Bioengineering — Open Access Journal

The formation of hybrid bioactive and inherently conductive constructs of composites formed from polyaniline-polyacrylamidomethylpropane sulfonic acid (PAn-PAAMPSA) nanomaterials (0.00–10.0 wt%) within poly(2-hydroxy ethyl methacrylate-co-N-{Tris(hydroxymethyl)methyl} acrylamide)-co-polyethyleneglycol methacrylate) p(HEMA-co-HMMA-co-PEGMA) hydrogels was made possible using microlithographic fabrication and 3-D printing. Hybrid constructs formed by combining a non-conductive base (0.00 wt% PAn-PAAMPSA) and electroconductive (ECH) (varying wt% PAn-PAAMPSA) hydrogels using these two production techniques were directly compared. Hydrogels were electrically characterized using two-point probe resistivity and electrochemical impedance spectroscopy. Results show that incorporation of >0.10 wt% PAn-PAAMPSA within the base hydrogel matrices was enough to achieve percolation and high conductivity with a membrane resistance (R_M) of 2140 Ω and 87.9 Ω for base (0.00 wt%) and ECH (10.0 wt%), respectively. UV-vis spectroscopy of electroconductive hydrogels indicated a bandgap of 2.8 eV that was measurable at concentrations of >0.10 wt% PAn-PAAMPSA. Both base and electroconductive hydrogels supported the attachment and growth of NIH/3T3 fibroblast cells. When the base hydrogel was rendered bioactive by the inclusion of collagen (>200 µg/mL), it also supported the attachment, but not the differentiation, of PC-12 neural progenitor cells. Full article

Due to pronounced species differences, hepatotoxicity of new drugs often cannot be detected in animal studies. Alternatively, human hepatocytes could be used, but there are some limitations. The cells are not always available on demand or in sufficient amounts, so far there has been only limited success to allow the transport of freshly isolated hepatocytes without massive loss of function or their cultivation for a long time. Since it is well accepted that the cultivation of hepatocytes in 3D is related to an improved function, we here tested the Optimaix-3D Scaffold from Matricel for the transport and cultivation of hepatocytes. After characterization of the scaffold, we shipped cells on the scaffold and/or cultivated them over 10 days. With the evaluation of hepatocyte functions such as urea production, albumin synthesis, and CYP activity, we showed that the metabolic activity of the cells on the scaffold remained nearly constant over the culture time whereas a significant decrease in metabolic activity occurred in 2D cultures. In addition, we demonstrated that significantly fewer cells were lost during transport. In summary, the collagen-based scaffold allows the transport and cultivation of hepatocytes without loss of function over 10 days. Full article

Children with central nervous system (CNS) malignancies often suffer from high symptom burden and risk of death. Pediatric palliative care is a medical specialty, provided by an interdisciplinary team, which focuses on enhancing quality of life and minimizing suffering for children with life-threatening or life-limiting disease, and their families. Primary palliative care skills, which include basic symptom management, facilitation of goals-of-care discussions, and transition to hospice, can and should be developed by all providers of neuro-oncology care. This chapter will review the fundamentals of providing primary pediatric palliative care. Full article

Computational elbow joint models, capable of simulating medial collateral ligament deficiency, can be extremely valuable tools for surgical planning and refinement of therapeutic strategies. The objective of this study was to investigate the effects of varying levels of medial collateral ligament deficiency on elbow joint stability using subject-specific computational models. Two elbow joint models were placed at the pronated forearm position and passively flexed by applying a vertical downward motion on humeral head. The models included three-dimensional bone geometries, multiple ligament bundles wrapped around the joint, and the discretized cartilage representation. Four different ligament conditions were simulated: All intact ligaments, isolated medial collateral ligament (MCL) anterior bundle deficiency, isolated MCL posterior bundle deficiency, and complete MCL deficiency. Minimal kinematic differences were observed for isolated anterior and posterior bundle deficient elbows. However, sectioning the entire MCL resulted in significant kinematic differences and induced substantial elbow instability. Joint contact areas were nearly similar for the intact and isolated posterior bundle deficiency. Minor differences were observed for the isolated anterior bundle deficiency, and major differences were observed for the entire MCL deficiency. Complete elbow dislocations were not observed for any ligament deficiency level. As expected, during isolated anterior bundle deficiency, the remaining posterior bundle experiences higher load and vice versa. Overall, the results indicate that either MCL anterior or posterior bundle can provide anterior elbow stability, but the anterior bundle has a somewhat bigger influence on joint kinematics and contact characteristics than posterior one. A study with a larger sample size could help to strengthen the conclusion and statistical significant. Full article

