The notion that genetic material could be transferred to a host patient for therapeutic benefit has been around for over half a century. However, it wasn’t until 2017 that the concept became a clinical reality, following the approval of the first CAR-T cell therapy in the US by the FDA and subsequent approval by the E.U. Since the approval of this first product, many more gene therapies have come to market, and the number of products in late-stage clinical trials indicate that gene therapy could become one of the fastest growing sectors in the biopharmaceutical industry. A key aspect for the commercial success of any biopharmaceutical is the ability to economically manufacture the therapeutic product at a large enough scale to meet market demand. To date, manufacturing processes have been able to produce gene therapy viral vectors at the necessary scale to satisfy the demands of clinical studies. However, current biomanufacturing processes will need to be scaled-up and optimized to meet commercial demand, especially for therapies that treat diseases with large patient populations.

Addressing thrombosis and biofouling of indwelling medical devices within healthcare institutions is an ongoing problem. In this work, two types of ultra-low fouling surfaces (i.e., superhydrophobic and lubricant-infused slippery surfaces) were fabricated to enhance the biocompatibility of commercial medical grade silicone rubber (SR) tubes that are widely used in clinical care. The superhydrophobic (SH) coatings on the tubing substrates were successfully created by dip-coating in superhydrophobic paints consisting of polydimethylsiloxane (PDMS), perfluorosilane-coated hydrophobic zinc oxide (ZnO) and copper (Cu) nanoparticles (NPs) in tetrahydrofuran (THF). The SH surfaces were converted to lubricant-infused slippery (LIS) surfaces through the infusion of silicone oil. The anti-biofouling properties of the coatings were investigated by adsorption of platelets, whole blood coagulation, and biofilm formation in vitro. The results revealed that the LIS tubes possess superior resistance to clot formation and platelet adhesion than uncoated and SH tubes. In addition, bacterial adhesion was investigated over 7 days in a drip-flow bioreactor, where the SH-ZnO-Cu tube and its slippery counterpart significantly reduced bacterial adhesion and biofilm formation of Escherichia coli relative to control tubes (>5 log(10) and >3 log(10) reduction, respectively). The coatings also demonstrated good compatibility with fibroblast cells. Therefore, the proposed coatings may find potential applications in high-efficiency on-demand prevention of biofilm and thrombosis formation on medical devices to improve their biocompatibility and reduce the risk of complications from medical devices. (C) 2021 Elsevier Inc. All rights reserved.

Mesenchymal Stromal Cells (MSCs) hold great promise to treat a number of diseases either directly, by repairing traumatic tissue injury or damage caused by degenerative diseases, or indirectly through secretion of trophic or immunomodulatory factors. However, it is estimated that 1010–1013 MSCs are needed for a single dose. This, combined with the fact that MSC populations are heterogenous, presents a number of manufacturing challenges. Selection of the appropriate cell culture medium can greatly influence cell metabolism and phenotype, which is important for reducing heterogeneity and batch-to-batch variability. The use of autologous cells vs. allogeneic cells has implications for large scale production and the choice between scale-up or scale-out. Traditional stirred tank bioreactors are better suited for scale-up whereas hollow fiber and packed bed bioreactors may be more appropriate for scale-out strategies. As MSCs are anchorage-dependent, the choice of microcarrier will be important regardless of the bioreactor type and mode of operation. Finally, the clinical success of MSCs is subject to the identification and ability to measure Critical Quality Attributes (CQAs) as a means of determining potency and efficacy. Here we discuss the current state of the cell manufacturing process.

