A novel on-a-chip system with a 3D-bioinspired gut mucus suitable to investigate bacterial endotoxins dynamics

The possible pathogenic impact of pro-inflammatory molecules produced by the gut microbiota is one of the hypotheses considered at the basis of the biomolecular dialogue governing the microbiota-gut-brain axis. Among these molecules, lipopolysaccharides (LPS) produced by Gram-negative gut microbiota strains may have a potential key role due to their toxic effects in both the gut and the brain. In this work, we engineered a new dynamic fluidic system, the MINERVA device (MI-device), with the potential to advance the current knowledge of the biological mechanisms regulating the microbiota-gut molecular crosstalk. The MI-device supported the growth of bacteria that are part of the intestinal microbiota under dynamic conditions within a 3D moving mucus model, with features comparable to the physiological conditions (storage modulus of 80 ± 19 Pa, network mesh size of 41 ± 3 nm), without affecting their viability (∼ 109 bacteria/mL). The integration of a fluidically optimized and user-friendly design with a bioinspired microenvironment enabled the sterile extraction and quantification of the LPS produced within the mucus by bacteria (from 423 ± 34 ng/mL to 1785 ± 91 ng/mL). Compatibility with commercially available Transwell-like inserts allows the user to precisely control the transport phenomena that occur between the two chambers by selecting the pore density of the insert membrane without changing the design of the system. The MI-device is able to provide the flow of sterile medium enriched with LPS directly produced by bacteria, opening up the possibility of studying the effects of bacteria-derived molecules on cells in depth, as well as the assessment and characterization of their effects in a physiological or pathological scenario.

Engineering biological gradients

Biological gradients profoundly influence many cellular activities, such as adhesion, migration, and differentiation, which are the key to biological processes, such as inflammation, remodeling, and tissue regeneration. Thus, engineered structures containing bioinspired gradients can not only support a better understanding of these phenomena, but also guide and improve the current limits of regenerative medicine. In this review, we outline the challenges behind the engineering of devices containing chemical-physical and biomolecular gradients, classifying them according to gradient-making methods and the finalities of the systems. Different manufacturing processes can generate gradients in either in-vitro systems or scaffolds, which are suitable tools for the study of cellular behavior and for regenerative medicine; within these, rapid prototyping techniques may have a huge impact on the controlled production of gradients. The parallel need to develop characterization techniques is addressed, underlining advantages and weaknesses in the analysis of both chemical and physical gradients.

Evaluating outcome of prophylaxis in haemophilia: objective and self-reported instruments should be combined

INTRODUCTION

Routine outcome assessment of prophylaxis should use validated tools, while balancing comprehensiveness and burden. Collecting overlapping information should be avoided.

AIM

To assess correlations between different outcome assessment tools in haemophilia.

METHODS

From an international cross-sectional study, data on objective outcome (Haemophilia Joint Health Score (HJHS 2.1, range 0-124), radiological Pettersson score) and self-reported joint bleeding, Haemophilia Activities List (HAL, range 100-0), health-related quality of life (SF-36, including five physical and five mental domain scores, range 100-0), and Utility (SF6D and EQ-5D, range 1.0-0) were extracted. Spearman's correlations were calculated: ≥0.8 very strong, 0.60-0.79 strong, 0.40-0.59 moderate.

RESULTS

Ninety patients with severe haemophilia, on prophylaxis since median age 3.4 years, were evaluated at median 25.5 years (range 16.0-37.6). Objective outcome was favourable (median HJHS 2.1 6 points, Pettersson score 9 points). Self-reported outcome showed a median of 7 joint bleeds in 5 years, median HAL sum 96 points, high scores for physical domains of SF-36 (median 80-95) and high Utility values (median SF6D 0.87; EQ-5D 0.84). Physical examination (HJHS 2.1) showed strong correlation with radiological scores, moderate correlation with physical domains of the SF-36 and Utility, but no correlation with self-reported bleeding or limitations in activities (HAL). Bleeding was not associated with any other outcome parameter. The HAL was only correlated with the SF36 'Physical functioning' domain.

CONCLUSION

For the evaluation of patients on early prophylaxis, information on bleeding should be complemented by objective joint assessment as well as self-reported limitations in activities and quality of life.

External and internal gelation of pectin solutions: microscopic dynamics versus macroscopic rheology

Pectin is a natural biopolymer that forms, in the presence of divalent cations, ionic-bound gels typifying a large class of biological gels stabilized by non-covalent cross-links. We investigate and compare the kinetics of formation and aging of pectin gels obtained either through external gelation via perfusion of free Ca(2+) ions, or by internal gelation due to the supply of the same ions from the dissolution of CaCO3 nanoparticles. The microscopic dynamics obtained with photon correlation imaging, a novel optical technique that allows obtaining the microscopic dynamics of the sample while retaining the spatial resolution of imaging techniques, is contrasted with macroscopic rheological measurements at constant strain. Pectin gelation is found to display peculiar two-stage kinetics, highlighted by non-monotonic growth in time of both microscopic correlations and gel mechanical strength. These results are compared to those found for alginate, another biopolymer extensively used in food formulation.

