1 ) [ figure 3d ] .
a total of 33 of 60 patients ( 55% ) died due to a variety of factors ( leukemia relapse , gvhd , infections , interstitial pneumonia / idiopathic pneumonia syndrome , graft rejection , etc . ) in the ss - bm group .
in contrast , only 25.6% ( 11/43 ) of the g - bm group and 26.0% ( 32/123 ) of the g - pbsc group died due to the same reasons .
agvhd : acute graft - versus - host disease ; cgvhd : chronic graft - versus - host disease ; hvod : hepatic veno - occlusive disease ; g - pbsc : g - peripheral blood stem cell ; g - bm : g - csf - primed bone marrow .
meanwhile , there was no significant difference between aml and cml on os ( [ 59.8  5.0]% versus [ 67.7  4.7]% , p > 0.05 ) , lfs ( [ 57.3  5.1]% vs. [ 66.0  4.8]% , p > 0.05 ) , and trm ( [ 23.7  4.4]% versus [ 24.1  4.4]% , p > 0.05 ) .
however , aml is associated with more leukemia relapse compared to cml ( [ 27.7  5.1]% versus [ 16.4  4.2]% , p < 0.05 ) .
the median time to neutrophil recovery was 15 days ( range , 1126 ) , 17 days ( range , 1331 ) , and 25 days ( range , 1563 ) in the g - pbsc group , the g - bm group , and the ss - bm group , respectively [ figure 1a ] .
the median time to platelet recovery were 22 days ( range , 12176 ) , 32 days ( range , 15365 ) , and 47 days ( range , 21200 ) in the g - pbsc group , the g - bm group , and the ss - bm group , respectively [ figure 1b ] .
the time to neutrophils and platelet engraftment was significantly different among all groups ( g - pbsc vs. g - bm , g - pbsc vs. ss - bm , g - bm vs. ss - bm ) ( p < 0.05 ) .
iv agvhd were ( 30.4  7.0)% , ( 26.7  5.9)% , and ( 36.2  4.4)% in the g - bm , ss - bm , and g - pbsc group , respectively [ figure 2a ] . there was no significant difference on incidence of agvhd among these groups ( p > 0.05 ) .
iv agvhd in the g - bm group ( [ 4.7  3.2]% ) was significantly lower than that in the ss - bm group ( [ 17.5  5.0]% , p < 0.05 ) .
iv agvhd in the g - pbsc group compared to ss - bm , although it was not statistically significant ( [ 16.4  3.4]% vs. [ 17.5  5.0]% , p = 0.058 ) [ figure 2b ] .
the cumulative incidence in the g - bm group was similar to that in the ss - bm group ( [ 28.4  7.8]% vs. [ 34.0  6.9]% , p > 0.01 ) , while there was significant differences between the g - bm and g - pbsc group ( [ 28.4  7.80]% vs. [ 64.4  5.1]% , p < 0.05 ) , and between the ss - bm and g - pbsc group ( [ 34.0  6.9]% vs. [ 64.4  5.1]% , p < 0.05 ) [ figure 2c ] .
similar patterns were observed when the cumulative incidences of extensive cgvhd were analyzed ( g - bm vs. g - pbsc : [ 11.8  5.6]% vs. [ 42.7  5.1]% , p <
0.05 ; g - bm vs. ss - bm : [ 11.8  5.6]% vs. [ 21.7  6.1]% , p < 0.05 ) [ figure 2d ] .
the os rate in the g - bm group and the g - pbsc group were ( 76.3  6.6)% and ( 70.3  4.6)% , respectively . both were significantly higher than the ss - bm group ( [ 45.1  6.6]% , p < 0.05 ) [ figure 3a ] .
the incidences of lfs in the g - bm and g - pbsc were ( 68.7  7.2)% and ( 68.9  4.7)% , both were significantly higher than that in the ss - bm group ( [ 45.3  6.6]% , p < 0.05 ) [ figure 3b ] .
the cumulative incidence of trm in the ss - bm group was ( 41.2  6.7)% , which was significantly higher than that in the g - pbsc and the g - bm groups ( [ 19.0  3.9]% , p < 0.05 ; [ 12.0  5.0]% , p < 0.05 ) [ figure 3c ] .
however , there were no significant differences in leukemia relapse rates between any two groups ( g - bm , [ 23.9  7.0]% ; g - pbsc , [ 20.3  4.4]% ; ss - bm , [ 24.0  7.0]% ) ( p > 0.1 ) [ figure 3d ] .