Biofilm and thrombus formation on surfaces results in significant morbidity and mortality worldwide, which highlights the importance of the development of efficacious fouling-prevention approaches. In this work, novel highly robust and superhydrophobic coatings with outstanding multiliquid repellency, bactericidal performance, and extremely low bacterial and blood adhesion are fabricated by a simple two-step dip-coating method. The coatings are prepared combining 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FAS-17)-coated hydrophobic zinc oxide and copper nanoparticles to construct hierarchical micro/nanostructures on commercial polyurethane (PU) sponges followed by polydimethylsiloxane (PDMS) treatment that is used to improve the binding degree between the nanoparticles and the sponge surface. The micro/nanotextured samples can repel various liquids including water, milk, coffee, juice, and blood. Relative to the original PU, the superhydrophobic characteristics of the fabricated sponge cause a significant reduction in the adhesion of bacteria (Staphylococcus aureus) by up to 99.9% over a 4-day period in a continuous drip-flow bioreactor. The sponge is also highly resistant to the adhesion of fibrinogen and activated platelets with ∼76 and 64% reduction, respectively, hence reducing the risk of blood coagulation and thrombus formation. More importantly, the sponge can sustain its superhydrophobicity even after being subjected to different types of harsh mechanical damage such as finger-wiping, knife-scratching, tape-peeling, hand-kneading, hand-rubbing, bending, compress-release (1000 cycles) tests, and 1000 cm sandpaper abrasion under 250 g of loading. Hence, this novel hybrid surface with robustness and the ability to resist blood adhesion and bacterial contamination makes it an attractive candidate for use in diverse application areas.

Direct recognition of invading pathogens by innate immune cells is a critical driver of the inflammatory response. However, cells of the innate immune system can also sense their local microenvironment and respond to physiological fluctuations in temperature, pH, oxygen and nutrient availability, which are altered during inflammation. Although cells of the immune system experience force and pressure throughout their life cycle, little is known about how these mechanical processes regulate the immune response. Here we show that cyclical hydrostatic pressure, similar to that experienced by immune cells in the lung, initiates an inflammatory response via the mechanically activated ion channel PIEZO1. Mice lacking PIEZO1 in innate immune cells showed ablated pulmonary inflammation in the context of bacterial infection or fibrotic autoinflammation. Our results reveal an environmental sensory axis that stimulates innate immune cells to mount an inflammatory response, and demonstrate a physiological role for PIEZO1 and mechanosensation in immunity.

Left ventricle assist devices (VADs) aid the heart pumping blood into the systemic circulation and grant the required cardiac output (CO) when the heart itself cannot provide it. However, it is unclear how effective these devices are at restoring not only physiological CO values but also normal intraventricular hemodynamics. In this work, the modified hemodynamics due to a VAD implantation is studied in vitro using an elastic ventricle made of silicone, which is incorporated into a pulse-duplicator setup prescribing a realistic pulsatile flow. Thereafter, a continuous axial pump is connected at the ventricle apex to mimic a VAD and its effect on the ventricular hemodynamics is investigated as a function of the pump flow suction. Using particle image velocimetry (PIV), we observe that the continuous pump flow effectively provides unloading on the ventricle and yields an increased CO. Conversely, the continuous blood suction from the ventricle apex deeply alters the hemodynamics and, in addition, the VAD obstruction in the ventricle behaves as a bluff body that affects the vorticity distribution in the LV thus creating a stagnant region at the ventricle apex. This phenomenon is rationalized by measuring in a modified set-up the benefits on the hemodynamics of a flush-mounted device. Additionally, the suction operated by the VAD reduces the ventricular pressure and yields an increase in the swirling motion around the ventricle axis, in a similar fashion as the bath-tub vortex effect, thus further modifying the intraventricular hemodynamics with respect to healthy conditions.

Current protocols for mechanical preconditioning of tissue engineered heart valves have focused on application of pressure, flexure and fluid flow to stimulate collagen production, ECM remodeling and improving mechanical performance. The aim of this study was to determine if mechanical preconditioning with cyclic stretch could promote an intact endothelium that resembled the viability and morphology of a native valve. Confocal laser scanning microscopy was used to image endothelial cells on aortic valve strips subjected to static incubation or physiological strain regimens. An automated image analysis program was designed and implemented to detect and analyze live and dead cells in images captured of a live aortic valve endothelium. The images were preprocessed, segmented, and quantitatively analyzed for live/dead cell ratio, minimum neighbor distance and circularity. Significant differences in live/dead cellular ratio and the minimum distance between cells were observed between static and strained endothelia, indicating that cyclic strain is an important stimulus for maintaining a healthy endothelium. In conclusion, in vitro application of physiological levels of cyclic strain to tissue engineered heart valves seeded with autologous endothelial cells would be advantageous.