Third Åland islands conference on von Willebrand disease, 26-28 September 2012: meeting report

The first meeting of international specialists in the field of von Willebrand disease (VWD) was held in the Åland islands in 1998 where Erik von Willebrand had first observed a bleeding disorder in some members of a family from Föglö and a summary of the meeting was published in 1999. The second meeting was held in 2010 and a report of the meeting was published in 2012. Topics covered included progress in understanding of VWD over the last 50 years; multimers; classification of VWD; pharmacokinetics and laboratory assays; genetics; treating the paediatric patient; prophylaxis; geriatrics; gene therapy and treatment guidelines. This third meeting held over 3 days covered the structure and function of von Willebrand factor (VWF); type 1 VWD, the most common form of the disease; a lifespan of pharmacokinetics in VWD; detecting inhibitors in VWD patients; and special challenges in understanding and treating the female VWD patient.

von Willebrand's disease: a report from a meeting in the Åland islands

von Willebrand's disease (VWD) is probably the most common bleeding disorder, with some studies indicating that up to 1% of the population may have the condition. Over recent years interest in VWD has fallen compared to that of haemophilia, partly the result of focus on blood-borne diseases such as HIV and hepatitis. Now the time has come to revisit VWD, and in view of this some 60 international physicians with clinical and scientific interest in VWD met over 4 days in 2010 in the Åland islands to discuss state-of-the-art issues in the disease. The Åland islands are where Erik von Willebrand had first observed a bleeding disorder in a number of members of a family from Föglö, and 2010 was also the 140th anniversary of his birth. This report summarizes the main papers presented at the symposium; topics ranged from genetics and biochemistry through to classification of VWD, pharmacokinetics and laboratory assays used in the diagnosis of the disease, inhibitors, treatment guidelines in different age groups including the elderly who often have comorbid conditions that present challenges, and prophylaxis. Other topics included managing surgeries in patients with VWD and the role of FVIII in VWF replacement, a controversial subject.

Joint health and functional ability in children with haemophilia who receive intensive replacement therapy

Joint physical examination is an important outcome in haemophilia; however its relationship with functional ability is not well established in children with intensive replacement therapy. Boys aged 4-16 years were recruited from two European and three North American treatment centres. Joint physical structure and function was measured with the Haemophilia Joint Health Score (HJHS) while functional ability was measured with the revised Childhood Health Assessment Questionnaire (CHAQ₃₈. Two haemophilia-specific domains were created by selecting items of the CHAQ₃₈ that cover haemophilia-specific problems. Associations between CHAQ, HJHS, cumulative number of haemarthroses and age were assessed. A total of 226 subjects - mean 10.8 years old (SD 3.8) - participated; the majority (68%) had severe haemophilia. Most severe patients (91%) were on prophylactic treatment. Lifetime number of haemarthroses [median=5; interquartile range (IQR)=1-12] and total HJHS (median = 5; IQR=1-12) correlated strongly (ρ = 0.51). Total HJHS did not correlate with age and only weakly (ρ=-0.19) with functional ability scores (median=0; IQR=-0.06-0). Overall, haemarthroses were reported most frequently in the ankles. Detailed analysis of ankle joint health scores revealed moderate associations (ρ=0.3-0.5) of strength, gait and atrophy with lower extremity tasks (e.g. stair climbing). In this population, HJHS summating six joints did not perform as well as individual joint scores, however, certain elements of ankle impairment, specifically muscle strength, atrophy and gait associated significantly with functional loss in lower extremity activities. Mild abnormalities in ankle assessment by HJHS may lead to functional loss. Therefore, ankle joints may warrant special attention in the follow up of these children.

Structural properties of polysaccharide-based microcapsules for soft tissue regeneration

Autologous and eterologous cell encapsulation has been extensively studied for clinical application in functional organs substitution, recombinant cell transplantation in gene therapy or in muscle and cartilage regeneration to treat degenerative pathologies. In this work, calcium alginate, calcium alginate/chitosan, calcium alginate/gelatin and pectin/chitosan microcapsules were prepared to be used as innovative injectable scaffolds for soft issue regeneration by a simple extrusion method from aqueous solutions. Prepared microcapsules had spherical morphology, whereas their size was deeply influenced by the polymeric composition. When incubated in a physiological-like environment up to 30 days, they underwent an initial swelling, followed by weight loss at different rates, depending on the microcapsules formulation. The encapsulation of mouse myoblast cells (C2C12 cell line) was obtained in calcium alginate, calcium alginate/chitosan, calcium alginate/gelatin microcapsules. Cells were alive throughout the encapsulation procedure, and were recovered by a mechanical rupture of the microcapsules. After 7 days, fractured microcapsules led cells to migrate gradually out.

Identifying and overcoming barriers to prophylaxis in the management of haemophilia

Haemophilia is often characterized by acute haemarthrosis and synovitis arising from spontaneous bleeding episodes, particularly in the muscles and joints of the elbows, knees and ankles. Current treatment for patients with severe haemophilia involves coagulation factor concentrate (CFC) replacement therapy given on demand at the time of bleeding or through long-term prophylaxis aimed at preventing future bleeds and joint disease. Although prophylaxis has many advantages over on-demand therapy (particularly if started before age 2 and prior to any signs of joint disease), its practice varies widely even among developed countries because of several barriers. Such barriers include CFC costs and availability; patient perceptions, lifestyles and bleeding patterns; difficulties and complications arising from the use of intravenous access devices (IVADs); the development of inhibitors; and the lack of randomized clinical trials. These barriers can be overcome by tailoring treatment regimens according to individual patient bleeding patterns and CFC pharmacokinetic profiles, using IVADs selectively and judiciously, helping patients maintain normal weight and physical exercise and providing the families of patients with continuous support from healthcare providers.

