Injection of vascular endothelial growth factor into knee joints induces osteoarthritis in mice.

UNLABELLED: Osteoarthritis (OA) is a common joint disorder affecting circa 2% of the population. OBJECTIVES: It has been suggested that secretion of vascular endothelial growth factor (VEGF) could play a role in the chain of events leading to OA. METHODS: In the present study, healthy mice were injected intra-articularly with VEGF. RESULTS: Shortly after the administration of VEGF, synovial hyperplasia, increased calcification of the articular cartilage and bone sclerosis were observed. Consequently, cartilage degradation characteristic of OA was found. These changes were seen to a lesser degree in the opposite knees of VEGF-injected mice and did not occur in the control mice. CONCLUSIONS: The findings suggest an active role of VEGF in the pathogenesis of OA and render support to a possible role for subchondral bone sclerosis in the pathogenesis of cartilage degradation.

Differential effects of bone graft substitutes on regeneration of bone marrow.

BACKGROUND: This study used a rat tibial marrow ablation model to test the hypothesis that bone remodeling within the medullary canal varies with bone graft materials of different chemical compositions and structural properties, impacting marrow cavity restoration. Bone graft materials were selected based on their relative resorption or degradation in vivo and their osteogenic properties. METHODS: Following ablation of the right tibial marrow in male Sabra-strain rats, materials were implanted in the proximal marrow cavity: poly-D,L-lactide-co-glycolide 75 : 25 (PLGA); coralline-hydroxyapatite (HA), calcium-sulfate (CaSO4), collagen-HA-tricalcium phosphate granules, anorganic bovine bone mineral, demineralized bone matrix (DBM), 45S5 Bioglass (BG), PLGA with BG 50 : 50, PLGA : BG 80 : 20, and PLGA and PLGA:BG 50 : 50 plus bone marrow (BM). Control tibias were ablated but received no implants. At 2 (endosteal bone healing), 4 (marrow cavity remodeling) and 8 weeks (marrow restoration), six to eight animals per group were euthanized and tibias processed for histomorphometry of proximal and distal medullary canals. RESULTS: Control tibias showed primary bone in proximal and distal medullary canals at 2 weeks, with trabeculae surrounded by cellular marrow. At 4 and 8 weeks, control trabeculae were thinned and marrow had more fat cells. In the treated tibias, trabecular bone volume (TBV) varied with time and was material specific. Most implants supported comparable TBV at 2 weeks. Sites with CaSO4 or DBM exhibited decreased TBV with time whereas trabecular bone was retained in proximal tibias containing other materials, closely juxtaposed to the implants. TBV did not always correlate directly with implant volume, but changes in BM volume were correlated inversely with TBV. Addition of BM increased marrow restoration in sites containing PLGA; however, BM reduced restoration of marrow when added to PLGA : BG. Although the presence of implants in the proximal tibia resulted in retention of trabecular bone, there was a time-dependent reduction in TBV in distal canals; the rate and extent of the distal TBV reduction were implant dependent. CONCLUSIONS: Thus, although many materials can support bone formation in the marrow cavity, bone quality, quantity, and physical relationship to the implant, and its rate of resorption differ in a material-dependent manner, resulting in differences in the restoration of marrow. CLINICAL RELEVANCE: Bone graft materials should be selected not only for their ability to support new bone formation but also for their impact on the remodeling phase of bone healing.

[The styloid process elongation syndrome (Eagle syndrome): a case report].

Eagle syndrome is an aggregate of symptoms that includes recurrent throat pain, foreign body sensation, dysphagia, and/or facial pain as a direct result of an elongated styloid process or calcified stylohyoid ligament. The etiology is poorly understood and several theories have been proposed. The pathophysiological mechanism of symptoms is debated as well. Diagnosis is made both radiographically and by physical examination. Treatment of Eagle syndrome is either surgical or non surgical. A case report of temporomandibular joint pain that has been finally diagnosed as Eagle syndrome is presented and discussed.

[Salivary tests as a diagnostic tool in oral disease management].

Saliva plays an important role in maintaining the oral and the dental health, by lubricating the mucosae and protecting the teeth from caries attack. Furthermore, saliva participates in the taste sensation and recognition processes and is a central component in the first stage of the food digestion. Saliva collection, either in the pure or in the whole form, is a relatively easy procedure. Since the collection is non invasive, it is not harmful to the patient and has no complications. The paper discusses the use of saliva in the diagnosis of oral and systemic diseases and in monitoring the levels of molecules like hormones and medicines. The experience accumulated in our department in that field is also presented.

