scholarly journals Identification of novel B-lineage cells in human fetal bone marrow that coexpress CD7 [see comments]

Blood ◽  
1991 ◽  
Vol 77 (1) ◽  
pp. 64-68 ◽  
Author(s):  
ER Grumayer ◽  
F Griesinger ◽  
DS Hummell ◽  
RD Brunning ◽  
JH Kersey
Keyword(s):  
Bone Marrow ◽  
Cell Sorting ◽  
B Cell Development ◽  
Multiparameter Flow Cytometry ◽  
Fetal Bone ◽  
Lymphoid Development ◽  
Alternate Pathway ◽  
Lineage Markers ◽  
B Lineage

Abstract In the present study we used multiparameter flow cytometry and cell sorting to evaluate fetal bone marrow, a rich source of cells early in lymphoid development. We found CD7 to be expressed on a subset of CD19+ cells, including some that had matured to cytoplasmic mu+ (pre-B) and surface mu+ (B) cells. In addition, a less mature CD7+19+ population was characterized as mu- and CD34+/-. The CD7+19+ population was clearly distinct from the mature T cells. The CD7+19+ cells were negative for nuclear TdT in contrast to CD7–19+ cells, which frequently contained TdT. CD10, which is coexpressed on the cell surface of more than 90% of CD19+ lymphocytes, was detected in a minority of CD7+19+ lymphocytes. The CD7+19+34+ cell population may be B-lineage committed, or may represent uncommitted lymphoid precursors. The biologic role of the expression of CD7 on immature and mature cells, including those of the B lineage, may indicate (1) the presence of CD7+19+ lymphoid precursor cells and/or (2) an alternate pathway of B-cell development, in which cells coexpress CD7 with other B-lineage markers.

scholarly journals Identification of novel B-lineage cells in human fetal bone marrow that coexpress CD7 [see comments]

Blood ◽  
1991 ◽  
Vol 77 (1) ◽  
pp. 64-68 ◽  
Author(s):  
ER Grumayer ◽  
F Griesinger ◽  
DS Hummell ◽  
RD Brunning ◽  
JH Kersey
Keyword(s):  
Bone Marrow ◽  
Cell Sorting ◽  
B Cell Development ◽  
Multiparameter Flow Cytometry ◽  
Fetal Bone ◽  
Lymphoid Development ◽  
Alternate Pathway ◽  
Lineage Markers ◽  
B Lineage

In the present study we used multiparameter flow cytometry and cell sorting to evaluate fetal bone marrow, a rich source of cells early in lymphoid development. We found CD7 to be expressed on a subset of CD19+ cells, including some that had matured to cytoplasmic mu+ (pre-B) and surface mu+ (B) cells. In addition, a less mature CD7+19+ population was characterized as mu- and CD34+/-. The CD7+19+ population was clearly distinct from the mature T cells. The CD7+19+ cells were negative for nuclear TdT in contrast to CD7–19+ cells, which frequently contained TdT. CD10, which is coexpressed on the cell surface of more than 90% of CD19+ lymphocytes, was detected in a minority of CD7+19+ lymphocytes. The CD7+19+34+ cell population may be B-lineage committed, or may represent uncommitted lymphoid precursors. The biologic role of the expression of CD7 on immature and mature cells, including those of the B lineage, may indicate (1) the presence of CD7+19+ lymphoid precursor cells and/or (2) an alternate pathway of B-cell development, in which cells coexpress CD7 with other B-lineage markers.

Haploinsufficiency of Ebf1 Collaborates with BCR-ABL1 to Decrease the Latency of Acute Lymphoblastic Leukemia.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3363-3363
Author(s):  
Salil Goorha ◽  
Noel T. Lenny ◽  
Christopher B Miller ◽  
S. Scott Perry ◽  
Xiaoping Su ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Lymphoblastic Leukemia ◽  
B Cells ◽  
B Cell ◽  
Copy Number ◽  
Lymphoblastic Leukemia ◽  
B Cell Development ◽  
B Lineage ◽  
B Lymphoid