Problem-based learning (PBL) is a pedagogy that has attracted attention for many biomedical engineering curricula. The aim of the current study was to address the research question, Does PBL enable students to develop desirable professional engineering skills?' The desirable skills identified were communication, teamwork, problem solving and self-directed learning. Forty-seven students enrolled in a biomedical materials course participated in the case study. Students worked in teams to complete a series of problems throughout the semester. The results showed that students made significant improvements in their problem-solving skills, written communication and self-directed learning. Students also demonstrated an ability to work in teams and communicate orally. In conclusion, this case study provides empirical evidence of the efficacy of PBL on student learning. We discuss findings from our study and provide observations of student performance and perceptions that could be useful for faculty and researchers interested in PBL for biomedical engineering education.

AbstractGene therapy has faced many challenges over the past 20 years as it has made its way toward clinical realization. In 2012, theEMAapproved the first gene therapy for European markets, marking a landmark for the technology. Other gene therapies will inevitably follow with an increasing number now progressing to late‐stage clinical trials. To date, manufacturing processes have been able to produce enough viral vectors to satisfy the demands of these studies. However, current processes need to be scaled up if commercial demand is to be met, especially for therapies that treat diseases with large patient populations.

To increase participation in professional society activities and promote extracurricular professional growth, the College of Engineering at a major research university in the southeast US introduced a college-wide technical society initiative in fall 2013. The purpose of the initiative was to encourage student integration in their disciplines and to promote professional development through active participation in society events. Overall, the college observed membership in technical societies increase from 19.5% to 82% and 33% to 96% at the undergraduate and graduate levels, respectively, with a combined membership of 83% for all eligible (i.e., full-time) students. This was an increase from 21% prior to the initiative. Detailed description of the technical society initiative and the rationale for its implementation is presented. Although it is too soon to offer an in-depth assessment of the full impact of this initiative, the early indications point to the growing interest on the part of the undergraduate students to seek greater involvement in technical society activities.

Background and aim of the study: Aortic valve ectopic calcification occurs exclusively on the fibrosa surface. This may be due to the distinct mechanical environments on either side of the valve, or to the existence of unique, side-specific endothelial sub-phenotypes. The study aim was to determine if side-specific endothelial cells (ECs) would differentially express cell-cell and cell-matrix adhesion molecules in response to elevated levels of equibiaxial tensile strain.Methods: Side-specific porcine aortic valve ECs were isolated and strained at 10% or 20% using a Flexcell 4000T for 24 h, and compared to static controls. The quantity and pattern of distribution of adhesion proteins was then assessed using ELISA and fluorescence microscopy, respectively. The adhesion proteins of interest were platelet endothelial cell adhesion molecule-1 (PECAM-1), beta(1)-integrin, VE-cadherin, and vinculin.Results: Overall, ventricular ECs were more reactive to changes in cyclic strain, with significant increases in VE-cadherin and vinculin at 20% strain. However, the expression of (beta(1)-integrin was significantly increased at 20% strain in fibrosa ECs. Expression of PECAM-1 was not significantly changed at all strain levels for both sub-populations of ECs.Conclusion: Endothelial cells isolated from the fibrosa and ventricularis surfaces of porcine aortic valves showed significantly different expression profiles of cell-cell and cell-extracellular matrix adhesion molecules under elevated tensile strain. These differences in response to cyclic strain suggest that different endothelial sub-phenotypes exist on the fibrosa and ventricularis surfaces of the aortic valve.

