Xiaofeng Luo

The immunogenicity of platelet-derived FVIII in hemophilia A mice with or without preexisting anti-FVIII immunity

Evidence shows that factor VIII (FVIII) ectopically expressed in platelets (2bF8) is therapeutic in FVIII(null) mice even with anti-FVIII inhibitory antibodies (inhibitors). If current efforts to generate platelets in vitro succeed, genetically manipulated platelets containing FVIII may be used therapeutically in hemophilia A patients with inhibitors. One important concern is the immunogenicity of platelet-derived FVIII. To address this concern, we infused 2bF8 transgenic (2bF8(Tg)) platelets into naïve FVIII(null) mice weekly for 8 weeks. No anti-FVIII antibodies were detected in the infused animals during the study course. We then explored whether platelet-derived FVIII is immunogenic in FVIII(null) mice with inhibitors. The 2bF8(Tg) platelets were transfused into rhF8-primed FVIII(null) mice, resulting in no augmentation of anti-FVIII antibodies. To investigate whether preconditioning affects the immune response, animals were sublethally irradiated and subsequently transfused with 2bF8(Tg) platelets. No anti-FVIII antibodies were detected in the recipients after platelet infusions. Following further challenge with rhF8, the inhibitor titer in this group was significantly lower than in naïve FVIII(null) mice utilizing the same immunization protocol. Thus, our data demonstrate that infusion of platelets containing FVIII triggers neither primary nor memory anti-FVIII immune response in FVIII(null) mice and that sublethal irradiation plus 2bF8(Tg) platelet infusion suppresses anti-FVIII immune response in FVIII(null) mice.

Bone marrow-derived mesenchymal stem cells overexpressing MiR-21 efficiently repair myocardial damage in rats

Objective We investigated the ability of bone marrow derived mesenchymal stem cells (BMSCs) overexpressing microRNA-21 (miR-21) to repair cardiac damage induced by anthracyclines in rats. Methods Sprague-Dawley (SD) rats of 2~3 weeks old were selected to isolate and culture BMSCs. A lentivirus harboring pLVX-miR-21 was generated and transfected into rat BMSCs. The rats were assigned into an untreated negative control group, and groups injected with adriamycin alone or with adriamycin followed by BMSCs, pLVX-BMSCs or pLVX-miR-21-BMSCs (n = 10 each). Proliferation and migration of cells were detected by cholecystokinin-8 (CCK- 8) and transwell. MiR-21 expression, mRNA expressions of B cell lymphoma 2 (Bcl2), BAX (BCL-2-associated X protein) and vascular endothelial growth factor (VEGF) were tested by qRT-PCR. Western blotting was applied to detect protein expressions of Bcl-2, Bax and VEGF. Results Using CCK- 8 and transwell assays, we found that pLVX-miR-21-BMSCs, which overexpressed miR-21, exhibited greater proliferation and migration than untransfected BMSCs or pLVX-BMSCs. Ultrasonic cardiograms and immunohistochemical analysis demonstrated that among the five groups, the pLVX-miR-21-BMSC group exhibited the most improved heart function and enhanced angiogenesis. Moreover, the pLVX-miR-21-BMSC group showed enhanced expression of Bcl-2, VEGF and Cx43 and reduced expression of Bax, BNP and troponin T. Conclusion These findings suggest miR-21 overexpression enhanced the proliferation, invasiveness and differentiation of BMSCs as well as expression of key factors (Bcl-2, VEGF and Bax) essential for repairing the cardiac damage induced by anthracyclines and restoring heart function.

Immune tolerance induced by platelet‐targeted factor VIII gene therapy in hemophilia A mice is CD4 T cell mediated

Essentials The immune response is a significant concern in gene therapy. Platelet‐targeted gene therapy can restore hemostasis and induce immune tolerance. CD4 T cell compartment is tolerized after platelet gene therapy. Preconditioning regimen affects immune tolerance induction in platelet gene therapy.

TGF-β1 along with other platelet contents augments Treg cells to suppress anti-FVIII immune responses in hemophilia A mice

Platelets are a rich source of many cytokines and chemokines including transforming growth factor β 1 (TGF-β1). TGF-β1 is required to convert conventional CD4+ T (Tconv) cells into induced regulatory T (iTreg) cells that express the transcription factor Foxp3. Whether platelet contents will affect Treg cell properties has not been explored. In this study, we show that unfractionated platelet lysates (pltLys) containing TGF-β1 efficiently induced Foxp3 expression in Tconv cells. The common Treg cell surface phenotype and in vitro suppressive activity of unfractionated pltLys-iTreg cells were similar to those of iTreg cells generated using purified TGF-β1 (purTGFβ-iTreg) cells. However, there were substantial differences in gene expression between pltLys-iTreg and purTGFβ-iTreg cells, especially in granzyme B, interferon γ, and interleukin-2 (a 30.99-, 29.18-, and 17.94-fold difference, respectively) as determined by gene microarray analysis. In line with these gene signatures, we found that pltLys-iTreg cells improved cell recovery after transfer and immune suppressive function compared with purTGFβ-iTreg cells in factor VIII (FVIII)-deficient (F8null, hemophilia A model) mice after recombinant human FVIII (rhF8) infusion. Acute antibody-mediated platelet destruction in F8null mice followed by rhF8 infusion increased the number of Treg cells and suppressed the antibody response to rhF8. Consistent with these data, ex vivo proliferation of F8-specific Treg cells from platelet-depleted animals increased when restimulated with rhF8. Together, our data suggest that pltLys-iTreg cells may have advantages in emerging clinical applications and that platelet contents impact the properties of iTreg cells induced by TGF-β1.