Abstract In previously published genome-wide copy number analysis of leukemic samples from 242 pediatric acute lymphoblastic leukemia (ALL) patients, we reported that mutations in genes regulating B lymphoid development are the most common lesion in B-progenitor ALL, and these include PAX5, IKZF1, and EBF1. Mono-allelic deletion of EBF1 was observed in 8/200 B-progenitor leukemia samples, including a BCR-ABL1 ALL. EBF1 encodes a transcription factor that is required for the development of B cells, and with E2A regulates the expression of B-lineage specific genes. Mice null for Ebf1 arrest B cell development at the pro-B cell stage, whereas Ebf1+/− mice have a 50% reduction in the number of immature and mature B cells but a normal number of pro-B cells. Importantly, neither haploinsufficiency nor the complete loss of Ebf1 results in the development of leukemia in mice. To examine the role of genetic alterations targeting B-lymphoid differentiation in the pathogenesis in BCR-ABL1 ALL, we transduced Ebf1+/+ and Ebf1+/− bone marrow cells with MSCV-GFP-IRES-p185 BCR-ABL1 retrovirus and transplanted the resultant cells into lethally irradiated wild-type C57BL6 recipient mice. Mice transplanted with BCR-ABL1 Ebf1+/− cells developed B lineage ALLs at a shorter latency than observed with BCR-ABL1 Ebf1+/+ cells (median overall survival of 17 days in Ebf1+/− vs 42 days in Ebf1+/+, P<0.0001). All leukemias had a B220+Cd19+Bp1+ pre-B cell immunophenotype; however, the leukemias that developed from the Ebf1+/− cells aberrantly expressed high levels of the stem cell marker Sca1 (mean fluorescence level for Sca1 of 69.6 in Ebf1+/− (n=22) vs 16.8 in Ebf1+/+ (n=14), p<0.0001). To begin to understand how a decrease in the copy number of Ebf1 may contribute to leukemogenesis, we examined early B cell development in bone marrow (BM) cells from two week-old C57BL6 Ebf1+/− and Ebf1+/+ mice. Our analysis confirmed previous reports indicating a 2-fold reduction of B220+CD43− B cells in Ebf1+/− compared to Ebf1+/+ mice. Interestingly, however, we also detected an approximately 6-fold increase in a transitional population of B220loIL-7R+cKitlo Pre-pro B cells that also expressed Sca1 (2194 mean number of Ebf1+/− cells per 100,000 BM cells (n=10) vs 372 mean number of Ebf1+/+ cells per 100,000 BM cells (n=8), p<0.0001), an observation that raises the possibility that Ebf1 haploinsufficiency expands the pool of cells that are susceptible to transformation by BCR-ABL expression. It will be important to examine whether the accelerated tumorigenesis resulting from Ebf1 haploinsufficiency is a consequence of a subtle shift in differentiation, or some alternative mechanism of oncogenic cooperativity. Studies are underway to directly assess the role of B220loIL-7R+cKitlo Sca1+ cells in BCR-ABL1 driven ALL.

scholarly journals Differentiation of Acute Myeloid Leukemia from B- and T-Lineage Acute Lymphoid Leukemias by Real-Time Quantitative Reverse Transcription-PCR of Lineage Marker mRNAs

2004 ◽  
Vol 50 (7) ◽  
pp. 1165-1173 ◽  
Author(s):  
Pascale Saussoy ◽  
Jean-Luc Vaerman ◽  
Nicole Straetmans ◽  
Véronique Deneys ◽  
Guy Cornu ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Real Time ◽  
Reverse Transcription ◽  
Cell Sorting ◽  
Acute Leukemias ◽  
Ct Value ◽  
Blast Cells ◽  
Lineage Markers ◽  
B Lineage ◽  
Acute Myeloid

Abstract Background: Flow cytometry of lineage markers is useful in the classification of leukemias. Our aim was to assess whether the study of lineage genes at the RNA level would enable differentiation of acute myeloid leukemias (AMLs) from B-and T-lineage acute lymphoid leukemias (ALLs). Methods: We measured mRNA of four lineage markers [CD19, CD79a, CD3e, and myeloperoxidase (MPO)] by reverse transcription followed by real-time quantitative (RTQ)-PCR. We investigated 72 acute leukemias (40 AMLs with 23–93% blast cells plus 27 B-lineage ALLs and 5 T-lineage ALLs) defined by morphologic criteria at diagnosis. RTQ-PCR analysis was performed on bone marrow without cell sorting. The expression of each gene was calculated as the difference in the threshold cycle [ΔCT; CT value of target gene minus CT value of housekeeping gene (Abelson)]. Results: Three patterns of expression were detected. In the first, CD19, CD79a, and MPO mRNAs were less abundant than CD3e. In the second pattern, MPO mRNA was more abundant than the other three mRNAs. In the third, CD19 or CD79a was more highly expressed than CD3e and MPO. The three patterns corresponded to T-ALL, AML, and B-ALL, respectively. The use of cutoffs to establish qualitatively the pattern of coexpression of the four lineage markers provided the same information as the comparison among the four ΔCT values. Prospective use of the scoring system correctly classified each of 13 additional cases (8 AML, 4 B-lineage ALL, and 1 T-lineage ALL). Conclusion: Study of lineage markers at diagnosis by RTQ-PCR allows differentiation of AML from B-ALL or T-ALL without cell sorting, even when the bone marrow contains few blast cells.

