Enhancement of the osseointegration of a polyethylene terephthalate artificial ligament graft in a bone tunnel using 58S bioglass.

PURPOSE: The aim of the study was to investigate whether a bioactive glass (BG) coating on the polyethylene terephthalate (PET) artificial ligament could enhance graft osseointegration by promoting bone regeneration at the interface between PET graft and bone tunnel. METHODS: Thirty New Zealand white rabbits underwent artificial ligament graft transplantation in proximal tibial tunnels bilaterally. One limb was implanted with a 58S BG-coated PET graft, and the contralateral limb was implanted with a non-BG-coated PET graft as a control. The rabbits were randomly sacrificed at three, six and 12 weeks after surgery for biomechanical and histological examinations. RESULTS: The maximum load to failures of the BG-coated experimental group were significantly higher than those of the control group at 12 weeks (p = 0.0051). Histologically, at 12 weeks, the BG-coated PET graft induced great new bone formation between graft and host bone, and the average graft-bone interface width of the BG group became significantly lower than that of the control group. Furthermore, the BG coating on the ligament graft surface also stimulated greater expression of bone morphogenetic protein 2 (BMP-2) and vascular endothelial growth factor (VEGF) around the graft in vivo compared to the control group at three weeks (p < 0.05). CONCLUSIONS: This study has shown that a BG coating on the PET artificial ligament surface has a positive effect in the induction of artificial ligament osseointegration within the bone tunnel.

Hydroxyapatite coating enhances polyethylene terephthalate artificial ligament graft osseointegration in the bone tunnel.

The purpose of this study was to investigate whether hydroxyapatite (HAp) coating could induce polyethylene terephthalate (PET) artificial ligament graft osseointegration in the bone tunnel. Twenty-four New Zealand white rabbits underwent artificial ligament graft transplantation in bilateral proximal tibia tunnels. One limb was implanted with HAp-coated PET graft, and the contralateral limb was implanted with non-HAp-coated PET graft as control. The rabbits were randomly sacrificed at four and eight weeks after surgery. The loads to failure of the experimental group at eight weeks were significantly higher than those of the control group (p = 0.0057). Histologically, application of HAp coating induced new bone formation between graft and bone at eight weeks compared with the controls. Real-time polymerase chain reaction examination revealed significantly elevated messenger ribonucleic acid expression levels of osteopontin and collagen I in the grafts of the HAp group compared with the controls at four weeks (p < 0.05). The study has shown that HAp coating on the PET artificial ligament surface has a positive effect in the induction of artificial ligament osseointegration within the bone tunnel.

The effect of layer-by-layer chitosan-hyaluronic acid coating on graft-to-bone healing of a poly(ethylene terephthalate) artificial ligament.

Surface coating with an organic layer-by-layer self-assembled template of chitosan and hyaluronic acid on a poly(ethylene terephthalate) (PET) artificial ligament was designed for the promotion and enhancement of graft-to-bone healing after artificial ligament implantation in a bone tunnel. The results of in vitro culturing of MC3T3-E1 mouse osteoblastic cells supported the hypothesis that the layer-by-layer coating of chitosan and hyaluronic acid could promote the cell compatibility of grafts and could promote osteoblast proliferation. A rabbit extra-articular tendon-to-bone healing model was used to evaluate the effect of this kind of surface-modified stainless artificial ligament in vivo. The final results proved that this organic compound coating could significantly promote and enhance new bone formation at the graft-bone interface histologically and, correspondingly, the experimental group with coating had significantly higher biomechanical properties compared with controls at 8 weeks (P < 0.05).

Assessment of an asymmetrical coating stent with sirolimus released from ablumial matrix in porcine model.

BACKGROUND: Delayed endothelialization contributes to stent thrombosis of current drug-eluting stents. The asymmetrical coating technique provides an anti-proliferative effect abluminally without affecting luminal endothelialization. Layer-by-layer self-assembled chitosan/heparin (C/H LBL) has been proved to promote re-endothelialization. A novel stent system, C/H LBL coated luminally and sirolimus released abluminally (C/H LBL-SES), was fabricated. METHODS: Bare metal stents (BMS), traditionally circumferential sirolimus-eluting stents (SES), and C/H LBL-SES were implanted into porcine coronary arteries. At the 7, 14 and 28 days follow-up (FU), angiography, intravascular ultrasound (IVUS), vasomotor function induced by acetylcholine (Ach), scanning-electron microscopy and histopathology were performed. Remodeling index (RI) was based on IVUS and defined as cross-sectional area (CSA) of vessel at in-stent segment divided by CSA of reference vessel and expressed as a percentage with a normal range from 0.95 to 1.05. RESULTS: Thirty-eight mini pigs were enrolled and 74 stents (BMS = 23, C/H LBL = 28, SES = 23) were implanted in this study. At 28 days after implantation, the diameter stenosis of C/H LBL-SES by quantitative coronary angiography was 18.8 ± 2.5 %, the area stenosis by histomorphometry was 24.2 ± 2.9 %, which were comparable to that of SES and superior to BMS. At 14 days, re-endothelialization of C/H LBL-SES was almost completed, while only about 50 % of surface of SES was covered by endothelium. At 7, 14 and 28 days FU, although C/H LBL-SES suffered a greater vasoconstriction induced by Ach infusion than BMS (P < 0.05), it behaved better than SES (P < 0.01). No sign of stent malapposition was detected, while RI was within the normal range by IVUS. No acute or subacute thrombotic events occurred in all three groups. CONCLUSIONS: The asymmetrically designed C/H LBL-SES successfully inhibited neointima hyperplasia, while diminishing vasoconstriction after Ach-stress. Endothelialization of C/H LBL-SES was less affected compared with traditionally circumferentially coated SES.

Synthesis of a zwitterionic silane and its application in the surface modification of silicon-based material surfaces for improved hemocompatibility.

A phosphorylcholine-like silane coupling agent bearing zwitterionic molecular structure was synthesized and studied. The chemical structure of this silane coupling agent was characterized by FTIR, 1H NMR and 31P NMR. The zwitterionic structure was successfully constructed onto the surface of silicon as a self-assembled layer (SAL). Static water contact angle, and atomic force microscopy (AFM) were used to investigate the wettability and surface topography of the modified silicon surfaces. Static water contact angle results indicated that the hydrophilicity of the surfaces could be effectively improved by the modification with this zwitterionic silane coupling agent. The changes of the topography and water contact angle of the modified surfaces with different incubation periods in PBS solution were also measured to evaluate the stability of the SALs. Blood compatibility of the modified surfaces were evaluated by testing the full-blood activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT), as well as by observing the adhered blood platelets onto the surface. The modified surfaces showed prolonged clotting time and fewer adherent platelets, revealing that the blood compatibility was evidently improved by the modification using this zwitterionic silane.