[Melatonin-Mediated Inhibitory Effect on Hyperimmune Status of Acquired Aplastic Anemia].

OBJECTIVE: To evaluate the expression level of melatonin and its effects on immune function in aplastic anemia (AA) patients. METHODS: The enzyme-linked immunosorbent assay (ELISA) was used to detect the plasma levels of melatonin in AA patients, and the correlation between melatonin levels and laboratory indexs was analyzed. The activation, proliferation, and apoptosis of T cells from AA patients were analyzed by flow cytometry with or without melatonin in vitro. RESULTS: The plasma levels of melatonin in AA patients were significantly lower compared with healthy controls (HC) (12.23 pg/ml vs 20.04 pg/ml, P < 0.01), while the plasma melatonin levels of AA patients in remission group after immunosuppressive therapy (IST) were significantly higher than those in non-remission group (29.16 pg/ml vs 11.73 pg/ml, P =0.04). Moreover, the melatonin levels were positively correlated with platelets (r =0.49), the absolute reticulocyte count (r =0.45), and the percentage of neutrophils (r =0.43). Meanwhile, there was a negative correlation between melatonin levels and the percentages of lymphocytes (r =-0.45). The expressions of CD25 and CD69 in both CD4+ and CD8+ T cells from AA patients were remarkably inhibited by melatonin in vitro (all P < 0.05). When cultured with melatonin, the proliferation rates of both CD4+ and CD8+ T cells from AA patients were markedly suppressed (P =0.01 andP < 0.01). CONCLUSION: The plasma levels of melatonin were decreased in AA patients, which might play an important role in the mechanism of immunological abnormalities. The hyperimmune status of AA patients could be partially ameliorated by melatonin in vitro.

[Deciphering Hypoplastic Myelodysplastic Syndrome and Aplastic Anemia via In-Depth Analysis of Lymphocyte Subsets].

OBJECTIVE: To explore the difference of lymphocyte subsets in peripheral blood (PB) between aplastic anemia (AA) and hypoplastic myelodysplastic syndrome (hypo-MDS) patients, meanwhile to compare the clinical parameters obtained from PB and bone marrow (BM). METHODS: The lymphocyte subsets in hypo-MDS (n=25) and AA (n=33) patients were investigated by flow cytometry. Meanwhile, the differences in PB cell counts, biochemical indicators, BM cell counts and abnormal chromosomes between the two groups were analyzed. RESULTS: The percentage of CD8+T cells in AA group was significantly higher than that in hypo-MDS group (P=0.001), while the percentage of CD4+ T cells and the CD4+/CD8+ ratio in AA group were obviously lower than those in hypo-MDS group (P=0.015 and 0.001, respectively). Furthermore, the proportion of CD4+ and CD8+ activated T (TA) cells, and memory Tregs in AA group was distinctly lower than those in hypo-MDS group (P=0.043, 0.015 and 0.024, respectively). Nevertheless, the percentage of CD8+ naive T (TN) cells in AA patients was remarkably higher (P=0.044). And hypo-MDS patients had declined lymphocyte counts (P=0.025), increased levels of total bilirubin (TBil), lactate dehydrogenase (LDH), vitamin B12 and proportion of BM blasts than AA patients (P=0.019, 0.023, 0.027 and 0.045, respectively). CONCLUSION: In this study it was confirmed that the percentages of CD4+ and CD8+ TA cells, memory Tregs and CD8+ TN cells were significantly different between AA and hypo-MDS patients, which provide an essential basis for the identification of these two diseases.

[Effect of CD106+ Mesenchymal Stem Cell on Bone Marrow Vascular Failure in Patients with Aplastic Anemia].

