Benchtop Models Research Articles

ID: 344721 Removal Procedure of a Helical Wire Structure Electrode from Benchtop and Chronic Porcine Models

ID: 344721 Removal Procedure of a Helical Wire Structure Electrode from Benchtop and Chronic Porcine Models

Development of A 3D Lung Tumor Model For Cell Death Assessment in Microwave Ablation

AbstractPrimary lung cancer is the leading cause of cancer‐related death worldwide. Recent statistics estimate 1.8 million new cases and 1.6 million deaths per year. Despite significant advances in surgery, chemotherapy, and radiotherapy, the 5‐year survival rate remains at just 18%. Thermal ablation is an established treatment that is safe and effective. It refers to the local application of controlled heat to induce irreversible cell injury and ultimately tumor apoptosis and necrosis. This approach is particularly suitable for the treatment of small tumors in patients who are not suitable for surgery. However, the lack of suitable benchtop models to assess ablation devices complicates prognostic prediction and the development of effective treatment strategies. In this context, the development of a 3D lung tumor model is presented using a cancer cell‐laden hydrogel composed of 2% hyaluronic acid–tyramine (HA‐TA) and 0.5% agarose, resulting in a tumor mimetic of clinically relevant size. This innovative model provides a valuable platform for testing ablation devices and provides insights that can significantly improve prognostic ability and refine treatment approaches for lung cancer patients.

A Systematic Review of Simulation in Burn Care: Education, Assessment, and Management.

Assessment and management of burns require nuanced, timely interventions in high-stake settings, creating challenges for trainees. Simulation-based education has become increasingly popular in surgical and nonsurgical subspecialties to supplement training without compromising patient safety. This study aimed to systematically review the literature on existing burn management-related simulations. A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Articles describing burn-specific surgical and nonsurgical simulation models were included. The model type, study description, simulated skills, assessment methods, fidelity, cost, and outcomes were collected. Of 3,472 articles, 31 met inclusion criteria. The majority of simulations were high-fidelity (n=17, 54.8%). Most were immersive (n=17, 54.8%) and used synthetic benchtop models (n=13, 41.9%), whereas none were augmented/virtual reality. Simulations of acute and early surgical intervention techniques (n=16, 51.6%) and burn wound assessments (n=15, 48.4%) were the most common, whereas burn reconstruction was the least common (n=3, 9.7%). Technical skills were taught more often (n=29, 93.5%) than non-technical skills (n=15, 48.4%). Subjective assessments (n=18, 58.1%) were used more often than objective assessments (n=23, 74.2%). Of the studies that reported costs, 91.7% (n=11) reported low costs. This review identified the need to expand burn simulator options, especially for burn reconstruction, and highlighted the paucity of animal, cadavers, and augmented/virtual reality models. Developing validated, accessible burn simulations to supplement training may improve education, patient safety, and outcomes.

Peeling fingers in an elastic Hele-Shaw channel

Using experiments and a depth-averaged numerical model, we study instabilities of two-phase flows in a Hele-Shaw channel with an elastic upper boundary and a non-uniform cross-section prescribed by initial collapse. Experimentally, we find increasingly complex and unsteady modes of air-finger propagation as the dimensionless bubble speed $Ca$ and level of collapse are increased, including pointed fingers, indented fingers and the feathered modes first identified by Cuttle et al. (J. Fluid Mech., vol. 886, 2020, A20). By introducing a measure of the viscous contribution to finger propagation, we identify a $Ca$ threshold beyond which viscous forces are superseded by elastic effects. Quantitative prediction of this transition between ‘viscous’ and ‘elastic’ reopening regimes across levels of collapse establishes the fidelity of the numerical model. In the viscous regime, we recover the non-monotonic dependence on $Ca$ of the finger pressure, which is characteristic of benchtop models of airway reopening. To explore the elastic regime numerically, we extend the depth-averaged model introduced by Fontana et al. (J. Fluid Mech., vol. 916, 2021, A27) to include an artificial disjoining pressure that prevents the unphysical self-intersection of the interface. Using time simulations, we capture for the first time the majority of experimental finger dynamics, including feathered modes. We show that these disordered states evolve continually, with no evidence of convergence to steady or periodic states. We find that the steady bifurcation structure satisfactorily predicts the bubble pressure as a function of $Ca$ , but that it does not provide sufficient information to predict the transition to unsteady dynamics that appears strongly nonlinear.