The outcome of teeth with periapical periodontitis treated with nonsurgical endodontic treatment: a computerized morphometric study.

OBJECTIVES: This study investigated the prognosis for successful endodontic treatment and the correlation between the size of the periapical lesion, the quality of the root canal treatment, and the type of coronal restoration. METHOD AND MATERIALS: Periapical radiographs of 319 teeth with periapical periodontitis were studied. The area of each lesion was measured before treatment and 1 to 12 years after completion of the endodontic treatment. The measurements were performed using computerized morphometry. RESULTS: In 65.2% of the teeth, the size of the lesion decreased, while in 34.8% of teeth, there was an increase. Lesions larger than 10 mm2 had a greater tendency for healing. CONCLUSION: No significant correlation was found between the quality of root canal treatment, the type of the coronal restoration, and the success rate of the endodontic treatment.

Primary mineralization at the surfaces of implants.

Osteogenesis around implants is affected by the physical and chemical characteristics of the biomaterials used. The osteoprogenitor cells must migrate to the implant site and synthesize and secrete a mineralizable extracellular matrix. Because this is neo-bone formation, the mechanism by which the cells calcify their matrix involves extracellular organelles called matrix vesicles in a process termed "primary mineralization". Two different methods for assessing the effects of implant materials on primary mineralization are presented in this report. In the first approach, different implant materials used in dentistry and orthopedic surgery were placed in rat tibial bones after marrow ablation. Two groups of implants were used, bone-bonding and non-bonding materials. We examined the effects of the materials on calcification morphometrically by quantitating changes in matrix vesicle morphology and distribution in endosteal tissue around implants as compared with normal endosteal bone healing. In addition, matrix vesicles were isolated from the endosteal tissue around the implant as well as from the contralateral limb and were examined biochemically. The results demonstrated that bone-bonding materials induced a greater increase in matrix vesicle enzyme activity than did non-bonding materials. However, all materials caused changes in matrix vesicles that were different from those seen in normal endosteal bone formation following injury. The effects of implant materials on biochemical markers of mineralization, including specific activities of matrix vesicle alkaline phosphatase and phospholipase A2 and phosphatidylserine content, demonstrated a high correlation with the morphometric observations with regard to enhancement and/or delay of primary mineralization. In the other approach, we used a radioisotopic method to evaluate the effects of implant materials on primary mineralization. This analysis revealed that implants alter bone healing, as shown by the differential uptake of 99mTc and 32P in different bone compartments. Decreased 32P uptake by the organic phase in the presence of bone-bonding implants suggests that cleavage of 99mTcMD32P into its technetium and methylene diphosphonate moieties was inhibited by the presence of the implants. In summary, these approaches to evaluating the effects of materials on primary mineralization demonstrate that the marrow ablation model can easily distinguish between bone-bonding and non-bonding materials. The use of this model can be valuable in the development of new materials.

Retinoic acid enhances the effect of collagen on bone union, following induced non-union defect in guinea pig ulna.

OBJECTIVE AND DESIGN: The aim of the present study is to evaluate the involvement of retinoic acid and collagen in wound healing, by combining them in a therapeutic modality for treating a non-union bone defect in a guinea-pig ulnar-bone model. METHODS: a 4-mm disc was excised from the guinea-pig's ulnar-bone, and the space formed between the two ulnar fragments was filled with either collagen solution, retinoic acid solution or a combination of both. The guinea-pigs were sacrificed 2 or 6 weeks later, and the defected ulnar bones were studied by X-ray, by histology and by computerized histomorphometry. RESULTS: After 6 weeks, the long bone area fraction within the histological sections of the bone, was increased after treatment with this mixture by 180%, as compared to the untreated controls. The cartilage area in those sections was decreased by 44% after the combined treatment, as compared to increases of 133% and 182% following treatments with collagen alone. CONCLUSION: These findings demonstrate that addition of 500 IU of retinoic acid to collagen at a site of a bone defect, is superior to either agent in enhancing regeneration of new bone, achieving union across the defect and leading to its complete repair.

Woven bone formation around implants and the effect of bacterial infection.