Objective To investigate the vascularization ability of mesenchymal stem cells(MSCs)and explore its influencing factors in aplastic anemia(AA) patients. Methods MSCs were isolated from the bone marrow of AA patients(AA MSCs) and normal controls(N MSCs) were cultured and then evaluated by flow cytometry and immunofluorescene staining technique.The expression level of vascular cell adhesion molecule-1(CD106) was detected by gene sequencing,and the content and fluorescene intensity of CD106+MSCs was determined by fluorescence-activated cell sorting.The content of CD105+CD106+MSCs in fresh AA bone marrow was measured,followed by the determination of the capability of endothelial differentiation from AA MSCs and N MSCs with immunofluorescene analysis;finally,the capability of CD31+cell differentiation from CD106-blocking N MSCs and its tubular structures formation in matrigel were tested.Results The expression of CD106 in AA patients was defective(decreased by 12.13 times when compared with N MSCs) and the concentration and fluorescene degree of CD106+MSCs was also decreased in AA patients [(28.03±17.71)% vs.(59.61±12.26)%,P=0.000].The content of CD105+CD106+MSCs decreased significantly in the fresh bone marrow [(0.33±0.10)% vs.(2.98±0.46)%,P=0.0005].Besides, the capability of CD31+cell differentiation from AA MSCs was significantly delayed [(13.67±1.50)% vs.(43.24±0.96)%,P=0.0004].Also,the capability of CD31+cell differentiation and tubular structures formation of CD106-blocking N MSCs was also obviously decreased [(26.00±2.65)% vs.(91.78±2.44)%,P=0.000;(13.81±1.98)mm vs.(68.12±6.78)mm,P=0.0015].Conclusion The deficient or decreased expression of CD106+MSCs accelerate the bone marrow vascularization failure in AA patients.

[Differential Expression Profiles of MicroRNAs between de novo and Complete Response Severe Aplastic Anemia].

OBJECTIVE: To detect the expression of miRNA in de novo and complete response SAA patients and predict the targets of the miRNAs. METHODS: The expression profiles of miRNA from bone marrow mononuclear cells of the SAA patients with de novo and CR were detected by miRNA microarray. RESULTS: Totally 35 up-regulated and 37 down-regulated miRNA were identified in CR SAA patients in comparison with de novo SAA patients. Furthermore, by predicting the targets of the differentlly expressed miRNA, it was found that some targets associated with T cell receptor signaling pathway and cell adhesion molecules. CONCLUSION: Some miRNA may be involved in the pathogenesis of SAA.

[Long-term Follow-up of Patients with Hepatitis-Associated Aplastic Anemia].

OBJECTIVE: To explore the clinical characteristic, therapeutic efficacy and prognosis of patients with hepatitis-associated aplasitc anemia (HAAA). METHODS: the clinical data and labrotatory examination results of 30 cases of HAAA were analyzed retrospectively, the 6-month response ratio and overall survival (OS) were assessed. RESULTS: HAAA most commonly occured in males, with the occurence rate of males and females was 4:1, the median onset age was 16 (4-43) years old, HAAA oriented focus on sever aplastic anemia (SAA)(4 cases,13%) and very sever aplastic anemia (VSAA)(22 cases,73%). Aplastic anemia (AA) could be seen on occurence of hepatitis (accompanied aplastic anemia) (7 cases,23%), or after the onset of hepatits (delayed aplastic anemia) (23 cases,77%), but more often occured in the latter. Statistical analysis showed that when compared with the patients of delayed aplastic anemia, patients accompanied aplastic anemia possesses lower levels of glutamic-pyruvic transaminase(ALT), aspertate aminotransferase (AST) and total bilirubin (TBIL)(P=0.042,0.012,0.001), and possessed a more obvious lymphoid cell disorder when AA occured, with more lower peripheral blood CD19+ B cells proportion (P=0.046) and more obvious imbalance of CD4+/CD8+ ratio, but the difference was no statistical significant (P=0538). Factors affecting the 6-month respose were the severity of AA (P=0.044), the peak level of bilirubin of hepatitis (P=0.006) and the propotion of mature monocyte in bone marrow (P=0.034). The long-term follow-up showed that the 2-year OS of HAAA was 64.3±9.2%, the 6-month curative efficacy significantly affect the prognosis (P<0.001). CONCLUSION: HAAA more often occur in young male, HAAA is mainly SAA and VSAA and mostly non-A-C hepatitis associated aplastic anemia, patients usually have a high incidence of early infection. Patients acompanied with aplastic anemia possess more obvious immunological derangement; the treatment efficacy for HAAA is poor, patients who haven't obtained 6-month response indicate a sinister prognosis, allogeneic hematopoietic stem cell transplantion is a better choice for these patients.

[Clinical Characteristics and Gene Mutations of Gilbert Syndrome Complicated with Myeloproliferative Neoplasm].

