Gastric cancer is the fourth most common cancer, and the second-highest cause of cancer-related deaths worldwide. Despite extensive research to identify novel diagnostic and therapeutic agents, patients with advanced gastric cancer suffer from a poor quality of life and poor prognosis, and treatment is dependent mainly on conventional cytotoxic chemotherapy. To improve the quality of life and survival of gastric cancer patients, a better understanding of the underlying molecular pathologies, and their application towards the development of novel targeted therapies, is urgently needed. Chemokines are a group of small proteins associated with cytoskeletal rearrangements, the directional migration of several cell types during development and physiology, and the host immune response via interactions with G-protein coupled receptors. There is also growing evidence to suggest that chemokines not only play a role in the immune system, but are also involved in the development and progression of tumors. In gastric cancer, CXC chemokines and chemokine receptors regulate the trafficking of cells in and out of the tumor microenvironment. CXC chemokines and their receptors can also directly influence tumorigenesis by modulating tumor transformation, survival, growth, invasion and metastasis, as well as indirectly by regulating angiogenesis, and tumor-leukocyte interactions. In this review, we will focus on the roles of CXC chemokines and their receptors in the development, progression, and metastasis of gastric tumors, and discuss their therapeutic potential for gastric cancer.
Chemokine; Chemokine receptor; Gastric neoplasm; Therapeutic target
To determine the approximate incidence and clinical features of pernicious anemia in a Korean population, we retrospectively analyzed clinical data for patients with pernicious anemia who were diagnosed between 1995 and 2010 at five hospitals in Chungnam province. Ninety-seven patients were enrolled, who accounted for 24% of patients with vitamin B12 deficiency anemia. The approximate annual incidence of pernicious anemia was 0.3 per 100,000. The median age was 66 (range, 32-98) yr, and the male/female ratio was 1.25. Anemia-associated discomfort was the most common symptom (79.4%), followed by gastrointestinal and neurological symptoms (78.4% and 38.1%, respectively). Pancytopenia was found in 36 patients (37.1%), and autoimmune disorders were found in 15 patients (15.5%). Antibody to intrinsic factor was detected in 62 (77.5%) of 80 patients examined, and antibody to parietal cells was detected in 35 (43.2%) of 81 patients examined. Of the 34 patients who underwent tests for Helicobacter pylori, 7 (12.5%) were positive. The anemia-associated and gastrointestinal symptoms resolved completely in all patients after intramuscular injection of cobalamin, whereas neurological symptoms remained in some. In conclusion, pernicious anemia is less frequent in Koreans than in Western populations; however, the clinical features of this disorder in Koreans do not differ from those of Western cases.
Anemia, Pernicious; Vitamin B12; Anti-Intrinsic Factor Antibody; Anti-Parietal Cell Antibody; Helicobacter Pylori
Antiphospholipid antibodies (aPL) have been detected in various proportions of patients with primary immune thrombocytopenia (ITP), but the clinical significance of this is debatable. The present study aimed to determine the frequency and clinical implications of elevated aPL in adult patients with ITP.
We prospectively studied newly diagnosed adult patients with ITP who were enrolled between January 2003 and December 2008 at Chungnam National University Hospital. They were evaluated for the presence of lupus anticoagulant (LA) and anticardiolipin antibodies (aCL) at diagnosis and were followed for the development of thrombosis.
Seventy consecutive patients with ITP (median age, 48 years; range, 18 to 79) were enrolled. Twenty patients (28.5%) were positive for aPL at the time of diagnosis: aCL alone in 15 (75%), aCL and LA in two (10%), and LA alone in three (15%). Patients who had platelet counts < 50,000/µL were administered oral prednisolone with or without intravenous immune globulin. No difference was found between the aPL-positive and -negative groups regarding gender, initial platelet count, and response to the therapy. After a median follow-up of 20 months (range, 2 to 68), two of 20 patients who were aPL-positive (10%) developed thrombosis, whereas no thrombotic event was found among those who were aPL-negative.
Our data suggest that aPL levels should be determined at the initial presentation of ITP and that patients found to be aPL-positive should receive closer follow-up for thrombotic events.
