A CD36-dependent non-canonical lipid metabolism program promotes immune escape and resistance to hypomethylating agent therapy in AML.

Environmental lipids are essential for fueling tumor energetics, but whether these exogenous lipids transported into cancer cells facilitate immune escape remains unclear. Here, we find that CD36, a transporter for exogenous lipids, promotes acute myeloid leukemia (AML) immune evasion. We show that, separately from its established role in lipid oxidation, CD36 on AML cells senses oxidized low-density lipoprotein (OxLDL) to prime the TLR4-LYN-MYD88-nuclear factor κB (NF-κB) pathway, and exogenous palmitate transfer via CD36 further potentiates this innate immune pathway by supporting ZDHHC6-mediated MYD88 palmitoylation. Subsequently, NF-κB drives the expression of immunosuppressive genes that inhibit anti-tumor T cell responses. Notably, high-fat-diet or hypomethylating agent decitabine treatment boosts the immunosuppressive potential of AML cells by hijacking CD36-dependent innate immune signaling, leading to a dampened therapeutic effect. This work is of translational interest because lipid restriction by US Food and Drug Administration (FDA)-approved lipid-lowering statin drugs improves the efficacy of decitabine therapy by weakening leukemic CD36-mediated immunosuppression.

miR-29c&b2 encourage extramedullary infiltration resulting in the poor prognosis of acute myeloid leukemia.

Extramedullary infiltration (EMI), as a concomitant symptom of acute myeloid leukemia (AML), is associated with low complete remission and poor prognosis in AML. However, the mechanism of EMI remains indistinct. Clinical trials showed that increased miR-29s were associated with a poor overall survival in AML [14]. Nevertheless, they were proved to work as tumor suppressor genes by encouraging apoptosis and inhibiting proliferation in vitro. These contradictory results led us to the hypothesis that miR-29s may play a notable role in the prognosis of AML rather than leukemogenesis. Thus, we explored the specimens of AML patients and addressed this issue into miR-29c&b2 knockout mice. As a result, a poor overall survival and invasive blast cells were observed in high miR-29c&b2-expression patients, and the wildtype mice presented a shorter survival with heavier leukemia infiltration in extramedullary organs. Subsequently, we found that the miR-29c&b2 inside leukemia cells promoted EMI, but not the one in the microenvironment. The analysis of signal pathway revealed that miR-29c&b2 could target HMG-box transcription factor 1 (Hbp1) directly, then reduced Hbp1 bound to the promoter of non-muscle myosin IIB (Myh10) as a transcript inhibitor. Thus, increased Myh10 encouraged the migration of leukemia cells. Accordingly, AML patients with EMI were confirmed to have high miR-29c&b2 and MYH10 with low HBP1. Therefore, we identify that miR-29c&b2 contribute to the poor prognosis of AML patients by promoting EMI, and related genes analyses are prospectively feasible in assessment of AML outcome.

Leukemia cells remodel marrow adipocytes via TRPV4-dependent lipolysis.

Remodeling of adipocyte morphology and function plays a critical role in prostate cancer development. We previously reported that leukemia cells secrete growth differentiation factor 15 (GDF15)，which remodels the residual bone marrow (BM) adipocytes into small adipocytes and is associated with a poor prognosis in acute myeloid leukemia (AML) patients. However, little is known about how GDF15 drives BM adipocyte remodeling. In this study, we examined the role of the transient receptor potential vanilloid (TRPV) channels in the remodeling of BM adipocytes exposed to GDF15. We found that TRPV4 negatively regulated GDF15-induced remodeling of BM adipocytes. Furthermore, transforming growth factor-ß type II receptor (TGFßRII) was identified as the main receptor for GDF15 on BM adipocytes. PI3K inhibitor treatment reduced GDF15-induced pAKT, identifying PI3K/AKT as the downstream stress response pathway. Subsequently, GDF15 reduced the expression of the transcription factor Forkhead box C1 (FOXC1) in BM adipocytes subjected to RNA-seq screening and Western blot analyse. Moreover, it was also confirmed that FOXC1 combined with the TRPV4 promoter by the Chip-qPCR experiments, which suggests that FOXC1 mediates GDF15 regulation of TRPV4. In addition, an AML mouse model exhibited smaller BM adipocytes, whereas the TRPV4 activator 4α-phorbol 12,13-didecanoate (4αPDD) partly rescued this process and increased survival. In conclusion, TRPV4 plays a critical role in BM adipocyte remodeling induced by leukemia cells, suggesting that targeting TRPV4 may constitute a novel strategy for AML therapy.