OBJECTIVE: To investigate the clinical characteristics and gene mutations of patients with Gilbert syndrome complicated with myeloproliferative neoplasms (MPN). METHODS: Peripheral blood samples from 1 patient with Gilbert syndrome complicated with MPN and his son were collected to analyse all exon mutations of UGT1A1 gene. RESULTS: The patient with leukocytosis, thrombocythemia, mild anemia and positive JAK2/V617F mutation was initially diagnosed as MPN. The hyperbilirubinemia suggested concurrent disease. Further gene evaluation disclosed a insertion mutation in the (TA)6TAA box, and a missense mutation(G→A) at 211 bp of exon 1, corresponding to the deficiency in the bilirubin-conjugating enzyme uridine-diphosphoglucuronosyl transferase1A1 (UGT1A1). His son only carried some polymorphism mutation without manifestation of this disease. CONCLUSION: It is a first report case of MPN complicated with Gilbert syndrome that can highlight the differential diagnosis for hyperbilirubinemia.

Clinical Analysis of 70 Adult Patients with Paroxysmal Nocturnal Hemoglobinuria.

OBJECTIVE: To investigate the clinical characteristics of Chinese patients with paroxysmal nocturnal hemoglobinuria (PNH). METHODS: The clinical data of 70 adult PNH cases in our hospital from January 2000 to December 2009 were analyzed retrospectively, and the clinical manifestation, laboratory examination, treatment, complications and prognostic factors influencing survival rate were assessed. RESULTS: The nosopoietic median age of 70 cases(41 male cases and 29 female cases) was 37 (18-73) years old. The clinical manifestation included fatigue (87.1%), hemogolobinuria (44.3%), infection (22.9%), bleeding (37.1%), and abdominal pain (2.9%). FHb (free hemoglobin) in 56 patients (80%) was <50 mg/L. Hp (haptoglobin) in 54 patients (77.1%) was <0.5 g/L, and LDH in 49 patients (70.0%) was <220 U/L. The overall 10 year-survival rate after diagnosis was 72.2% estimated by Kaplan-Meier. The complications in this study were as follow: recurrent abdominal pain crisis (2.9%), infections (30.0%), thrombotic events (8.6%), evolution to MDS/AML (5.7%), calculus (11.4%) and death (17.1%). Both univariate and multivariate analyses identified risk factors affecting survival, including development of thrombotic events, progression to myelodysplastic syndrome or acute myelogenous leukemia (MDS/AML) and recurrent infections. CONCLUSION: This larger number of cases for the first time allowed us to carry out a detailed analysis of prognostic factors for this rare disease. Evaluation of PNH prognostic factors may provide a basis to assess the current and future therapies of this disease.

[Study on abnormal iron metabolism and iron overload in patients with aplastic anemia].

OBJECTIVE: To investigate the abnormalities of iron metabolism, the prevalence and risk factors of iron overload and clinical characteristics of patients with aplastic anemia (AA). METHODS: A cross-sectional study was conducted on 520 newly diagnosed AA patients. RESULTS: Iron overload was observed in 66(13%) of 520 AA patients,in which a higher prevalence of iron overload was seen not only in patients with infections(19/86, 22%)than those without infections (47/434, 11%, P<0.01), but also in patients with hepatitis associated AA(HAAA) (6/22, 19%) than the idiopathic cases (60/488, 12%, P>0.05). Excluded the patients with infections and/or HAAA, 43 of 405(11%)cases had iron overload, including 14 of 248(6%) cases without history of blood transfusion and 29 of 157 patients (18%, P<0.01) with transfusion. In univariate analysis, higher levels of serum ferritin (SF), serum iron (SI) and transferrin saturation (TS) were mainly observed in adult male patients with severe AA (SAA) and significantly upward with increasing blood transfusion (P<0.01). No differences of soluble transferrin receptor (sTfR) were observed between adults and children, males and females, hepatitis and idiopathic AA. However, patients with infections had significantly lower level of sTfR (0.50 mg/L) than cases without infections (0.79 mg/L, P<0.01). The level of sTfR in SAA patients (0.70 mg/L) was only half of that in non-SAA (NSAA) (1.36 mg/L, P<0.01). Patients with increasing blood transfusion had significantly downward levels of sTfR (P<0.01). In multivariate analysis, more than 8 U blood transfusion (OR=10.52, P<0.01), adults (OR=3.48, P<0.01), males (OR=3.32, P<0.01) and infections (OR=2.09, P<0.01) were independent risk factors. CONCLUSION: AA patients had higher iron burden and were high-risk populations occurring iron overload. The iron overload occurred in 18% of patients with blood transfusion and in 6% of patients without transfusion.