Several implant materials used in dental and orthopedic surgery were placed in rat tibial bones to study their effects on mineralization. The implants consisted of bone bonding and non-bonding materials. Changes in mineralization were defined by morphometric analysis of matrix vesicle distribution at the implant interface and in normal bone healing following marrow injury. Bone-bonding materials induced an increase in matrix vesicle activity. This finding was supported by study of the biochemical changes in the same model that manifested high correlations to the morphometrical observations with regard to enhancement or delay of primary mineralization. In addition, the study of healing using nuclear methods indicated that implants alter bone healing as shown by the different uptakes of 99mTc and 32P in the different bone compartments. Decreased 32P uptake by the organic phase in the presence of bone-bonding implants suggested that cleavage of 99mTc-MD32P into its technetium and methylene diphosphonate moieties was inhibited by administration of implants. Further studies on the effect of bacterial infection on the peri-implant tissues revealed a decrease in woven bone formation due to infection.

Adaptation of Class II Vitremer restorations with and without primer: a morphometric study.

PURPOSE: The aim of this study was to assess the adaptation of Vitremer with and without primer and compare to that of Z100 with Scotchbond Multi-Purpose. METHODS: Fifty-seven Class II cavities were prepared in 32 extracted or exfoliated primary molars. The cavities were randomly assigned to one of three groups and restored as follows: group A, Vitremer with primer (20 preps); group B, Vitremer without primer (19 preps); and group C, Z100 with Scotchbond Multi-Purpose (18 preps). The restored teeth were thermocycled, embedded in acrylic resin, and sectioned. At least three 1-mm thick sections were obtained from each restoration. Adaptation of the materials was assessed by computerized quantitative morphometry using an image analysis system. In addition to the margin, the entire contact length between the tooth and the restorative material was measured. Voids were recorded separately for the base and cavity margins, and the percentage of defected length was calculated. At least three sections of each restoration were assessed. The section with the worst results was selected as the representative of the restoration. RESULTS: Margin defects were present in 14% of all the restorations, equally distributed between the three groups (A, 10%; B, 16%; C, 17%). A significant difference was found between groups B and C when the percentage of defects in the base was assessed. CONCLUSIONS: Vitremer without primer presented considerably fewer voids when compared with Z100/Scotchbond Multi-Purpose. Although no difference in margin defects could be observed between the three groups a better adaptation to the cavity base was seen in the Vitremer restorations without primer. This finding might be of clinical importance and should be tested in other in-vitro and in-vivo studies.

A histological and quantitative histomorphometric study of apexification of nonvital permanent incisors of vervet monkeys after repeated root filling with a calcium hydroxide paste.

The purpose of this study was to compare the effect of a monthly refilling of the root canals with calcium hydroxide paste with a single packing or replacement of the paste at 3 months on the apexification of nonvital maxillary incisors of vervet monkeys. Forty-eight maxillary incisors from 12 monkeys were used following radiographic determination that root development was incomplete. The pulps were extirpated under general anesthesia and the root canals filed and cleaned. The root canals were filled with a commercial calcium hydroxide paste, Calxyl, and a temporary cavity filling placed. Twelve teeth were left without further treatment. The calcium hydroxide paste was replaced in 12 teeth after a 3-month interval, and in the remaining 24 teeth the calcium hydroxide root filling was replaced five times at monthly intervals. The monkeys were killed after 6 months, and blocks of the teeth and surrounding tissues were embedded, decalcified and 6 microns serial sections prepared and stained. The sections were studied histologically to evaluate 11 parameters. Significant differences were found in the amount of calcium hydroxide at the apices, the presence of new cementum on the roots and the degree of inflammation, all of which were better in the monthly refill group. Histomorphometric measurements to evaluate the obturation of the open apices and the volume of new primary osteocementum showed no significant difference between the three groups. It was suggested that after the initial root filling with calcium hydroxide there was nothing to be gained by repeated root filling either monthly or after 3 months, for at least 6 months.

Histomorphometric analysis of heterotopic bone formed by stromal-osteogenic subpopulations.

MBA-15.4 and MBA-15.6 cell lines are marrow stromal clonal subpopulations and represent various stages of differentiation of the osteoblastic family. These cells vary in terms of morphology, proliferation rate, synthesis of matrix proteins as collagen and noncollagenous proteins, and by their responses to hormones and growth factors. Their differential properties directly reflect the clonal cells' ability to form bone in vivo. When the cells were transplanted at an ectopic site, under the kidney capsule, MBA-15.4 line formed small foci of bone whereas MBA-15.6 cell line formed massive woven bone during the same period of time. In this study, we focused on the histomorphometric analysis of ectopic ossicles formed by the clonal cell lines. Assessments of bone mass changes involved measurements of cellular components, osteoid, and formation of primary bone. The bony tissue formed was condensed, no hemopoiesis was noted, and the ossicle was not remodeled. The histology studies were used for quantitative analysis of the ossicle formation and describe the dynamics of ossicles formed by the individual cell types.