Antibacterial activity of zinc modified titanium oxide surface

Titanium-based implants are successfully used for various biomedical applications. However, in some cases, e.g. in dental implants, failures due to bacterial colonization are reported. Surface modification is a commonly proposed strategy to prevent infections. In this work, titanium oxide, naturally occurring on the surface of titanium, was modified by promoting the formation of a mixed titanium and zinc oxide, on the basis of the idea that zinc oxide on titanium surface may act as the zinc oxide used in pharmaceutical formulation for its lenitive and antibacterial effects. The present work shows that it is possible to form a mixed titanium and zinc oxide on titanium surfaces, as shown by Scanning Electron Microscopy and XPS analysis. To this end titanium was preactivated by UV on crystalline titanium oxide, both in the anatase form or in the co-presence of anatase and rutile. By performing antibacterial assays, we provide evidence of a significant reduction in the viability of five streptococcal oral strains on titanium oxide surfaces modified with zinc. In conclusion, this type of chemical modification of titanium oxide surfaces with zinc might be considered a new way to reduce the risk of bacterial colonization, increasing the lifetime of dental system applications.

Hemorrhagic symptoms and bleeding risk in obligatory carriers of type 3 von Willebrand disease: an international, multicenter study

OBJECTIVES

We undertook an international, multicenter study to describe the clinical picture and to estimate the bleeding risk in a group of obligatory carriers of type 3 von Willebrand disease (VWD).

PATIENTS AND METHODS

Obligatory carriers (OC) of type 3 VWD were identified by the presence of offspring with type 3 VWD or by being an offspring of a type 3 patient. Normal controls were age- and sex-matched with the obligatory carriers. A physician-administered standardized questionnaire was used to evaluate hemorrhagic symptoms at presentation. A score system ranging from 0 (no symptom) to 3 (hospitalization, replacement therapy, blood transfusion) was used to quantitate bleeding manifestations. Odds ratios were computed for each symptom.

RESULTS

Ten centers participated to the study, enrolling a total of 35 type 3 VWD families, with 70 OC. A total of 215 normal controls and 42 OC for type 1 VWD were also included. About 40% of type 3 OC had at least one bleeding symptom compared to 23% of normal controls and 81.8% of type 1 OC (P < 0.0001 by chi-squared test), showing that type 3 OC clearly represent a distinct population from type 1 OC. The clinical situations associated with an increase of bleeding risk in type 3 OC were epistaxis [odds ratio 3.6; 90% confidence intervals (CI) 1.84-21.5], cutaneous bleeding (odds ratio 5.5; 90% CI 2.5-14.1) and postsurgical bleeding (odds ratio 16.3; 90% CI 4.5-59). The severity of bleeding score correlated with the degree of factor (F) VIII reduction in plasma.

CONCLUSIONS

OC for type 3 VWD represent a distinctive population from type 1 OC. These patients, however, present with more frequent bleeding symptoms in comparison to normal controls, especially in case of significantly low FVIII. Desmopressin and/or tranexamic acid might be useful to prevent or treat bleeding in these cases.

Hemophilia joint health score reliability study

Measurement of joint health is critically important when assessing children with haemophilia. Few measures exist; they lack sensitivity to small changes, don't account for normal development and were never formally validated. To address these concerns, the Hemophilia Joint Health Score (HJHS) was developed by modifying existing scores.

OBJECTIVE

To test the inter-observer and test-retest reliability of the HJHS.

METHODS

Using a fully factorial design, four physiotherapists (from Canada, the United States and Sweden) examined eight boys with severe haemophilia A on two consecutive days using the HJHS. The boys ranged in age from 4-12 years and presented with variable joint damage. Six index joints (elbows, knees and ankles) were assessed on 11 impairment items including swelling, flexion and extension loss and gait. Concordance was measured by the intra-class correlation co-efficient.

RESULTS

Reliability of the HJHS was excellent with an inter-observer co-efficient of 0.83 and a test-retest of 0.89.

CONCLUSION

This study is the first in a series to assess the psychometric properties of the HJHS, a promising new measure of joint health in boys with haemophilia.

Recent developments in clinimetric instruments

Assessment of impairment and function is essential in order to monitor joint status and evaluate therapeutic interventions in patients with haemophilia. The improvements in the treatment of haemophilia have required the development of more sensitive tools to detect the more minor dysfunctions that may now be apparent. This paper outlines some of the recent developments in this field. The Haemophilia Joint Health Score (HJHS) provides a systematic and robust measure of joint impairment. The MRI Scoring System has been designed to provide a comprehensive scoring system combining both progressive and additive scales. The Functional Independence Score for Haemophilia (FISH) has been developed to assess performance of functional activities and can be used in conjunction with the Haemophilia Activities List (HAL) which provides a self report measure of function. It is recommended that both measures are evaluated as these tools measure different constructs. Further refinement and testing of the psychometric properties of all of these tools is in progress. More widespread use of these tools will enable the sharing of data across the world so promoting best practice and ultimately enhancing patient care.

Towards the goal of prophylaxis: experience and treatment strategies from Sweden, France and Hungary

The only form of haemophilia treatment that is able to prevent arthropathy and other consequences of bleeding symptoms in patients with severe haemophilia is prophylaxis started at an early age (primary prophylaxis). It is also highly beneficial for the psychological and social wellbeing of patients and their families. Scientific institutions and international organizations such as WHO, the World Federation of Hemophilia (WFH) and the National Haemophilia Foundation (NHF) have recommended that prophylaxis be considered optimum therapy. This paper discusses the barriers to prophylaxis, such as the perceived need, costs and availability, and difficulty of venous access, and describes the authors' experiences with the therapy.

