Abstract
Layer-by-layer heparinization of therapeutic cells prior to transplantation is an effective way to inhibit the instant blood-mediated inflammatory reactions (IBMIRs), which are the major cause of early cell graft loss during post-transplantation. Here, a conjugate of heparin-binding peptide (HBP) and human serum albumin (HSA), HBP-HSA, was synthesized by using heterobifunctional crosslinker. After the first heparin layer was coated on human umbilical vein endothelial cells (HUVECs) by means of the HBP-polyethylene glycol-phospholipid conjugate, HBP-HSA and heparin were then applied to the cell surface sequentially to form multiple layers. The immobilization and retention of heparin were analyzed by confocal microscopy and flow cytometry, respectively, and the cytotoxity of HBP-HSA was further evaluated by cell viability assay. Results indicated that heparin was successfully introduced to the cell surface in a layer-by-layer way and retained for at least 24 h, while the cytotoxity of HBP-HSA was negligible at the working concentration. Accordingly, this conjugate provides a promising method for co-immobilization of heparin and HSA to the cell surface under physiological conditions with improved biocompatibility.
Highlights
Transplantation of therapeutic cells such as pancreatic islets or mesenchymal stem cells is a promising therapy for a variety of difficult diseases, and it shows several advantages over whole-organ transplantation
heparin-binding peptide (HBP) was conjugated with human serum albumin (HSA) by using the amine-to-sulfhydryl crosslinker Succinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate (SMCC)
The reaction mixture was applied on a Hitrap desalting column (GE) to remove excess SMCC, and the purified SMCC-HSA was subsequently reacted with the sulfhydryl group of the cysteine-containing HBP at pH 7.2; the unreacted HBP was removed by the Hitrap desalting column, and the product HBP-HSA was obtained
Summary
Transplantation of therapeutic cells such as pancreatic islets or mesenchymal stem cells is a promising therapy for a variety of difficult diseases, and it shows several advantages over whole-organ transplantation. One of the major challenges of this treatment is that once these therapeutic cells contact the recipients’ blood, an innate immune response called instant blood-mediated inflammatory reaction (IBMIR) will be triggered by both coagulation and complement systems of recipient, which is followed by a rapid binding of platelets and infiltration of leukocytes into the clot, resulting in great loss of transplanted cells and a significant influence on the clinical results of transplantation. The systemic administration of anticoagulants leads an increased risk of bleeding, especially in patients with impaired liver and kidney functions. To resolve this problem, many attempts have been made to avoid systemic treatment, and researchers found that
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