A quantitative morphometric study of the kinetics of tissue regeneration after administration of cisplatin.

The effect of the anti-neoplastic drug cisplatin was investigated on several rat tissues using a novel computerized morphometric image analysis system. The rats were sacrificed in pre-determined intervals, ranging from 1 to 36 days after drug administration, and their liver, kidneys and external ears were sampled and sectioned. Tritiated thymidine was injected into each rat 1 h prior to sacrifice to enable autoradiographical explorations. All sections were histomorphometrically studied by a computerized system. The kidneys of the experimental group revealed increased tubular diameters, especially in the corticomedular region. In the ears, decreases of the mean epithelial thickness, in the mean number of nuclei and in the mean nuclear surface were observed. The thickness of the connective tissue also decreased significantly by the end of the first week and returned to its normal size later on. No changes were detected in the ear cartilage. In the liver, no morphometrical differences were noticed in the hepatocyte density, Kupffer cell density or nuclear area. The nuclei of the hepatocytes and Kupffer cells retained a constant ratio to the total number of cells throughout the whole experiment. Liver autoradiography revealed that the hepatocyte and Kupffer cell labelling indexes after cisplatin administration were significantly higher than those of the control group, indicating enhanced replication of cells and increased synthesis of DNA, which in turn is accumulated in the nuclei and turn the cells into polyploids. In addition, the mean radius of the liver acini after cisplatin was diminished, followed by a significant reduction in the size of the progenitor compartment. It is concluded that while the kidneys are the organs most affected by cisplatin, the progenitor compartment of the liver is heavily affected as well. Computerized morphometry was demonstrated as a highly reproducible and accurate quantitative method for evaluation of histopathological changes in various mammalian tissues.

Uptake and biodistribution of 99mtechnetium methylene-[32P] diphosphonate during endosteal healing around titanium, stainless steel and hydroxyapatite implants in rat tibial bone.

Early evaluation of intraosseous implant success and failure is critical, but, until now, there have been no reliable systems of measurement. The present study assessed whether the use of 99mtechnetium methylene-[32P]diphosphonate (99mTcMD32P), a marker for both bone formation and mineralization, can indicate if an implant is bone-bonding or non-bonding. Moreover, this study examined how bone-bonding (titanium and hydroxyapatite) and non-bonding (stainless steel) implants affected the normal healing of bone after marrow ablation, as measured by uptake of 99mTc and 32P. Titanium, hydroxyapatite and stainless steel implants were placed in the right tibiae of Sabra strain rats following ablation of the marrow, and 99mTcMD32P was injected 18 h before harvest. AT 3, 6, 14, 21 and 42 d (and in some experiments, on days 28 and 35) post-injury, the treated and contralateral tibiae were removed and cleaned of soft tissue. The uptake of 99mTc and 32P was measured in the whole bone, as well as in its organic and inorganic phases. Effects of the implants were assessed by comparing the treated to the untreated tibia in each rat. The distribution of 99mTc and 32P varied with each implant. After the insertion of titanium, increased 99mTc uptake was seen in whole bone and in the inorganic and organic phases at days 6-14. 32P uptake in whole bone and in the inorganic phase increased only at day 6, and 32P uptake was decreased in the organic phase at that time. In tibiae implanted with hydroxyapatite, 99mTc and 32P uptake was seen in the whole bone at days 6 and 14. While 99mTc uptake was increased in both the organic and inorganic phases, 32P uptake into the organic phase was decreased at both day 6 and day 14. In tibiae implanted with stainless steel, effects were observed only on day 6. The increased 99mTc uptake in whole bone reflected increases in both the organic and mineral phases. Increased 32P uptake was observed in whole bone as well, due to an increase in the 32P uptake in the mineral phase only; incorporation of 32P in the organic phase was comparable to that found in the contralateral limb. The results of this study indicate that implants alter bone healing, as indicated by the uptake of 99mTc and 32P in the different bone compartments. Moreover, decreased 32P uptake by the organic phase in the presence of bone-bonding implants suggests that cleavage of 99mTcMD32P into its technetium and methylene diphosphonate moieties was inhibited, perhaps as a function of the onset of calcification in the newly synthesized osteoid. The effect of the implants on bone healing was observed on days 6-14, when active bone formation and mineralization were occurring, supporting the hypothesis that these materials events associated with initial calcification. Uptake of 99mTc varies as a function of time, and uptake of 32P varies with time and distribution in the mineral or organic phase of bone, suggesting that these parameters may be useful as indicators of bone-bonding.