[The clinical study of myelodysplastic syndromes with PNH clones].

OBJECTIVE: To analyze the clinical characteristics and risk factors on responses and survival of myelodysplastic syndromes (MDS) patients with paroxysmal nocturnal hemoglobinuria (PNH) clones. METHODS: The clinical data of 31 MDS cases with PNH clones from October 2004 to June 2012 were retrospectively analyzed to reveal the influence of PNH clone size on responses and survival. RESULTS: ①The chromosome karyotypes were analyzed in all patients, 23 patients with normal karyotype, 7 patients with abnormal karyotype [including 3 patients with +8, 2 -Y, 1 del(7q) and 1 Xp+] and 1 patient with no mitosis. 1 patient belonged to low-risk, 27 intermediate-1 risk, 2 intermediate-2 risk and 1 high-risk groups, respectively, according to IPSS. There were significantly statistical differences between responders and nonresponders in terms of infection, ANC, Reticulocyte count and IPSS (P values were 0.049, 0.006, 0.031 and 0.043, respectively). ②The overall responsive rate was 67.7%, no patients progressed to acute leukemia (AL) during median follow-up of 19 months after immunosuppressive therapy (IST). The 3-year and 5-year overall survival rates were 82.7% and 55.1%,respectively. ③According to univariate analysis,age, infection and ANC had significant influence on survival (P values were 0.050, 0.031 and 0.026, respectively). ④The PNH clone size had no significant influence on survival through univariate and COX analyses (P=0.393). CONCLUSION: MDS patients with PNH clone had less cytogenetic abnormalities, higher probability of response to IST and lower probability of progression to AL; Furthermore, the PNH clone size had no significant influence on response and survival.

[A long-term follow up study on 345 severe aplastic anemia patients treated with antithymocyte globulin/lymphoglobulin].

OBJECTIVE: To assess the short term curative efficacy and long-term survival outcomes of severe aplastic anemia patients following antithymocyte globulin/lymphoglobulin (ATG/ALG) with or without cyclosporine (CsA). METHODS: A total of 345 cases hospitalized in our hospital between December 1982 and June 2011 were enrolled into this study. We assessed the response rates 3 and 6 months after ATG/ALG, and estimated the overall survival (OS) by Kaplan-Meier method for this cohort of patients. RESULTS: The cohort of 345 patients was routinely followed-up with a median follow-up of 44.0 (range, 0.5 - 244.0) months. The response rates at 3 and 6 months were 29.9% and 45.4%, respectively. The differences in response rates at both 3 (39.2% vs 19.6%, P < 0.01) and 6 months (55.6% vs 34.0%, P < 0.01) between 184 non-severe aplastic anemia (mSAA) and 161 very severe aplastic anemia (VSAA) were statistically significant. The response rates among the different ATG preparations were comparative; but 3-(10.6%) and 6-month (25.5%) responses produced by rATG-Fresenius were significantly inferior to those by rATG-Sangstat (36.6% and 56.6%, respectively) (all P < 0.01). The 5-year OS was 61.7% (95%CI 55.4% - 68.0%) for the entire cohort of patients, and 5-year OS for mSAA patients \[71.0% (95%CI 62.9% - 79.1%)\] was superior to that of VSAA patients \[50.4% (95%CI 40.1% - 60.7%), P < 0.01\]; but for the patients treated from 2007, the difference of OS in the last 5 years between VSAA and mSAA was not significant \[ 73.7% (95%CI 52.2% - 95.2%) vs 89.7% (95%CI 79.5% - 99.9%); P = 0.24\]. Our study also confirmed the superiority of ATG/ALG + CsA regimen \[64.8% (95%CI 57.9% - 71.7%)\] over ATG/ALG alone \[32.6% (95%CI 15.7% - 49.5%)\] with regard to 5-year OS (P < 0.01); but the addition of recombinant human granulocyte colony-stimulating factor (rhG-CSF) to ATG/ALG had no benefit in terms of OS. rATG-S produced significantly better 5-year OS \[66.1% (95%CI 55.8% - 76.4%)\] than rATG-F \[46.6% (95%CI 35.9% - 57.3%); P < 0.01\]. CONCLUSIONS: (1) The outcome of mSAA was superior to that of VSAA, but the latter was markedly improved in the last 5 years; (2) rATG-F was inferior to rATG-S with regard to 5-year OS; (3) Immunosuppressive treatment with ATG/ALG plus CsA was more effective than ATG/ALG alone; (4) The addition of rhG-CSF to ATG/ALG had no benefit in terms of OS.