Experimental testing combined with inverse-FE for mechanical characterisation of penile tissues

Erectile dysfunction (ED) predominantly affects men in their 40–70s and can lead to poor quality of life. One option for ED treatment is surgical implantation of an inflatable penile prosthesis (IPP). However, they can be associated with negative outcomes including infection, migration or fibrosis. To improve outcomes, the interaction between the IPP device and surrounding tissues needs further investigation and this could be achieved using pre-clinical testbeds, but they need to be informed by extensive tissue testing.In this study, an experimental approach is adopted to characterise the mechanics of horse penile tissue and establish a testing protocol for penile tissue. The whole penis segments were tested in plate compression tests to obtain whole penis behaviour which is necessary for validation of a pre-clinical testbed, whilst tensile and compression tests were performed on individual penile tissues, namely corpus cavernosa and tunica albuginea. The second part of the paper deals with the development of a computational model employing an inverse finite element approach to estimate the material parameters of each tissue layer. These material parameters are in good agreement with the experimental results obtained from the individual tissue layers and whole organ tissue tests. This paper presents the first study proposing realistic nonlinear elastic material parameters for penile tissues and offers a validated testbed for IPPs. Statement of significanceErectile Dysfunction (ED) affects over half the male population aged 40–70 potentially leading to poor quality of life. Patients not responding to conventional treatments of ED, are advised to use penile prostheses which can create an erection using implanted inflatable cylinders. A significant drawback of such prostheses, however, is the substantial tissue damage they can induce during their usage. Preclinical testbeds, including computational and bench-top models, could offer an efficient means of improving device designs to mitigate this damage but such testbeds require extensive knowledge of penile tissue properties. In this study, the authors determine penile tissue mechanics and apply an inverse FE approach to characterise the penile material properties required to validate preclinical models of the penis.

Guinea Pig Round Window Membrane Explantation for Ex Vivo Studies.

Efficient and minimally invasive drug delivery to the inner ear is a significant challenge. The round window membrane (RWM), being one of the few entry points to the inner ear, has become a vital focus of investigation. However, due to the complexities of isolating the RWM, our understanding of its pharmacokinetics remains limited. The RWM comprises three distinct layers: the outer epithelium, the middle connective tissue layer, and the inner epithelial layer, each potentially possessing unique delivery properties. Current models for investigating transport across the RWM utilize in vivo animal models or ex vivo RWM models which rely on cell cultures or membrane fragments. Guinea pigs serve as a validated preclinical model for the investigation of drug pharmacokinetics within the inner ear and are an important animal model for the translational development of delivery vehicles to the cochlea. In this study, we describe an approach for explantation of a guinea pig RWM with surrounding cochlear bone for benchtop drug delivery experiments. This method allows for preservation of native RWM architecture and may provide a more realistic representation of barriers to transport than current benchtop models.

A novel, benchtop model for quantitative analysis of resistance in ventricular catheters.

The mechanisms of catheter obstruction are still poorly understood, but the literature suggests that resistance to fluid flow plays a significant role. We developed and assessed a gravity-driven device that measures flow through ventricular catheters. We used this device to quantitatively analyze the resistances of unused ventricular catheters used in the treatment of hydrocephalus; failed hydrocephalus catheters from our catheter biorepository were also evaluated quantitatively. Catheters of three manufacturing companies were inserted into the benchtop model, which records time, flow rate, and pressure data using sensors. The relative resistances of catheters across six design models were evaluated. Experiments were performed to evaluate changes in the relative resistance of a catheter when the catheter's holes were progressively closed. The relative resistance of explanted catheters from our catheter biorepository was also measured. Experimental results showed significant differences (P<0.05) between the relative resistances of different catheter models just after being removed from their packaging. A non-linear trend of increasing resistance was observed in experiments on catheters with artificially obstructed holes. Data from five individual benchtop models were compared, and the differences in measured data between the models were found to be negligible. A significant increase (P < 0.05) in relative resistance was observed in explanted catheters. The current study sought to propose a novel in-vitro model and use it to examine data on differences in relative resistance among catheter models. From these experiments, we can rapidly correlate clinical patient cohorts to identify mechanisms of luminal shunt obstruction.

