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Perinatal-related tissues, such as the placenta, umbilical cord, and amniotic membrane, are generally discarded after delivery and are increasingly attracting attention as alternative sources for decellularized extracellular matrix (dECM) isolation. Recent studies indicate that glycosaminoglycans (GAGs) in the dECM play key roles during tissue regeneration. However, the dECM is organ specific, and the glycosaminoglycanomics of dECMs from perinatal tissues and the regulatory function of GAGs have been poorly investigated. In this study, we explored the glycosaminoglycanomics of dECMs from the placenta, umbilical cord and amniotic membrane. We hypothesized that the therapeutic effects of dECMs are related to the detailed composition of GAGs. Hydrogels of dECM derived from perinatal tissues were generated, and glycosaminoglycanomics analysis was employed to identify the cues that promote tissue repair and regeneration in a murine cutaneous wound-healing model. We utilized highly sensitive liquid chromatography-tandem mass spectrometry for glycosaminoglycanomics analysis. Our results revealed that placenta-derived dECM (PL-dECM) hydrogel has higher contents of chondroitin sulfate (CS) and heparan sulfate (HS). In addition, molecular imaging showed that the PL-dECM hydrogel exerted the best anti-inflammatory and proangiogenic effects in the skin wound healing model. Further in vitro analyses demonstrated that CS with 6-O-sulfo group (CS-6S) has an anti-inflammatory effect, while HS with 6-O-sulfo group (HS-6S) plays a crucial role in angiogenesis. In conclusion, this study highlights the critical roles of GAGs in perinatal tissue-derived dECMs by promoting angiogenesis and inhibiting inflammation and indicates that it is feasible to utilize 6-sulfated GAG-enriched placental dECM hydrogel as an attractive candidate for tissue engineering and drug delivery. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Therapeutic angiogenesis with mesenchymal stem cells (MSCs) is promising for the clinical treatment of peripheral artery disease (PAD). However, the heterogeneous proangiogenic nature of MSCs is a key challenge in developing more effective treatments with MSCs for therapeutic angiogenesis purposes. Here, we propose to enhance the therapeutic function of human placenta-derived MSCs (hP-MSCs) in hindlimb ischemia therapy by using nitric oxide (NO)-releasing chitosan hydrogel (CS-NO). Our data showed that the co-transplantation of CS-NO hydrogel with hP-MSCs remarkably improved the grafting of hP-MSCs and ameliorated the functional recovery of ischemic hindlimbs. Moreover, we found that the neovascularization of damaged hindlimbs was significantly increased after co-transplanting CS-NO hydrogel and hP-MSCs, as confirmed by bioluminescence imaging (BLI). Further analysis revealed an endothelial-like status transformation of hP-MSCs in the presence of NO, which was identified as a potential mechanism contributing to the enhanced endothelium-protective and proangiogenic capacities of hP-MSCs that promote angiogenesis in mouse models of hindlimb ischemia. In conclusion, this study provides a promising approach for using NO hydrogel to improve the proangiogenic potency of MSCs in ischemic diseases, and the strategy used here facilitates the development of controlled-release scaffolds for enhancing the therapeutic efficiency of MSCs in angiogenic therapy. The heterogeneous proangiogenic nature of mesenchymal stem cells (MSCs) is a key challenge in developing more effective treatments with MSCs for therapeutic angiogenesis purposes. In this study, we investigated whether nitric oxide (NO)-releasing chitosan hydrogel (CS-NO) could improve the proangiogenic potency of MSCs in ischemic diseases. Our results revealed an endothelial-like status transformation of human placenta-derived MSCs (hP-MSCs) in the presence of NO, which was identified as a potential mechanism contributing to the enhanced endothelium-protective and proangiogenic capacities of hP-MSCs that promote angiogenesis in mouse models of hindlimb ischemia. The strategy for enhancing the pro-angiogenic activity of MSCs with biomaterials provides a practical idea for overcoming the challenges associated with the clinical application of MSCs in therapeutic angiogenesis. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Abstract: Aplastic anemia (AA) is a marrow failure syndrome mediated by aberrant T-cell subsets. Mesenchymal stem cells (MSCs) play an important role in maintaining immune homeostasis through modulating a variety of immune cells. However, little is known about the immunomodulation potential of bone marrow MSCs (BM-MSCs) in AA. Here, we reported that BM-MSCs from AA patients were reduced in suppressing the proliferation and clonogenic potential of CD4+ T cells and the production of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), which was associated with decreased prostaglandin E2 (PGE2). Meanwhile, BM-MSCs from AA patients were defective to promote CD4+CD25+FOXP3+ regulatory T cells expansion through reduced transforming growth factor-β (TGF-β). No significant difference between AA and normal BM-MSCs was observed in affecting the production of interleukins (IL)-4, IL-10 and IL-17. Our data indicate that BM-MSCs were impaired in maintaining the immune homeostasis associated with CD4+ T cells, which might aggravate the marrow failure in AA. [Copyright &y& Elsevier]

