Journal of biomedical materials research
-
J. Biomed. Mater. Res. · Dec 2002
In vivo biocompatibility testing of peek polymer for a spinal implant system: a study in rabbits.
We are developing a new spinal implant system (SIS) without fusion (bone graft). This SIS is made from two materials, metal and polyetheretherketone (PEEK) polymer. The Food and Drug Administration recommended testing in vivo, in an animal model, whether the PEEK polymer could be used in a SIS without any harm of wear debris to the nervous tissue (spinal cord and nerve roots). ⋯ The macroscopic and semiquantitative histologic analyses of the spinal cords (dura mater) showed normal vascularization and particle adherence to the connective tissue especially at the injection sites. Neither necrosis nor swelling of the dura mater and nerve roots was observed. The PEEK polymer is harmless to the spinal cord; thus it might be used as component in the spinal implant system.
-
J. Biomed. Mater. Res. · Jun 2002
Morphologic and functional evaluation of peripheral nerve fibers regenerated through polyimide sieve electrodes over long-term implantation.
We evaluated by morphologic and functional analysis the regeneration of peripheral nerve fibers through polyimide regenerative-type electrodes over long-term implantation. Polyimide sieve electrodes were placed in silicone chambers and implanted between the severed ends of the sciatic nerve in rats. The sieve part had 281 round via holes of 40 microm in diameter, with nine integrated recording-stimulating electrodes arranged around the via holes. ⋯ The majority of the myelinated fibers that crossed the via holes and had been regenerated through the distal nerve had a normal appearance. Sieve electrodes were useful for nerve stimulation at postimplantation. Stimulation through different active electrodes excited nerve bundles, evoking compound muscle action potentials of varying shape and amplitude, indicative of selective axonal stimulation.
-
J. Biomed. Mater. Res. · Mar 2002
Biocompatibility of lipid-protein-sugar particles containing bupivacaine in the epineurium.
Novel lipid-protein-sugar particles (LPSPs) are potentially biocompatible because they are composed of naturally occurring ingredients and their expected tissue dwell times are relatively short. In this research, we used histological sections to study tissue reaction to LPSPs (4.4-microm median diameter) when used for sciatic nerve block in the rat. As a reference, we compared LPSPs to 60-microm median diameter poly(lactic-co-glycolic) acid (PLGA) microspheres (110,000 MW PLGA, glycolic/lactic ratio 65:35). ⋯ In summary, the LPSPs and PLGA microspheres studied herein have excellent biocompatibility, but tissue reaction to the former is of much shorter duration. Myotoxicity and inflammation of surrounding tissue is largely attributed to bupivacaine. Foreign-body giant cells may be attributed to particle size rather than a specific reaction to PLGA.
-
J. Biomed. Mater. Res. · Feb 2002
Transforming growth factor-beta1 incorporation in a calcium phosphate bone cement: material properties and release characteristics.
The bone regenerative properties of calcium phosphate cements (CPCs) may be improved by the addition of growth factors, such as recombinant human transforming growth factor-beta1 (rhTGF-beta1). Previously, we showed that rhTGF-beta1 in CPC stimulated the differentiation of preosteoblastic cells from adult rat long bones. The intermixing of rhTGF-beta1 in CPC, which was subsequently applied to rat calvarial defects, enhanced bone growth around the cement and increased the degradation of the cement. ⋯ The faster diminishing compressive strength of modified cement from 24 h to 8 weeks likely results in early breakdown and so might be favorable for bone regeneration. Together with the beneficial effects on bone regeneration from the addition of rhTGF-beta1 to CPC, as shown in our previous studies, we conclude that the envisaged applications for CPC in bone defects are upgraded by the intermixing of rhTGF-beta1. Therefore, the combination of CPC and rhTGF-beta1 forms a promising synthetic bone graft.
-
J. Biomed. Mater. Res. · Jan 2002
Randomized Controlled Trial Comparative Study Clinical TrialEvaluation of a novel hemostatic device in an ovine parenchymal organ bleeding model of normal and impaired hemostasis.
Bleeding is a problem encountered by many surgeons, often complicated by the presence of coagulopathy or anticoagulant. The hemostatic effectiveness of CoStasis Surgical Hemostat (with bovine collagen, bovine thrombin, and autologous plasma) was evaluated and compared to a collagen sponge and to two investigational fibrin-sealant preparations under conditions of normal and impaired coagulation. A liver resection and controlled incisions in spleens and kidneys were made in sheep. ⋯ CoStasis-treated sites demonstrated higher levels of tissue repair (lower inflammation, more extensive tissue repair, and less residual implant) compared to fibrin-sealant- or collagen-sponge-treated sites in Phases I and II. These findings demonstrate that CoStasis is a highly effective hemostatic agent for control of bleeding from parenchymal organs. Furthermore, under conditions of compromised coagulation, treatment with CoStasis demonstrates a reduction in average blood loss when compared to treatment with fibrin sealant.