Physical therapy and imaging outcome measures in a haemophilia population treated with factor prophylaxis: current status and future directions

Routine infusions of factor VIII to prevent bleeding, known as prophylaxis, and other intensive therapies are being more broadly applied to patients with haemophilia. These therapies differ widely in replacement product usage, cost, frequency of venous access and parental effort. In order to address residual issues relating to recommendations, implementation, and evaluations of prophylaxis therapy in persons with haemophila, a multinational working group was formed and called the International Prophylaxis Study Group (IPSG). The group was comprised of haemophilia treaters actively involved in studies of prophylaxis from North America and Europe. Two expert committees, the Physical Therapy (PT) Working Group and the Magnetic Resonance Imaging (MRI) Working Group were organized to critically assess existing tools for assessment of joint outcome. These two committees independently concluded that the WFH Physical Examination Scale (WFH PE Scale) and the WFH X-ray Scale (WFH XR Scale) were inadequately sensitive to detect early changes in joints. New scales were developed based on suggested modifications of the existing scales and called the Haemophilia Joint Health Score (HJHS) and the International MRI Scales. The new scales were piloted. Concordance was measured by the intra-class correlation coefficient of variation. Reliability of the HJHS was excellent with an inter-observer co-efficient of 0.83 and a test-retest value of 0.89. The MRI study was conducted using both Denver and European scoring approaches; inter-reader reliability using the two approaches was 0.88 and 0.87; test-retest reliability was 0.92 and 0.93. These new PT and MRI scales promise to improve outcome assessment in children on early preventive treatment regimens.

Design, synthesis and properties of polyurethane hydrogels for tissue engineering

Due to their similarity to natural soft tissues, water-swellable polymeric materials (hydrogels) are, in principle, ideal candidates for scaffolds/matrices in tissue engineering. Polyurethanes (PU), hydrophilic but water-insoluble, can be obtained by the incorporation of hydrophilic soft segments, e.g. poly(ethylene oxide) (PEO). These materials possess the favorable characteristics of the family of PUs as well as the ability to mimic soft tissues. In this work, new crosslinked PU-hydrogels were prepared in a one-step bulk polymerization process using an aliphatic diisocyanate, PEO, a low molecular weight diol, and a tri-functional crosslinking agent. A porous structure was also obtained by air-incorporation under mechanical stirring at a controlled high speed during the polymerization. Structural characteristics of the compact (PU-HyC) and the porous (PU-HyP) material were investigated. Molecular weight between cross-links, M(c), and crosslinking density, rho(x), were typical of a low crosslinking degree. A homogeneous distribution of non-interconnecting pores (phi100 microm) was observed in PU-HyP. Both materials showed a high water adsorption. The swelling behavior and weight loss in water was affected by porosity. For their mechanical behavior in the swollen state, the novel PU hydrogels can be considered for biomedical applications where good mechanical properties are required (i.e. 3D scaffold for tissue engineering).

Consensus perspectives on prophylactic therapy for haemophilia: summary statement

Participants in an international conference on prophylactic therapy for severe haemophilia developed a consensus summary of the findings and conclusions of the conference. In the consensus, participants agreed upon revised definitions for primary and secondary prophylaxis and also made recommendations concerning the need for an international system of pharmacovigilance. Considerations on starting prophylaxis, monitoring outcomes, and individualizing treatment regimens were discussed. Several research questions were identified as needing further investigation, including when to start and when to stop prophylaxis, optimal dosing and dose interval, and methods for assessment of long-term treatment effects. Such studies should include carefully defined cohorts, validated orthopaedic and quality-of-life assessment instruments, and cost-benefit analyses.

How to start prophylaxis

A cohort study was performed to assess the efficacy of a gradual introduction to primary prophylaxis by peripheral vein injections. Bleeding symptoms prior to the initiation of prophylaxis and during the time from the start of home treatment were investigated. Forty-seven boys with severe haemophilia, born between 1987 and 2000, were studied. The mean age at the start of prophylaxis was 16 months and the mean age for the boys on home treatment and full prophylaxis was 30 months. Our results show that primary prophylaxis with injections in a peripheral vein is possible in most patients (83%). Even with this early start, 59% of the children had been treated with clotting factor concentrate before prophylaxis was initiated. Seventy-two percent of the boys had no symptoms from the joints or muscles in the time from initiation to full prophylaxis every second (haemophilia A) or third day (haemophilia B). None of the patients developed cerebral bleeding during this period, but one patient had an epidural bleeding as the presenting symptom of haemophilia.

Inhibitors in the Swedish population with severe haemophilia A and B: a 20-year survey

AIM

To survey the entire population (n = 116) afflicted with severe haemophilia A or B born in Sweden over a 20-y period (1980-1999), and to examine the epidemiological, genetic and clinical aspects of development of inhibitors to factors VIII and IX (FVIII/FIX).

METHODS

One hundred of the subjects had haemophilia A and 16 had haemophilia B. All of these subjects had received prophylactic treatment and had a check-up of inhibitor status at least twice a year. Sixty-one were born between 1980 and 1989 and 55 between 1990 and 1999.

RESULTS

Nineteen percent (19/100) of those with haemophilia A and 37% (6/16) with haemophilia B developed inhibitors at 12-18 mo of age, after exposure to FVIII/FIX concentrates for an average of 14 d in the case of haemophilia A and 16 d in haemophilia B. All patients with inhibitors carried mutations that impaired protein synthesis. The high incidence of FIX inhibitors may have been due to the large number of complete deletions (13%) in the Swedish haemophilia B population. Patients with haemophilia A showed no significant increase (p = 0.65) in incidence of inhibitors (n = 10/48, total incidence 21%) in the 1990s, when they were treated mainly with recombinant products, as compared to the 1980s (n = 9/52, 17%), when they received intermediate/high-purity plasma-derived concentrates.

