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| 2. |
- Asif, Sana, et al.
(author)
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Heparinization of cell surfaces with short peptide-conjugated PEG-lipid regulates thromboinflammation in transplantation of human MSCs and hepatocytes
- 2016
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In: Acta Biomaterialia. - : Elsevier BV. - 1742-7061 .- 1878-7568. ; 35, s. 194-205
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Journal article (peer-reviewed)abstract
- Infusion of therapeutic cells into humans is associated with immune responses, including thromboinflammation, which result in a large loss of transplanted cells\ To address these problems, heparinization of the cell surfaces was achieved by a cell-surface modification technique using polyethylene glycol conjugated phospholipid (PEG-lipid) derivatives. A short heparin-binding peptide was conjugated to the PEG-lipid for immobilization of heparin conjugates on the surface of human mesenchymal stem cells (hMSCs) and human hepatocytes. Here three kinds of heparin-binding peptides were used for immobilizing heparin conjugates and examined for the antithrombogenic effects on the cell surface. The heparinized cells were incubated in human whole blood to evaluate their hemocompatibility by measuring blood parameters such as platelet count, coagulation markers, complement markers, and Factor Xa activity. We found that one of the heparin-binding peptides did not show cytotoxicity after the immobilization with heparin conjugates. The degree of binding of the heparin conjugates on the cell surface (analyzed by flow cytometer) depended on the ratio of the active peptide to control peptide. For both human MSCs and hepatocytes in whole-blood experiments, no platelet aggregation was seen in the heparin conjugate-immobilized cell group vs. the controls (non-coated cells or control peptide). Also, the levels of thrombin-antithrombin complex (TAT), C3a, and sC5b-9 were significantly lower than those of the controls, indicating a lower activation of coagulation and complement. Factor Xa analysis indicated that the heparin conjugate was still active on the cell surface at 24 h post-coating. It is possible to immobilize heparin conjugates onto hMSC and human hepatocyte surfaces and thereby protect the cell surfaces from damaging thromboinflammation. Statement of Signigficance We present a promising approach to enhance the biocompatibility of therapeutic cells. Here we used short peptide-conjugated PEG-lipid for cell surface modification and heparin conjugates for the coating of human hepatocytes and MSCs. We screened the short peptides to find higher affinity for heparinization of cell surface and performed hemocompatibility assay of heparinized human hepatocytes and human MSCs in human whole blood. Using heparin-binding peptide with higher affinity, not only coagulation activation but also complement activation was significantly suppressed. Thus, it was possible to protect human hepatocytes and human MSCs from the attack of thromboinflammatory activation, which can contribute to the improvement graft survival. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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| 3. |
- Asif, Sana, M.D, PhD student
(author)
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Regulation of thromboinflammation in therapeutic medicine : Special focus on surface coating strategies
- 2019
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Doctoral thesis (other academic/artistic)abstract
- Biomaterials are an integral part of modern health care and offer potential treatment modalities to diseases and conditions otherwise intractable. However, the critical issue herein is incompatibility reactions.Our innate immune system is fundamental in protection against pathogens and foreign intruders and controls the discrimination between self and non-self. Biomaterials come in contact with blood upon implantation where they are sensed by innate immune mediators which through a cascade of complex, multifaceted reactions induce inflammation as well as thrombosis which may induce biomaterial dysfunction and rejection. This explains why patients undergoing haemodialysis therapy exhibit an increased incidence of whole-body inflammation and other thrombotic events. Similarly, therapeutic cells such as hepatocytes upon implantation initiate an instant blood mediated inflammatory reaction, responsible for cell damage and death via apoptosis.In order to achieve safer and more efficient therapeutic interventions, engineering of materials and cells that can avoid these adverse reactions is essential. Fabrication of biomaterials consisting of coating of bioinert polymers to avoid immune recognition and activation is a promising approach to modulate immune reactions.In this thesis, we have employed a PEG-lipid polymer coating, which intercalates in to biomembranes via hydrophobic interactions and thus shields from immune rejection. Treatment with PEG-lipid not only makes the surface “invisible” to immune cells but it also acts as a filter which prevents entry of immune cells without inducing cytotoxicity. Results from this thesis illustrate that fabrication of bio-surfaces by bio-inert PEG-lipid polymer is a harmless procedure which not only attenuates thrombo-inflammation but also assist in design of self-tailored materials for a wide range of biomedical applications.
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| 4. |
- Asif, Sana, M.D, PhD student, et al.
