Immobilization of anticoagulant-loaded liposomes on cell surfaces by DNA hybridization
ABSTRACT An unresolved obstacle in transplantation of islets of Langerhans is the early graft loss caused by thrombotic reactions on the surface of islets after intraportal transplantation. We investigated a versatile method for modifying the surface of islets with liposomes carrying the anticoagulant argatroban using an amphiphilic poly(ethylene glycol)-phospholipid conjugate derivative (PEG-lipid) and DNA hybridization. Argatroban was gradually released from the liposomes on the islets, and antithrombic activity was detected in culture medium. Modified islets retained the ability to control insulin release in response to glucose concentration changes. Although we mainly examined surface modification of islets, this technique may be useful for immobilizing various types of small molecules on cells and tissues and thus may have many applications in cell therapy and regenerative medicine.
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ABSTRACT: Hepatocyte-based therapies are promising regenerative approaches for liver diseases. In this study, we sought to develop a versatile method to modify the surface of hepatocytes by immobilizing synthetic polymers around the cells. The surface of murine primary hepatocytes was modified using poly(ethylene glycol)-phospholipids conjugate bearing FITC (FITC-PEG-lipid) in suspension. Hepatocyte function was assessed in vitro by examining cell viability, plating efficiency, protein production, metabolizing activity, hepatocyte-specific gene expressions, and cytochrome P450 induction. The engraftment of the PEG-lipid modified cells was studied following transplantation to both the liver or alternate ectopic sites. Among the types of phospholipids analyzed in our study, 1,2-dimyristoil -sn-glycerol-3-phosphatidylethanolamine (DMPE) was found to be uniformly anchored to the hepatocyte cell membrane (>99% of hepatocytes). Cell surface modification using FITC-PEG-DMPE did not result in any loss of in vitro functional parameters nor affect the engraftment potential in vivo by the modified cells. This modification was also successfully performed on dispersed hepatocytes and engineered hepatocyte sheets. In all, the ability to modify the surface of isolated hepatocytes with functional proteins, instead of FITC as shown in our proof-of-concept study, has the potential to move hepatocyte-based cell therapy another step forward as a viable therapeutic application.Biomaterials 01/2012; 33(3):821-8. DOI:10.1016/j.biomaterials.2011.10.016 · 8.31 Impact Factor
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ABSTRACT: Sertoli cells play a crucial role in creating the immunoprivileged environment of the testis. We examined the survival of islets of Langerhans after co-transplantation with Sertoli cells. Sertoli cells near islets should protect the graft from rejection. In this study, conjugates of single stranded oligonucleotides, poly(ethylene glycol) and phospholipids (ssDNA-PEG-DPPE) were used to immobilize Sertoli cells on islets. The 20-mer of deoxyadenylic acid (oligo(dA)20) and 20-mer of deoxythymidylic acid (oligo(dT)20) were presented as ssDNAs on the surfaces of Sertoli cells and islets, respectively, through the hydrophobic interaction between a lipid unit of the conjugates and the cell membrane. The Sertoli cells were immobilized on the islets through hybridization between oligo(dA)20 and oligo(dT)20. When Sertoli cell-immobilized islets were infused into the liver of mice through the portal vein, the Sertoli cells remained around the islets.02/2013; 1(3):315-321. DOI:10.1039/C2BM00048B
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ABSTRACT: Ischemia-reperfusion damage is a problem in organ transplantation. Reactive oxygen species are produced in cells by blood-mediated reactions at the time of blood reperfusion. In this study, we developed a method to immobilize and internalize antioxidants in endothelial cells, using vitamin E-loaded liposomes. The liposomes loaded with vitamin E and human umbilical vein endothelial cells (HUVECs) were modified with poly(ethylene glycol)-phospholipid conjugates carrying 20-mer of deoxyadenylic acid (oligo(dA)20) and 20-mer of complementary deoxythymidylic acid (oligo(dT)20), respectively. The liposomes were effectively immobilized on HUVECs through DNA hybridization between oligo(dA)20 and oligo(dT)20. The liposomes loaded with vitamin E were gradually internalized into HUVECs. Then, the cells were treated with antimycin A to induce oxidative stress. We found the amount of reactive oxygen species was greatly reduced in HUVECs carrying vitamin E-loaded liposomes.Bioorganic & medicinal chemistry 11/2013; 22(1). DOI:10.1016/j.bmc.2013.11.023 · 2.95 Impact Factor