FVIII is synthesized as a single chain precursor of approximately 280 kD with the domain structure of A1-A2-B-A3-C1-C2 and it circulates as a series of metal ion-linked heterodimers that result from cleavages at B-A3 junction as well as additional cleavages within B domain. Factor VIII is converted to its active form, factor VIIIa, upon proteolytic cleavages by thrombin and is a heterotrimer composed of the A1, A2, and A3-C1-C2 subunits. A1 subunits of factor VIIIa terminates with 36 residue segment (Met337-Arg372) rich in acidic residues. This segment is removed after cleavages at Arg336 by activated protein C, which results in inactivation of the cofactor. In the present study, site-directed mutagenesis of FVIII at Arg336 to Gln336 was performed in order to produce an inactivation resistant mutant rFVIII (rFVIIIm) with an extended physiological stability. A recombinant mutant heavy chain of FVIII (rFVIII-Hm; Arg336 to Gln336) and wild-type light chain of FVIII (rFVIII-L) were expressed in Baculovirus-insect cell (Sf9) system, and a biologically active recombinant mutant FVIII (rFVIIIm) was reconstituted from rFVIII-Hm and rFVIII-L in the FVIII-depleted human plasma containing 40 mM CaCl2. The rFVIIIm exhibited cofactor activity of FVIIIa (2.85 x 10(-2) units/mg protein) that sustained the high level activity during in vitro incubation at 37 degrees C for 24 h, while the cofactor activity of normal plasma was declined steadily for the period. These results indicate that rFVIIIm (Arg336 to Gln336) expressed in Baculovirus-insect cell system is inactivation resistant in the plasma coagulation milieu and may be useful for the treatment of hemophilia A.
Animal ; Baculoviridae/genetics ; Blotting, Western ; Cell Line ; Factor VIII/metabolism* ; Factor VIII/genetics ; Factor VIII/chemistry ; Factor VIII/biosynthesis ; Genetic Vectors ; Human ; Mutagenesis, Site-Directed ; Recombinant Proteins/metabolism ; Recombinant Proteins/genetics ; Recombinant Proteins/chemistry ; Recombinant Proteins/biosynthesis ; Spodoptera

In our recent study by exploring an intein-based dual-vector to deliver a B-domain-deleted FVIII (BDD-FVIII) gene, it showed that covalently ligated intact BDD-FVIII molecules with a specific coagulant activity could be produced from expressed heavy and light chains by protein trans-splicing. Here, we assessed the hypothesis that the efficiency of trans-splicing may be increased by adding to the intein sequences a pair of leucine zippers that are known to bring about specific and strong protein binding. The intein-fused heavy and light chain genes were co-transferred into cultured COS-7 cells using a dual-vector system. After transient expression, the intracellular BDD-FVIII splicing was observed and the spliced BDD-FVIII and bioactivity secreted to culture media were quantitatively analyzed. An enhanced splicing of BDD-FVIII with decreased protein precursors from gene co-transfected cells was observed by Western blotting. The amount of spliced BDD-FVIII and bioactivity secreted to the culture media were 106 +/- 12 ng x mL(-1) and 0.89 +/- 0.11 U x mL(-1) analyzed by ELISA and Coatest method respectively, which was greater than leucine zipper free intein-fused heavy and light chain genes co-transfected cells (72 +/- 10 ng x mL(-1) and 0.62 +/- 0.07 U x mL(-1)). The activity of cellular mechanism-independent protein splicing was also improved, as showed by the increasing of spliced BDD-FVIII and bioactivity in culture media from combined cells separately transfected with heavy and light chain genes which was 36 +/- 11 ng x mL(-1) and 0.28 +/- 0.09 U x mL(-1). It demonstrated that the leucine zippers could be used to increase the efficiency of protein trans-splicing to improve the efficacy of a dual-vector mediated BDD-FVIII gene delivery by strengthening the interaction between the two intein-pieces fused to heavy and light chains. It provided evidence for further study in animal model using a dual-adeno-associated virus vector to deliver FVIII gene in vivo.
Animals ; COS Cells ; Cercopithecus aethiops ; Factor VIII ; chemistry ; genetics ; metabolism ; Genetic Vectors ; Inteins ; Leucine Zippers ; Peptide Fragments ; chemistry ; genetics ; metabolism ; Protein Splicing ; Trans-Splicing ; Transfection