Abstract: There is a growing interest in the clinical application of stem cells as a novel therapeutic approach for treatment of myocardial infarction and prevention of subsequent heart failure. Transplanted stem cells improve cardiac functions through multiple mechanisms, which include but are not limited to promoting angiogenesis, replacing dead cardiomyocytes, modulating cardiac remodeling. Most of the results obtained so far are exciting and very promising, spawning an increasing number of clinical trials recently. However, many problems still remain to be resolved such as the best delivery method for transplantation of cells to the injured myocardium and the issue of how to optimize the delivery of targeted cells is of exceptional clinical relevance. In this review, we focus on the different delivery strategies in cardiac regenerative therapy, as well as provide a brief overview of current clinical trials utilizing cell-based therapy in patients with ischemic heart disease. [Copyright &y& Elsevier]

Cellular therapy has emerged as a potentially novel treatment for severe ischemic heart disease, and there is increasing evidence that stem cell transplantation may improve the perfusion and contractile function of ischemic myocardium. However, the problem of poor donor cell engraftment and survival in ischemic myocardium limits the successful use of cellular therapy for treating ischemic heart disease. This review discusses the state-of-the-art understanding of the low level of cell engraftment and cell survival after transplantation into the ischemic heart, with a focus on the approaches that have been investigated for supporting and improving the survival and engraftment of transplanted cells in this setting. [ABSTRACT FROM AUTHOR]

Summary: Recruited bone marrow-derived circulating cells (RBCCs) play a key role in therapeutic neovascularization. Several important steps take place during this process, which include mobilization, migration, recruitment, adhesion and invasion, entrapment, differentiation, as well as paracrine functions. Recent study indicated that recruitment and entrapment of RBCCs are vital steps in vascular endothelial growth factor (VEGF)-induced angiogenesis. This entrapment is modulated by another important chemokine: stromal derived factor 1 (SDF-1). We reason that the enhancement of entrapment might be a novel target for therapeutic neovascularization. Therefore we hypothesize that mesenchymal stem/stromal cells that secrete VEGF in situ could be transfected with SDF-1 (MSCSDF-1). Their combination could augment mobilization, recruitment, survival, and above all the entrapment of RBCCs, all of which might greatly augment the angiogenesis pathway. For these reasons, we further hypothesize that MSCSDF-1 might become a next generation cell/chemokine therapy for therapeutic neovascularization. [Copyright &y& Elsevier]

Abstract: Angiogenesis, the generation of new blood capillaries from preexisting blood vessels, is tightly regulated in the adult organism. Although many of the initial studies were performed on solid tumors, increasing evidence indicates that angiogenesis also plays an important role in hematologic malignancies. Overexpression of angiogenic factors in particular VEGF and bFGF in most hematologic malignancies may explain the increased angiogenesis found in these malignancies and correlate with poor prognosis as well as decreased overall survival. In this review, we focus on the current literature of angiogenesis and antiangiogenic therapy in hematologic malignancies, and finally describe advances and potential challenges in antiangiogenic treatment in hematologic malignancies. [Copyright &y& Elsevier]