Overview of Benchtop Models for Comparison of Surgical Treatments for Benign Prostatic Hyperplasia.

Benign prostatic hyperplasia (BPH) is a disease of the lower urinary tract which often requires surgical treatment. Recently, there has been a deluge of new treatment options, rarely validated or compared to current treatments on a benchtop model. The purpose of this review is to examine the literature and report which benchtop models are currently being used, which therapies have been tested on them, and what outcomes are being studied on each model. There are various benchtop models to choose from, each with their unique benefits and drawbacks. Perfused porcine kidney models are used to assess bleeding on the benchtop, ex-vivo human prostate helps to see specific interactions of devices with the prostatic tissue, and all other models have evaluated tissue ablation rates and depth of coagulation. There are currently no synthetic or non-animal tissues being used for this purpose, and surgical techniques such as enucleation, water-jet ablation, prostate stents, and water vapor thermal therapy have no representation in these benchtop tests. Benchtop testing serves an important role in the evaluation and comparison of surgical treatments for BPH. This testing allows these therapies to be objectively compared to one another, helping novel medical devices in their path to market and urologists make treatment decisions. Future directions may include further validation of the animal models currently being used and development of synthetic models which mimic the prostate on the benchtop.

Benchtop Models of Patient-Specific Intraventricular Flow During Heart Failure and LVAD Support.

The characterization of intraventricular flow is critical to evaluate the efficiency of fluid transport and potential thromboembolic risk but challenging to measure directly in advanced heart failure (HF) patients with left ventricular assist device (LVAD) support. The study aims to validate an in-house mock loop (ML) by simulating specific conditions of HF patients with normal and prosthetic mitral valves (MV) and LVAD patients with small and dilated left ventricle volumes, then comparing the flow-related indices result of vortex parameters, residence time (RT), and shear-activation potential (SAP). Patient-specific inputs for the ML studies included heart rate, end-diastolic and end-systolic volumes, ejection fraction, aortic pressure, E/A ratio, and LVAD speed. The ML effectively replicated vortex development and circulation patterns, as well as RT, particularly for HF patient cases. The LVAD velocity fields reflected altered flow paths, in which all or most incoming blood formed a dominant stream directing flow straight from the mitral valve to the apex. RT estimation of patient and ML compared well for all conditions, but SAP was substantially higher in the LVAD cases of the ML. The benchtop system generated comparable and reproducible hemodynamics and fluid dynamics for patient-specific conditions, validating its reliability and clinical relevance. This study demonstrated that ML is a suitable platform to investigate the fluid dynamics of HF and LVAD patients and can be utilized to investigate heart-implant interactions.

762 A Systematic Review of Surgical Simulation in Burn Surgery: Education, Assessment, and Management

Abstract Introduction Proper assessment and management of burn patients requires practical knowledge and timely interventions in a high-stakes setting. Although much of burn care emphasizes critical care, nuances exist among this patient population, creating challenges for surgeons-in-training. As a result, low- and high-fidelity burn simulations have become increasingly popular means to educate burn care physicians and their teams in a safe environment without compromising care or endangering patients. The aim of this report is to systematically review the literature for existing simulations related to burn care. Methods A systematic review was conducted using the following databases: PubMed, Scopus, Embase, Web of Science, and Cochrane. Inclusion criteria were peer-reviewed articles about surgical simulation models related to burn care and surgery. Skills and techniques taught, assessment methods, model type, fidelity, and equipment were extracted from included studies. Conference proceedings, reviews, non-English and non-burn-specific literature were excluded. Results Our search criteria identified 2,585 articles, 16 of which met inclusion criteria. Simulation methods included 7 simulation courses (43.8%), 6 synthetic benchtop models (37.5%), 2 augmented/virtual reality interfaces (12.5%), and 2 iOS applications (12.5%). There were no burn-specific animal or cadaveric models. Model fidelities included 9 (56.3%) high-, 3 (18.8%) medium-, and 4 (25.0%) low-fidelity. The most common topics included in the simulations were burn wound assessment/management (n=10, 62.5%), escharotomy (n=6, 37.5%), fluid management (n=2, 12.5%), electrical burns (n=1, 6.2%), skin graft harvest (n=1, 6.2%), tangential excision (n=1, 6.2%), and cricothyrotomy (n=1, 6.2%). Conclusions Burn management requires an expansive breadth of intensive care knowledge and surgical expertise combined with a distinct, burn-specific skill set. A paucity exists in the literature for augmented/virtual reality and animal/cadaver models unique to burn care and surgery. Our review identified a need to expand simulator options to improve training in skin grafting, burn reconstruction, and burns-specific intensive care management. Applicability of Research to Practice Given the rapidly expanding emphasis on remote learning in the post-COVID era, developing accessible surgical simulation infrastructure adjacent to clinical training may better prepare global burn providers for the complexity of burn care.