We studied the ligation of coagulation factor VIII heavy and light chains in Escherichia coli by utilizing the intein-mediated protein trans-splicing. A B-domain deleted factor VIII (BDD-FVIII) gene was broken into two halves of heavy and light chains before Ser1657 which meets the splicing required conserved residue and then fused to 106 and 48 amino acid-containing N-part termed Int-N and C-part termed Int-C coding sequences of split mini Ssp DnaB intein respectively. These two fusion genes were constructed into a prokaryotic expression vector pBV220. Through induction for expression of recombinant protein it displayed an obvious protein band as predicted size of BDD-FVIII protein on SDS-PAGE gel. Western blotting using factor VIII specific antibodies confirmed that this protein band is BDD-FVIII produced by protein trans-splicing. It demonstrated that the heavy and light chains of BDD-FVIII can be efficiently ligated with the Ssp DnaB intein-mediated protein trans-splicing. These results provided evidence for encouraging our ongoing investigation with intein as a means in dual AAV vectors carrying the factor VIII gene to overcome the packaging size limitation of a single AAV vector in hemophilia A gene therapy.
DnaB Helicases ; genetics ; Escherichia coli ; genetics ; metabolism ; Factor VIII ; chemistry ; genetics ; metabolism ; Inteins ; physiology ; Peptide Fragments ; chemistry ; genetics ; metabolism ; Protein Splicing ; physiology

OBJECTIVETo investigate the feasibility of differentiation of bone marrow mesenchymal stem cells (MSCs) into vascular endothelial cells and the mechanism of its involvement in wound healing.

METHODSPorcine MSCs were harvested from porcine marrow, and they were isolated and purified by density gradient centrifugation. After being cultured and amplified in vitro, the MSCs were labelled with BrdU (5-bromodeoxy-uridine). Full skin loss wound was created on the back of the mini-swine whose bone marrow was obtained. The labelled MSCs with fibrin glue as the vector were regrafted back to the donor animal wound. The wound tissue specimens were harvested at 2, 4, 6, 8 and 12 post-operation weeks and were immunohistochemically stained by BrdU and factor VIII (FVIII) for comparative study.

RESULTSMost BrdU positive cells aggregated around small blood vessels in the granulation tissue of the wounds. Only individual vascular endothelial cells were BrdU positive. There was FVIII expression in the cytoplasm of BrdU positive cells.

CONCLUSIONMSCs were closely correlated with the formation of small blood vessels in granulation tissue during wound healing process. The porcine MSCs possessed the potential to differentiate into vascular entoehelial cells and to participate in wound healing under the micro-enviroment of the wound.

Animals ; Bone Marrow Cells ; chemistry ; cytology ; Bromodeoxyuridine ; analysis ; Cell Differentiation ; Dermatologic Surgical Procedures ; Endothelium, Vascular ; chemistry ; cytology ; Factor VIII ; analysis ; Hematopoietic Stem Cells ; chemistry ; cytology ; Immunohistochemistry ; Mesoderm ; chemistry ; cytology ; Skin ; chemistry ; injuries ; Skin Transplantation ; methods ; Swine ; Swine, Miniature ; Wound Healing