Glioblastoma Multiforme (GBM) is a common primary brain cancer with a poor prognosis and a median survival of less than 14 months. Current modes of treatment are associated with deleterious side effects that reduce the life span of the patients. Nanomedicine enables site-specific delivery of active pharmaceutical ingredients and facilitates entrapment inside the tumor. Polo-like kinase 1 (PLK-1) inhibitors have shown promising results in tumor cells. GSK461364A (GSK) is one such targeted inhibitor with reported toxicity issues in phase 1 clinical trials. We have demonstrated in our study that the action of GSK is time dependent across all concentrations. There is a distinct 15−20% decrease in cell viability via apoptosis in U87-MG cells dosed with GSK at low concentrations (within the nanomolar and lower micromolar range) compared to higher concentrations of the drug. Additionally, we have confirmed that PLGA-PEG nanoparticles (NPs) containing GSK have shown significant reduction in cell viability of tumor cells compared to their free equivalents. Thus, this polymeric nanoconstruct encapsulating GSK can be effective even at low concentrations and could improve the effectiveness of the drug while reducing side effects at the lower effective dose. This is the first study to report a PLK-1 inhibitor (GSK) encapsulated in a nanocarrier for cancer applications. Full article

Human adipose-derived stem cells (hASCs) have been shown to differentiate down many lineages including endothelial lineage. We hypothesized that hASCs would more efficiently differentiate toward the endothelial lineage when formed as three-dimensional (3D) spheroids and with the addition of vascular endothelial growth factor (VEGF). Three conditions were tested: uncoated tissue culture polystyrene (TCPS) surfaces that induced a 2D monolayer formation; elastin-like polypeptide (ELP)-collagen composite hydrogel scaffolds that induced encapsulated 3D spheroid culture; and ELP-polyethyleneimine-coated TCPS surfaces that induced 3D spheroid formation in scaffold-free condition. Cells were exposed to endothelial differentiation medium containing no additional VEGF or 20 and 50 ng/mL of VEGF for 7 days and assayed for viability and endothelial differentiation markers. While endothelial differentiation media supported endothelial differentiation of hASCs, our 3D spheroid cultures augmented this differentiation and produced more von Willebrand factor than 2D cultures. Likewise, 3D cultures were able to uptake LDL, whereas the 2D cultures were not. Higher concentrations of VEGF further enhanced differentiation. Establishing angiogenesis is a key factor in regenerative medicine. Future studies aim to elucidate how to produce physiological changes such as neoangiogenesis and sprouting of vessels which may enhance the survival of regenerated tissues. Full article

Approximately five out of 100,000 children from 0 to 19 years old are diagnosed with a brain tumor. These children are treated with medication designed for adults that are highly toxic to a developing brain. Those that survive are at high risk for a lifetime of limited physical, psychological, and cognitive abilities. Despite much effort, not one drug exists that was designed specifically for pediatric patients. Stagnant government funding and the lack of economic incentives for the pharmaceutical industry greatly limits preclinical research and the development of clinically applicable pediatric brain tumor models. As more data are collected, the recognition of disease sub-groups based on molecular heterogeneity increases the need for designing specific models suitable for predictive drug screening. To overcome these challenges, preclinical approaches will need continual enhancement. In this review, we examine the advantages and shortcomings of in vitro and in vivo preclinical pediatric brain tumor models and explore potential solutions based on past, present, and future strategies for improving their clinical relevancy. Full article