scholarly journals Lsh/HELLS is required for B lymphocyte development and immunoglobulin class switch recombination

2020 ◽  
Vol 117 (33) ◽  
pp. 20100-20108
Author(s):  
Yafeng He ◽  
Jianke Ren ◽  
Xiaoping Xu ◽  
Kai Ni ◽  
Andrew Schwader ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Bone Marrow Transplantation ◽  
B Cell ◽  
Marrow Transplantation ◽  
Class Switch Recombination ◽  
B Cell Development ◽  
Hematopoietic Cell ◽  
Cell Numbers ◽  
Class Switch

Mutation of HELLS (Helicase, Lymphoid-Specific)/Lsh in human DNA causes a severe immunodeficiency syndrome, but the nature of the defect remains unknown. We assessed here the role of Lsh in hematopoiesis using conditional Lsh knockout mice with expression of Mx1 or Vav Cre-recombinase. Bone marrow transplantation studies revealed that Lsh depletion in hematopoietic stem cells severely reduced B cell numbers and impaired B cell development in a hematopoietic cell-autonomous manner. Lsh-deficient mice without bone marrow transplantation exhibited lower Ig levels in vivo compared to controls despite normal peripheral B cell numbers. Purified B lymphocytes proliferated normally but produced less immunoglobulins in response to in vitro stimulation, indicating a reduced capacity to undergo class switch recombination (CSR). Analysis of germline transcripts, examination of double-stranded breaks using biotin-labeling DNA break assay, and End-seq analysis indicated that the initiation of the recombination process was unscathed. In contrast, digestion–circularization PCR analysis and high-throughput sequencing analyses of CSR junctions and a chromosomal break repair assay indicated an impaired ability of the canonical end-joining pathway in Lsh-deficient B cells. Our data suggest a hematopoietic cell-intrinsic role of Lsh in B cell development and in CSR providing a potential target for immunodeficiency therapy.

scholarly journals Mutations of the Igβ gene cause agammaglobulinemia in man

2007 ◽  
Vol 204 (9) ◽  
pp. 2047-2051 ◽  
Author(s):  
Simona Ferrari ◽  
Vassilios Lougaris ◽  
Stefano Caraffi ◽  
Roberta Zuntini ◽  
Jianying Yang ◽  
...  
Keyword(s):  
Bone Marrow ◽  
B Cell ◽  
Transmembrane Protein ◽  
Serum Levels ◽  
Cell Development ◽  
B Cell Development ◽  
Surrogate Light Chain ◽  
Human B Cell ◽  
Homozygous Nonsense Mutation

Agammaglobulinemia is a rare primary immunodeficiency characterized by an early block of B cell development in the bone marrow, resulting in the absence of peripheral B cells and low/absent immunoglobulin serum levels. So far, mutations in Btk, μ heavy chain, surrogate light chain, Igα, and B cell linker have been found in 85–90% of patients with agammaglobulinemia. We report on the first patient with agammaglobulinemia caused by a homozygous nonsense mutation in Igβ, which is a transmembrane protein that associates with Igα as part of the preBCR complex. Transfection experiments using Drosophila melanogaster S2 Schneider cells showed that the mutant Igβ is no longer able to associate with Igα, and that assembly of the BCR complex on the cell surface is abrogated. The essential role of Igβ for human B cell development was further demonstrated by immunofluorescence analysis of the patient's bone marrow, which showed a complete block of B cell development at the pro-B to preB transition. These results indicate that mutations in Igβ can cause agammaglobulinemia in man.