Consolidation Chemotherapy Prevents Relapse by Indirectly Regulating Bone Marrow Adipogenesis in Patients with Acute Myeloid Leukemia.

BACKGROUND/AIMS: Chemotherapy is still the main strategy used to prevent the relapse of acute myeloid leukaemia (AML). As the most abundant stromal component in bone marrow (BM), marrow adipocytes have been previously shown to promote leukaemogenesis. The present study was designed to further validate whether marrow adipocytes exert synergistic effects on strengthening chemotherapeutic efficacy and evaluate the underlying mechanism. METHODS: A retrospective study of BM biopsies from 80 patients with AML in remission and 71 control subjects was applied to quantitatively analyse the marrow adipocyte volume. Toxicity tests were used to assess the effect of chemotherapy drugs on BM cells. The possible mechanisms by which chemotherapy regulated the reduced marrow adipocyte content were investigated using antibody neutralization experiments, with an emphasis on growth differentiation factor 15 (GDF15). RESULTS: In our study, the marrow adipocyte content was obviously reduced in the AML- complete remission (CR) group compared with the control group (P<0.001). Moreover, patients with a reduced adipocyte content exhibited longer relapse-free survival (RFS) (P<0.001). We also confirmed that GDF15 was overexpressed in mononuclear cells (MNCs) after treatment with chemotherapy drugs and partially blocked mesenchymal stem cells (MSCs) adipogenesis. Intriguingly, this inhibitory effect on adipogenesis was rescued by treatment with a neutralizing anti-GDF15 antibody. CONCLUSION: Chemotherapy indirectly inhibited adipogenesis by promoting GDF15 secretion from BM MNCs, subsequently strengthening the efficacy of consolidation chemotherapy in patients with AML during CR.

Growth differentiation factor 15 contributes to marrow adipocyte remodeling in response to the growth of leukemic cells.

BACKGROUND: The adipocyte remodeling, including of the morphological change, might indicate special pathological function. Our previous study found that the morphological remodeling of larger marrow adipocytes into small marrow adipocytes correlates with a poor prognosis for acute myeloid leukemia (AML) patients. However, the mechanisms contributed to the marrow adipocyte remodeling are still poorly understood. METHODS: GDF15 expression was analyzed by RT-qPCR and western blotting assays in the leukemic cells. The enhancing and antibody neutralization tests in vitro were employed to evaluate the effect of GDF15 on the morphology of mature adipocytes. CCK8 test was used to detect the proliferation of leukemic cells after co-cultivation with small marrow adipocytes. Flow cytometry was used to analysis the proportion of cell cycle of leukemic cells. Immunofluorescence staining and linear analysis were applied to verify the GDF15 expression and the relationship between GDF15 and small marrow adipocytes in AML patients. RESULTS: In this study, we found that leukemic cell lines not only expressed significantly higher growth differentiation factor 15 (GDF15) than the other three cytokines associated with adipocyte differentiation in RNA level but also secreted GDF15 factor. Furthermore, the in vitro experiments demonstrated that GDF15 was involved in the conversion of small marrow adipocytes from larger marrow adipocytes. Correspondingly, the leukemic cells proliferated more rapidly through regulating the cell cycle when co-cultured with GDF15-induced small marrow adipocytes. The immunofluorescence staining on the bone marrow sections of AML patients further exhibited that GDF15 was partly produced by leukemic cells. The positive correlation between the concentration of GDF15 in the marrow aspirates and the number and the volume of small marrow adipocytes might suggest the contribution of GDF15 in AML patients (r = 0.72, r = 0.67). CONCLUSIONS: GDF15 secreted by leukemic cells was involved in the morphological remodeling of marrow adipocytes, which can in turn promote leukemic cell growth, indicating that GDF15 may be a promising treatment target for AML patients.

cAMP induces cell apoptosis in multiple myeloma and overcomes bortezomib resistance.