(author)
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Validation of an MPC polymer coating to attenuate surface- induced cross-talk between the complement and coagulation systems in whole blood in in vitro and in vivo models
- 2019
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In: Macromolecular Bioscience. - : Wiley-VCH Verlagsgesellschaft. - 1616-5187 .- 1616-5195. ; 19:5
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Journal article (peer-reviewed)abstract
- Artificial surfaces that come into contact with blood induce an immediate activation of the cascade systems of the blood, leading to a thrombotic and/or inflammatory response that can eventually cause damage to the biomaterial or the patient, or to both. Heparin coating has been used to improve hemocompatibility, and another approach is 2-methacryloyloxyethyl phosphorylcholine (MPC)-based polymer coatings. Here, the aim is to evaluate the hemocompatibility of MPC polymer coating by studying the interactions with coagulation and complement systems using human blood in vitro model and pig in vivo model. The stability of the coatings is investigated in vitro and MPC polymer-coated catheters are tested in vivo by insertion into the external jugular vein of pigs to monitor the catheters' antithrombotic properties. There is no significant activation of platelets or of the coagulation and complement systems in the MPC polymer-coated one, which was superior in hemocompatibility to non-coated matrix surfaces. The protective effect of the MPC polymer coat does not decline after incubation in human plasma for up to 2 weeks. With MPC polymer-coated catheters, it is possible to easily draw blood from pig for 4 days in contrast to the case for non-coated catheters, in which substantial clotting is seen.
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| 5. |
- Gustafson, Elisabet, et al.
(author)
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Control of IBMIR Induced by Fresh and Cryopreserved Hepatocytes by Low Molecular Weight Dextran Sulfate Versus Heparin
- 2017
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In: Cell Transplantation. - : Sage Publications. - 0963-6897 .- 1555-3892. ; 26:1, s. 71-81
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Journal article (peer-reviewed)abstract
- Rapid destruction of hepatocytes after hepatocyte transplantation has hampered the application of this procedure clinically. The instant blood-mediated inflammatory reaction (IBMIR) is a plausible underlying cause for this cell loss. The present study was designed to evaluate the capacity of low molecular weight dextran sulfate (LMW-DS) to control these initial reactions from the innate immune system. Fresh and cryopreserved hepatocytes were tested in an in vitro whole-blood model using ABO-compatible blood. The ability to elicit IBMIR and the capacity of LMW-DS (100 mu g/ml) to attenuate the degree of activation of the cascade systems were monitored. The effect was also compared to conventional anticoagulant therapy using unfractionated heparin (1 IU/ml). Both fresh and freeze thawed hepatocytes elicited IBMIR to the same extent. LMW-DS reduced the platelet loss and maintained the cell counts at the same degree as unfractionated heparin, but controlled the coagulation and complement systems significantly more efficiently than heparin. LMW-DS also attenuated the IBMIR elicited by freeze thawed cells. Therefore, LMW-DS inhibits the cascade systems and maintains the cell counts in blood triggered by both fresh and cryopreserved hepatocytes in direct contact with ABO-matched blood. LMW-DS at a previously used and clinically applicable concentration (100 mu g/ml) inhibits IBMIR in vitro and is therefore a potential IBMIR inhibitor in hepatocyte transplantation.
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| 8. |
- Nilsson Ekdahl, Kristina, et al.
(author)
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Dangerous liaisons : complement, coagulation, and kallikrein/kinin cross-talk act as a linchpin in the events leading to thromboinflammation
- 2016
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In: Immunological Reviews. - : Wiley. - 0105-2896 .- 1600-065X. ; 274:1, s. 245-269
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Research review (peer-reviewed)abstract
- Innate immunity is fundamental to our defense against microorganisms. Physiologically, the intravascular innate immune system acts as a purging system that identifies and removes foreign substances leading to thromboinflammatory responses, tissue remodeling, and repair. It is also a key contributor to the adverse effects observed in many diseases and therapies involving biomaterials and therapeutic cells/organs. The intravascular innate immune system consists of the cascade systems of the blood (the complement, contact, coagulation, and fibrinolytic systems), the blood cells (polymorphonuclear cells, monocytes, platelets), and the endothelial cell lining of the vessels. Activation of the intravascular innate immune system in vivo leads to thromboinflammation that can be activated by several of the system's pathways and that initiates repair after tissue damage and leads to adverse reactions in several disorders and treatment modalities. In this review, we summarize the current knowledge in the field and discuss the obstacles that exist in order to study the cross-talk between the components of the intravascular innate immune system. These include the use of purified in vitro systems, animal models and various types of anticoagulants. In order to avoid some of these obstacles we have developed specialized human whole blood models that allow investigation of the cross-talk between the various cascade systems and the blood cells. We in particular stress that platelets are involved in these interactions and that the lectin pathway of the complement system is an emerging part of innate immunity that interacts with the contact/coagulation system. Understanding the resulting thromboinflammation will allow development of new therapeutic modalities.
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| 9. |
- Nilsson Ekdahl, Kristina, et al.