Antibodies, anticardiolipin; Antiphospholipid syndrome; Purpura, thrombocytopenic, idiopathic; Lupus coagulation inhibitor; Thrombosis
Antagonists of CXC chemokine receptor 4 (CXCR4), including AMD3100, induce peripheral mobilization of hematopoietic stem cells and have been approved for clinical use. We explored whether the CXCR4 antagonists affected the survival and proliferation of myeloid leukemia cells in vitro.
The effects of CXCR4 antagonists AMD3100 and T140 on the survival and proliferation of myeloid leukemia cell lines (U937, HL-60, MO7e, KG1a, and K562) as well as CD34+ cells obtained from patients with AML and CML were analyzed by flow cytometry by using annexin V and a colorimetric cell proliferation assay.
AMD3100, but not T140, stimulated the proliferation of leukemia cells in vitro in a dose-dependent manner for up to 5 days (~2-fold increase at a concentration of 10-5 M), which was not abrogated by pretreatment of the cells with pertussis toxin, but was attenuated by RNAi knockdown of CXCR7 transcripts. In contrast, AMD3100 induced a marked decrease in the cell numbers after 5-7 days. AMD3100, but not T140, induced phosphorylation of MAPK p44/p42. AMD3100 increased the number and size of leukemia cell colonies and reduced cell apoptosis during the first 5-7 days of incubation, but the phenomena were reversed during the later period of incubation.
The effects of CXCR4 antagonists on the proliferation of myeloid leukemia cells are not uniform. AMD3100, but not T140, exerts dual effects, initially enhancing and subsequently inhibiting the survival and proliferation of the cells in vitro.
AMD3100; CXCR4; SDF-1; Myeloid leukemia; Cell proliferation; Apoptosis
There has been no report on the clinical features or natural history of autoimmune hemolytic anemia (AIHA) in the Korean adult population. This study retrospectively analyzed the clinical characteristics and long-term outcomes of AIHA in the Korean adults.
Patients newly diagnosed with AIHA between January 1994 and December 2010 at Chungnam National University Hospital were enrolled. Patient characteristics at diagnosis, response to treatment, and the natural course of the disease were documented.
Thirty-two patients (31 females and 1 male) with a median age of 48 years (range, 17-86) were enrolled. Of these, 21.9% were initially diagnosed with secondary AIHA. Thirteen patients (40.6%) were initially diagnosed with Evans' syndrome. Of the 29 patients who were placed on therapy, 27 (93.1%) showed a partial response or better. Nevertheless, 1 year after initiating treatment, 80% of the patients were still treatment-dependent. During follow-up (median length 14 months; range, 0.5-238), 14 of 25 patients (56.0%) who were initially diagnosed with primary warm antibody AIHA were found to have systemic lupus erythematosus (SLE). Median time to conversion to SLE was 8.0 months (95% CI, 4.3-11.7), and the probabilities of conversion at 12 and 24 months were 63% and 91%, respectively. Younger age (<60 years) and a positive fluorescent anti-nuclear antibody test were associated with a higher probability of SLE conversion (P=0.01 and P<0.001, respectively).
Primary AIHA is rare. Regular, vigilant testing for SLE is required in patients initially diagnosed with AIHA.
Autoimmune hemolytic anemia; Evans' syndrome; Systemic lupus erythematosus; Thrombosis
Hypocellularity of bone marrow (BM), not associated with significant dyshematopoiesis, is often found in patients with isolated thrombocytopenia, but its clinical implications have not been studied. We prospectively studied the clinical features and natural history of these patients.
Adults with isolated thrombocytopenia (platelet counts <100×109/L) in the absence of dyshematopoiesis, cytogenetic abnormalities, or megakaryocytic hyperplasia and who had BM hypocellularity (below 30% in patients aged less than 60 years; below 20% in patients aged 60 years or more) were enrolled at Chungnam National University Hospital between January 2002 and December 2006. They were monitored regularly for changes in platelet counts or development of additional cytopenia.
Twenty patients (17 men and 3 women) were enrolled in the study. The median age was 29 years (range, 18-70 years). At initial presentation, the platelet counts ranged from 12×109/L to 99×109/L (median, 63×109/L) and were >50×109/L in 16 patients (80%). BM cellularity ranged from 5% to 25% (median, 15%) and was ≤10% in 6 patients (30%). During the median 48-month follow-up (range, 12-90 months), platelet counts of 3 of the 20 patients recovered to normal levels (>150×109/L) after 12, 56 and 66 months. Three patients developed pancytopenia after 11, 70 and 90 months. Two patients were consistent with moderate aplastic anemia, and 1 was confirmed as having refractory cytopenia with multilineage dysplasia. In the remainder of the patients, platelet counts remained unchanged.