The acquired resistance to bortezomib represents a major obstacle for multiple myeloma (MM) treatment. Studies revealed that the treatment with cyclic adenosine monophosphate (cAMP) may be a promising strategy for MM therapy. Therefore, the present study aimed to explore the mechanism of action of cAMP in MM cells. Our results showed that 8-CPT-cAMP and bortezomib synergistically induced growth inhibition and apoptosis in MM bortezomib-resistant cell lines and primary MM cells, in which protein kinase A (PKA) activation was involved. Furthermore, 8-CPT-cAMP induced the degradation of cyclinD1 and downregulation of myeloid cell leukemia-1 (Mcl-1). Moreover, 8-CPT-cAMP enhanced endoplasmic reticulum stress caused by bortezomib. A synergy between bortezomib and cAMP was also revealed in a murine MOPC315 xenograft model, which was evidenced by the significantly inhibited tumor growth and the improved multiple cancer-related parameters by the combination of the cAMP-elevating compound forskolin and bortezomib. Taken together, this study suggests that the treatment with cAMP may be a promising strategy for enhancing the therapeutic efficacy of bortezomib in MM treatment.

Once-Weekly 1.6 mg/m2 Bortezomib BCD Regimen in Elderly Patients with Newly Diagnosed Multiple Myeloma Who are Unfit for Standard Dose Chemotherapy.

Bortezomib has shown anti-myeloma effects in combination with alkylating agents, but clinical benefits can be limited by neurotoxicity. There is less information on the efficacy and tolerability of once-weekly 1.6 mg/m2 bortezomib combined with cyclophosphamide and dexamethasone (BCD) regimen in elderly patients with newly diagnosed multiple myeloma who are unfit for standard dose chemotherapy. Here, we report our experience of weekly 1.6 mg/m2 intravenous bortezomib in this group of patients. Between March 2010 and February 2015, we treated 34 newly diagnosed elderly patients with the combination of bortezomib 1.6 mg/m2 intravenously on days 1 and 8; cyclophosphamide 200 mg/m2 intravenously on days 1-4; dexamethasone 20 mg intravenously on days 1-4, and 8-11. Among the 34 patients, 14 (41 %) responded with complete response (CR), 6 (18 %) with very good partial response (VGPR) and 10 (29 %) with partial response (PR). The overall response rates were 88 %. After 2 cycles of treatments, the survival of patients who attained a response of VGPR or CR was significantly longer than those with PR or resistance to BCD, for both progression-free survival (PFS) (21.4 vs. 10.6 months, p = 0.002) and overall survival (OS) (23.0 vs. 16.8 months, p = 0.043). The 2-year PFS and OS were 26.5 and 64.7 % respectively in these elderly multiple myeloma patients in our study. Grade 1/2 neuropathy was observed in 20 % of the cycles while grade 3/4 neuropathy was not observed. No patients withdrew due to neuropathy or other side effects. Once-weekly bortezomib at 1.6 mg/m2 BCD regimen is both effective and safe in elderly patients with newly diagnosed multiple myeloma who are unfit for standard dose chemotherapy.

Growth differentiation factor 15 contributes to cancer-associated fibroblasts-mediated chemo-protection of AML cells.

BACKGROUND: Chemo-resistance is still a major obstacle in efforts to overcome acute myeloid leukemia (AML). An emerging concept has proposed that interactions between the bone marrow (BM) microenvironment and leukemia cells reduce the sensitivity of the leukemia cells to chemotherapy. As an important element of the tumor microenvironment, the cancer-associated fibroblasts (CAFs) are considered to be activated modulators in the chemo-resistance of many solid tumors. But their contribution to AML has yet to be fully understood. Here we report a critical role for CAFs which were thought to be a survival and chemo-protective factor for leukemia cells. METHODS: A retrospective study on the BM biopsies from 63 primary AML patients and 59 normal controls was applied to quantitative analysis the fiber stroma in the BM sections. Then immunohistochemistry on the BM biopsies were used to detect the makers of the CAFs. Their effects on drug resistance of leukemia cells were further to be assessed by co-cultured experiments in vitro. Moreover, the possible mechanisms involved in CAF-mediated chemo-protection of AML cells was investigated by antibody neutralization and siRNA knockdown experiments, with particular emphasis on the role of GDF15. RESULTS: In our study, excessive reticular fibers in the BM led to higher frequency of relapse and mortality in primary AML patients, bringing the inspiration for us to investigate the functional roles of the fiber-devied cells. We declared that the CAF cells which expressed higher levels of FSP1, α-SMA or FAP protein were widely distributed in the marrow of AML. Then in vitro co-cultured tests showed that these CAFs could protect leukemia cell lines (THP-1/K562) from chemotherapy. Interestingly, this effect could be decreased by either treatment with a neutralizing anti-GDF15 antibody or knockdown GDF15 (with siGDF15) in CAFs. Furthermore, we also confirmed that the GDF15(+) cells mainly co-localized with FAP, which was identified as the typical phenotype of CAFs in the BM stroma. CONCLUSIONS: We firstly demonstrate that the functional CAFs are widespread within the BM of AML patients and should be a critical chemo-protective element for AML cells by producing amount of GDF15.