CONCLUSION

Our population-based study verifies that genotype has a general impact on the incidence of FVIII/FIX inhibitors, and that recombinant FIII/FIX concentrates are not a predisposing factor for inhibitor development.

Cytocompatibility of polyurethane foams as biointegrable matrices for the preparation of scaffolds for bone reconstruction

This work reports preliminary results on the development of biointegrable scaffolds, composed of biostable 3D polymer matrices and bioabsorbable inorganic salts, to be used for cell anchorage in bone regeneration. Three crosslinked polyurethane foams (PUFs), prepared by one-step bulk polymerisation from a polyether-polyol mixture, polymeric MDI and water as expanding agent, were tested for their ability to promote adhesion and growth of bone-derived cells. The open porosity of these foams ranged from 16 to 31% with an average pore size of 470 /600 microm, compressive strength (at 10% &#949; ) of 0.28/0.38 MPa and elastic moduli of 4.88/6.61 MPa. The human osteosarcoma line Saos-2, and primary cultures of normal human articular chondrocytes and bone marrow-derived (HBM) stromal cells were used for in vitro cytocompatibility tests. For cell adhesion and proliferation analysis, DNA synthesis was evaluated by 3 H-thymidine uptake. Osteoblastic differentiation of Saos-2 adherent cells was determined by measuring the enzymatic activity of alkaline phosphatase (ALP). All cell types were able to adhere to all tested PUFs and to synthesize DNA. At 48 hr culture, HBM stromal cells showed the maximal rate of adhesion with the highest rate of proliferation onto PUFs with the largest pore size, whereas both chondrocytes and Saos-2 appeared to adhere preferentially onto foams exhibiting the highest percentage of open porosity. Up to 8 days in culture Saos-2 cells were able to proliferate into all PUFs, with a time-dependent increase of DNA synthesis and ALP activity. At SEM, the morphology of cells adherent to PUF pores was spread with cytoplasmatic extroflessions, indicating a good metabolic activation. These results demonstrate a good cytocompatibility of the proposed 3D matrices, suggesting that their use in the preparation of composite scaffolds is worth further investigation. (Journal of Applied Biomaterials & Biomechanics 2003; 1: 58-66)ABSTRACT: This work reports preliminary results on the development of biointegrable scaffolds, composed of biostable 3D polymer matrices and bioabsorbable inorganic salts, to be used for cell anchorage in bone regeneration. Three crosslinked polyurethane foams (PUFs), prepared by one-step bulk polymerisation from a polyether-polyol mixture, polymeric MDI and water as expanding agent, were tested for their ability to promote adhesion and growth of bone-derived cells. The open porosity of these foams ranged from 16 to 31% with an average pore size of 470 /600 microm, compressive strength (at 10% &#949; ) of 0.28/0.38 MPa and elastic moduli of 4.88/6.61 MPa. The human osteosarcoma line Saos-2, and primary cultures of normal human articular chondrocytes and bone marrow-derived (HBM) stromal cells were used for in vitro cytocompatibility tests. For cell adhesion and proliferation analysis, DNA synthesis was evaluated by 3 H-thymidine uptake. Osteoblastic differentiation of Saos-2 adherent cells was determined by measuring the enzymatic activity of alkaline phosphatase (ALP). All cell types were able to adhere to all tested PUFs and to synthesize DNA. At 48 hr culture, HBM stromal cells showed the maximal rate of adhesion with the highest rate of proliferation onto PUFs with the largest pore size, whereas both chondrocytes and Saos-2 appeared to adhere preferentially onto foams exhibiting the highest percentage of open porosity. Up to 8 days in culture Saos-2 cells were able to proliferate into all PUFs, with a time-dependent increase of DNA synthesis and ALP activity. At SEM, the morphology of cells adherent to PUF pores was spread with cytoplasmatic extroflessions, indicating a good metabolic activation. These results demonstrate a good cytocompatibility of the proposed 3D matrices, suggesting that their use in the preparation of composite scaffolds is worth further investigation. (Journal of Applied Biomaterials & Biomechanics 2003; 1: 58-66).

Breastfeeding does not influence the development of inhibitors in haemophilia

Our aim was to test the hypothesis that breastfeeding may reduce development of inhibitors in male infants with haemophilia by inducing an oral immune tolerance to factor VIII. To achieve that goal, we performed a structured epidemiological survey comprising all males born with severe haemophilia A (in all 100 patients, 19 with inhibitors) or haemophilia B (in all 16 patients, six with inhibitors) in Sweden in 1980-99. Our results show no protective effect of breastfeeding.

Silk fibroin-polyurethane scaffolds for tissue engineering

Silk fibroin (SF) is a highly promising protein for its surface and structural properties, associated with a good bio- and hemo-compatibility. However, its mechanical properties and architecture cannot be easily tailored to meet the requirements of specific applications. In this work, SF was used to modify the surface properties of polyurethanes (PUs), thus obtaining 2D and 3D scaffolds for tissue regeneration. PUs were chosen for their well known advantageous properties and versatility; they can be obtained either as 2D (films) or 3D (foams) substrates. Films of a medical-grade poly-carbonate-urethane were prepared by solvent casting; PU foams were purposely designed and prepared with a morphology (porosity and cell size) adequate for cell growth. PU substrates were coated with fibroin by a dipping technique. To stabilize the coating layer, a conformational change of the protein from the alpha-form (water soluble) to the beta-form (not water soluble) was induced. Novel methodology in UV spectroscopy were developed for quantitatively analyzing the SF-concentration in dilute solutions. Pure fibroin was used as standard, as an alternative to the commonly used albumin, allowing real concentration values to be obtained. SF-coatings showed good stability in physiological-like conditions. A treatment with methanol further stabilized the coating. Preliminary results with human fibroblasts indicated that SF coating promote cell adhesion and growth, suggesting that SF-modified PUs appear to be suitable scaffolds for tissue engineering applications.