Background: Cell transplantation offers the promise in the restoration of cardiac function after myocardial infarction. We investigate the therapeutic potential of human umbilical cord derived stem (UCDS) cells in a rat myocardial infarction model. Methods: Two weeks after induction of myocardial infarction, the surviving rats with left ventricular ejection fraction less than 60% were randomly divided into a phosphate-buffered saline control group and a UCDS cell treated group. Cardiac function was assessed by echocardiography 2 weeks and 4 weeks after cell transplantation. Histologic study and immunofluorescence were performed to investigate differentiation of transplanted cells, capillary and arteriole density, secretion of cytokines, and cardiomyocytes apoptosis. Results: A statistically significant improvement of cardiac function was observed in the experimental group of rats compared with the control group. Four weeks after transplantation, histologic examination revealed that some of the transplanted UCDS cells survived in the infarcted myocardium and accumulated around arterioles and scattered in capillary networks. We observed some of the cells expressed cardiac troponin-T, von Willebrand factor, and smooth muscle actin, indicating regeneration of damaged myocardium by cardiomyocytic, endothelial, and smooth muscle differentiation of UCDS cells in the infarcted myocardium. The capillary and arteriole density were also markedly increased in the UCDS-cell–treated group. In addition, the apoptotic cells were decreased significantly compared with the phosphate-buffered saline controls. Conclusions: Our findings demonstrate that transplanted UCDS cells provide benefit in cardiac function recovery after acute myocardial infarction in rats, suggesting UCDS cells represent a promising cell source for future routine cell therapy applications. [Copyright &y& Elsevier]

Summary: The limited ability of the heart to regenerate damaged tissue following a myocardial infarct results in progressive dysfunctions and consequently leads to heart failure. Cell therapy with stem cells for cardiac repair is emerging as an alternative strategy and demonstrates promising results. Recent advances suggest human umbilical cord may be a new source for stem cells. Human umbilical cords are easy to obtain and umbilical cord derived stem cells can be easily extracted and cryopreserved, allowing for individuals to store their own samples for possible future autologous use even if there were no immediate indication that stem cell therapy would be required. Therefore, we hypothesize that human umbilical cord derived stem cells may be the new cell source for the injured heart. [Copyright &y& Elsevier]

Summary: Microvascular insufficiency represents a major cause of end-organ failure among diabetics. Prevention at early stage of disease is therefore necessary and is a focus of current investigations. Progression of diabetes is complicated by endothelial cell apoptosis as well as occlusion of arteriole and capillary leading to microvascular rarefaction. This favors the formation of non-healing limb ulcers and limits the benefit of revascularization. Recent study indicated that reduction of platelet derived growth factor (PDGF) expression was indeed critical, in causing functional and morphological vascular changes, namely the dissociation of pericytes from the capillaries in muscles. Diabetic microangiopathy is a result of pericytes dissociation from reduced PDGF as well as vessel rarefaction from reduced number of endothelial progenitor cells (EPCs) and EPC dysfunction. Since blood vessels develop through the assembly of these two principal cell types – endothelial cells and pericytes/smooth muscle cells, prevention of diabetic microangiopathy requires interventions targeting at both cell types in a complementary and synergistic manner. An improved recruitment of EPCs will help repair of injured endothelium while molecular targeting with PDGF will enhance pericytes recruitment. EPCs modified with PDGF therefore hold promise as the next generation of agents for prevention of microangiopathy. [Copyright &y& Elsevier]