Markers of primary mineralization are correlated with bone-bonding ability of titanium or stainless steel in vivo.

Critical events in the adaptation of osseous tissues to implant materials involve initial calcification of the newly synthesized bone. Previous studies indicated that bone-bonding but not nonbonding glass ceramics increase the matrix vesicle number, thereby compensating for delayed maturation of the extracellular organelles. The present study assessed whether this was also true for metal implants commonly used in orthopaedics and oral medicine. Bone-bonding titanium (Ti) or nonbonding stainless steel (SS) implants were placed in the right tibias of Sabra rats following ablation of the marrow. At 3, 6, 14, and 21 days postinjury, newly formed endosteal bone in the treated and contralateral limbs was removed and matrix vesicle-enriched membranes isolated. Alkaline phosphatase and phospholipase A2 specific activities and phosphatidylserine (PS) content were determined and compared with those of a nonsurgical control group. Results show that matrix vesicle alkaline phosphatase and phospholipase A2 activity and PS content was increased in the Ti-implanted limbs at 6 (peak), 14, and 21 days, although at levels less than observed in normal healing. Alkaline phosphatase activity remained elevated throughout the healing period. In contrast, these parameters were markedly inhibited in the SS-implanted limbs with respect to Ti or to normal healing. Both implants altered the systemic response associated with marrow ablation, but in an implant-specific manner. The results support the hypothesis that cells adjacent to bone-bonding materials can compensate for negative effects on primary mineralization during osteogenesis, whereas cells adjacent to nonbonding materials either do not compensate or are further depressed. The data support the use of the rat marrow ablation model as a tool for rapid, initial assessment of biomaterials in bone.

Effect of 17-beta-estradiol on the healing of tibial bone after marrow ablation.

The present study has been undertaken to demonstrate the effect of 17 beta-estradiol on the healing of tibial bones after marrow ablation. Ninety-six 4-month-old female rats were divided into three experimental groups: group 1 was subjected to ablation in both tibiae and to injection of vehicle; group 2 to ablation in both tibiae and estradiol administration, and group 3 to estradiol administration without ablation. Before the rats were killed, all on the same day, 8 animals of each group underwent treatment for 3, 6, 14 and 21 days, respectively: every second day, 0.1 ml arachis oil was injected intramuscularly into group 1 and 17 beta-estradiol into groups 2 and 3. An additional 8 untreated animals were used as controls. Tibial bones were studied chemically and morphologically. While the control and ablated animals gained weight, there was a significant decrease in the gain in body weight of estradiol-treated rats. Bone and ash weight were increased in all experimental groups. The ratios (%) of tibial ash weight and of tibial Ca and Mg contents to body weight significantly increased in all experimental groups, compared to the controls; whereas P increased only at 6 and 14 days. As shown by computerized histomorphometry, the height of the proximal tibial growth plate was increased following ablation, but not with estradiol treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of hydroxyapatite implants on primary mineralization during rat tibial healing: biochemical and morphometric analyses.

The effect of 40- to 60-mesh hydroxyapatite (HA) granules (Calcitek, Inc., Carlsbad, CA) on the process of primary mineralization during bone healing was examined following insertion of the HA granules into rat tibial bone after marrow ablation. Response to HA was assessed by monitoring morphometric and biochemical changes in matrix vesicles, which are extracellular organelles associated with initial calcification. Following insertion of HA, matrix vesicle-enriched membranes (MVEMs) were isolated from the tissue adjacent to the implant and from the endosteum of the contralateral limb at 3, 6, 14, and 21 days and from a nonimplanted control group (t = 0). MVEM alkaline phosphatase- and phospholipase A2-specific activities were increased on days 6 (peak) and 14; phosphatidylserine content was also elevated on days 6 and 14 (peak). Comparable changes were seen in the contralateral limb but at lesser magnitudes. Morphological changes were observed as well. The number of matrix vesicles/micron2 matrix increased on days 6 (peak) and 14. The mean diameter of the matrix vesicles was elevated on days 6 (peak), 14, and 21. Mean distance from the calcifying front increased on day 6 but was decreased on days 14 and 21. These results indicated that HA behaves like bone-bonding implants in that there is a stimulation of matrix vesicle enzymes, increased phosphatidylserine content, and increase numbers of matrix vesicles. However, the increases occur only after 6 days postimplantation, indicating a delay in response when compared to normal healing. This delay is confirmed by the morphometric measurements. HA causes a reduction in the response associated with marrow ablation. In addition, the effects of HA are comparable locally and systemically but with different intensity. These observations suggest that osteogenic cells are able to compensate for the inhibitory effects of HA and primary calcification involves normal matrix vesicle production and maturation, if somewhat delayed and reduced in magnitude. The ability to support primary mineral formation may contribute to the successful bonding of HA with surrounding osseous tissue.