scholarly journals Regulated Expression of the Eph-Related Receptor Tyrosine Kinase Hek11 in Early Human B Lymphopoiesis

Blood ◽  
1997 ◽  
Vol 90 (9) ◽  
pp. 3613-3622 ◽  
Author(s):  
Hans-Christian Aasheim ◽  
Leon W.M.M. Terstappen ◽  
Ton Logtenberg
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Expression Patterns ◽  
B Lymphopoiesis ◽  
Fetal Bone ◽  
Degenerate Oligonucleotide ◽  
Regulated Expression ◽  
B Lineage ◽  
B Lineage Cells

Abstract Members of the large Eph family of receptor tyrosine kinases (RTKs) display temporally and spatially restricted expression patterns during embryogenesis, suggesting a role in various developmental processes. We have begun to investigate the expression of members of this receptor family during human hematopoiesis, in particular B lymphopoiesis. Expression of Eph RTKs in cells of the B-lymphoid lineage was assessed by using degenerate oligonucleotide primers based on stretches of conserved nucleic acid sequences in members of the Eph family. First, the content of Eph-family RTKs was assessed in freshly sorted fetal bone marrow pro–B cells. This population was found to harbor transcripts of the Hek8 and Hek11 members of this gene family. Subsequent analysis of expression of these genes in B cells representing various differentiation and ontogenic stages showed that the Hek8 transcript is constitutively present in all fetal and adult B-lineage cells, with high levels of expression in peripheral blood B cells. In contrast, the Hek11 transcript was exclusively found in fetal bone marrow pro–B cells and pre–B cells, but not in more mature fetal B-lineage cells. All adult B-lineage cells, from early pro–B cells to end-stage plasma cells, lacked Hek11 transcripts. The developmentally regulated expression of Hek11 during fetal B lymphopoiesis suggests a role for this gene in pre/pro–B cell expansion and/or differentiation and defines a difference in progenitor B cell populations isolated from fetal versus adult human bone marrow.

Application of Multiparameter Flow Cytometry for the Identification of Dysplasia in Granulocytic, Monocytic, and Erythrocytic Lineages and Blasts in Patients with Myelodysplastic Syndromes.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2615-2615
Author(s):  
Wolfgang Kern ◽  
Claudia Schoch ◽  
Susanne Schnittger ◽  
Torsten Haferlach
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
Myelodysplastic Syndromes ◽  
Erythroid Cell ◽  
Multiparameter Flow Cytometry ◽  
Cell Populations ◽  
Aberrant Expression ◽  
Hla Dr ◽  
Cd16 Expression

The diagnosis and classification of myelodysplastic syndromes (MDS) are based on cytomorphology (CM) and cytogenetics. A high degree of experience in CM is required to allow the accurate identification of dysmyelopoiesis and quantification of bone marrow blasts. The identification of dysplastic features in all lineages by multiparameter flow cytometry (MFC) has been shown feasible. To further analyze the potential role of MFC in the diagnostic work-up of MDS we analyzed 224 bone marrow samples from patients with suspected of proven MDS by MFC, CM, and cytogenetics in parallel. Blast counts as determined by CM and MFC, respectively, ranged from 0% to 21% (median, 5%) and from 0% to 33% (median, 4%; correlation: r=0.192, p=0.018). The median number of aberrant features detected by MFC were 0 for blasts (range, 0 to 4), 2 for granulocytes (0 to 7), 1 for monocytes (0 to 5), and 0 for erythrocytes (0 to 2). The most frequent dysplastic features observed in the blast populations included aberrant coexpression of CD11b (20.5%), CD15 (14.3%) and CD64 (14.3%). The most frequent dysplastic features observed in the granulocytic cell populations included reduced side-scatter signal corresponding to hypogranulation (71.4%), aberrant coexpression of CD56 (29.0%), aberrant pattern of CD13/CD16 expression (26.3%), aberrant pattern of CD11b/CD16 expression (25.9%), reduced expression of CD64 (17.0%), and aberrant expression of HLA-DR (14.7%). The most frequent dysplastic features observed in the monocytic cell populations included aberrant coexpression of CD56 (31.3%), aberrant coexpression of CD16 (26.3%), an aberrant pattern of CD11b/HLA-DR expression (6.7%), and aberrant coexpression of CD2 (5.8%). The most frequent dysplastic features observed in the erythroid cell populations included an aberrantly strong expression of CD71 and CD235a (23.7%), a lack of CD71 expression (10.7%), and an aberratly homogeneous expression of CD71 (7.1%). The presence of dysplastic features by CM as well as the presence of cytogenetic aberrations tended to be associated with a higher number of dysplastic features by MFC. These data suggest that the identification of dysplastic features by MFC is feasible although there is a large heterogeneity in aberrantly expressed antigens. Thus, a comprehensive panel of antibodies must be applied to allow the detection of dysplasia. Future studies will define the role of MFC in optimizing the diagnosis of MDS in cooperation with CM and cytogenetics.