A 5-day cytoreductive chemotherapy followed by haplo-identical hsct (FA5-BUCY) as a tumor-ablative regimen improved the survival of patients with advanced hematological malignancies

Haplo-HSCT has been used when HLA-matched siblings are not available. Conditioning regimens aim to reduce tumor burden prior to HSCT and provide sufficient immunoablation. We report the outcome of haplo-HSCT in 63 consecutive patients from 2/2013 to 12/2015 (19 females/44 males) with high-risk or relapsed/refractory hematological malignancies (n=29-AML; 8-sAML; 19-ALL; 5-advanced-MDS; 2-CML-BC). Median age was 20 years (range: 1.1-49). Twenty-one patients achieved remission prior to transplant, while 42 did not. Patients received FA5-BUCY, i.e., 5-day salvage chemotherapy (Fludarabine/Ara-C) and conditioning (Busulfan/Cyclophosphamide). GvHD prophylaxis included ATG, CsA, MMF and short-term MTX. All patients received stem cells from bone marrow and peripheral blood, and achieved successful engraftment, except two who died before. With a median follow-up of 269 days (120-1081), 42/63 patients are still alive and disease-free. Two-year OS and RFS were similar in patients not in remission and in those in complete remission (61.3% vs 56.3%, p=0.88; 58.3% vs 56.3%, p=0.991). Non-relapse mortality and relapse incidence were 22.2% and 11.1%, respectively. Severe acute-GvHD occurred in 4/63 patients. Transplant-related mortality was low at day+100 (17.5%) and for the entire study period (20.6%). Unexpectedly, few patients experienced mild-to-moderate toxicity, and main causes of death were infection and GvHD. BM blast counts, age, and donor-recipient gender-pairs did not affect the outcome. Less chemotherapy cycles prior to HSCT might result in more favorable outcome. Thus, haplo-HSCT with FA5-BUCY appears promising for advanced disease, especially when TBI and amsacrine, used for FLAMSA, are not available and in pediatric patients for whom TBI is not recommended.

Platelet Gene Therapy Promotes Targeted Peripheral Tolerance by Clonal Deletion and Induction of Antigen-Specific Regulatory T Cells

Delivery of gene therapy as well as of biologic therapeutics is often hampered by the immune response of the subject receiving the therapy. We have reported that effective gene therapy for hemophilia utilizing platelets as a delivery vehicle engenders profound tolerance to the therapeutic product. In this study, we investigated whether this strategy can be applied to induce immune tolerance to a non-coagulant protein and explored the fundamental mechanism of immune tolerance induced by platelet-targeted gene delivery. We used ovalbumin (OVA) as a surrogate non-coagulant protein and constructed a lentiviral vector in which OVA is driven by the platelet-specific αIIb promoter. Platelet-specific OVA expression was introduced by bone marrow transduction and transplantation. Greater than 95% of OVA was stored in platelet α-granules. Control mice immunized with OVA generated OVA-specific IgG antibodies; however, mice expressing OVA in platelets did not. Furthermore, OVA expression in platelets was sufficient to prevent the rejection of skin grafts from CAG-OVA mice, demonstrating that immune tolerance developed in platelet-specific OVA-transduced recipients. To assess the mechanism(s) involved in this tolerance we used OTII mice that express CD4+ effector T cells specific for an OVA-derived peptide. After platelet-specific OVA gene transfer, these mice showed normal thymic maturation of the T cells ruling against central tolerance. In the periphery, tolerance involved elimination of OVA-specific CD4+ effector T cells by apoptosis and expansion of an OVA-specific regulatory T cell population. These experiments reveal the existence of natural peripheral tolerance processes to platelet granule contents which can be co-opted to deliver therapeutically important products.