Isolated thrombocytopenia accompanied by hypocellular marrow encompasses a group of heterogeneous conditions.
Thrombocytopenia; Idiopathic thrombocytopenic purpura; Bone marrow; Aplastic anemia; Myelodysplastic syndromes
AMD3100, an antagonist of the CXCR4 chemokine receptor is soon to be used clinically for the peripheral mobilization of hematopoietic stem cells (HSCs) in patients with multiple myeloma. AMD3100 has been shown to activate a G protein coupled with CXCR4 and thus acts as a partial CXCR4 agonist in vitro. Thus, we explored whether AMD3100 affected the survival and proliferation of myeloma cells in vitro.
Materials and Methods
The effects of AMD3100 on survival and proliferation of two myeloma cell lines (RPMI8226 and U266) as well as CD138+ cells obtained from several patients with multiple myeloma were analyzed by flow cytometry using annexin V and a colorimetric cell proliferation assay (CCK-8 assay).
AMD3100, but not T140, another CXCR4 antagonist, stimulated the proliferation of myeloma cell lines and CD138+ primary human myeloma cells (-2-fold increase) in a dose-dependent manner in serum-free culture for up to 5 days, which was inhibited by pretreating the cells with pertussis toxin. AMD3100 enhanced the proliferation of U266 cells induced by interleukin-6 and partially reversed AG490-mediated growth inhibition and apoptosis induced by serum deprivation in RPMI8226 cells. AMD3100 induced the phosphorylation of Akt and MAPK p44/p42 in U266 cells and MAPK p44/p42 in RPMI8226 cells. In contrast, AMD3100 markedly increased the cell apoptosis and reduced the number of RPMI8226 cells after 5 to 7 days of culture under serum-free conditions.
AMD3100 exerts dual effects, initially enhancing and subsequently inhibiting the survival and proliferation of myeloma cells, signaling via CXCR4 in vitro.
AMD3100; CXCR4 protein; Multiple myeloma; Cell proliferation
The chemokine receptor CXCR4 plays a role in the metastasis and progression of a broad range of malignant tumors; however, its influence on hepatocellular carcinoma (HCC) is not well defined. Thus, we analyzed the expression of CXCR4 and its functions in HCC cell lines in vitro.
Materials and Methods
Five HCC cell lines (HepG2, Hep3B, SK-HEP-1, NCI-H630 and PLC/PRF5) were investigated. The CXCR4 expression was analyzed by RT-PCR, Western blotting, flow cytometry and immunofluorescence staining. In addition, the effects of stromal cell-derived factor-1 (SDF-1) on the migration, proliferation and survival of the cells were investigated, as well as the SDF-1-induced phosphorylation of signaling molecules.
All five cell lines had abundant CXCR4 in their cytoplasm, whereas a cell surface CXCR4 expression was only detected in a very small population of PLC/PRF5 cells. In contrast, SDF-1 bound to all the cells. SDF-1 induced the phosphorylation of AKT and ERK1/2 in the PLC/PRF5 cells and the phosphorylation of Stat3, AKT and ERK1/2 in the Hep3B cells. Nonetheless, SDF-1 did not induce migration or proliferation in any of the cells, nor did it rescue the cells from serum deprivation-induced apoptosis. Recruitment of CXCR4 from the cytoplasm to the cell surface was not elicited by dexamethasone, proinflammatory cytokines or VEGF. Hypoxia increased both the cytoplasmic and cell surface expressions of CXCR4 in only the PLC/PRF5 cells.
CXCR4 is trapped in the cytoplasm and it is not recruited to the cell surface by standard extrinsic stimuli in the majority of HCC cell lines, and the result of this is a negligible response to SDF-1.
