The use of non-viral gene vectors for bioactive poly-(D,L-lactide) implant surfaces in bone tissue engineering

The application of scaffolds in bone tissue engineering often comes along with side effects such as poor integrity, low regeneration rates of bone tissue with inadequate functionality, and, in case of non-degradable implants, the necessity of a second removal surgery after therapy. In this study, we coated a bioresorbable FDA-approved poly-(ε-caprolactone)-scaffold for bone regeneration with a poly-(D,L-lactide) layer containing copolymer-protected gene vectors to locally provide bone morphogenetic protein-2 (BMP-2). Results show that the presence of such gene vectors did not affect the distribution and attachment of seeded cells on gene-activated surfaces. BMP-2 was released into cell culture supernatants and furthermore detected in homogenised scaffolds. Increased amounts of osteoblastic markers, such as osteocalcin, osteopontin and the activity of alkaline phosphatase, in gene-activated scaffolds in vitro suggest a transdifferentiation of myoblastic C2C12 cells into the osteoblastic phenotype. With this study we present a new technology to bioactivate implant surfaces with non-viral gene vectors. This tool allows the stimulation of tissue regeneration by a local release of therapeutic proteins in vivo

Analysis of Synaptic Proteins in the Cerebrospinal Fluid as a New Tool in the Study of Inborn Errors of Neurotransmission

Abstract In a few rare diseases, specialised studies in cerebrospinal fluid (CSF) are required to identify the underlying metabolic disorder. We aimed to explore the possibility of detecting key synaptic proteins in the CSF, in particular dopaminergic and gabaergic, as new procedures that could be useful for both pathophysiological and diagnostic purposes in investigation of inherited disorders of neurotransmission. Dopamine receptor type 2 (D2R), dopamine transporter (DAT) and vesicular monoamine transporter type 2 (VMAT2) were analysed in CSF samplesfrom 30 healthy controls (11 days to 17 years) by western blot analysis. Because VMAT2 was the only protein with intracellular localisation, and in order to compare results, GABA vesicular transporter, which is another intracellular protein, was also studied. Spearman’s correlation and Student’s t tests were applied to compare optical density signals between different proteins. All these synaptic proteins could be easily detected and quantified in the CSF. DAT, D2R and GABA VT expression decrease with age, particularly in the first months of life, reflecting the expected intense synaptic activity and neuronal circuitry formation. A statistically significant relationship was found between D2R and DAT expression, reinforcing the previous evidence of DAT regulation by D2R. To our knowledge, there are no previous studies on human CSF reporting a reliable analysis of these proteins. These kinds of studies could help elucidate new causes of disturbed dopaminergic and gabaergic transmission as well as understanding different responses to L-dopa in inherited disorders affecting dopamine metabolism. Moreover, this approach to synaptic activity in vivo can be extended to different groups of proteins and diseases

Effect of body tilt angle on fatigue and EMG activities in lower limbs during cycling

This study compared the rate of fatigue and lower limb EMG activities during high-intensity constantload cycling in upright and supine postures. Eleven active males performed seven cycling exercise tests: one upright graded test, four fatigue tests (two upright, two supine) and two EMG tests (one upright, one supine). During the fatigue tests participants initially performed a 10 s all-out effort followed by a constant-load test with 10 s all-out bouts interspersed every minute. The load for the initial two fatigue tests was 80% of the peak power (PP) achieved during the graded test and these continued until failure. The remaining two fatigue tests were performed at 20% PP and were limited to the times achieved during the 80% PP tests. During the EMG tests subjects performed a 10 s all-out effort followed by a constant-load test to failure at 80% PP. Normalised EMG activities (% maximum, NEMG) were assessed in five lower limb muscles. Maximum power and maximum EMG activity prior to each fatigue and EMG test were unaffected by posture. The rate of fatigue at 80% PP was significantly higher during supine compared with upright posture (-68 &plusmn; 14 vs. -26 &plusmn; 6 W min-1, respectively, P\0.05) and the divergence of the fatigue responses occurred by the second minute of exercise. NEMG responses were significantly higher in the supine posture by 1&ndash;4 min of exercise. Results show that fatigue is significantly greater during supine compared with upright high-intensity cycling and this effect is accompanied by a reduced activation of musculature that is active during cycling.<br /

Exercise performance and V0₂ kinetics during upright and recumbent high-intensity cycling exercise

This study investigated cycling performance and oxygen uptake (VO2) kinetics between upright and two commonly used recumbent (R) postures, 65&ordm;R and 30&ordm;R. On three occasions, ten young active males performed three bouts of high-intensity constant-load (85% peak workload achieved during a graded test) cycling in one of the three randomly assigned postures (upright, 65&ordm;R or 30&ordm;R). The first bout was performed to fatigue and second and third bouts were limited to 7 min. A subset of seven subjects performed a final constant-load test to failure in the supine posture. Exercise time to failure was not altered when the body inclination was lowered from the upright (13.1 &plusmn; 4.5 min) to 65&ordm;R (10.5 &plusmn; 2.7 min) and 30&ordm;R (11.5 &plusmn; 4.6 min) postures; but it was significantly shorter in the supine posture (5.8 &plusmn; 2.1 min) when compared with the three inclined postures. Resulting kinetic parameters from a tri-exponential analysis of breath-by-breath VO2 data during the first 7 min of exercise were also not different between the three inclined postures. However, inert gas rebreathing analysis of cardiac output revealed a greater cardiac output and stroke volume in both recumbent postures compared with the upright posture at 30 s into the exercise. These data suggest that increased cardiac function may counteract the reduction of hydrostatic pressure from upright ~25 mmHg; to 65&ordm;R ~22 mmHg; and 30&ordm;R ~18 mmHg such that perfusion of active muscle presumably remains largely unchanged, and also therefore, VO2 kinetics and performance during high-intensity cycling.<br /

The stiffness of living tissues and its implications for tissue engineering

The past 20 years have witnessed ever- growing evidence that the mechanical properties of biological tissues, from nanoscale to macroscale dimensions, are fundamental for cellular behaviour and consequent tissue functionality. This knowledge, combined with previously known biochemical cues, has greatly advanced the field of biomaterial development, tissue engineering and regenerative medicine. It is now established that approaches to engineer biological tissues must integrate and approximate the mechanics, both static and dynamic, of native tissues. Nevertheless, the literature on the mechanical properties of biological tissues differs greatly in methodology, and the available data are widely dispersed. This Review gathers together the most important data on the stiffness of living tissues and discusses the intricacies of tissue stiffness from a materials perspective, highlighting the main challenges associated with engineering lifelike tissues and proposing a unified view of this as yet unreported topic. Emerging advances that might pave the way for the next decadeâ s take on bioengineered tissue stiffness are also presented, and differences and similarities between tissues in health and disease are discussed, along with various techniques for characterizing tissue stiffness at various dimensions from individual cells to organs.The authors would like to acknowledge financial support from the European Research Council, grant agreement ERC-2012-ADG 20120216-321266 (project ComplexiTE). C.F.G. acknowledges scholarship grant no. PD/BD/135253/2017 from Fundação para a Ciência e Tecnologia (FCT). The authors also thank the peer-reviewers for the constructive comments and suggestions that helped to shape this manuscript