AbstractPentraxin 3 (ptx3) is a member of the long pentraxin family and is rapidly produced and released by many cell types, including endothelial cells, in response to primary inflammatory signals. In our preliminary work, PTX3 gene expression was significantly increased in aortic valve tissue following exposure to elevated cyclic pressure. Consequently, we hypothesized that ptx3 would be a useful biomarker for the early diagnosis of aortic valve sclerosis. Isolated aortic VICs were treated with Angiotensin II (300nM), TNF-alpha (10 ng/ml) or elevated cyclic pressure for six hours. The cell culture supernatant was collected and used to determine ptx3 protein expression using ELISA. Total RNA was isolated from the cells and PTX3 gene expression was determined using semi-quantitative RT-PCR. In addition to cell culture studies, ptx3 protein expression was determined in hypertensive New Zealand White rabbits. Rabbits underwent Goldblatt one-clip/one-kidney surgery to induce hypertension (n=5). Four sham models served as a control. Blood pressure, echocardiography data and serum samples were collected at 0, 2 and 4 months. After 4 months, rabbits were euthanized and aortic valve tissue was collected for histological and gene expression analysis. Data from the cell culture studies showed that elevated cyclic pressure caused an increase in PTX3 gene expression and ptx3 protein expression. However, no significant changes were observed in gene or protein expression from cells treated with Ang II or TNF-alpha. Data collected from the animal model showed that blood pressure increased significantly for the experimental group but not the control group. Levels of ptx3 protein were measured from the serum and showed a slight increase over the four-month course of the experiments. The data suggest that ptx3 expression is mechanosensitive in the aortic valve and is not stimulated by biochemical factors such as TNF-alpha or Ang II. The increase in ptx3 expression in hypertensive rabbits demonstrates that this could be a potential diagnostic marker for aortic stenosis.

Biomass-derived hydrocarbons that include gasoline, diesel, and jet fuel can help replace finite fossil fuel hydrocarbons of the same range. The objective of this study was to prove that gasoline-range hydrocarbons could be created from gasified woody biomass (producer gas) using thermochemical conversion with a Mo/H+ZSM-5 catalyst and compare these results to gasoline-range hydrocarbons created from contaminate-free synthesis gas (syngas). This study was also performed to help understand obstacles related to a scaled-up reactor system using a Mo/H+ZSM-5 catalyst with producer gas. The CO conversion, C selectivity and amount of product created from each type of gas were examined. Contaminate-free syngas composed of 40% H2, 20% CO, 12% CO2, 2% CH4, and 26% N2 (2:1 H2–CO) was used to test near ideal stoichiometric molar values comparable to producer gas for gas to liquid creation. Contaminate-free syngas composed of 19% H2, 20% CO, 12% CO2, 2% CH4, 47% N2 and producer gas composed of 19% H2, 20% CO, 12% CO2, 2% CH4, and 46% N2 was also used in this study to determine the feasibility of using gasified biomass syngas to produce gasoline-range hydrocarbons. The liquid hydrocarbon (organic phase) yield for the 2:1 syngas, 1:1 syngas and producer gas was 0.00844±0.00315, 0.00327±0.00101, and 0.00040±0.00058%, respectively.

Gasified woody biomass (producer gas) was converted over a Mo/H(+)ZSM-5 catalyst to produce gasoline-range hydrocarbons. The effect of contaminants in the producer gas showed that key retardants in the system included ammonia and oxygen. The production of gasoline-range hydrocarbons derived from producer gas was studied and compared with gasoline-range hydrocarbon production from two control syngas mixes. Certain mole ratios of syngas mixes were introduced into the system to evaluate whether or not the heat created from the exothermic reaction could be properly controlled Contaminant-free syngas was used to determine hydrocarbon production with similar mole values of the producer gas from the gasifier. Contaminant-free syngas was also used to test an ideal contaminant-free synthesis gas situation to mimic our particular downdraft gasifier Producer gas was used in this study to determine the feasibility of using producer gas to create gasoline-range hydrocarbons on an industrial scale using a specific Mo/H+ZSM-5 catalyst. It was determined that after removing the ammonia, other contaminants poisoned the catalyst and retarded the hydrocarbon production process as well.