Hepatocellular carcinoma; Stromal cell-derived factor-1; CXCR4
Androgens remain a common treatment for certain type of anemia, based upon its myelostimulating effects; however, it has not been established whether androgens affect apoptosis of hematopoietic progenitor cells (HPCs). We investigated the effects of the androgens, such as testosterone, 5β-dihydrotestosterone (5-DHT), and oxymetholone, on apoptosis of normal hematopoietic progenitor cells in vitro. Androgens did not rescue normal bone marrow (BM) CD34+ cells and colony-forming cells (CFCs), other than mature erythroid CFCs, from apoptosis induced by serum- and growth factor deprivation. Oxymetholone did not affect growth factor-mediated survival of normal CD34+ cells or its inhibition by interferon-gamma (IFN-γ). In a standard methylcellulose clonogenic assay, low concentrations of oxymetholone and 5-DHT stimulated the clonal growth of colony-forming unit (CFU)-erythroid, but did not affect growth of CFU-granulocyte/macrophage or burst-forming unit-erythroid. Oxymetholone and 5-DHT stimulated the production of stem cell factor in normal bone marrow stromal cells (BMSCs) via transcriptional regulation. In agreement with this, oxymetholone-treated BMSCs better supported the survival of HPCs. These data indicate that survival-enhancing or growth-stimulatory effects of androgens on hematopoietic progenitor cells are minimal and mostly restricted to mature erythroid progenitors, and its myelostimulating effects could be attributed, at least in part, to the stimulation of production of hematopoietic growth factors in BMSCs.
Androgens; Erythroid Progenitor Cells; Myeloid Progenitor Cells; Apoptosis
We conducted a prospective multicenter study identifying the role of bortezomib in patients with relapsed or refractory plasma cell myeloma (PCM) in bone resorption and formation via bone turnover markers. A total of 104 patients received at least 1 cycle of bortezomib. Most of them had advanced disease (n = 89). Among them, 75 patients completed 4 cycles of treatment. Most of the patients (81.7%) were treated in combination with steroid. After the 4th cycle treatment, 47 of 75 patients achieved CR, nCR, VGPR, and PR (64.4%), while 26 patients achieved less than PR (35.6%). The proportion of patients who achieved ≥ PR increased as patients received more treatment cycles, reaching 90% after the 8th cycle. DKK-1 levels decreased significantly posttreatment. Bone formation markers (bALP and OC) and osteoclast regulator such as sRANKL also decreased significantly. These findings were observed primarily in patients who received steroid and who had a longer disease duration. While sRANKL demonstrated significant reduction posttreatment, osteoprotegerin (OPG) level did not significantly change posttreatment, resulting in a decreased sRANKL/OPG ratio (P = 0.037). In conclusion, our clinical data suggest that treatment with bortezomib and steroid may rearrange the metabolic balance between osteoblast and osteoclast activities in PCM.
We assessed the success rate of empirical antifungal therapy with itraconazole and evaluated risk factors for predicting the failure of empirical antifungal therapy. A multicenter, prospective, observational study was performed in patients with hematological malignancies who had neutropenic fever and received empirical antifungal therapy with itraconazole at 22 centers. A total of 391 patients who had abnormal findings on chest imaging tests (31.0%) or a positive result of enzyme immunoassay for serum galactomannan (17.6%) showed a 56.5% overall success rate. Positive galactomannan tests before the initiation of the empirical antifungal therapy (P=0.026, hazard ratio [HR], 2.28; 95% confidence interval [CI], 1.10-4.69) and abnormal findings on the chest imaging tests before initiation of the empirical antifungal therapy (P=0.022, HR, 2.03; 95% CI, 1.11-3.71) were significantly associated with poor outcomes for the empirical antifungal therapy. Eight patients (2.0%) had premature discontinuation of itraconazole therapy due to toxicity. It is suggested that positive galactomannan tests and abnormal findings on the chest imaging tests at the time of initiation of the empirical antifungal therapy are risk factors for predicting the failure of the empirical antifungal therapy with itraconazole. (Clinical Trial Registration on National Cancer Institute website, NCT01060462)
Hematological Malignancy; Itraconazole; Empirical Antifungal Therapy; Galactomannan Test
Many Korean patients with transfusion-induced iron overload experience serious clinical sequelae, including organ damage, and require lifelong chelation therapy. However, due to a lack of compliance and/or unavailability of an appropriate chelator, most patients have not been treated effectively. Deferasirox (DFX), a once-daily oral iron chelator for both adult and pediatric patients with transfusion-induced iron overload, is now available in Korea. The effectiveness of deferasirox in reducing or maintaining body iron has been demonstrated in many studies of patients with a variety of transfusion-induced anemias such as myelodysplastic syndromes, aplastic anemia, and other chronic anemias. The recommended initial daily dose of DFX is 20 mg/kg body weight, taken on an empty stomach at least 30 min before food and serum ferritin levels should be maintained below 1000 ng/mL. To optimize the management of transfusion-induced iron overload, the Korean Society of Hematology Aplastic Anemia Working Party (KSHAAWP) reviewed the general consensus on iron overload and the Korean data on the clinical benefits of iron chelation therapy, and developed a Korean guideline for the treatment of iron overload.