[The clinical significance of evolution of paroxysmal nocturnal haemoglobinuria clones in aplastic anemia patients].

OBJECTIVE: To explore the clinical significance of evolution of paroxysmal nocturnal hemoglobinuria (PNH) clones in aplastic anemia (AA) patients. METHODS: The positive rate of PNH clones in 678 AA cases at first diagnosis from January 2002 to December 2009 were analyzed, and to compare the response rate and overall survival (OS) between AA patients with or without PNH clones. All patients were sequentially followed-up to assess the incidence rate and risk factors for AA evolving to overt PNH. RESULTS: (1) Of 119/678 (17.6%) AA patients at initial diagnosis presented with PNH clones,the positive rates of PNH clones among non-severe AA (NSAA), severe AA (SAA) and very severe AA (VSAA) were 16.7% (37/ 222), 17.3% (45/260) and 18.9% (37/196), respectively. There was no statistical difference among the three groups. (Chi2 = 0.369; P = 0.832); (2) 678 newly diagnosed AA cases were divided into 5 subgroups according to PNH clones, severity of disease and treatment regimens. There was no statistical difference among the five subgroups regarding 6m-response rate (RR) and OS. (3) Serial follow-up revealed that persistent PNH negative clones were found in 516 (76.1%) cases, and evolved to PNH positive clones after therapy in 43 (6.3%) cases. Persistent PNH positive clones were found in 72 (10.6%) cases, and disappeared the clones after treatment in 47 (6.9%) cases. There was no statistical difference among the four subgroups in terms of the 6m RR (Chi2 = 2.489,P = 0.426) and OS (P = 0.477); (4) 17 out of 678 AA cases (2.5%) evolved to overt PNH and the estimated incidence of evolution to overt PNH was (3.7 +/- 0.9)% at 10 years. The incidences of AA patients with or without PNH clones at initial diagnosis evolved to overt PNH were 3.4% and 2.3%, respectively. There was no statistical difference between the two groups, (Chi2 = 0.111; P = 0.739); and so was found in OS by Kaplan-Meier analysis (P = 0.868). Cox regression model analysis showed that none of the severity of AA, with or without PNH clone at initial diagnosis, treatment regimen and 6m RR was the risk factor for evolution to overt PNH. CONCLUSION: There is no difference between AA patients presented with or without PNH clones at initial diagnosis regarding the RR and prognosis. The appearance of PNH clones in AA is not identified as a risk factor for developing into overt PNH.

[The effects of stem cell factor on proliferation, transmigration, capillary tube formation of endothelial cells and on the chemotaxis of CD133(+) cells].

OBJECTIVE: To explore the effects of stem cell factor (SCF) on proliferation, transmigration, capillary tube formation of human umbilical vein endothelial cells (HUVEC) and on the chemotaxis of CD133(+) cells. METHODS: In the presence of blank control, SCF, vascular endothelial growth factor (VEGF), anti-human SCF (anti-SCF) or human IgG, the difference in proliferation capacity of HUVEC was analyzed by MTT and CCK-8 methods, and wound scratch assay and three-dimensional in vitro Matrigel assay were used for transmigration and capillary tube formation of HUVEC, respectively. In addition, the chemotaxis of CD133(+) cells sorted from human umbilical cord blood by flow cytometry was investigated by Transwell migration assay. RESULTS: SCF didn't improve the proliferative capacity of HUVEC, but significantly enhanced the transmigration capacity, and increased capillary tube formation in a dose-dependent manner. The number of intact tubules [(30.0 ± 3.4)/10(5) HUVEC] formed by HUVECs in the presence of the optimal concentration of SCF (100 ng/ml) was remarkably higher than that in blank control group [(5.0 ± 2.6)/10(5) HUVEC, P < 0.01]. SCF also significantly induced a chemotactic response of CD133(+) cells, the transmembrane migration cell number into Transwell lower chamber was significantly higher in SCF group [(118.0 ± 6.5)/10(4) CD133(+) cells] than in blank control group [(47.0 ± 4.7)/10(4) CD133(+) cells, P < 0.01 ]. CONCLUSIONS: SCF significantly promotes the transmigration and capillary tube formation of HUVEC, and induces a chemotactic response of CD133(+) cells. SCF/c-kit signaling possibly plays a critical role in regulating angiogenesis of vascular endothelial cells and vasculogenesis of endothelial progenitor cells.