Abstract: Acquired aplastic anemia (AA) is considered as an immune-mediated bone marrow failure syndrome, characterized by hypoplasia and pancytopenia with fatty bone marrow. Abnormal immunity is the major factor mediating the pathogenesis of acquired AA. Activated DCs might promote the polarization to Th1 cells, and activate CD8+ T cells. A variety of immune molecules including IFN-γ, TNF-α, MIP-1α and IL-2, 8, 12, 15, 17, 23, produced by them and stromal cells, compose a cytokine network to destruct stem/progenitor cells as well as hematopoietic stem/progenitor cells, mesenchymal stem cells (MSCs) and angioblasts/endothelial progenitor cells. Inversely, deficient MSCs, CD4+CD25+ T cells, NK cells, NKT cells and early hematopoietic growth factors diminish the capacity of immune regulation and the support of hematopoiesis. As a result, stem/progenitor cells are significantly impaired to be disabled cells with markedly deficient proliferation, differentiation, induced apoptosis and dysfunctional response to growth factor stimuli, together with rare normal ones. Although some patients can be ameliorated by stem-cell transplantation or immunosuppressive therapy, more effective and convenient therapies such as patient-specific pluripotent iPS cells based on definite pathogenesis are expected. [Copyright &y& Elsevier]

Abstract: Introduction of antigen into anterior chamber (AC) induces a deviant immune response termed anterior chamber-associated immune deviation (ACAID) that protects the eye from inflammatory destruction consequent to a systemic immune response. Mesenchymal stem cells (MSCs) can modulate a variety of immune responses. However, the effects of systemic administration of MSCs on ACAID have not been explored. In this study, C57BL/6 mice were inoculated with ovalbumin in the AC to induce ACAID, control group received AC injection of solvent alone. Immediately after the AC injection, the mice were injected through the tail vein with human Umbilical Cord-derived MSCs (hUC-MSC) or phosphate buffer saline. All animals were subcutaneously immunized with ovalbumin one week later. Delayed-type hypersensitivity assay was performed another week following immunization. The splenic monocytes were then isolated, cultured and stimulated with ovalbumin. Levels of IL-10, TGF-β, and IFN-γ in culture media were measured by ELISA. The frequencies of CD4+CD25+Foxp3+ and CD8+Foxp3+ regulatory T cells (Tregs) were determined by flow cytometry. The results showed that the AC inoculation of ovalbumin induced significantly less ear swelling than controls, confirming the establishment of ACAID. MSCs potentiated IL-10 and TGF-β production, further suppressed IFN-γ secretion from splenic monocytes in ACAID mice, and enhanced expansion of CD4+CD25+Foxp3+ and CD8+Foxp3+ Tregs isolated from the spleen of ACAID mice. Therefore, our study, for the first time, provides clear evidence that systemic administration of MSCs augments cytokine production and Treg expansion from ACAID spleens, which may contribute to promotion and maintenance of ACAID. [Copyright &y& Elsevier]

Summary: Interleukin-27 (IL-27) is a novel IL-12 family member that plays a critical role in the regulation of T-cell responses. Its immunoregulatory effects on endothelial cells (EC) remain unexplored. Here we show a role for IL-27 in the induction of major histocompatibility complex (MHC) expression in primary human EC. Stimulation of human umbilical vein ECs by IL-27 rapidly induces IFN regulatory factor–1 and dramatically increases the expression of major histocompatibility class II transactivator (CIITA) isoform IV. Expression of this transactivator correlates with increased MHC class II gene expression. IL-27 also enhances expression of MHC class I molecules. Furthermore expression of β2-microglobulin and transporter associated with antigen processing–1 transcripts increases in response to IL-27. Additional microarray analysis demonstrates that IL-27 significantly upregulates a panel of genes that correlates with immune regulation, including the chemokines CXCL9, CXCL10, and CX3CL1 in human umbilical vein ECs. This first demonstration that both MHC II and I expression are increased in EC after IL-27 stimulation suggests that IL-27 may be important in conferring immune function on vascular endothelium. [Copyright &y& Elsevier]