Use of recombinant factor VIIa (NovoSeven) in patients with Glanzmann thrombasthenia

Recombinant factor VIIa (rFVIIa; NovoSeven, Novo Nordisk, Bagsvaerd, Denmark) appears effective and relatively safe for the treatment of bleeding and for surgical prophylaxis in patients with Glanzmann thrombasthenia as reported to the International Registry on rFVIIa and Congenital Platelet Disorders. One of the shortcomings of the Registry data is the heterogeneity of treatment protocol, including dosage, number of doses used, duration of treatment before declaration of failure, and mode of rFVIIa administration (bolus v continuous infusion). The data are not yet sufficient to define optimal regimens for various indications such as the type of bleeding or the type of procedures. The place of this drug compared to platelet transfusion in the overall management of patients with Glanzmann thrombasthenia will need to be determined in relationship to a number of challenges and unresolved issues in the clinical care of these patients. These issues include: how to improve local measures for patients with mucosal bleeds, optimal management of young women during menarche, optimal platelet transfusion regimens for various indications, the relationship between antiplatelet antibodies detected by monoclonal antibody-specific immobilization of platelet antigens (MAIPA) and effectiveness of platelet transfusion, whether there are other biological tests that may correlate with effectiveness of platelet transfusion, and management of pregnancy and delivery regarding antiplatelet immunization.

An approach to study the viral safety of plasma-derived products in previously treated, non-infected patients

Using the polymerase chain reaction (PCR), we designed a study concept to evaluate the safety of plasma derivatives in previously treated patients who are non-infected by the specific viruses studied. Several product lots can be studied in a single patient, with a study period for each lot of 3 months. In the present study 19 patients were included for treatment with Baxter Hyland Immuno's PCR-screened factor VIII concentrate Immunate (n=7), factor IX concentrate Immunine (n=10), the by-passing agent FEIBA plus Immunine (n=1), and the protein C concentrate Ceprotin (n=1). PCR testing for hepatitis B, C or HIV genomic material in patient samples was done as well as serological testing. All patients remained negative for the tested markers. All seven Immunate patients completed three treatment periods with three different lots of the study drug. The median study period was 282 days and the median dose 115 000 units, with a median of 115 exposure days. Five of the 10 Immunine patients completed three treatment periods and four patients, two treatment periods. One Immunine patient was discontinued from the study for reasons unrelated to the study drug administration. The median study period was 305 days and the median total dose 82 200 units, with a median of 88 exposure days. Our study presents a new design to approach the evaluation of viral safety of new plasma derivatives in previously treated, non-infected patients (NIPs) and offers several advantages over the currently recommended studies using testing for serological markers of infection in previously untreated patients (PUPs).

Haemophilia B mutations in Sweden: a population-based study of mutational heterogeneity

The present series comprises all families (n = 77) with haemophilia B in Sweden and may be considered to be representative for the purposes of a population-based study of mutational heterogeneity. The 77 families (38 severe, 10 moderate, 29 mild) had 51 different mutations in total. Thirteen families had total, partial or small deletions, two had mutations in the promoter, eight families had splice site mutations, 14 had nonsense and the remaining 41 had missense mutations. Ten of the mutations, all C-->T or G-->A, recurred in 1--6 other families. Using haplotype analysis of seven polymorphisms in the factor IX (FIX) gene, we found that the 77 families carried 65 unique, independent mutations. Of the 48 families with severe or moderate haemophilia, 23 (48%) had a sporadic case of haemophilia compared with 31 families out of 78 (40%) in the whole series. Five of those 23 sporadic cases carried de novo mutations, 11 out of 23 of the mothers were proven carriers and, in the remaining seven families, it was not possible to determine carriership. Eleven of the 48 patients (23%) with severe haemophilia B developed inhibitors and all of them had deletions or nonsense mutations. Thus, 11 out of 37 (30%) patients with severe haemophilia B as a result of deletion/nonsense mutations developed inhibitors compared with 0 out of 11 patients with missense mutations. The ratio of male to female mutation rates was 5.3 and the overall mutation rate was 5.4 x 10(-6) per gamete per generation.

Novel poly(urethane-aminoamides): an in vitro study of the interaction with heparin

In order to obtain heparin-binding polyurethanes, tertiary amino-groups have been introduced in the polymer backbone by attributing a key-role to the chain extender, i.e. substituting butanediol, commonly used in polyurethane synthesis, with a tailor-made diamino-diamide-diol. In this work a poly(ether-urethane-aminoamide) (PEU/PIME/al) was obtained with poly(oxytetramethylene) glycol 2000, 1,6-hexamethylene-diisocyanate and the new chain extender, in the molar ratio 1:2:1. The heparin binding capacity of PEU/PIME/al was evaluated with 125I labelled heparin, using for comparison the analogous polymer obtained with a diamide-diol (i.e. the poly(ether-urethane-amide) PEU/PIBLO/al), and two commercially available biomedical polyurethanes (Pellethane 2363 and Corethane). pH and ionic strength dependence of the heparin uptake were investigated by treating all the polyurethanes with solutions of 125I heparin into buffers from pH 4 to 9 or NaCl molarity from 0.0 to 1.0. The stability of the interaction with bound heparin was investigated by sequential washing treatments (PBS, 1 N NaOH, 2% SDS solution), then analysing the residual radioactivity on the materials. Results indicated that the heparin binding of PEU/PIME/al is significantly higher and more stable than that of the other polyurethanes, with a time-dependent kinetic. The interaction with heparin appears to be prevalently ionic, with the contribution of other electrostatic and hydrophobic interactions. Activated partial thromboplastin time (APTT), performed on human plasma with polyurethane-coated, heparinized test tubes, indicated that bound heparin maintains its biological activity after the adsorption.