( b ) leukemia - free survival . ( c ) transplant - related mortality .
a total of 33 of 60 patients ( 55% ) died due to a variety of factors ( leukemia relapse , gvhd , infections , interstitial pneumonia / idiopathic pneumonia syndrome , graft rejection , etc . ) in the ss - bm group .
in contrast , only 25.6% ( 11/43 ) of the g - bm group and 26.0% ( 32/123 ) of the g - pbsc group died due to the same reasons .
agvhd : acute graft - versus - host disease ; cgvhd : chronic graft - versus - host disease ; hvod : hepatic veno - occlusive disease ; g - pbsc : g - peripheral blood stem cell ; g - bm : g - csf - primed bone marrow .
meanwhile , there was no significant difference between aml and cml on os ( [ 59.8  5.0]% versus [ 67.7  4.7]% , p > 0.05 ) , lfs ( [ 57.3  5.1]% vs. [ 66.0  4.8]% , p > 0.05 ) , and trm ( [ 23.7  4.4]% versus [ 24.1  4.4]% , p > 0.05 ) .
however , aml is associated with more leukemia relapse compared to cml ( [ 27.7  5.1]% versus [ 16.4  4.2]% , p < 0.05 ) .
steady - state bone marrow , g - pbsc , and g - bm are the main stem - cell sources in allogeneic hsct .
a number of groups have reported on the clinical outcomes of patients who received g - bm , g - pbsc , or ss - bm during hla - identical sibling hsct .
these studies show that g - bm and g - pbsc resulted in significantly faster neutrophil and platelet recovery than ss - bm , which is consistent with the results presented here . however , previous studies indicated that g - bm appeared to have no advantage in survivals when compared to ss - bm . in this study , compared with patients treated with ss - bm , those patients who were treated with g - bm and g - pbsc had significantly higher os [ figure 3a ] and lfs [ figure 3b ] .
as to trm and iii - iv grade agvhd , the incidences of patients treated with g - bm were significantly lower chance to develop agvhd and greater chance of survival than those treated with ss - bm [ figure 2a and b ] .
interestingly , g - bm could significantly decrease the incidences of cgvhd and extensive cgvhd , compared with g - pbsc [ figures 2c and d ] , which was consistent with a previous study .
however , g - bm did not increase the incidences of leukemia relapse [ figure 2d ] .
these results clearly indicated that g - bm shared the advantages of both g - pbsc and ss - bm , which was characterized by fast engraftment , low incidences of very severe agvhd / cgvhd / trm , and high incidences of lfs / os .
this report was the first study that included all three main stem - cell sources ( g - bm , g - pbsc , ss - bm ) , and we concluded that g - bm was an excellent stem - cell source for hla - identical sibling hsct .
many groups have compared the different clinical outcomes of g - bm with ss - bm or g - pbsc in hla - identical sibling hsct , however , the results have been very controversial , especially regarding the os .
our study indicated that g - bm was superior to ss - bm and g - pbsc , and that a significant improvement in os was observed in the g - bm group .
previous reports studied fewer patients ( 22 , 48 , and 50 patients ) with shorter follow - up duration ( the median time < 12 months ) .
we have conducted the current study with more patients ( 226 ) and longer follow - up time ( median time , g - bm : 60 months ; g - pbsc : 30 months ; ss - bm : 40 months ) , which could reach a sufficient statistical power . the second was the g - csf priming schedules .
previous studies have shown that g - csf stimulation caused a 1.41.7-fold increase in cd34 + cell count , a 3-fold increase in colony - forming cells , and 5090-fold increase in short - term repopulating cells in g - bm , when compared to ss - bm .
however , different priming schedules ( doses and duration of g - csf administration ) might cause controversial results regarding the engraftment capability of g - bm , which would in turn cause different treatment outcomes .
the dose of g - csf for bm priming ranged from 5 gkgd to 12.1 gkgd and the length of g - csf treatment ranged from 2 to 5 days . in the present study ,
all donors received a uniformed g - csf priming schedule , which was 5.0 gkgd for 3 consecutive days .
in addition , the disease status before the transplantation would have an impact on the outcome . to rule out the interference of disease status
, we only included patients with de novo aml ( cr1 ) and cml ( cp1 ) .
we found that aml patients had higher leukemia relapse rates than cml , which suggested that different underlying disease before transplantation might play a role in the treatment effect of hsct .
finally , the preparative regimens , the gvhd prophylaxis , and the supportive care might play a role in the outcome .
we used the classic cy routine combined with fractionated tbi as preparative regimens and standard csa plus short - term mtx as prophylactic measures to prevent gvhd in all patients .