Transcranial acoustoelectric imaging: Towards noninvasive mapping of current densities in the human brain

Acoustoelectric Imaging (AEI) is a disruptive technology that exploits an ultrasound (US) beam to transiently interact with physiologic or artificial currents, producing a radiofrequency signature detected by one or more surface electrodes. By rapidly sweeping the US beam and simultaneously detecting the acoustoelectric modulations, 4D current density images are generated at high spatial resolution determined by the ultrasound beam focus. The principle has been used for in vivo mapping of currents in the swine heart during the cardiac activation wave. When applied to the brain, transcranial acoustoelectric imaging (tABI) overcomes limitations with electroencephalography (EEG), which suffers from poor spatial resolution and inaccuracies due to blurring of electrical signals as they pass through the brain and skull, and, unlike fMRI and PET that measure slow metabolic or hemodynamic signals, tABI directly maps fast time-varying current within a defined brain volume at the mm and ms scales. This invited presentation will describe the underlying physics and mathematics of tABI, recent progress and challenges using numerical simulations and bench-top models, and its potential impact as a cutting-edge noninvasive modality for fast and accurate electrical brain mapping in humans.

Preclinical research performed on reanimated/perfused swine kidneys: The Visible Kidney™ methodologies.

Preclinical research remains the essential platform in the development and optimization of medical therapies and advancements in translational medicines. However, specifically to animal research, federal laws, and institutional policies require investigators to apply the principles of the 3R's (replacement, reduction, and refinement). The concept of benchtop models utilizing isolated organs, in which multiple variables can be controlled to recreate human function, has been innovative advancements in preclinical research models that adhere to these principles. More specifically, isolated perfused kidney (IPK) models have been invaluable preclinical tools that have led to numerous advancements over the decades, including understanding renal physiology, pharmacologic therapies, and improvements in renal transplantation. However, pre-existing IPK models are not without their own limitations, leaving areas for improvement. An isolated perfused kidney apparatus was designed to best recreate human use conditions as a preclinical tool. Porcine renal blocks were chosen over the more commonly used rodent models, due to their greater similarities to human anatomies. Sixteen porcine kidney pairs obtained en bloc were extracted and placed onto an apparatus where aortic flows, pressures, and overall systemic temperatures were controlled. Organ viability was assessed in 10 renal blocks (n= 8 fresh and n= 2 previously frozen specimens) via both urinary flows and compositions at timepoints up to 180 min. Multimodality imaging, which included fluoroscopy, ultrasound, optical coherence tomography (OCT), and video scopes, was also employed to capture internal and external images to determine renal artery orientations and dimensions. Anatomical measurements and viability assessments of porcine renal blocks were successfully achieved in our perfusion model. Renal main artery diameters averaged smaller in our sample size than in human anatomy while also having more superior takeoff angles. Yet, the average lengths of each main segment were comparable to human anatomy: 32.09 ± 7.97 mm and 42.23 ± 7.33 mm in the left and right renal main artery, respectively. Urine production and urine composition of the fresh renal blocks, when compared to the frozen blocks and baseline perfusate, showed kidney viabilities of up to 3h via excretion and retention of various metabolites. In this paper, we described a protocol for an isolated perfused kidney apparatus using large mammalian renal blocks. We believe this protocol to be an improvement from similar pre-existing models in better representing human physiologic function while allowing for multimodal imaging. The resulting Visible Kidney™ preclinical model, which has shown viability after isolation and reperfusion, can be a fast and reliable tool for the development of medical devices while also reducing the unnecessary use of animals for research.

