The effect of the carbon fibres diameter on cell response

W ramach pracy otrzymano włókninę zbudowaną z włókien o różnych średnicach i wielkości, której mikrostruktura posiada biomimetyczny charakter, tzn. składa się z włókien o średnicach zbliżonych do średnic włókien występujących w tkankach. Badania biologiczne wykazały, że włókna o niskich średnicach są gorzej tolerowane przez tkanki.A three dimensional fibrous material, made from fibres differing in diameters and porosity, has been designed and prepared. These materials will constitute a 3D scaffold containing fibrous components mimicking the structure of natural tissue. The biological studies indicate that the fibres with bigger diameter allow for more intense and quick regeneration of surrounding tissue

Long-term clinical and experimental/surface analytical studies of carbon/carbon maxillofacial implants

BACKGROUND:Over the past 30-40years, various carbon implant materials have become more interesting, because they are well accepted by the biological environment. The traditional carbon-based polymers give rise to many complications. The polymer complication may be eliminated through carbon fibres bound by pyrocarbon (carbon/carbon). The aim of this study is to present the long-term clinical results of carbon/carbon implants, and the results of the scanning electron microscope and energy dispersive spectrometer investigation of an implant retrieved from the human body after 8years.METHODS:Mandibular reconstruction (8-10years ago) was performed with pure (99.99%) carbon implants in 16 patients (10 malignant tumours, 4 large cystic lesions and 2 augmentative processes). The long-term effect of the human body on the carbon/carbon implant was investigated by comparing the structure, the surface morphology and the composition of an implant retrieved after 8years to a sterilized, but not implanted one.RESULTS:Of the 16 patients, the implants had to be removed earlier in 5 patients because of the defect that arose on the oral mucosa above the carbon plates. During the long-term follow-up, plate fracture, loosening of the screws, infection or inflammations around the carbon/carbon implants were not observed. The thickness of the carbon fibres constituting the implants did not change during the 8-year period, the surface of the implant retrieved was covered with a thin surface layer not present on the unimplanted implant. The composition of this layer is identical to the composition of the underlying carbon fibres. Residual soft tissue penetrating the bulk material between the carbon fibre bunches was found on the retrieved implant indicating the importance of the surface morphology in tissue growth and adhering implants.CONCLUSIONS:The surface morphology and the structure were not changed after 8years. The two main components of the implant retrieved from the human body are still carbon and oxygen, but the amount of oxygen is 3-4 times higher than on the surface of the reference implant, which can be attributed to the oxidative effect of the human body, consequently in the integration and biocompatibility of the implant. The clinical conclusion is that if the soft part cover is appropriate, the carbon implants are cosmetically and functionally more suitable than titanium plates

In vitro and in vivo studies on biocompatibility of carbon fibres

In the present study we focused on the in vitro and in vivo evaluation of two types of carbon fibres (CFs): hydroxyapatite modified carbon fibres and porous carbon fibres. Porous CFs used as scaffold for tissues regeneration could simultaneously serve as a support for drug delivery or biologically active agents which would stimulate the tissue growth; while addition of nanohydroxyapatite to CFs precursor can modify their biological properties (such as bioactivity) without subsequent surface modifications, making the process cost and time effective. Presented results indicated that fibre modification with HAp promoted formation of apatite on the fibre surface during incubation in simulated body fluid. The materials biocompatibility was determined by culturing human osteoblast-like cells of the line MG 63 in contact with both types of CFs. Both tested materials gave good support to adhesion and growth of bone-derived cells. Materials were implanted into the skeletal rat muscle and a comparative analysis of tissue reaction to the presence of the two types of CFs was done. Activities of marker metabolic enzymes: cytochrome c oxidase (CCO) and acid phosphatase were examined to estimate the effect of implants on the metabolic state of surrounding tissues. Presented results evidence the biocompatibility of porous CFs and activity that stimulates the growth of connective tissues. In case of CFs modified with hydroxyapatite the time of inflammatory reaction was shorter than in case of traditional CFs

Three-dimensional bio-printing and bone tissue engineering: technical innovations and potential applications in maxillofacial reconstructive surgery