[Long-term follow-up of malignant clonal evolution in patients with acquired aplastic anemia].

OBJECTIVE: To assess the incidence and risk factors for evolution of acquired aplastic anemia (AA) into myelodysplastic syndrome/acute myeloid leukemia (MDS/AML). METHOD: A total of 1003 AA patients hospitalized in our institute hospital between January 1991 and December 2009 enrolled into this study. The incidence and risk factors for AA developing MDS/AML by the Kaplan-Meier method and Cox proportional hazards models, respectively. RESULTS: The median follow-up was 62 (2 - 423) months and the projected 5-year survival rate was (78.0 +/- 1.0)%. Twenty-seven patients evolved to MDS/AML, of whom 11, 6 and 10 were from NSAA, SAA and VSAA subgroups, respectively. The estimated cumulative incidence of MDS/AML transformation for these 1003 patients after diagnosis was (4.5 +/- 1.0)% at 10 year. The incidence of MDS/AML transformation in VSAA subgroup [(12.8 +/- 3.5)%] was significantly higher than in NSAA subgroup [(4.1 +/- 1.9)%] (P < 0.001) and SAA subgroup [(3.5 +/- 1.4)% ] (P = 0.008), but no difference between the latter two subgroups (P = 0.616). Age [RR = 3.527 (95% CI: 1.598 - 7.784), P = 0.002], severity of disease [RR = 5.122 (95% CI: 2.214 - 11.853), P < 0.001], the duration (days) of rhuG-CSF therapy [RR = 10.782 (95% CI: 4.600 - 25.269), P < 0.001] and exposure to ray, chemicals or drugs [RR = 3.401 (95% CI: 1.535 - 7.534), P = 0.003] were risk factors for the transformation in both univariate and multivariate analyses. CONCLUSION: Long-term follow-up is essential to assess the incidence and risk factors for evolutions of acquired AA into MDS/AML, and to administer salvage therapy for transformation in time during follow-up.

[Treatment of severe aplastic anemia with intensified immunosuppressive therapy and two different regimens with recombinant human granulocyte colony-stimulating factor: a retrospective study based on long-term follow-up].

OBJECTIVE: To compare the efficacy and safety of two different regimens with recombinant human granulocyte colony-stimulating factor (rhG-CSF) combined with intensified immunosuppressive therapy (IIST) in severe aplastic anemia (SAA). METHODS: Retrospectively analyzed 176 SAA treated with IIST and rhG-CSF in our hospital from March 1994 to December 2007. Regimen A (Group A, n = 96), rhG-CSF 300 µg/d was initiated on day 31 after IIST and subcutaneously administered 1-3 days a week for 3 months. Regimen B (Group B, n = 80), rhG-CSF was initiated at 5 µg·kg(-1)·d(-1) before IIST until hematologic recovery. RESULTS: (1) The early response rate of Group B (67.5%) was significantly higher than that of Group A (37.5%) (P < 0.01), the interval from IIST to response in Group B was shorter than that in Group A. Moreover, infection-related deaths during first 4 months after IIST were significantly reduced in Group B (6.3%) when compared with Group A (16.7%) (P = 0.034). The cumulative incidence of survival at 4 years in Groups B [(77.7 ± 4.9)%] was also significantly higher than that in Group A [(57.2 ± 5.1)%] (P = 0.006). (2) With regard to 93 refractory patients with no response 4 months after IIST, rhG-CSF therapy was continued in Group B meanwhile stopped in Group A. There were no differences between two groups in terms of survival and the response rates (P = 0.288, 0.066), but there was an increasing risk of evolving into MDS/AML in Group B (22.3%) when compared with Group A (3.71%) (P = 0.023). (3) By multivariate analysis, the severity of disease (P = 0.010, RR = 1.922) and the early response (P < 0.01, RR = 5.749) were associated with the overall survival. Moreover, the number of days of rhG-CSF therapy was the only significant risk factor for SAA evolving into MDS/AML (P = 0.017, RR = 1.004). CONCLUSIONS: The early initiation of rhG-CSF therapy with proper dose might contribute to a desirable early response and reduced infection-related death rate, but extended administration of rhG-CSF did not improve the long-term outcome of refractory SAA and may further facilitate the progression of SAA into MDS/AML.