What factors should influence the dosage and interval of prophylactic treatment in patients with severe haemophilia A and B?

In order to prevent arthropathy, prophylaxis has to start at a young age before recurrent joint bleedings have taken place. The use of central venous lines has facilitated an early beginning to treatment, but due to side-effects, most European paediatricians prefer peripheral injections whenever possible. By starting primary prophylaxis at the age of 1--2 years with one injection weekly, the need for surgical implants may be reduced. In this study, only four of 34 boys born 1988--98 with severe haemophilia A or B needed a Port-a-Cath for primary prophylaxis. Trough levels were measured in these patients and 79% showed a trough level < 1%, while 21% reached a level > 1%. Despite this, joint bleedings during 1998 were rare in both groups [0--4] and 59% of the boys with trough levels < 1% did not report any haemartroses during that year. Mean annual joint bleedings were the same in both groups [0.70, 0.71]. The lowest effective level of factors VIII and IX must be determined individually for each patient on primary or secondary prophylaxis.

Treatment of children with haemophilia in Europe: a survey of 20 centres in 16 countries

A survey was made of the current status of treatment of haemophilic boys at 20 centres in 16 European countries and includes approximately 1500 of the estimated 6500 haemophiliacs in the participating countries. Many mild haemophiliacs are not seen, or seen infrequently, at haemophilia centres and this requires study. Nine of 18 centres provide continuous prophylaxis to 80-100% of their patients, five centres provide it to 55-80% and the remaining four centres to 15-40% of the boys. The median dose given was 6240 U kg-1 year-1 (range 3120-7800). Four centres administered only recombinant concentrates to children with severe haemophilia A, while seven centres administered recombinant concentrates to 75-90% and the remaining centres to less than 50% of the boys (two centres < 10%). When asked for the choice of concentrate for a newly diagnosed boy with severe haemophilia A, all but one centre preferred recombinant concentrate. Most boys below 6 years received concentrates via a peripheral vein but three centres preferred a central venous line for 80-100% of the boys. Thirteen of 18 centres applied home treatment to 84-100% of the boys and the remaining five centres to 57-77% of the boys.

Factor VIII inhibitors in two families with mild haemophilia A: structural analysis of the mutations

The development of inhibitory antibodies against coagulation factor VIII (FVIII) in patients with mild haemophilia A is uncommon. We describe here two families in which three or two members have developed inhibitors, suggesting a familial predisposition. The mutations found, in the A2 (Arg593Cys) and C1 domains (Tyr2105Cys), have been reported to give rise to inhibitor development in single individuals in addition to the family cluster we describe, strongly suggesting that these amino acid substitutions give rise to a more immunogenic protein. The analysis of structural models of activated factor VIII revealed that Arg593 is solvent-exposed and involved in a network of electrostatic interactions while Tyr2105 is partially buried and has hydrophobic interactions essentially with Ile2144. All these residues are strictly conserved in the FVIII amino acid sequence from man, pig and mouse, suggesting, at least, that they have structural roles. We propose that the two mutations in these families could cause mild haemophilia A because they induce local conformational changes (and possible secretion or intermolecular interaction problems, e.g., with von Willebrand factor) compatible with immunogenicity and production of inhibitors against the infused wild-type FVIII.

In vitro stability of polyether and polycarbonate urethanes

The in vitro structural stability of poly-ether-urethanes (PEUs) and poly-carbonate-urethanes (PCUs) was examined under strong acidic (HNO3) or alkaline (NaClO) oxidative conditions and in presence of a constant strain state. Polyurethane (PU) samples were represented by sheets solvent-cast from commercial pellets or by tubular specimens cut from commercial catheters. The specimens were strained at 100% uniaxial elongation over appropriate extension devices and completely immersed into the oxidative solutions at 50 degrees C for 7-14 days. The changes induced by the oxidative treatments were then evaluated by molecular weight analysis, tensile mechanical tests, and scanning electron microscopy. In the experiments with solvent-cast samples, the PEU Pellethane was degraded more in the alkaline oxidative conditions and mainly in the absence of an applied uniaxial stress. All the tested PCUs were, on the contrary, more affected by the acidic oxidative agent. All the PCUs proved to have overall better stability than the PEU. The susceptibility to oxidation was also dependent on the shape and bulk/surface organisation acquired by the same polymer during its processing. When the oxidative test was applied to catheters made of a PEU and a PCU, the results confirmed the better stability of poly-carbonate-urethanes.

Polyurethane-maleamides for cardiovascular applications: synthesis and properties

Several polyurethane-maleamides (PUMAs) containing polyether or polycarbonate soft segments, and aromatic or aliphatic hard segments were synthesized by solution or bulk polymerization, using maleic acid (MA) or a mixture of MA and butanediol as chain extenders. Using this process, activated double bonds are introduced into the polymer chains and the base polyurethanes may undergo further modification via specific grafting, thus improving their tissue compatibility. PUMAs chemicophysical properties were evaluated by gel permeation chromatography (GPC), intrinsic viscosity analyses, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR) and tensile mechanical tests. Polycarbonate diol (PCU)-based PUMAs showed higher molecular weights than polyether diol (PEU)-based ones. The use of butanediol in mixture with maleic acid led to an increase of molecular weights. FT-IR confirmed the presence of the bands related to the amide groups and to the conjugated double bond, yet more evident for the polymer obtained in solution. The higher crystallinity shown by this polymer was also indicative of a better phase separation. All the PCU-PUMAs exhibited similar tensile properties with a higher stiffness than PEU-PUMAs. Among the PEU-PUMAs, the highest tensile properties were shown by the polymer obtained in solution, and by the one derived from a mixture of maleic acid and butanediol.

