Modulation of Hematopoietic Chemokine Effects In Vitro and In Vivo by DPP-4/CD26.

Dipeptidyl peptidase 4 (DPP4)/CD26 truncates certain proteins, and this posttranslational modification can influence their activity. Truncated (T) colony-stimulating factors (CSFs) are decreased in potency for stimulating proliferation of hematopoietic progenitor cells (HPCs). T-CXCL12, a modified chemokine, is inactive as an HPC chemotactic, survival, and enhancing factor for replating or ex-vivo expansion of HPCs.

Enhancing Hematopoietic Stem Cell Transplantation Efficacy by Mitigating Oxygen Shock.

Hematopoietic stem cells (HSCs) reside in hypoxic niches within bone marrow and cord blood. Yet, essentially all HSC studies have been performed with cells isolated and processed in non-physiologic ambient air. By collecting and manipulating bone marrow and cord blood in native conditions of hypoxia, we demonstrate that brief exposure to ambient oxygen decreases recovery of long-term repopulating HSCs and increases progenitor cells, a phenomenon we term extraphysiologic oxygen shock/stress (EPHOSS).

Mild Heat Treatment Primes Human CD34(+) Cord Blood Cells for Migration Toward SDF-1α and Enhances Engraftment in an NSG Mouse Model.

Simple efforts are needed to enhance cord blood (CB) transplantation. We hypothesized that short-term exposure of CD34(+) CB cells to 39.5°C would enhance their response to stromal-derived factor-1 (SDF-1), by increasing lipid raft aggregation and CXCR4 expression, thus leading to enhanced engraftment.

Nonmarrow hematopoiesis occurs in a hyaluronic-acid-rich node and duct system in mice.

A hyaluronic-acid-rich node and duct system (HAR-NDS) was found on the surface of internal organs of mice, and inside their blood and lymph vessels. The nodes (HAR-Ns) were filled with immune cells of the innate system and were especially enriched with mast cells and histiocytes. They also contained hematopoietic progenitor cells (HPCs), such as granulocyte-macrophage, erythroid, multipotential progenitors, and mast cell progenitors (MCPs).

Peroxisome proliferator-activated-γ coactivator-1α-mediated mitochondrial biogenesis is important for hematopoietic recovery in response to stress.

Hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) play a vital role in replenishment of blood cells. In addition to growth factors, energy metabolism plays an important role in cellular proliferation. Oxidative phosphorylation that occurs in the mitochondria is the major source of ATP.

Dipeptidylpeptidase 4 negatively regulates colony-stimulating factor activity and stress hematopoiesis.

Enhancement of hematopoietic recovery after radiation, chemotherapy, or hematopoietic stem cell (HSC) transplantation is clinically relevant. Dipeptidylpeptidase (DPP4) cleaves a wide variety of substrates, including the chemokine stromal cell-derived factor-1 (SDF-1). In the course of experiments showing that inhibition of DPP4 enhances SDF-1-mediated progenitor cell survival, ex vivo cytokine expansion and replating frequency, we unexpectedly found that DPP4 has a more general role in regulating colony-stimulating factor (CSF) activity.

Bcl6 controls the Th2 inflammatory activity of regulatory T cells by repressing Gata3 function.

The transcriptional repressor Bcl6 is a critical arbiter of Th cell fate, promoting the follicular Th lineage while repressing other Th cell lineages. Bcl6-deficient (Bcl6(-/-)) mice develop a spontaneous and severe Th2-type inflammatory disease, thus warranting assessment of Bcl6 in regulatory T cell (Treg) function. Bcl6(-/-) Tregs were competent at suppressing T cell proliferation in vitro and Th1-type colitogenic T cell responses in vivo.

Mouse hematopoietic cell-targeted STAT3 deletion: stem/progenitor cell defects, mitochondrial dysfunction, ROS overproduction, and a rapid aging-like phenotype.

Nuclear transcription factor Stat3 is important for proper regulation of hematopoietic stem cell (HSC) and hematopoietic progenitor cell (HPC) proliferation, survival, and cytokine signaling responses. A new, noncanonical role for Stat3 in mitochondrial function has been discovered recently. However, there is little information on the role(s) of mitochondrial Stat3 in HSC/HPC function, especially potential effects of Stat3/mitochondrial dysregulation in human diseases.

CD1d expression on and regulation of murine hematopoietic stem and progenitor cells.

In the present study, surface CD1d, which is involved in immune cell interactions, was assessed for effects on hematopoiesis. Mouse BM hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) express CD1d. The numbers and cycling status of HPCs in the BM and spleen of different strains of cd1d(-/-) mice were enhanced significantly, suggesting that CD1d is a negative regulator of HPCs.