(author)
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Thromboinflammation in Therapeutic Medicine
- 2015
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In: Advances in Experimental Medicine and Biology. - Cham : Springer International Publishing. - 0065-2598 .- 2214-8019. - 9783319186023 - 9783319186030 ; 865, s. 3-17
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Research review (peer-reviewed)abstract
- Thromboinflammation is primarily triggered by the humoral innate immune system, which mainly consists of the cascade systems of the blood, i.e., the complement, contact/coagulation and fibrinolytic systems. Activation of these systems subsequently induces activation of endothelial cells, leukocytes and platelets, finally resulting in thrombotic and inflammatory reactions. Such reactions are triggered by a number of medical procedures, e.g., treatment with biomaterials or drug delivery devices as well as in transplantation with cells, cell clusters or whole vascularized organs. Here, we (1) describe basic mechanisms for thromboinflammation; (2) review thromboinflammatory reactions in therapeutic medicine; and (3) discuss emerging strategies to dampen thromboinflammation.
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| 10. |
- Teramura, Yuji, et al.
(author)
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A cell glue : Inducing cell adhesion using surface modification with cell-penetrating peptide-peg-lipid for 3d cell structures
- 2019
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In: The Pinnacle of Biomaterials Innovationand Excellence. - : Society for Biomaterials. - 9781510883901 ; , s. 678-
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Conference paper (peer-reviewed)abstract
- Statement of Purpose: The ultimate goal of regenerative therapy is the transplantation of functional stem cells-derived tissues and organs to replace those lost as the result of pathology or tissue damage. Since tissues and organs are complicated 3D structures, 3D scaffolds such as decellularized organs and tissues, are required to properly orient living functional cells of different types. 3D scaffolds offer an environment for cell adhesion that differs from that of conventional 2D culture. Therefore, the induction and control of cell attachment, not only to 2D substrate surfaces but also to 3D scaffolds, is of great importance. Here, we propose new type of cell glue made of cell-penetrating peptides (CPP) and PEG-conjugated lipid, which are used for cell-surface modification. PEG-lipid derivatives are incorporated into the lipid bilayer membranes of cells via hydrophobic interactions, and the CPP anchored onto the cell membrane could work as an adhesive domain. In our study, various floating cells, (i.e., T cells, B cells) were used to examine the adhesive efficacy by cell surface modification with CPP-PEG-lipid onto material surface as well as PS microfiber-based 3D scaffolds.
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| 11. |
- Teramura, Yuji, et al.
(author)
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Cell Adhesion Induced Using Surface Modification with Cell-Penetrating Peptide-Conjugated Poly(ethylene glycol)-Lipid : A New Cell Glue for 3D Cell-Based Structures
- 2017
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In: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 9:1, s. 244-254
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Journal article (peer-reviewed)abstract
- We synthesized a novel material, cell-penetrating peptide conjugated poly(ethylene glycol)-lipid (CPP-PEG-lipid), that can induce the adhesion of floating cells. Firm cell adhesion with spreading could be induced by cell surface modification with the CPP-PEG-lipids. Cell adhesion was induced by CPPs but not by any other cationic short peptides we tested. Here, we demonstrated adherence using the floating cell line CCRF-CEM as well as primary human T cells, B cells, erythrocytes, and hepatocytes. As compared to cells grown in suspension, adherent cells were more rapidly induced to attach to substrates with the cell-surface modification. The critical factor for attachment was localization of CPPs at the cell membrane by PEG-lipids with PEG > 20 kDa. These cationic CPPs on PEG chains were able to interact with substrate surfaces such as polystyrene (PS) surfaces, glass surfaces, and PS microfibers that are negatively charged, inducing firm cell adhesion and cell spreading. Also, as opposed to normal cationic peptides that interact strongly with cell membranes, CPPs were less interactive with the cell surfaces because of their cell-penetrating property, making them more available for adhering cells to the substrate surface. No effects on cell viability or cell proliferation were observed after the induction of cell adhesion. With this technique, cells could be easily immobilized onto PS microfibers, an important step in fabricating 3D cell-based structures. Cells immobilized onto 3D PS microfibers were alive, and human hepatocytes showed normal production of urea and albumin on the microfibers. This method is novel in inducing firm cell adhesion-via a one-step treatment.
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| 12. |
- Teramura, Yuji, et al.
(author)
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Cell surface engineering for regulation of immune reactions in cell therapy
- 2015
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In: Advances in Experimental Medicine and Biology. - Cham : Springer. - 0065-2598 .- 2214-8019. - 9783319186023 - 9783319186030 ; 865, s. 189-209
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Journal article (peer-reviewed)abstract
- Transplantation of the pancreatic islets of Langerhans (islets) is a promising cell therapy for treating insulin-dependent type 1 diabetes mellitus. Islet transplantation is a minimally-invasive technique involving relatively simple surgery. However, after intraportal transplantation, the transplanted islets are attacked by the recipient’s immune system, because they activate a number of systems, including coagulation, complement response, inflammation, immune rejection, and recurrence of autoimmune disease. We have developed a surface modification and microencapsulation technique that protects cells and islets with biomaterials and bioactive substances, which may be useful in clinical settings. This approach employs amphiphilic polymers, which can interact with lipid bilayer membranes, without increasing cell volume. Molecules attached to these polymers can protect transplanted cells and islets from attack by the host immune system. We expect that this surface modification technique will improve graft survival in clinical islet transplantation.
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