Effective identification and localization of immature precursors in bone marrow biopsy.

Abnormal localization of immature precursors (ALIP) aggregating and clustering in bone marrow biopsy appears earlier than that of bone marrow smears in detection of the relapse of acute myelocytic leukemia (AML). But traditional manual ALIP recognition has many shortcomings such as prone to false alarms, neglect of distribution law before three immature precursor cells gathered, and qualitative analysis instead of quantitative one. So, it is very important to develop a novel automatic method to identify and localize immature precursor cells for computer-aided diagnosis, to disclose their patterns before ALIP with the development of AML. The contributions of this paper are as follows. (1) After preprocessing the image with Otsu method, we identify both precursor cells and trabecular bone by multiple morphological operations and thresholds. (2) We localize the precursors in different regions according to their distances with the nearest trabecular bone based on chamfer distance transform, followed by discussion for the presumptions and limitations of our method. The accuracy of recognition and localization is evaluated based on a comparison with visual evaluation by two blinded observers.

Leukemia propagating cells rebuild an evolving niche in response to therapy.

Residence of cancer-propagating cells (CPCs) within preferential microenvironmental niches has a major part in evading therapy. However, the nature of niches involved and the mechanisms protecting CPCs remain largely unknown. We addressed these issues in mouse transplantation models of acute lymphoblastic leukemia (ALL). When the engrafted leukemic cells substantially damaged adjacent microenvironment in the bone marrow (BM), after chemotherapy small foci of CPCs were retained, surrounded by sheaths of supporting cells that comprise a protective niche. We investigated patients' BM biopsies and found evidence of a similar process in patients receiving induction therapy. The efficacy of chemotherapy was enhanced by interfering with the niche formation or function. We therefore identified a therapy-induced niche that protects CPCs.

[Correlation between ALIP-like cluster and fibrous proliferation in bone marrow of patients with acute myeloid leukemia in CR phase].

This study was purposed to elucidate the prognostic values of ALIP (abnormal location of immature precursors)-like clusters and fibrous proliferation in bone marrow of AML patients in CR phase and the correlation between them. The bone marrow biopsy sections from 47 AML patients during admitting to relapse or till lost follow-up were examined retrospectively. The 47 patients were divided into pre-relapsed group and non-relapsed group according to relapse or not at end of follow-up. The concentration of ALIP-like cluster and reticulin fiber density (RFD) in sections were compared between the two groups respectively, the prognostic value of these two factors and the underlying relationship between them were estimated by statistical analysis. The results showed that ALIP-like cluster was (3.46 ± 2.71)/mm(2) during CR and RFD was (2.76% ± 1.50%) in pre-relapsed cases, which both were higher than those in non-relapsed cases (P < 0.05). Cases with ALIP-like cluster over 4/mm(2) or with RFD>1.68% showed high relapse rates of 89.5% or 95.2% respectively. RFD were (2.47% ± 2.48%) and (2.44% ± 2.23%) in cases with >4/mm(2) or ≤ 4/mm(2) respectively, there was no statistical significance (P > 0.05) . Meanwhile, the amount of ALIP-like cluster in CR not related with the paired RFD (r = 0.057, P > 0.05). It is concluded that both ALIP-like cluster in CR and RFD are poor prognostic factors for heralding early relapse. However, ALIP-like cluster and RFD show no correlation, and suggest that forming of ALIP not depends on fibrogenesis.

Clustered precursors in bone marrow sections predict early relapse in patients with acute myeloid leukemia within hematologic remission.