Angiopoietin-like-2 and -3 act through their coiled-coil domains to enhance survival and replating capacity of human cord blood hematopoietic progenitors.

Several angiopoietin-like (ANGPTL) molecules have been implicated in enhancement of ex-vivo expansion of murine and human (hu) hematopoietic stem cells, but there are no reports on hematopoietic progenitor cells (HPCs). We assessed purified recombinant endotoxin-free hu ANGPTL-2 Coiled-Coil (CC), -3, -3CC, -3 fibrinogen-like domain (FLD), -4, -4CC, -5CC, -6 and -7 for effects on proliferation and survival of HPCs from hu cord blood (CB). None of the ANGPTL molecules stimulated CB HPC proliferation, or enhanced or inhibited colony formation of CB HPC stimulated by various growth factors.

DEK regulates hematopoietic stem engraftment and progenitor cell proliferation.

DEK is a biochemically distinct protein that is generally found in the nucleus, where it is vital to global heterochromatin integrity. However, DEK is also secreted by cells (eg, macrophages) and influences other adjacent cells (eg, acts as a chemoattractant for certain mature blood cells). We hypothesized that DEK may modulate functions of hematopoietic stem (HSCs) and progenitor (HPCs) cells.

Cyclin dependent kinase inhibitors differentially modulate synergistic cytokine responsiveness of hematopoietic progenitor cells.

Cyclin dependent kinase inhibitors (CDKIs) influence proliferation of hematopoietic progenitor cells (HPCs), but little is known of how they influence proliferative responsiveness of HPCs to colony stimulating factors (CSFs), alone and in combination with other hematopoietically active factors, such as the potent co-stimulating cytokine stem cell factor (SCF), or inhibition by myelosuppressive chemokines. Using mice with deletions in p18(INK4c), p21(CIP1/WAF1), or p27(KIP1) genes, and in mice with double gene deletions for either p18/p21 or p18/p27, we determined effects of absence of these CDKIs and their interactions on functional HPC numbers in vivo, and HPC proliferative responsiveness in vitro. There is a decrease in bone marrow HPC proliferation in p18(-/-) mice commensurate with decreased numbers of HPC, suggesting a positive role for p18 on HPC in vivo, similar to that for p21.

Neurexophilin 1 suppresses the proliferation of hematopoietic progenitor cells.

Neurexin I α (NRXN1α) and Dystroglycan (DAG1) are membrane receptors which serve as mutual ligands in the neuronal system. Neurexophilins (NXPHs) bind NRXN1α. NRXN1α was expressed in primitive populations in human CB (huCB) and murine BM (muBM).

STAT3-dependent IL-21 production from T helper cells regulates hematopoietic progenitor cell homeostasis.

The contribution of specific cell types to the production of cytokines that regulate hematopoiesis is still not well defined. We have previously identified T cell-dependent regulation of hematopoietic progenitor cell (HPC) numbers and cycling. In this report, we demonstrated that HPC activity is decreased in mice with STAT3-deficient T cells, a phenotype that is not because of decreased expression of IL-17 or RORγt.

TIP110/p110nrb/SART3/p110 regulation of hematopoiesis through CMYC.

Intracellular factors are involved in and essential for hematopoiesis. HIV-1 Tat-interacting protein of 110 kDa (TIP110; p110(nrb)/SART3/p110) is an RNA-binding nuclear protein implicated in the regulation of HIV-1 gene and host gene transcription, pre-mRNA splicing, and cancer immunology. In the present study, we demonstrate a role for TIP110 in the regulation of hematopoiesis.

Ex vivo rapamycin treatment of human cord blood CD34+ cells enhances their engraftment of NSG mice.

Since cord blood (CB) has become a commonly used source of transplantable hematopoietic stem (HSC) and hematopoietic progenitor cells (HPC), there has been a need to overcome the limited HSC and HPC numbers available to transplant from a single CB, especially for adult recipients. Our laboratory previously demonstrated that Rheb2 overexpression significantly impaired the repopulating ability of HSC. Since overexpression of Rheb2 leads to increased signaling through mTOR, we examined the effect of the mTOR inhibitor rapamycin ex vivo on cytokine expanded CD34(+) CB cells for the engraftment of these cells in non-obese diabetic, severe combined immunodeficient, IL-2 receptor γ chain null (NSG) mice.

Hematopoietic stem/progenitor cells, generation of induced pluripotent stem cells, and isolation of endothelial progenitors from 21- to 23.5-year cryopreserved cord blood.