Although two chain transfering separately could be used to overcome the volume limitation of adeno-associated virus vectors (AAV) in coagulation factor VIII (FVIII) gene delivery, it leads to chain imbalance for inefficient heavy chain secretion. In this study we aimed to improve the efficacy of two chain strategy in FVIII gene delivery through the degradation of glucose-regulated protein 78 (GRP78) known as a protein chaperone in endoplasmic reticulum (ER) by deoxynivalenol (DON) to decrease GRP78-bound FVIII heavy chain. By treating the two-chain gene transduced 293 cells with DON, the heavy chain (HC) secretion and FVIII bioactivity were observed. Data showed that 293 cells after three hours post-treatment with DON at a concentration of 500 ng mL(-1) resulted in obvious decrease the level of GRP78 but no effect on the cell proliferation. The HC secreted from DON-treated cells transfected with HC gene alone was 59 +/- 11 ng mL(-1), higher than that secreted by control cells (15 +/- 4 ng mL(-1)), and the HC secretion was further increasing to 146 +/- 34 ng mL(-1) in light chain (LC) gene co-transfected cells with an activity measured up to 0.66 +/- 0.15 U mL(-1), also greater than control cells (76 +/- 17 ng mL(-1) and 0.35 +/- 0.09 U mL(-1)). Taken together, these data suggest that DON-mediated GRP78 down-regulation could improve the efficacy of two-chain FVIII gene transfering by facilitating HC secretion, providing an experimental basis for in vivo dual-AAV application in FVIII gene delivery.
Cell Proliferation ; Down-Regulation ; Factor VIII ; chemistry ; genetics ; secretion ; Gene Transfer Techniques ; HEK293 Cells ; Heat-Shock Proteins ; metabolism ; Humans ; Transfection ; Trichothecenes ; pharmacology

OBJECTIVETo establish a long-term in vitro culture of the fibroblasts obtained from burn wounds.

METHODSSkin samples were harvested from normal volunteers and the deep partial thickness burn wound in burn patients on the 5th, 10th, 21st, 28th and 35th postburn days (PBDs). The non-dermal tissue was removed from the samples and primed by chlorhexidine solution in concentration of 2.5 g/L. The skin sample was then digested by trypsin-EDTA in concentration of 1.25 g/L and was centrifuged before the cells were harvested and cultured. When the cells grew nearly to form sheet, multiple passage culture, freezing storage and revivification were carried out with routine methods. The cell morphology was continuously observed during the culture. And the cell doubling time was calculated.

RESULTSThe wound-origin fibroblasts exhibited higher purity and better activity. The cellular growth features and gross morphology kept stable during primary and secondary culture, and during freezing storage and after revivification. The cells kept their activity above 80% of their original after many times of revivification.

CONCLUSIONThe establishment of the in vitro culture of fibroblasts from burn wounds might be useful in the exploration of the pathogenesis and therapeutic measures of scars.

Burns ; metabolism ; pathology ; Cell Culture Techniques ; methods ; Cell Division ; Cell Survival ; Cells, Cultured ; Cryopreservation ; Factor VIII ; analysis ; Fibroblasts ; chemistry ; cytology ; Humans ; Immunohistochemistry ; Time Factors

We made fusion protein of fastatin and FIII 9-10, termed tetra-cell adhesion molecule (T-CAM) that can interact simultaneously with alphavbeta3 and alpha5beta1 integrins, both playing important roles in tumor angiogenesis. T-CAM can serve as a cell adhesion substrate mediating adhesion and migration of endothelial cells in alphavbeta3 and alpha5beta1 integrin-dependent manner. T-CAM showed pronounced anti-angiogenic activities such as inhibition of endothelial cell tube formation, endothelial cell proliferation, and induction of endothelial cell apoptosis. T-CAM also inhibited angiogenesis and tumor growth in mouse xenograft model. The anti-angiogenic and anti-tumoral activity of molecule like fastatin could be improved by fusing it with integrin-recognizing cell adhesion domain from other distinct proteins. The strategy of combining two distinct anti-angiogenic molecules or cell adhesion domains could facilitate designing improved anticancer agent of therapeutic value.
Angiogenesis Inhibitors/chemistry/*pharmacology ; Animals ; Antineoplastic Agents/chemistry/*pharmacology ; Base Sequence ; Benzocaine/chemistry/*pharmacology ; Cell Line, Tumor ; Cell Movement ; Cell Proliferation ; Cells, Cultured ; Chloramphenicol/chemistry/*pharmacology ; DNA Primers ; Drug Combinations ; Factor VIII/chemistry/*pharmacology ; Humans ; Integrin alpha5beta1/*physiology ; Integrin alphaVbeta3/*physiology ; Male ; Mice ; Mice, Inbred BALB C ; Nitrofurazone/chemistry/*pharmacology ; Recombinant Fusion Proteins/chemistry/*pharmacology