Abstract: Cardiovascular diseases are the leading cause of morbidity and mortality. Tissue engineering offers new option in the myocardial repair techniques. The cellular component of this regenerative approach will play a key role in bringing these tissue engineered constructs from the laboratory bench to the clinical bedside. However, the ideal source of cells still remains unclear and may differ depending upon the application. Current research for many applications is focused on the use of stem cells. The combination of stem cell technology and tissue engineering has been investigated and offers promising avenues for myocardial tissue regeneration, and this shows great promise in future reconstructive surgery. We explore the basic concepts and methods for myocardial tissue reconstruction and emphasize the progress made and remaining challenges of stem cells in myocardial tissue engineering. [Copyright &y& Elsevier]

Abstract: Excision repair cross-complementation group 1 (ERCC1) is important in repairing DNA damage and genomic instability, and polymorphisms in ERCC1 may play a role in human tumors. In this study, the relationship of two ERCC1 polymorphisms, 8092C > A and 19007G > A, with susceptibility to acute lymphoblastic leukemia (ALL) was investigated in 183 childhood patients. For the ERCC1 8092C > A polymorphism, individuals carrying the ERCC1 8092CC genotype had a significantly higher risk when compared with those carrying at least one A allele gene (AA/AC). Analysis after stratification for sex showed that the males carrying ERCC1 8092CC genotype were associated with highly significant increased risk of ALL (1.94-fold) but not females. There was no association between ERCC1 19007G > A polymorphism and ALL risk when all patients as a group were analyzed. However, the males carrying ERCC119007A allele were associated with highly significant increased risk of ALL (2.36-fold). For the ERCC1 8092C > A polymorphism, individuals under 8 years old (median age) carrying CC genotype had significantly higher risk. However, the 19007G > A polymorphism was not associated with such age-related ALL risk. These results suggest that the ERCC1 8092C > A polymorphism may be related to the occurrence of childhood ALL in a Chinese population. [Copyright &y& Elsevier]

Abstract: Peroxisome proliferator-activated receptor γ (PPAR-γ) belongs to the family of nuclear hormone receptors (NHRs) and is a ligand-activated transcription factor. There are four mRNAs, PPAR-γ1, PPAR-γ2, PPAR-γ3 and PPAR-γ4, which encode two proteins, PPAR-γ1and PPAR-γ2. PPAR-γ consists of five or six structural regions (A–F) in four functional domains. The NH2-terminal A/B domain harbors a ligand-independent transcriptional activation function (AF-1), the C domain is a DNA binding domain (DBD), the D hinge region is important for co-factor docking and the complex multifunctional COOH-terminal portion (E/F) encompasses the ligand binding domain (LBD), a dimerization interface and the ligand-dependent activation domain AF-2. Some long-chain polyunsaturated fatty acids, arachidonic acid metabolites and fatty acid derived components are natural ligands of PPAR-γ. The anti-diabetic thiazolidinedione class of drugs, certain non-steroidal anti-inflammatory drugs (NSAIDs) and some non-thiazolidinedione tyrosine are the synthetic ligands of PPAR-γ. After activation, it forms heterodimer with the retinoid X receptor (RXR) and then binds to specific recognition sites in the target gene, the peroxisome proliferator response elements (PPREs), and regulates transcription of specific genes. PPAR-γ has potential anti-neoplastic effects both in solid cancer and in leukemia through inhibition of cell proliferation, induction of apoptosis and terminal differentiation, as well as inhibition of angiogenesis. The ligands of PPAR-γ may represent a promising, novel therapeutic approach for certain human malignancies. [Copyright &y& Elsevier]

Transfusion of ex vivo expanded megakaryocyte (MK) progenitor cells has been suggested to shorten the time of platelet recovery in the thrombocytopenia induced by radiotherapy or chemotherapy. Here, we report an effective and simple expansion system of MK progenitor cells from cord blood (CB) CD34+ cells using a combination of thrombopoietin (TPO), interleukin (IL)-11, and heparin. When the CB CD34+ cells were cultured in a liquid expansion system in the presence of TPO + recombination human (rh)IL-11 + heparin for 7 days, the number of CB CD34+/CD41a+ cells was significantly increased compared to control groups (p < 0.05). When the suspension cells collected from 7-day liquid culture were replated in semisolid cultures, increased large MK colonies were observed in the culture with combination of TPO + IL-11 + heparin compared to those of control groups. In vivo, transfusion of CD34+ cells expanded with TPO + IL-11 + heparin into irradiated nonobese diabetic/severe combined immunodeficient mice significantly accelerated platelet recovery. These data indicate that heparin as effective cofactor for TPO and IL-11 promotes expansion of MK progenitor cells from CB CD34+ cells. This expansion system is simple and effective and could be used for the treatment of thrombocytopenia after radiotherapy or chemotherapy. [Copyright &y& Elsevier]