Raman spectroscopy is a novel tool used in the on-line monitoring and control of bioprocesses, offering both quantitative and qualitative determination of key process variables through spectroscopic analysis. However, the wide-spread application of Raman spectroscopy analysers to industrial fermentation processes has been hindered by problems related to the high background fluorescence signal associated with the analysis of biological samples. To address this issue, we investigated the influence of fluorescence on the spectra collected from two Raman spectroscopic devices with different wavelengths and detectors in the analysis of the critical process parameters (CPPs) and critical quality attributes (CQAs) of a fungal fermentation process. The spectra collected using a Raman analyser with the shorter wavelength (903 nm) and a charged coupled device detector (CCD) was corrupted by high fluorescence and was therefore unusable in the prediction of these CPPs and CQAs. In contrast, the spectra collected using a Raman analyser with the longer wavelength (993 nm) and an indium gallium arsenide (InGaAs) detector was only moderately affected by fluorescence and enabled the generation of accurate estimates of the fermentation’s critical variables. This novel work is the first direct comparison of two different Raman spectroscopy probes on the same process highlighting the significant detrimental effect caused by high fluorescence on spectra recorded throughout fermentation runs. Furthermore, this paper demonstrates the importance of correctly selecting both the incident wavelength and detector material type of the Raman spectroscopy devices to ensure corrupting fluorescence is minimised during bioprocess monitoring applications. Full article

Embryonal tumors (ET) of the central nervous system (CNS) in children encompass a wide clinical spectrum of aggressive malignancies. Until recently, the overlapping morphological features of these lesions posed a diagnostic challenge and undermined discovery of optimal treatment strategies. However, with the advances in genomic technology and the outpouring of biological data over the last decade, clear insights into the molecular heterogeneity of these tumors are now well delineated. The major subtypes of ETs of the CNS in children include medulloblastoma, atypical teratoid rhabdoid tumor (ATRT), and embryonal tumors with multilayered rosettes (ETMR), which are now biologically and clinically characterized as different entities. These important developments have paved the way for treatments guided by risk stratification as well as novel targeted therapies in efforts to improve survival and reduce treatment burden. Full article

Background: During pregnancy, the maternal-fetal contact may lead to the development of tolerance against the maternal human leukocyte antigen (HLA) that is not inherited by the fetus. These non-inherited maternal antigens (NIMAs) define acceptable HLA mismatches; therefore, the number of HLA phenotypes that are suitable matches for patients who need a hematopoietic stem cell transplant could be increased. Cord blood unit (CBU) transplantations to patients mismatched for a HLA loci, but similar to the ΝΙΜAs of the CBU, have a prognosis similar to 6/6-matched ones. Methods: The Hellenic Cord Blood Bank (HCBB) identified the maternal HLA of 380 cord blood donors, specifying the NIMA haplotypes of the related cryostored CBUs. Results: The HCBB extended the pool of HLA phenotypes through the generation of unique virtual phenotypes (VPs). A “VP database” was set up, using Microsoft Office—Access™, in order to provide NIMA-matched CBUs for potential recipients. The effectiveness of VPs’ matching was tested in 80 Greek patients. Conclusion: This methodology may contribute to the increase of the number of available CBUs for patients, in the case where there is no available CBU, or in case an additional one is needed. Through this method, the CBUs could be used faster and more effectively, rather than being cryostored for long periods of time. Full article

Angiogenesis, sprouting of new blood vessels from pre-existing vasculatures, plays a critical role in regulating tumor growth. Binding interactions between integrin, a heterodimeric transmembrane glycoprotein receptor, and its extracellular matrix (ECM) protein ligands govern the angiogenic potential of tumor endothelial cells. Integrin receptors are attractive targets in cancer therapy due to their overexpression on tumor endothelial cells, but not on quiescent blood vessels. These receptors are finding increasing applications in anti-angiogenic therapy via targeted delivery of chemotherapeutic drugs and nucleic acids to tumor vasculatures. The current article attempts to provide a retrospective account of the past developments, highlight important contemporary contributions and unresolved set-backs of this emerging field. Full article