BACKGROUND: Bone marrow (BM) aspiration is largely used for relapse assessment in acute myeloid leukemia (AML). It remains unclear what roles that BM trephine biopsy plays on relapse assessment. METHODS: Bone marrow (BM) sections during complete remission (CR) from 60 acute myeloid leukemia (AML) patients were retrospectively analyzed. Computer image processing technology was performed for detection of the distance between precursors and endosteum, and density of precursors was also calculated under light microscopic image. Immunohistochemistry was used to identify the immunophenotype of clustered precursors. RESULTS: Except for single and double precursors, there existed clustered precursors of 3-5 cells during CR. Here, we demonstrated that clustered precursors, but not single and double precursors, were useful in risk factor of relapse. Area under the receiving operator curve (ROC) was of 0.007 (CI 95%, from 0.572 to 0.851). Using a standard cut-off value of >4.0/mm² for cluster density, early relapse was detected with a sensitivity of 51.5% and a specificity of 85.7%.Multivariate Cox regression analysis revealed that clustered precursor is an independent risk factor for early relapse (Adjusted HR: 0.325, 95% CI: 0.156-0.679, p = 0.003). CONCLUSIONS: Cumulatively, clustered precursors in BM sections during CR may serve as an independent risk factor of early relapse and poor outcome for AML patients in cluster density > 4.0/mm² in sections. Early aggressive interventions are needed to prevent hematologic relapse.

Clustered immature myeloid precursors in intertrabecular region during remission evolve from leukemia stem cell near endosteum and contribute to disease relapse in acute myeloid leukemia.

Most acute myeloid leukemia (AML) cannot be cured because leukemia stem cells (LSC) will contribute to eventual relapse. However, how LSC initiate relapse is not yet fully understood. We performed a retrospective study on bone marrow sections from AML patients during complete remission (CR), demonstrating that single and double immature myeloid precursors were located near endosteum and clustered precursors (≥ 3 cells/group) in intertrabecular region. Based on our observations, we hypothesize that after retrieval of myelotoxic regimen, LSC harboring near endosteum divide and differentiate into progeny cells which proliferate and then form colony clusters. Meanwhile, these clusters may migrate to intertrabecular region under the actions of cell migration factors. Without any interventions, clustered immature myeloid precursors may proliferate and hematologic relapse is then unavoidable.

[Influence of pre-ALIP number and its distance from trabeculae on AML relapse].

This study was purposed to detect the abnormal quantity and localization of pre-ALIP in bone marrow of acute myelocytic leukemia patients (AML) during the complete remission (CR) and investigate their correlation with AML relapse. The bone marrow biopsy and prognosis of 62 patients with CR were retrospectively analyzed. The bone marrow was divided into the pre-relapse group and the no-relapse group according to prognosis of patients. In order to clarify the correlation of abnormal quantity and localization of pre-ALIP with AML relapse, the number of single and double-cluster precursor cells and the sum of both were calculated, and their distance from bone trabeculae was surveyed with the computer image segment method. The results showed that the number of pre-ALIP in pre-relapse group (11 ± 11.71/mm(2)) and no-relapse group (8.33 ± 9.17/mm(2)) were more than that in normal control group (5.29 ± 4.00) (P < 0.01). The number of pre-ALIP more than 11/mm(2) was observed in 17 among all AML patients, and out of them 12 patients with pre-ALIP number >11/mm(2) (70.6) were found in the pre-relapse group, which was higher than that in no-relapse group (P < 0.05). While the distance between pre-ALIP and trabeculae [(341.31 ± 266.16) µm] in pre-relapse group showed the tendency of migrating to the intermediate zone of bone trabeculae, compared with that in no-relapse group [(242.41 ± 174.65) µm, P < 0.01]. Moreover, about 77.8 of 18 patients showed the distance of pre-ALIP from trabeculae was more than 341 µm in the pre-relapse group, and significantly higher than that in no-relapse group (P < 0.01). It is concluded that the average number of "pre-ALIP" more than 11/mm(2) or the average distance from trabeculae longer than 341 µm in bone marrow sections during CR may be the indicators for early relapse of AML.

[Characteristics of "pre-ALIP" in bone marrow sections of patients with acute myeloid leukemia].