Uptake and biodistribution of technetium-99m-MD32P during rat tibial bone repair.

The present study was carried out in order to test the hypothesis that intravenously injected Tc-MDP separates into its technetium and methylene diphosphonate components in the bone, and that the technetium is preferentially taken-up by the newly-formed osteoid, while the methylene diphosphonate is taken up by the forming mineral. Uptake of Tc-MDP was studied in a rat model of primary bone formation following tibial bone marrow ablation. Each of five radiopharmaceuticals (99mTCO4, 99mTc-MDP, Tc-MD32P, 99mTc-MD32P or MD32P) was injected and their uptake was followed in the whole bone as well as in the organic and inorganic phases of the bone. Irrespective of the radionuclides injected, 99mTc was always taken-up preferentially by the organic phase, while the 32P was preferentially taken-up by the inorganic phase. When 99mTcO4 was injected, it was not taken up by the bone at all. These results indicate that the increased incorporation of 99mTc, when administered as 99mTc-MDP during bone healing, reflects an enhancement in the formation of the organic matrix and not of the calcification process. The study also suggests that the 99mTc-MDP dissociates into its technetium and methylene diphosphonate moieties, which are then adsorbed onto the organic and inorganic phases respectively.

Modulation of matrix vesicle enzyme activity and phosphatidylserine content by ceramic implant materials during endosteal bone healing.

This study examined effects of bone bonding and nonbonding implants on parameters associated with matrix vesicle-mediated primary bone formation, matrix vesicle alkaline phosphatase and phospholipase A2 specific activities, and phosphatidylserine content. Tibia marrow ablation followed by implantation of KG-Cera, Mina 13 (bonding), KGy-213, or M 8/1 (nonbonding) was used as the experimental model. Postsurgery, matrix vesicle-enriched microsomes (MVEM) were isolated from implanted and contralateral limbs. MVEM alkaline phosphatase and phospholipase A2 were stimulated adjacent to bonding implants with similar, though reduced, effects contralaterally. Alkaline phosphatase exhibited slight stimulation in nonbonding tissue; phospholipase A2 was inhibited or unchanged in treated and contralateral limbs. Phosphatidylserine content of MVEM was differentially affected by the implant materials. Thus, MVEM are modulated by implant materials locally and systemically. The data demonstrate that the model is a biologically relevant diagnostic for assessing the tissue/implant interface, primary calcification is affected by implant materials, and implant-specific effects are detected in the contralateral unimplanted limb.

Introducing a selectively biodegradable filament wound arterial prosthesis: a short-term implantation study.

This article introduces a new compliant and selectively biodegradable filament wound vascular graft and reports the findings of a short-term implantation study. A basic feature of filament winding is its ability to tailor and better control the mechanical properties of the prosthesis, so that a closer match with the anisotropic properties of native arteries is achieved. The elastomeric vascular grafts comprise poly(ether urethane urea) fibers (Lycra) embedded in a two-component matrix consisting of poly(ether urethane) (Pellethane) and a highly flexible poly(ethylene glycol)/poly(lactic acid) biodegradable segmented copolymer (PELA). Typical tensile modulus values fall in the few megapascals (MPa) range, this being comparable to that of natural arteries. The wound graft exhibits excellent handling and suturability characteristics as well as enhanced burst strength. Furthermore, due to its biodegradable constituent, the prosthesis combines minimal intraoperative blood loss and high healing porosity. The graft displays initially negligible in vitro water permeation, which increases gradually with time. In this short-term study, the prostheses were implanted in the canine carotid, and their biological performance was compared to that of expanded Gore-Tex. The luminal surface of the wound grafts was coated with a thin layer of pseudointima, strongly adhered to the prosthesis surface. Contrasting with the very stiff Gore-Tex grafts, the filament wound prostheses retained their high compliance, being highly pulsatile upon explanation. Histological studies fully corroborated these findings, underscoring the healing properties of these new filament wound vascular prostheses.