Precursor B Cell Acute Lymphoblastic Leukemia Induces Pro-Leukemic Changes in the Bone Marrow Microenvironment That Contribute to Therapeutic Resistance

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1466-1466
Author(s):  
Christopher D Chien ◽  
Elizabeth D Hicks ◽  
Paul P Su ◽  
Haiying Qin ◽  
Terry J Fry
Keyword(s):  
Bone Marrow ◽  
Acute Lymphoblastic Leukemia ◽  
B Cells ◽  
B Cell ◽  
Lymphoblastic Leukemia ◽  
Cell Development ◽  
B Cell Development ◽  
Bone Marrow Microenvironment ◽  
Therapeutic Resistance

Abstract Abstract 1466 Pediatric acute lymphoblastic leukemia (ALL) is the most common childhood malignancy. Although cure rates for this disease are approximately 90%, ALL remains one of the leading causes cancer-related deaths in children. Thus, new treatments are needed for those patients that do not respond to or recur following standard chemotherapy. Understanding the mechanisms underlying resistance of pediatric ALL to therapy offers one approach to improving outcomes. Recent studies have demonstrated the importance of communication between cancer cells and their microenvironment and how this contributes to the progression and therapeutic resistance but this has not been well studied in the context of ALL. Since the bone marrow is presumed to be the site of initiation of B precursor ALL we set out in our study to determine how ALL cells utilize the bone marrow milieu in a syngeneic transplantable model of preB cell ALL in immunocompetent mice. In this model, intravenously injected preB ALL develops first in the bone marrow, followed by infiltration into the spleen, lymph node, and liver. Using flow cytometry to detect the CD45.2 isoform following injection into B6CD45.1+ congenic recipients, leukemic cells can be identified in the bone marrow as early as 5 days after IV injection with a sensitivity of 0.01%-0.1%. The pre-B ALL line is B220+/CD19+/CD43+/BP1+/IL-7Ralpha (CD127)+/CD25-/Surface IgM-/cytoplasmic IgM+ consistent with a pre-pro B cell phenotype. We find that increasing amounts of leukemic infiltration in the bone marrow leads to an accumulation of non-malignant developing B cells at stages immediately prior to the pre-pro B cell (CD43+BP1-CD25-) and a reduction in non-malignant developing pre B cells at the developmental stage just after to the pre-pro B cell stage (CD43+BP1+CD25+). These data potentially suggest occupancy of normal B cell developmental niches by leukemia resulting in block in normal B cell development. Further supporting this hypothesis, we find significant reduction in early progression of ALL in aged (10–12 month old) mice known to have a deficiency in B cell developmental niches. We next explored whether specific factors that support normal B cell development can contribute to progression of precursor B cell leukemia. The normal B cell niche has only recently been characterized and the specific contribution of this niche to early ALL progression has not been extensively studied. Using a candidate approach, we examined the role of specific cytokines such as Interleukin-7 (IL-7) and thymic stromal lymphopoietin (TSLP) in early ALL progression. Our preB ALL line expresses high levels of IL-7Ralpha and low but detectable levels of TLSPR. In the presence of IL-7 (0.1 ng/ml) and TSLP (50 ng/ml) phosphSTAT5 is detectable indicating that these receptors are functional but that supraphysiologic levels of TSLP are required. Consistent with the importance of IL-7 in leukemia progression, preliminary data demonstrates reduced lethality of pr-B cell ALL in IL-7 deficient mice. Overexpression of TSLP receptor (TSLPR) has been associated with high rates of relapse and poor overall survival in precursor B cell ALL. We are currently generating a TSLPR overepressing preBALL line to determine the effect on early ALL progression and are using GFP-expressing preB ALL cells to identify the initial location of preB ALL occupancy in the bone marrow. In conclusion, or model of early ALL progression provides insight into the role of the bone marrow microenvironment in early ALL progression and provides an opportunity to examine how these microenvironmental factors contribute to therapeutic resistance. Given recent advances in immunotherapy for hematologic malignancies, the ability to study this in an immunocompetent host will be critical. Disclosures: No relevant conflicts of interest to declare.