Korean Guideline; Iron Overload; Deferasirox
Novel agents to treat multiple myeloma (MM) have increased complete respone (CR) rates compared with conventional chemotherapy, and the quality of the response to treatment has been correlated with survival. The purpose of our study was to show how of early response to bortezomib combined chemotherapy influences survival in patients with newly diagnosed MM who are ineligible for stem cell transplantation. We assessed patient responses to at least four cycles of bortezomib using the International Myeloma Working Group response criteria. The endpoints were comparisons of progression free survival (PFS) and overall survival (OS) between early good response group (A group) and poor response group (B group). We retrospectively analyzed data from 129 patients registered by the Korean Multiple Myeloma Working Party, a nationwide registration of MM patients. The 3 yr PFS for the A and B groups was 55.6% and 18.4%, respectively (P < 0.001). The 3 yr OS for the A and B groups was 65.3% and 52.9%, respectively (P = 0.078). The early response to at least four cycle of bortezomib before next chemotherapy may help predict PFS in patients with MM who are ineligible stem cell transplantation.
Early Response; Multiple Myeloma; Bortezomib; Survival
Metastatic tumors in the oral cavity are rare and usually affect the jaws more often than the oral soft tissues. In particular, metastases confined to the oral mucosa are extremely rare and originate mainly from the lung and breast. Only one case restricted to the oral mucosa and originating from urinary bladder carcinoma has previously been described. We report on a painful polypoid mass located in the oral mucosa with no bone involvement that was confirmed to be a metastatic oral tumor that originated from transitional cell carcinoma of the urinary bladder and progressed rapidly.
urinary bladder neoplasm; neoplasm metastasis; mouth neoplasm
Lymph node metastasis is considered to be a significant prognostic factor for early gastric cancer (EGC). However, no real consensus exists on which patient and/or tumor characteristics are associated with lymph node metastasis. We investigated whether stromal cell-derived factor (SDF)-1α expression correlates with lymph node metastasis in patients with EGC by immunohistochemically examining the expression of SDF-1α in 138 archival tissue specimens of EGC. Of these specimens, 59 (42.8%) and 79 (57.2%) were grouped into SDF-1α-positive and SDF-1α-negative groups, respectively. No significant differences existed with respect to age, gender, tumor location, proportion of tumors >20 mm in size, macroscopic type, depth of invasion or histology between the SDF-1α-positive and -negative groups. However, the SDF-1α-positive group was significantly correlated with lymphovascular invasion and lymph node metastasis. Results of the univariate analyses indicated that lymphovascular invasion, undifferentiated histology and SDF-1α positivity were statistically significant risk factors affecting lymph node metastasis in patients with EGC. Multivariate analyses showed that lymphovascular invasion [hazard ratio (HR), 8.595; 95% confidence interval (CI), 1.694–43.595; P=0.009], undifferentiated histology (HR, 2.965; 95% CI, 1.037–8.471; P=0.043) and SDF-1α positivity (HR, 2.108; 95% CI, 1.316–10.135; P=0.013) were independent risk factors predicting lymph node metastasis in EGC. In conclusion, these results suggest that SDF-1α expression in tumor cells is a predictive marker of lymph node metastasis in EGC.