Abstract: Severe acute respiratory syndrome (SARS) is a highly infectious disease caused by a novel coronavirus (SARS-CoV). Specific monoclonal antibodies (mAbs) against the SARS-CoV are vital for early diagnosis and pathological studies of SARS. Direct intrasplenic inoculation of plasmid DNA encoding antigen is an effective and fast approach to generate specific mAb when the protein antigen is difficult to prepare or dangerous in use. In this study, we selected one fragment of SARS-CoV spike protein (S1-3) as antigenic determinant by immunoinformatics. Single intrasplenic immunization of plasmid DNA encoding S1-3 induced anti-spike protein antibodies. We established one hybridoma cell line secreting specific mAb and evaluated this mAb with murine leukemia virus pseudotyped with SARS-CoV spike protein (MLV/SARS-CoV). The mAb could recognize the spike protein on the MLV/SARS-CoV-infected Vero E6 cells albeit with no neutralizing effect on the infectivity of the pseudotype virus. Our results show that a single-shot intrasplenic DNA immunization is efficient for the production of specific mAb against SARS spike protein, and a linear epitope of the spike protein is recognized in this study. [Copyright &y& Elsevier]

Abstract: Freshly isolated or culture-expanded human umbilical cord blood mononuclear cells (CBMNCs) have been known to express neural phenotypes in vitro and to differentiate into neural cells and improve neurological function recovery after being administrated into rodent models of neurological diseases. However, the mechanism of action remains unclear. The present study observed that CBMNCs expressed higher level mRNAs of several neurotrophic factors than adult peripheral blood mononuclear cells (PBMCs). In addition, a significantly increase in the levels of brain-derived neurotrophic factor (BDNF) and neurotrophin-4/5 (NT4/5) was found in culture supernatants of CBMNCs compared to that of PBMNCs. These findings indicate that CBMNCs express several neurotrophic factors and suggest that the neurotrophic factors secreted by CBMNCs may be responsible for amelioration of central nervous system deficits in animal models after CBMNC administration. [Copyright &y& Elsevier]

Abstract: Idiopathic thrombocytopenic purpura (ITP) is an organ-specific autoimmune disorder characterized by a low platelet count and mucocutaneous bleeding. The decrease of platelets is caused by increased autoantibodies against self-antigens, particularly IgG antibodies against GPIIb/IIIa. The production of these autoantibodies by B cells depends on a number of cellular mechanisms that form a network of modulation, with T cells playing a pivotal role in pathophysiology. Delineation of the dysfunction of cellular immunity has recently been attempted. This review will focus on these recent advances applicable to ITP and to highlight how these may translate into novel approaches to treatment in the future. Multi-dysfunction in these networks may include a failure of self-antigen recognition and tolerance, involvement of abnormal cell surface molecules, altered Th1/Th2 cytokine profiles, impaired megakaryocytopoiesis and impaired cell-mediated cytotoxicity. In ITP, multi-step dysfunctions in these networks may take place that finally lead to the occurrence of the disease. Therefore, unveiling these dysfunctions is vital in understanding the pathophysiology of ITP and will finally lead to the development of new therapies to fight the disease. [Copyright &y& Elsevier]