To detect the characteristics of "pre-ALIP" and to investigate their relevance with the development of acute myeloid leukemia (AML) by computer image procession technology, bone marrow (BM) was collected by aspiration/trephine biopsy from AML patients during the complete remission (CR). BM sections were stained by HGF (haematoxylin-Giemsa-acid fuchsin) and photographed by optical microscope imaging system. 4 kinds of computer image segmentation technologies were compared to select the best one for detecting the localization and quantitation of the precursor cells. Planimetry was combined with morphology to segment bone trabeculae. The number of single and double-cluster precursor cells and their distance from bone trabeculae was detected with Euclidean distance change method in BM images of AML patients, and compared with the normal controls. Moreover, the morphological characteristics of "pre-ALIP" were investigated, and the correlation with the development of AML was analyzed. The results showed that the computer image segmentation method based on morphology could identify the precursor cells and bone trabeculae more exactly in BM image, as compared with the methods of 8-Sobel operater. Canny operator and watershed algorithm. Bone trabeculae could be segmented with combinative methods of morphology and planimetry. The number of single precursor cells (19.27 ± 11.60)/mm(2) and double-cluster precursor cells (1.77 ± 1.76)/mm(2) in CR group were higher than that in normal controls (p < 0.05). The distance of single precursor cells from bone trabeculae in CR group were closer to bone trabeculae than that in controls [(230.12 ± 97.68) µm vs (260.92 ± 99.88 µm)] (p < 0.05), but the distance of double-cluster precursor cells from bone trabeculae in AML patients was (274.56 ± 139.48) µm, which showed no statistically significant different from controls (p > 0.05), while the double-cluster precursor cells showed the tendency of migrating to the intermediate zone of bone trabeculae compared with the single precursor cells in CR group (p < 0.05). It is concluded that the structure of "pre-ALIP" in BM tissue exists before the occurrence of ALIP. The characteristics of "pre-ALIP" are single and double-cluster precursor cells with abnormal localization or quantitation, which showed correlation with the development of AML.

[Earlier hematopoietic reconstitution by mouse cord blood transplantation combined with bone marrow c-kit(+) hematopoietic progenitor cells].

This study was purposed to investigate the accelerating effect of newborn mouse cord blood transplantation combined with hematopoietic progenitor cells of bone marrow (BM) on the early hematopoietic reconstitution after transplantation, and the long-term chimerism of cord blood-derived cells, so as to develop a combined transplantation method for accelerating the early hematopoietic reconstitution. The lin(-)sca-1(-)c-kit(+) (c-kit(+)) cells and lin(-)sca-1(+) (sca-1(+)) cells in the bone marrow of BDF1 mice were isolated by MACS method. Biological characteristics in vitro of isolated fractions were observed and compared by semisolid colony culture combined with Giemsa staining. After transplantation of cord blood (CB) alone, or together with graded numbers of either c-kit(+) or sca-1(+) cells isolated from BDF1 mice (CD45.1) bone marrow into lethally irradiated CD45.2 congenic BDF1 mice, numbers of WBC and platelet were measured within 22 days of post-transplantation. The proportion of chimerism on granulocyte, T and B cell was dynamically measured by flow cytometry within 60 weeks of post-transplantation. The results showed that the number of colony from BM c-kit(+) cells cultured in semi-solid agar medium was significantly smaller than that from BM sca-1(+) population, which showed low proliferative potential in vitro and morphological characteristics of medium- or large-sized blast-like cells. The co transplantation of CB and BM c-kit(+) cells or sca-1(+) cells at the dosages of 1 × 10(4) or 2.5 × 10(4) or 5 × 10(4) to recipient mice leads to the quantity of WBC and platelets increased to 1 × 10(9)/L and 1 × 10(12)/L at day 12, whereas the injection of CB alone resulted at day 17. When mice were transplanted with CB together with BM c-kit(+)cells, and the CB-donor type cells in the peripheral blood increased progressively, while congenic donor BM-derived stem cells decreased gradually. After cotransplantation with CB and BM c-kit(+) cells for 60 weeks, a frequency of complete chimerism in CB-derived cells was continually maintained in granulates (96.68 ± 2.68)% and B lymphocytes (92.55 ± 3.04)%, while T lymphocytes (67.96 ± 7.91)% were dominantly derived from CB. On the other hand, congenic bone marrow or residual-derived cells were the dominant population, and the ratio of CB-derived cells in the peripheral blood was less than 10% (6.19 ± 7.62)% after cotransplantation with CB and sca-1(+)cells for 60 weeks. It is concluded that the cotransplantation of CB and BM congenic c-kit(+) cells is able to accelerate early hematopoietic reconstitution of recipient mice due to congenic marrow cells. Complete or main chimerism of cord blood is formed in long-term multilineage reconstitution of granulocytes, B cells and T lymphocytes.