Differential Effects of Wnt Signaling on Proliferation and Hematopoietic Support of Adult and Fetal Bone Marrow-Derived MSCs

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 5137-5137
Author(s):  
Maja Maria Paciejewska ◽  
Marijke Maijenburg ◽  
Christian Gilissen ◽  
Kim Vermeul ◽  
Marion Kleijer ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Wnt Signaling ◽  
Conditioned Medium ◽  
Differentially Expressed ◽  
Complete Medium ◽  
Beta Catenin ◽  
Short Term ◽  
Hematopoietic Stem ◽  
Fetal Bone

Abstract Human adult bone marrow-derived mesenchymal stromal cells MSC (ABMSC) are increasingly applied in the clinic to decrease graft versus host disease and to enhance hematopoietic recovery. Fetal bone marrow-derived MSC (FBMSC) display similar immune suppressive and regenerative capacities as adult MSC, and have been transplanted into patients. The proliferation capacity of FBMSC, however, is much larger than that of ABMSC. The aim of our studies is to understand the molecular mechanism of proliferation and hematopoietic support by MSC to optimize the expansion of functional MSC for clinical use. Comparison of gene expression between ABMSCs and FBMSCs identified 687 differentially expressed genes. Of these, 16 were Wnt-related, mainly Wnt-inhibitors and Frizzled receptors. Expression of SFRP4, WISP1, WISP2, WISP3, FZD1, FZD5, FZD8 and MYCBP2 was upregulated in ABMSC, whereas DKK1, DKK2, CCND2, WNT5a, MYC, FZD2, FZD6 and FZD7 are expressed at a higher level in FBMSC. Although the expression of few genes (e.g. DKK1) was culture density dependent, other genes such as Wnt5a, DKK2 and SFRP4 were consistently differentially expressed independent of culture conditions. Therefore we investigated the role of Wnt signaling in adult and fetal bone marrow-derived MSC. Wnt3a induced a concentration dependent increase of the canonical Wnt-target genes TCF and LEF in both ABMSC and FBMSC. However, ABMSC responded faster, and at a lower concentration of Wnt3a compared to FBMSC. In addition, Wnt3a increased the proliferation of ABMSC, but not of FBMSC. Interestingly, a complete medium change was already sufficient to increase TCF/LEF expression in ABMSC, but not in FBMSC, suggesting that ABMSC produced a soluble Wnt-inhibitor. Moreover, switching MSC conditioned medium between FBMSC and ABMSC indicated that FBMSC conditioned medium significantly stimulated the expansion of ABMSC while the reverse experiments did not show an inhibiting effect of ABMSC conditioned medium on the expansion of FBMSC. Thus, ABMSC produce a factor that only affects ABMSC, but not (the factors produced by) FBMSC. To block autocrine Wnt production, MSC were exposed for 48 h to the Inhibitor of Wnt Production 2 (IWP2). Abrogation of Wnt-production in FBMSC modestly decreased beta-catenin expression, and strongly decreased TCF/LEF expression, but did not affect ABMSC. Addition of IWP-2 to long-term cultures strongly inhibited proliferation of FBMSCs compared to ABMSCs. To unravel the role of MSC-produced Wnt factors in hematopoiesis, we co-cultured adult or fetal MSCs together with cord blood derived CD34+ cells in the presence or absence of IWP2 inhibitor. Addition of IWP2 to ABMSC decreased the short term support of hematopoietic stem and progenitors (HSPC), while IWP2 did not affect the support of HSPCs by FBMSC. Overall, ABMSCs provided a significant better short term hematopoietic support than FBMSCs. In conclusion, our data demonstrate that ABMSC produce both Wnt factors and inhibitors. FBMSC, in contrast, produce Wnt-related factors that seem to contribute more to the expansion capacity of FBMSC than to their hematopoietic support. To identify factors we current use mass spectroscopy of supernatant to determine the secretome. Modulation of (parts) of the Wnt pathway may improve clinical expansion protocols of ABMSC. Disclosures No relevant conflicts of interest to declare.

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