CD44 is a cell surface antigen that expresses on leukemia blasts from most acute myeloid leukemia (AML) patients. It has been reported that ligation of CD44 with some specific anti-CD44 monoclonal antibodies can reverse the differentiation blockage of leukemia cell lines. In this study, the differentiation and apoptosis-inducing effects of HI44a, another anti-CD44 monoclonal antibody (IgG2a), were investigated on leukemia cells obtained from 31 patients with AML-M2, AML-M3, AML-M4 or AML-M5. When the AML cells were treated with HI44a, the percentage of nitroblue tetrazolium (NBT)+ cells was significantly increased. The expression of CD11b, CD14 and CD15 on treated AML cells was also increased compared to control AML cells. In addition, HI44a was found to induce apoptosis of leukemia cells, as evidenced by an annexin-V assay. The mean percentage of apoptotic cells in HI44a-treated AML cells was significantly increased compared to that in control AML cells. Moreover, the level of c-myc transcript expression on AML cells was found to be obviously decreased in all detected patients. These results indicate that HI44a effectively induces both differentiation and apoptosis of AML cells and suggest that this activity of the anti-CD44 antibody may be associated with its inhibitory effect on c-myc transcript expression. [Copyright &y& Elsevier]

Platelet factor 4 (PF4) is a growth regulator of hematopoietic stem/progenitor cells (HSPCs), but its role in modulating the adhesive property of normal and leukemic cells remains unclear. We used CD34+ cord blood cells, KG1a cell line, human umbilical vein endothelial cells (HUVECs) and a transformed HUVECs ECV-304 cells to study the effect of PF4 on cell adhesion. When CD34+ cord blood cells were cultured either in fibronectin-coated (FN) culture plate or over the layer of HUVECs for 2 h, a concentration-dependent increase of the number of adhered cells was observed in the culture containing PF4. FACS analysis revealed that the treatment of PF4 resulted in an increased expression of CD49d and CXCR-4 on CD34+ cells. Moreover, when CD34+ cells were expanded in the presence of PF4, the adhesive ability to culture plate of CD34+ cells was significantly increased. To elucidate the mechanism of action of PF4, KG1a cells were incubated with or without PF4 for 2 h on pre-established layer of ECV-304 cells. The percentage of CD49d+ KG1a cells increased about 1.56±0.4 fold, and that of CD54+ ECV-304 increased about 1.7±0.6 fold. Furthermore, the mRNA expression of CD49d and CD54 was upregulated when KG1a or ECV-304 cells were incubated with PF4. The adhesion capacity of KG1a cells was reduced after incubation with the blocking monoclonal antibodies against CD49d and CD54, respectively. Our data demonstrate that PF4 is able to enhance the adhesive ability of normal and leukemia HSPCs. [Copyright &y& Elsevier]

Recent investigations support the idea that angiogenesis is involved in the pathophysiology of leukemia. Within a given microenvironment, the angiogenic response is regulated by a delicate balance of angiogenesis inducers and inhibitors. Thrombospondin-1 (TSP-1) is a multifunctional extracellular glycoprotein showing angiostatic properties in multiple in vitro and in vivo assays. Interestingly, there is also proangiogenic domain in this complex molecule. Development of TSP-1 as an antiangiogenic drug has been hindered by multiplicity of its functional effects, difficulties in its production and its poor pharmacokinetics. The aim of the present study was to establish a recombinant adenovirus (ADV·TSP-1f) expressing antiangiogenic fragment of TSP-1 (TSP-1f), and to determine the feasibility for use of the adenovirally expressed TSP-1f in leukemia gene therapy. The results of this investigation showed that TSP-1f was expressed efficiently in adenovirus-transduced human myelogenous leukemia K562 cells. Compared to the controls, although there was almost no effect on proliferation of K562 cells in vitro, adenovirus-mediated TSP-1f transduction inhibited the growth of K562 xenografts dramatically. Furthermore, the microvessel density (MVD) was much lower in the ADV·TSP-1f-treated tumors compared to the controls. These data support the use of in vivo gene delivery approach to produce antiangiogenic fragment of TSP-1 for leukemia therapy. [Copyright &y& Elsevier]