Linear poly(ethylene oxide)-based polyurethane hydrogels: polyurethane-ureas and polyurethane-amides

Over the last 30 years, water-swellable and water-insoluble hydrogels have been extensively investigated and developed, leading to a large family of materials which have found uses in a wide range of biomedical applications. While hydrogels usually present a crosslinked structure, linear polyurethane-ureas (PUUs) based on poly(ethylene oxide) have been shown to be able to absorb and swell with aqueous media without dissolving. This behavior is due to the phase separated domain morphology, where hydrogen bonded urethane/urea hard segment domains are dispersed in a PEO soft segment domain. This work investigates the possibility of obtaining linear poly(ethylene oxide)-based polyurethane-amide (PUA) hydrogels using two amide diols as chain extenders, a mono amide diol (AD) and a diamide diol (DD), and a dicarboxylic acid (maleic acid, MA). Poly(ethylene oxide) based PUAs were obtained using a "one-shot" bulk polymerization technique. The chemicophysical characterization and water-solubility tests showed that these materials, while having molecular weights similar to the PUUs, do not possess sufficient phase separation, hydrogen bonding and hydrophobicity of the hard segment domains to exhibit hydrogel behavior. Crosslinked PUAs using maleic acid as chain extender show interesting hydrogel properties.

Primary prophylaxis in severe haemophilia should be started at an early age but can be individualized

The frequency of joint bleeds and orthopaedic joint scores were evaluated in 121 patients with severe haemophilia who had started prophylactic treatment with clotting factor concentrates at least once weekly before the age of 10. 75 of the patients started before the age of 3, 31 at the age of 3-5 and 15 at the age of 6-9. Each subgroup was evaluated separately. In addition, a regimen of one infusion weekly was compared with that of two (haemophilia B) or three (haemophilia A) infusions weekly in each patient. A significant decrease in the overall number of joint bleeds per year was found after shortening the infusion interval (P<0.005), but the individual bleeding pattern varied. In survival analysis of the first pathologic joint score event, those who started prophylaxis before the age of 3 had a better outcome overall than those starting at later ages (P=0.001). However, in subgroup analysis, no significant difference was seen in the annual number of joint bleeds and the development of arthropathy between those starting with, or shifting to, the more intensive regimen before the age of 3 and those that were put on this regimen at the age of 3-5. Age at start of prophylaxis was found to be an independent predictor for the development of arthropathy (P=0.0002), whereas dose and infusion interval at start were not. Our data emphasize the importance of starting replacement therapy during the first years of life. However, it seems that when beginning the regimen it can be individualized and adjusted according to the bleeding pattern. In this way, the need for a venous access system may be assessed on an individual basis.

[Centralized care is the basis of care programs for hemophilia patients]

Haemophilia is a rare and potentially life-threatening disease. In Sweden, with a population of approximately 8.5 million, about 350 people suffer from the more severe forms of haemophilia or von Willebrand disease. Meticulous management is important if the patients are to be spared chronic disability and serious treatment complications. The disease is lifelong and affects psychosocial aspects of life among patients and their families. With the help of a grant from the Swedish Board of Halth and Welfare, a care programme has been designed to guarantee Swedish haemophiliacs comparable and optimal care. The programme has been drawn up by representatives of the three haemophilia centres in Sweden (at University Hospital, Malmö, Sahlgrenska University Hospital, Gothenburg, and Karolinska Hospital, Stockholm) in co-operation with the World Federation of National Haemophilia Organisations. To ensure optimal individual application of the programme, individualised management strategies and patient information leaflets have been prepared.

Synergistic effects of oxidative environments and mechanical stress on in vitro stability of polyetherurethanes and polycarbonateurethanes

The in vitro structural stability of polyetherurethanes (PEUs) and polycarbonateurethanes (PCUs and PCUUs) was examined under strong oxidative conditions (0.5N HNO3, pH 0.3; and NaClO, 4% Cl2 available, pH approximately 13) and in the presence of a constant strain state. Solvent-cast dog-bone shaped specimens were strained at 100% uniaxial elongation over extension devices and completely immersed in the oxidative solutions at 50 degrees C for 15 days. Unstrained polyurethane (PU) samples were treated in the same way for comparison. The modification of the PU molecular structure was determined by DSC, GPC, ATR-FTIR, static contact angle, and surface roughness analyses. The incubation in nitric acid and sodium hypochlorite brought about a greater degradation of samples tested under the applied strain with the exception of PEU treated with nitric acid. PEU was the most affected material, showing bulk deterioration in NaClO and significant modifications in nitric acid, with the appearance of new IR bands, which were assigned to oxidation products. A higher phase separation between soft and hard domains occurred in PCUs upon incubation in nitric acid, the treatment with NaClO gave rise to new bands in the IR spectra, denoting the presence of oxidation products at the surface. The surface roughness greatly increased in strained PCUs with SEM evidence of deep cracks and holes or ragged and stretched fractures perpendicular to the direction of stress. PCUU underwent complex chemical modifications with a marked decrease of N-H and urea IR absorptions and showed a lower degradation than PEU and PCUs under mechanical constraint. From these results, sodium hypochlorite appears to be able to create an ESC-like degradation for PUs that are resistant to other aggressive chemical environments.