the uniform management could reduce the interferences of these factors and give more credible results .
further investigation is needed to address how these factors influenced the treatment effects in hsct .
despite the availability of many new immune suppressive drugs and antibodies , gvhd still remained the most serious complications in hsct . to obtain the optimal results
, we need to decrease the gvhd while enhance the graft - versus - leukemia ( gvl ) effect .
to effect , a lot of approaches have been developed to minimize the gvhd , such as the depletion of t - cells in vitro and in vivo , and the introduction of suicide gene into t - cells .
these approaches could decrease the incidence of gvhd , but the lower gvhd rates might be due to using of anti - thymocyte globulin , depletion of t - cells , or other factors . in this study , we found that the gvl effect in g - bm was superior to g - pbsc and ss - bm . as presented in this study
, g - bm could remarkably lower the risk of gvhd ( iii - iv grade gvhd , cgvhd , extensive cgvhd ) , and accordingly improve the survival .
however , the incidence of leukemia relapse did not increase , suggesting that g - bm might be an alternative way to enhance gvl effect and lower the risk of gvhd .
meanwhile , the use of g - bm in hsct might be a simple and  low prices  approach to separate gvhd and gvl effects which did not require additional immunosuppression drugs or special measurements .
this was the first retrospective report on hla - identical sibling hsct that was conducted in a single center with all three main grafts ( g - bm , g - pbsc , ss - bm ) .
compared with previous studies , the overall clinical outcomes of g - bm , g - pbsc , and ss - bm in this study might be more credible because the number of patients was higher and the treatments ( preparative regimens , gvhd prophylaxis , and supportive care ) were uniform . recently
, a phase 3 , randomized trial comparing g - bm and ss - bm is ongoing , and another randomized multicenter study comparing g - pbsc and g - bm in patients receiving hla - identical sibling hsct is also being conducted in canada .
although the corresponding results are not released yet , we believe that these studies will further illuminate the advantages of g - bm in hsct .
this study has several limitations including the retrospective nature , the heterogeneous patient cohorts , and lacking of molecular typing .
however , the results are remarkable because of a comparatively large number of patients with a long follow - up as well as uniform data collection . in summary ,
our study has provided sufficient data to conclude that g - bm is an excellent stem - cell source in hla - identical sibling hsct .
g - bm transplant is characterized by fast engraftment , low incidence of severe agvhd / cgvhd , and improved survival .
we recommend g - bm rather than g - pbsc or ss - bm for patients receiving hla - identical sibling hsct .
meanwhile , g - bm is potentially a good stem - cell source in unrelated and haploidentical hsct , which need to be further investigated in the future .
 background : steady - state bone marrow ( ss - bm ) and granulocyte colony - stimulating growth factor - primed bm / peripheral blood stem - cell ( g - bm / g - pbsc ) are the main stem - cell sources used in allogeneic hematopoietic stem - cell transplantation . here , we evaluated the treatment effects of ss - bm and g - bm / g - pbsc in human leucocyte antigen ( hla)-identical sibling transplantation.methods:a total of 226 patients ( acute myelogenous leukemia - complete remission 1 , chronic myelogenous leukemia - chronic phase 1 ) received ss - bm , g - bm , or g - pbsc from an hla - identical sibling . 
 clinical outcomes ( graft - versus - host disease [ gvhd ] , overall survival , transplant - related mortality [ trm ] , and leukemia - free survival [ lfs ] ) were analyzed.results:when compared to ss - bm , g - bm gave faster recovery time to neutrophil or platelet ( p < 0.05 ) . 
 incidence of grade iii - iv acute gvhd and extensive chronic gvhd ( cgvhd ) was lower than seen with ss - bm ( p < 0.05 ) and similar to g - pbsc . 
 although the incidence of cgvhd in the g - bm group was similar to ss - bm , both were lower than g - pbsc ( p < 0.05 ) . 
 g - bm and g - pbsc exhibited similar survival , lfs , and trm , but were significantly different from ss - bm ( p < 0.05 ) . 
 there were no significant differences in leukemia relapse rates among the groups ( p > 0.05).conclusions : g - csf - primed bone marrow shared the advantages of g - pbsc and ss - bm . 
 we conclude that g - bm is an excellent stem - cell source that may be preferable to g - pbsc or ss - bm in patients receiving hla - identical sibling hematopoietic stem - cell transplantation . 
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Patients
Treatment
Evaluations and definitions
Statistic analysis
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Hematopoietic reconstitution
G-CSF-primed bone marrow reduced the risk of graft-versus-host disease
G-CSF-primed bone marrow increased the survival rates
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