The endometrium is an accessible source of mesenchymal stem cells. Most investigations of endometrial mesenchymal stem cells (eMSCs) have been conducted in humans. In animals, particularly in livestock, eMSC research is scarce. Such cells have been described in the bovine, ovine, caprine, porcine, and equine endometrium. Here we provide the state of the art of eMSCs in farm animals with a focus on the bovine species. In bovines, eMSCs have been identified during the phases of the estrous cycle, during which their functionality and the presence of eMSC-specific markers has been shown to change. Moreover, postpartum inflammation related to endometritis affects the presence and functionality of eMSCs, and prostaglandin E₂ (PGE₂) may be the mediator of such changes. We demonstrated that exposure to PGE₂ in vitro modifies the transcriptomic profile of eMSCs, showing its potential role in the fate of stem cell activation, migration, and homing during pathological uterine inflammation in endometritis and in healthy puerperal endometrium. Farm animal research on eMSCs can be of great value in translational research for certain uterine pathologies and for immunomodulation of local responses to pathogens, hormones, and other substances. Further research is necessary in areas such as in vivo location of the niches and their immunomodulatory and anti-infective properties. Full article

Artificial heart valves may dysfunction, leading to thrombus and/or pannus formations. Computational fluid dynamics is a promising tool for improved understanding of heart valve hemodynamics that quantify detailed flow velocities and turbulent stresses to complement Doppler measurements. This combined information can assist in choosing optimal prosthesis for individual patients, aiding in the development of improved valve designs, and illuminating subtle changes to help guide more timely early intervention of valve dysfunction. In this computational study, flow characteristics around a bileaflet mechanical heart valve were investigated. The study focused on the hemodynamic effects of leaflet immobility, specifically, where one leaflet does not fully open. Results showed that leaflet immobility increased the principal turbulent stresses (up to 400%), and increased forces and moments on both leaflets (up to 600% and 4000%, respectively). These unfavorable conditions elevate the risk of blood cell damage and platelet activation, which are known to cascade to more severe leaflet dysfunction. Leaflet immobility appeared to cause maximal velocity within the lateral orifices. This points to the possible importance of measuring maximal velocity at the lateral orifices by Doppler ultrasound (in addition to the central orifice, which is current practice) to determine accurate pressure gradients as markers of valve dysfunction. Full article

The late neurocognitive and psychosocial effects of treatment for pediatric brain tumor (PBT) represent important areas of clinical focus and ongoing research. Neurocognitive sequelae and associated problems with learning and socioemotional development negatively impact PBT survivors’ overall health-related quality of life, educational attainment and employment rates. Multiple factors including tumor features and associated complications, treatment methods, individual protective and vulnerability factors and accessibility of environmental supports contribute to the neurocognitive and psychosocial outcomes in PBT survivors. Declines in overall measured intelligence are common and may persist years after treatment. Core deficits in attention, processing speed and working memory are postulated to underlie problems with overall intellectual development, academic achievement and career attainment. Additionally, psychological problems after PBT can include depression, anxiety and psychosocial adjustment issues. Several intervention paradigms are briefly described, though to date research on innovative, specific and effective interventions for neurocognitive late effects is still in its early stages. This article reviews the existing research for understanding PBT late effects and highlights the need for innovative research to enhance neurocognitive and psychosocial outcomes in PBT survivors. Full article

Polyvinyl chloride (PVC) is one of the most widely used polymers in medicine but has very poor biocompatibility when in contact with tissue or blood. To increase biocompatibility, controlled release of nitric oxide (NO) can be utilized to mitigate and reduce the inflammatory response. A synthetic route is described where PVC is aminated to a specified degree and then further modified by covalently linking S-nitroso-N-acetyl-d-penicillamine (SNAP) groups to the free primary amine sites to create a nitric oxide releasing polymer (SNAP-PVC). Controllable release of NO from SNAP-PVC is described using photoinitiation from light emitting diodes (LEDs). Ion-mediated NO release is also demonstrated as another pathway to provide a passive mechanism for NO delivery. The large range of NO fluxes obtained from the SNAP-PVC films indicate many potential uses in mediating unwanted inflammatory response in blood- and tissue-contacting devices and as a tool for delivering precise amounts of NO in vitro. Full article