Background Bone grafting has been considered the gold standard for hard tissue reconstructive surgery and is widely used for large mandibular defect reconstruction. However, the midface encompasses delicate structures that are surrounded by a complex bone architecture, which makes bone grafting using traditional methods very challenging. Three-dimensional (3D) bioprinting is a developing technology that is derived from the evolution of additive manufacturing. It enables precise development of a scaffold from different available biomaterials that mimic the shape, size, and dimension of a defect without relying only on the surgeon’s skills and capabilities, and subsequently, may enhance surgical outcomes and, in turn, patient satisfaction and quality of life. Review This review summarizes different biomaterial classes that can be used in 3D bioprinters as bioinks to fabricate bone scaffolds, including polymers, bioceramics, and composites. It also describes the advantages and limitations of the three currently used 3D bioprinting technologies: inkjet bioprinting, micro-extrusion, and laser-assisted bioprinting. Conclusions Although 3D bioprinting technology is still in its infancy and requires further development and optimization both in biomaterials and techniques, it offers great promise and potential for facial reconstruction with improved outcome

Arterial stiffness & Sri Lankan chronic kidney disease of unknown origin

Chronic kidney disease (CKD) is common and independently associated with cardiovascular disease (CVD). Arterial stiffness contributes to CVD risk in CKD. In many developing countries a considerable proportion of CKD remains unexplained, termed CKDu. We assessed arterial stiffness in subjects with Sri Lankan CKDu, in matched controls without CKD and in those with defined CKD. Aortic blood pressure (BP), pulse wave velocity (PWV) and augmentation index (AIx) were assessed in 130 subjects (50 with CKDu, 45 with CKD and 35 without CKD) using the validated TensioMed™ Arteriograph monitor. Brachial and aortic BP was lower in controls than in CKDu and CKD subjects but no different between CKDu and CKD. Controls had a lower PWV compared to subjects with CKDu and CKD. Despite equivalent BP and renal dysfunction, CKDu subjects had a lower PWV than those with CKD (8.7 ± 1.5 vs. 9.9 ± 2.2 m/s, p < 0.01). Excluding diabetes accentuated the differences in PWV seen between groups (controls vs. CKDu vs. CKD: 6.7 ± 0.9 vs. 8.7 ± 1.5 vs. 10.4 ± 1.5 m/s, p < 0.001 for all). Sri Lankan CKDu is associated with less arterial stiffening than defined causes of CKD. Whether this translates to lower cardiovascular morbidity and mortality long term is unclear and should be the focus of future studies

Effect of sitagliptin on cardiovascular outcomes in type 2 diabetes

BACKGROUND: Data are lacking on the long-term effect on cardiovascular events of adding sitagliptin, a dipeptidyl peptidase 4 inhibitor, to usual care in patients with type 2 diabetes and cardiovascular disease. METHODS: In this randomized, double-blind study, we assigned 14,671 patients to add either sitagliptin or placebo to their existing therapy. Open-label use of antihyperglycemic therapy was encouraged as required, aimed at reaching individually appropriate glycemic targets in all patients. To determine whether sitagliptin was noninferior to placebo, we used a relative risk of 1.3 as the marginal upper boundary. The primary cardiovascular outcome was a composite of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for unstable angina. RESULTS: During a median follow-up of 3.0 years, there was a small difference in glycated hemoglobin levels (least-squares mean difference for sitagliptin vs. placebo, -0.29 percentage points; 95% confidence interval [CI], -0.32 to -0.27). Overall, the primary outcome occurred in 839 patients in the sitagliptin group (11.4%; 4.06 per 100 person-years) and 851 patients in the placebo group (11.6%; 4.17 per 100 person-years). Sitagliptin was noninferior to placebo for the primary composite cardiovascular outcome (hazard ratio, 0.98; 95% CI, 0.88 to 1.09; P<0.001). Rates of hospitalization for heart failure did not differ between the two groups (hazard ratio, 1.00; 95% CI, 0.83 to 1.20; P = 0.98). There were no significant between-group differences in rates of acute pancreatitis (P = 0.07) or pancreatic cancer (P = 0.32). CONCLUSIONS: Among patients with type 2 diabetes and established cardiovascular disease, adding sitagliptin to usual care did not appear to increase the risk of major adverse cardiovascular events, hospitalization for heart failure, or other adverse events