Hypertension is a known risk factor for aortic stenosis. The elevated blood pressure increases the transvalvular load and can elicit inflammation and extracellular matrix (ECM) remodeling. Elevated cyclic pressure and the vasoactive agent angiotensin II (Ang II) both promote collagen synthesis, an early hallmark of aortic sclerosis. In the current study, it was hypothesized that elevated cyclic pressure and/or angiotensin II decreases extensibility of aortic valve leaflets due to an increase in collagen content and/or interstitial cell stiffness. Porcine aortic valve leaflets were exposed to pressure conditions of increasing magnitude (static atmospheric pressure, 80, and 120 mmHg) with and without 10−6 M Ang II. Biaxial mechanical testing was performed to determine extensibility in the circumferential and radial directions and collagen content was determined using a quantitative dye-binding method at 24 and 48 h. Isolated aortic valve interstitial cells exposed to the same experimental conditions were subjected to atomic force microscopy to assess cellular stiffness at 24 h. Leaflet tissue incubated with Ang II decreased tissue extensibility in the radial direction, but not in the circumferential direction. Elevated cyclic pressure decreased extensibility in both the radial and circumferential directions. Ang II and elevated cyclic pressure both increased the collagen content in leaflet tissue. Interstitial cells incubated with Ang II were stiffer than those incubated without Ang II while elevated cyclic pressure caused a decrease in cell stiffness. The results of the current study demonstrated that both pressure and Ang II play a role in altering the biomechanical properties of aortic valve leaflets. Ang II and elevated cyclic pressure decreased the extensibility of aortic valve leaflet tissue. Ang II induced direction specific changes in extensibility, demonstrating different response mechanisms. These findings help to provide a better understanding of the responses of aortic valves to mechanical and biochemical changes that occur under hypertensive conditions.

Soft tissues, such as tendons, skin, arteries, or lung, are constantly subject to mechanical stresses in vivo. None more so than the aortic heart valve that experiences an array of forces including shear stress, cyclic pressure, strain, and flexion. Anisotropic biaxial cyclic stretch maintains valve homeostasis; however, abnormal forces are implicated in disease progression. The response of the valve endothelium to deviations from physiological levels has not been fully characterized. Here, we show the design and validation of a novel stretch apparatus capable of applying biaxial stretch to viable heart valve tissue, while simultaneously allowing for live en face endothelial cell imaging via confocal laser scanning microscopy (CLSM). Real-time imaging of tissue is possible while undergoing highly characterized mechanical conditions and maintaining the native extracellular matrix. Thus, it provides significant advantages over traditional cell culture or in vivo animal models. Planar biaxial tissue stretching with simultaneous live cell imaging could prove useful in studying the mechanobiology of any soft tissue.

The study aimed to identify mechanosensitive pathways and gene networks that are stimulated by elevated cyclic pressure in aortic valve interstitial cells (VICs) and lead to detrimental tissue remodeling and/or pathogenesis. Porcine aortic valve leaflets were exposed to cyclic pressures of 80 or 120 mmHg, corresponding to diastolic transvalvular pressure in normal and hypertensive conditions, respectively. Linear, two-cycle amplification of total RNA, followed by microarray was performed for transcriptome analysis (with qRT-PCR validation). A combination of systems biology modeling and pathway analysis identified novel genes and molecular mechanisms underlying the biological response of VICs to elevated pressure. 56 gene transcripts related to inflammatory response mechanisms were differentially expressed. TNF-α, IL-1α, and IL-1β were key cytokines identified from the gene network model. Also of interest was the discovery that pentraxin 3 (PTX3) was significantly upregulated under elevated pressure conditions (41-fold change). In conclusion, a gene network model showing differentially expressed inflammatory genes and their interactions in VICs exposed to elevated pressure has been developed. This system overview has detected key molecules that could be targeted for pharmacotherapy of aortic stenosis in hypertensive patients.