SDF-1α; early gastric cancer; lymph node metastasis
Chemokine stromal cell-derived factor (SDF)-1α and its receptor CXC chemokine receptor 4 (CXCR4) have been shown to impact cancer progression. Accumulating evidence suggests that CXCR4 and SDF-1α expression is useful for evaluating the risk of gastric cancer progression. Thus, combined analysis of SDF-1α and CXCR4 should have high prognostic potential as a molecular marker for gastric cancer. We investigated the expression of SDF-1α and CXCR4 using immunohistochemistry in relation to prognosis, clinicopathological features and clinical outcomes in 221 cases of primary gastric cancer. Patients were categorized into three groups according to CXCR4 and SDF-1α expression: high CXCR4/high SDF-1α, low CXCR4/low SDF-1α, and high CXCR4/low SDF-1α – low CXCR4/high SDF-1α. No significant differences were noted in age, gender, histology, tumor location, lymphovascular invasion or proportion of tumor size >5 cm among the three groups. However, high CXCR4/high SDF-1α expression in tumor cells was significantly associated with depth of invasion of the tumor, lymph node involvement, and higher tumor stage compared to tumors with low CXCR4/low SDF-1α expression or high CXCR4/low SDF-1α – low CXCR4/high SDF-1α expression. Furthermore, patients with high CXCR4/high SDF-1α expression had the worst patient prognosis, whereas patients who had low CXCR4/low SDF-1α expression showed the most favorable prognosis. In conclusion, CXCR4 and SDF-1α are useful prognostic factors in gastric cancer, and the combination of high CXCR4 protein expression with high SDF-1α expression suggests a dismal prognosis.
stromal cell-derived factor-1α; CXC chemokine receptor 4; gastric cancer; prognosis
Solid pseudopapillary tumor of the pancreas (SPTP) is a rare primary pancreatic tumor of an unknown etiology that is usually diagnosed in adolescent girls and young women. Most SPTPs are considered to be benign and only rarely metastasize. We report here on a 27-year old woman with recurrent SPTP with involvement of both the spleen and left kidney at the time of the initial diagnosis, and with aggressive behavior. In July 1995, she was admitted with abdominal discomfort and mass. She underwent exploratory laparotomy with distal pancrea tectomy, left nephrectomy and splenectomy, and was diagnosed with SPTP with invasion to both the spleen and left kidney. In June 2001, she again presented with abdominal pain and was diagnosed as having recurrence of the tumor. She underwent mass excision and omentectomy. Then she was lost to follow-up. In November 2005, she presented once again with an abdominal mass and was diagnosed with recurred SPTP, which formed a huge intraperitoneal mass with peritoneal seeding and the tumor showed multiple metastases in the liver. She is currently being treated conservatively.
Solid pseudopapillary tumor; Pancreas; Neoplasm metastasis
This study investigated the production of stromal cell-derived factor-1 (SDF-1) and the expression of CXCR4 in human bone marrow endothelial cells (BMECs). Human BMEC cell line BMEC-1 cells expressed SDF-1 mRNA, and conditioned medium induced chemoattraction of CD34+ cells. Migration was not inhibited by pretreating the input cells with pertussis toxin, indicating that the chemoattractive activity was not dependent on SDF-1. Three-day culture of BMEC-1 and primary human BMEC cells produced 1,710+/-204 and 1,050+/-153 pg/mL SDF-1alpha, respectively, which was much less than primary human BM stromal cells (29,536+/-532 pg/ mL). By immuno-histochemistry, CXCR4 was detected in the endothelial cells lining sinusoids, arterioles, and venules in the bone marrow. However, cultured BMECs and BMEC-1 cells did not express CXCR4 on their surfaces. These results indicate that BMECs produce and release small amounts of SDF-1 and express CXCR4 in vivo only.
Stromal cell–derived factor-1 (SDF-1) provides a potent chemotactic stimulus for CD34+ hematopoietic cells. We cultured mobilized peripheral blood (PB) and umbilical cord blood (CB) for up to 5 weeks and examined the migratory activity of cobblestone area–forming cells (CAFCs) and long-term culture–initiating cells (LTC-ICs) in a transwell assay. In this system, SDF-1 or MS-5 marrow stromal cells placed in the lower chamber induced transmembrane and transendothelial migration by 2- and 5-week-old CAFCs and LTC-ICs in 3 hours. Transmigration was blocked by preincubation of input CD34+ cells with antibody to CXCR4. Transendothelial migration of CB CAFCs and LTC-ICs was higher than that of PB. We expanded CD34+ cells from CB in serum-free medium with thrombopoietin, flk-2 ligand, and c-kit ligand, with or without IL-3 and found that CAFCs cultured in the absence of IL-3 had a chemotactic response equivalent to noncultured cells, even after 5 weeks. However, addition of IL-3 to the culture reduced this response by 20–50%. These data indicate that SDF-1 induces chemotaxis of primitive hematopoietic cells signaling through CXCR4 and that the chemoattraction could be downmodulated by culture ex vivo.