Properties of bilayer gelatin/polycaprolactone scaffolds

In this study, nanofibrous composite scaffolds have been fabricated in order to mimic the physical architecture of native extracellular matrix. Gelatin is a good candidate to mimic the chemical composition of natural collagen. It has many integrin-binding sites for cell adhesion and differentiation, which are found in collagen. However, electrospun scaffold made of gelatin had very poor mechanical properties. Therefore, in this study, bilayer nanofibrous scaffolds made of gelatin and poly(caprolactone) were produced by sequential electrospinning. The microscopic morphology, mechanical properties and porosity of electrospun bilayer gelatin/polycaprolactone scaffold were investigated

Evaluation of PCL and PCL/HAp scaffolds processed by electrospinning and porogen leaching techniques

In order to improve the pore size of the polycapro-lactone (PCL) and polycaprolactone/hydroxyapatite (PCL/HAp) nanofibrous scaffolds, salt-leaching technique together with electrospinning method were applied. Salt particles were incorporated within the polymer nanofibrous matrix and then were leached out to generate some macropores. Microstructure, pore size distribution and average fibre diameter of the scaffold were investigated by scanning electron microscopy and PMI capillary flow porometer. Mechanical properties were determined by means of tensile test. Presence of hydroxyapatite and chemical characterization of the scaffold were done by FTIR analysis

Assessment of the stability of PCL-fibres intended for use as scaffolds for tissue engineering in physiological fluids

Bardzo dużą rolę w procesie degradacji implantów odgrywa środowisko płynów fizjologicznych, których wpływ zależy od właściwości fizycznych i chemicznych materiału polimerowego oraz od jego reaktywności. W niniejszej pracy oceniono wpływ płynu PBS na trwałość kompozytowych włókien polikaprolakton / hydroksyapatyt w warunkach in vitro. Stopień degradacji włókien określano na podstawie zmian pH medium, stężenia jonów sodu i potasu w płynie po inkubacji próbek oraz zmian masy próbek podczas inkubacji. Ocenę zmian zachodzących we włóknach pod wpływem płynu PBS przeprowadzono wykorzystując skaningową mikroskopię elektronową (SEM) oraz rentgenowską analizę strukturalną (WAXD). Badania degradacji włókien przeprowadzone podczas inkubacji próbek w płynach fizjologicznych wykazały, że wytworzone włókna kompozytowe charakteryzuję się stabilnością w środowisku płynów ustrojowych przez długi okres czasu. Niewielkie zmiany na powierzchni włókien, zaobserwowane po 10 miesiącach inkubacji, w płynie fizjologicznym, wskazują na rozpoczęcie procesu degradacji, stąd też można przypuszczać, że czas całkowitej biodegradacji włókien może być skorelowany z czasem potrzebnym do kompletnego odtworzenia tkanki.Very important role in the process of implant degradation is played by the physiological fluid environment, the impact of which depends on the physical and chemical properties of the polymers and on its reactivity. This study evaluates the effect of PBS on the stability of composite polycaprolactone/hydroxyapatite fibres in vitro. The degree of degradation of the fibres was determined by the changes in pH of the fluid, the concentration of sodium and potassium ions in the fluid after incubation of the sample, and the changes in the weights of samples during incubation. Assessment of the changes in the fibres under the influence of PBS was carried out using scanning electron microscopy (SEM) and X-ray structural analysis (WAXD). The study of the degradation of fibres carried out during the incubation of samples in physiological fluids showed that the composite fibres produced are stable in the environment of physiological fluids over a long period of time. Minor changes on the surface of the fibres, observed after 10 months of incubation, in a body fluid, indicate the start of a process of degradation, hence it can be assumed that the time of total biodegradation of the fibres may be correlated with the time needed for a complete restoration of tissue