Cryopreservation of hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) is crucial for cord blood (CB) banking and transplantation. We evaluated recovery of functional HPC cryopreserved as mononuclear or unseparated cells for up to 23.5 years compared with prefreeze values of the same CB units.

Mad2 haploinsufficiency protects hematopoietic progenitor cells subjected to cell-cycle stress in vivo and to inhibition of redox function of Ape1/Ref-1 in vitro.

Objective: Cell-cycle checkpoints guarantee movement through the cell cycle. Mitotic arrest deficiency 2 (Mad2), a mitotic checkpoint protein, appears crucial for generating the wait anaphase signal to prevent onset of anaphase. We evaluated effects of Mad2 haploinsufficiency on hematopoietic stem (HSC) and progenitor (HPC) function in response to stress.

Overexpression of Rheb2 enhances mouse hematopoietic progenitor cell growth while impairing stem cell repopulation.

Molecular mechanisms preserving hematopoietic stem cell (HSC) self-renewal by maintaining a balance between proliferation, differentiation, and other processes are not fully understood. Hyperactivation of the mammalian target of rapamycin (mTOR) pathway, causing sustained proliferative signals, can lead to exhaustion of HSC repopulating ability. We examined the role of the novel ras gene Rheb2, an activator of the mTOR kinase, in colony-forming ability, survival, and repopulation of immature mouse hematopoietic cells.

Targeted disruption of Zfp36l2, encoding a CCCH tandem zinc finger RNA-binding protein, results in defective hematopoiesis.

Members of the tristetraprolin family of tandem CCCH finger proteins can bind to AU-rich elements in the 3'-untranslated region of mRNAs, leading to their deadenylation and subsequent degradation. Partial deficiency of 1 of the 4 mouse tristetraprolin family members, Zfp36l2, resulted in complete female infertility because of early embryo death. We have now generated mice completely deficient in the ZFP36L2 protein.

Identification of parameters required for efficient lentiviral vector transduction and engraftment of human cord blood CD34(+) NOD/SCID-repopulating cells.

Objective: Human cord blood (CB) is a potential source of hematopoietic stem cells (HSC) for gene therapy to treat patients with hematopoietic disorders. However, limited numbers of CB CD34(+) cells, low transduction efficiency with lentiviral vectors (LVs), and low engraftment efficiency of nonobese diabetic/severe combined immunodeficient (NOD/SCID) repopulating cells (SRC), a measure of HSC, are blocks to this procedure. To optimize culture and transduction conditions, we compared various lengths of time for prestimulation before transduction, transduction duration, and posttransduction cell culture.

Leukocytosis and Mobilization of CD34+ Hematopoietic Progenitor Cells by AMD3100, a CXCR4 Antagonist.

Stromal cell-derived factor-1 (SDF-1/CXCL12) plays a key regulatory role in the trafficking of hematopoietic cells. AMD3100 is a specific antagonist of the binding of SDF-1 to its receptor, CXCR4. This phase I study assessed the hematological effects, pharmacokinetics, and safety of administration of AMD3100 to 32 healthy volunteers, including its ability to mobilize CD34+ hematopoietic progenitor cells.

SDF-1/CXCL12 enhances in vitro replating capacity of murine and human multipotential and macrophage progenitor cells.

Hematopoietic progenitor cells (HPCs) manifest a limited self-renewal capacity, as determined by a surrogate assay involving replating capacity of single colonies in vitro with generation of secondary colonies. Stromal cell-derived factor-1 (SDF-1/CXCL12), has been implicated in regulation of hematopoiesis through its modulation of hematopoietic stem cell (HSC) and HPC migration, homing, mobilization, and survival. We used bone marrow cells from SDF-1/CXCL12 transgenic and littermate control mice, and culture of normal mouse bone marrow and human cord blood cells plated in the presence or absence of recombinant SDF-1/CXCL12 to evaluate a role for SDF-1/CXCL12 in the replating capability in vitro of multipotential [colony-forming units (CFU)-GEMM] and macrophage (CFU-M) progenitor cells.

Inhibition of CD26 in human cord blood CD34+ cells enhances their engraftment of nonobese diabetic/severe combined immunodeficiency mice.

CD26, a surface serine dipeptidylpeptidase IV (DPPIV) expressed on different cell types, cleaves the amino-terminal dipeptide from some chemokines, including stromal-derived factor-1 (SDF-1/CXCL12). SDF-1/CXCL12 plays important roles in hematopoietic stem cell (HSC) homing, engraftment, and mobilization. Inhibition of CD26 peptidase activity enhances homing, engraftment, and competitive repopulation in congenic mouse bone marrow cell transplants.