Emodin and Its Combination with Cytarabine Induce Apoptosis in Resistant Acute Myeloid Leukemia Cells in Vitro and in Vivo

Background/Aims: Acute myeloid leukemia (AML) remains a hematologic malignancy with poor survival and a high risk of relapse, which is mainly caused by the emergence of multidrug resistance (MDR). The identification of novel agents to improve therapeutic strategies becomes important priority for AML treatment. It has been shown that emodin has therapeutic effects on many kinds of human malignant tumors. In this study, we investigated the anti-leukemia effects of emodin alone or in combination with cytarabine (Ara-C) on multidrug-resistant AML HL-60/ADR cells and in a mouse xenograft model of human highly tumorigenic AML HL-60/H3 cells. The underlying mechanism was also addressed. Methods: Cell viability after treatment was measured by MTT assay. The DNA fragmentation assay, Annexin V-PE/7-AAD, AO/EB staining, and electron microscopy were introduced to assess the apoptotic induction effects. Changes in protein expression in the Akt and ERK signaling pathways were determined by western blotting. In vivo antileukemia effects on HL-60/H3 xenograft model and overall mouse survival outcomes were further analyzed in this study. Results: Emodin dose-dependently induced growth inhibition and apoptotic effects in resistant HL-60/ADR cells in vitro as well as in the HL-60/H3 xenograft models in vivo. Moreover, emodin significantly enhanced chemosensitivity of AML cells to Ara-C, inhibited leukemic cell growth, and improved survival in the mouse xenograft model of AML. Dual targeting of Akt and ERK signaling pathways might contribute to the anti-leukemia effects on AML cells in vitro and in vivo. Conclusion: Emodin and its combination with Ara-C may be considered a promising therapeutic approach in AML and worthy of further investigation.

In vitro effects of reprogramming factors on the expressions of pluripotent genes and CD34 gene in human acute promyelocytic leukemia HL-60 cells

OBJECTIVE Our study aims to explore the in vitro effects of reprogramming factors on the expressions of pluripotent genes and CD34 gene in HL-60 cells. METHODS According to the construction of lentiviral vector LV-OSCK of reprogramming factors (Oct-4, Sox2, Klf4, c-Myc), 293T cells were transfected to detect virus titer. The endogenous pluripotent genes (Oct4, SOX2, c-Myc and Klf4) and CD34 mRNA and protein expressions were detected by AP staining, immunofluorescence staining, qRT-PCR and flow cytometry. RESULTS Expressions of Oct4, SOX2, c-Myc and Klf4 were 0.220±0.013, 0.186±0.009, 0.287±0.015 and 0.153±0.007. These levels were significantly higher in the experimental group than the control and blank groups. CD34 protein expression in the experimental group was also discovered to be significantly higher than the other two groups. CONCLUSION The reprogramming factors could increase the expressions of pluripotent genes and CD34 gene in HL-60 cells.

The Construction and Identification of Induced Pluripotent Stem Cells Derived from Acute Myelogenous Leukemia Cells

Objective: The present study aimed to establish an induced pluripotent stem cell (iPSC) line from acute myelogenous leukemia (AML) cells in vitro and identify their biological characteristics. Methods: Cells from the AML-infiltrated skin from an M6 patient were infected with a lentivirus carrying OCT4, SOX2, KLF4 and C-MYC to induce iPSCs. The characteristics of the iPSCs were confirmed by alkaline phosphatase (ALP) staining. The proliferation ability of iPSCs was detected with a CCK-8 assay. The expression of pluripotency markers was measured by immunostaining, and the expression of stem cell-related genes was detected by qRT-PCR; distortion during the induction process was detected by karyotype analysis; the differentiation potential of iPSCs was determined by embryoid body-formation and teratoma-formation assays. ALP staining confirmed that these cells exhibited positive staining and had the characteristics of iPSCs. Results: The CCK-8 assay showed that the iPSCs had the ability to proliferate. Immunostaining demonstrated that iPSC clones showed positive expression of NANOG, SSEA-3, SSEA-4, TRA-1-60 and TRA-1-81. qRT-PCR results revealed that the mRNA expression of Nanog, Lin28, Cripto, FOX3, DNMT3b, DPPA2, and DPPA4 significantly increased in iPSCs. Karyotype analysis found no chromosome aberration in the iPSCs. The results of the embryoid body-formation and teratoma-formation assays indicated that the iPSCs had the potential to differentiate into all three germ layers. Conclusion: Our study provided evidence that an iPSC line derived from AML cells was successfully established.

Effects of Blood Purification on Serum Levels of Inflammatory Cytokines and Cardiac Function in a Rat Model of Sepsis

Objective: The study aimed to explore the effects of blood purification (BP) on serum levels of inflammatory cytokines and cardiac function in a rat model of sepsis. Methods: A rat model of sepsis was established by cecal ligation and puncture. All rats were divided into the normal control, sham operation, model, sham treatment, and BP treatment groups. Cardiac functions, inflammatory cytokines, myocardial enzymes, pathological score of cardiac muscle tissue, and myocardial apoptosis of rats in each group were compared. Results: Sepsis rats had higher serum levels of inflammatory cytokines and lower cardiac function than those in the normal control and sham operation groups. Compared with the model and sham treatment groups, improved cardiac functions, decreased inflammatory cytokines, myocardial enzymes, pathological score, and myocardial apoptosis and mortality were observed in the BP treatment group. Conclusion: BP may reduce serum levels of inflammatory cytokines and improve cardiac function of sepsis rats.