The technology of percutaneous coronary intervention (PCI) is constantly being refined in order to overcome the shortcomings of present day technologies. Even though current generation metallic drug-eluting stents (DES) perform very well in the short-term, concerns still exist about their long-term efficacy. Late clinical complications including late stent thrombosis (ST), restenosis, and neoatherosclerosis still exist and many of these events may be attributed to either the metallic platform and/or the drug and polymer left behind in the arterial wall. To overcome this limitation, the concept of totally bioresorbable vascular scaffolds (BRS) was invented with the idea that by eliminating long-term exposure of the vessel wall to the metal backbone, drug, and polymer, late outcomes would improve. The Absorb-bioabsorbable vascular scaffold (Absorb-BVS) represented the most advanced attempt to make such a device, with thicker struts, greater vessel surface area coverage and less radial force versus contemporary DES. Unfortunately, almost one year after its initial approval by the U.S. Food and Drug Administration, this scaffold was withdrawn from the market due to declining devise utilization driven by the concerns about scaffold thrombosis (ScT) seen in both early and late time points. Additionally, the specific causes of ScT have not yet been fully elucidated. In this review, we discuss the platform, vascular response, and clinical data of past and current metallic coronary stents with the Absorb-BVS and newer generation BRS, concentrating on their material/design and the mechanisms of thrombotic complications from the pre-clinical, pathologic, and clinical viewpoints. Full article

Pulsed illumination of a sample, e.g., of a biological tissue, causes a sudden temperature increase of light absorbing structures, such as blood vessels, which results in an outgoing acoustic wave, as well as heat diffusion, of the absorbed energy. Both of the signals, pressure and temperature, can be measured at the sample surface and are used to reconstruct the initial temperature or pressure distribution, called photoacoustic or photothermal reconstruction respectively. We have demonstrated that both signals at the same surface pixel are connected by a temporal transformation. This allows for the calculation of a so-called acoustical virtual wave from the surface temperature evolution as measured by an infrared camera. The virtual wave is the solution of a wave equation and can be used to reconstruct the initial temperature distribution immediately after the excitation pulse. This virtual wave reconstruction method was used for the reconstruction of inclined steel rods in an epoxy sample, which were heated by a short pulse. The reconstructed experimental images show clearly the degradation of the spatial resolution with increasing depth, which is theoretically described by a depth-dependent thermographic point-spread-function. Full article

Since most of the body’s extracellular matrix (ECM) is composed of collagen and elastin, we believe the choice of these materials is key for the future and promise of tissue engineering. Once it is known how elastin content of ECM guides cellular behavior (in 2D or 3D), one will be able to harness the power of collagen-elastin microenvironments to design and engineer stimuli-responsive tissues. Moreover, the implementation of such matrices to promote endothelial-mesenchymal transition of primary endothelial cells constitutes a powerful tool to engineer 3D tissues. Here, we design a 3D collagen-elastin scaffold to mimic the native ECM of heart valves, by providing the strength of collagen layers, as well as elasticity. Valve interstitial cells (VICs) were encapsulated in the collagen-elastin hydrogels and valve endothelial cells (VECs) cultured onto the surface to create an in vitro 3D VEC-VIC co-culture. Over a seven-day period, VICs had stable expression levels of integrin β1 and F-actin and continuously proliferated, while cell morphology changed to more elongated. VECs maintained endothelial phenotype up to day five, as indicated by low expression of F-actin and integrin β1, while transformed VECs accounted for less than 7% of the total VECs in culture. On day seven, over 20% VECs were transformed to mesenchymal phenotype, indicated by increased actin filaments and higher expression of integrin β1. These findings demonstrate that our 3D collagen-elastin scaffolds provided a novel tool to study cell-cell or cell-matrix interactions in vitro, promoting advances in the current knowledge of valvular endothelial cell mesenchymal transition. Full article