Virtual reality simulation training improve diagnostic knee arthroscopy and meniscectomy skills: a prospective transfer validity study

PurposeLimited data exist on the actual transfer of skills learned using a virtual reality (VR) simulator for arthroscopy training because studies mainly focused on VR performance improvement and not on transfer to real word (transfer validity). The purpose of this single-blinded, controlled trial was to objectively investigate transfer validity in the context of initial knee arthroscopy training.MethodsFor this study, 36 junior resident orthopaedic surgeons (postgraduate year one and year two) without prior experience in arthroscopic surgery were enrolled to receive standard knee arthroscopy surgery training (NON-VR group) or standard training plus training on a hybrid virtual reality knee arthroscopy simulator (1 h/month) (VR group). At inclusion, all participants completed a questionnaire on their current arthroscopic technical skills. After 6 months of training, both groups performed three exercises that were evaluated independently by two blinded trainers: i) arthroscopic partial meniscectomy on a bench-top knee simulator; ii) supervised diagnostic knee arthroscopy on a cadaveric knee; and iii) supervised knee partial meniscectomy on a cadaveric knee. Training level was determined with the Arthroscopic Surgical Skill Evaluation Tool (ASSET) score.ResultsOverall, performance (ASSET scores) was better in the VR group than NON-VR group (difference in the global scores: p < 0.001, in bench-top meniscectomy scores: p = 0.03, in diagnostic knee arthroscopy on a cadaveric knee scores: p = 0.04, and in partial meniscectomy on a cadaveric knee scores: p = 0.02). Subgroup analysis by postgraduate year showed that the year-one NON-VR subgroup performed worse than the other subgroups, regardless of the exercise.ConclusionThis study showed the transferability of the technical skills acquired by novice residents on a hybrid virtual reality simulator to the bench-top and cadaveric models. Surgical skill acquired with a VR arthroscopy surgical simulator might safely improve arthroscopy competences in the operating room, also helping to standardise resident training and follow their progress.Level of evidence2

Left Atrial Appendage Occlusion: Current Stroke Prevention Strategies and a Shift Toward Data-Driven, Patient-Specific Approaches.

The left atrial appendage (LAA) is a complex structure with unknown physiologic function protruding from the main body of the left atrium. In patients with atrial fibrillation, the left atrium does not contract effectively. Insufficient atrial and LAA contractility predisposes the LAA morphology to hemostasis and thrombus formation, leading to an increased risk of cardioembolic events. Oral anticoagulation therapies are the mainstay of stroke prevention options for patients; however, not all patients are candidates for long-term oral anticoagulation. Percutaneous occlusion devices are an attractive alternative to long-term anticoagulation therapy, although they are not without limitations, such as peri-implant leakage and device-related thrombosis. Although efforts have been made to reduce these risks, significant interpatient heterogeneity inevitably yields some degree of device-anatomy mismatch that is difficult to resolve using current devices and can ultimately lead to insufficient occlusion and poor patient outcomes. In this state-of-the-art review, we evaluated the anatomy of the LAA as well as the current pathophysiologic understanding and stroke prevention strategies used in the management of the risk of stroke associated with atrial fibrillation. We highlighted recent advances in computed tomography imaging, preprocedural planning, computational modeling, and novel additive manufacturing techniques, which represent the tools needed for a paradigm shift toward patient-centric LAA occlusion. Together, we envisage that these techniques will facilitate a pipeline from the imaging of patient anatomy to patient-specific computational and bench-top models that enable customized, data-driven approaches for LAA occlusion that are engineered specifically to meet each patient's unique needs.

A comparison of benchtop and micro NIR spectrometers for infant milk formula powder storage time discrimination and particle size prediction using chemometrics and denoising methods

This study compared benchtop and micro NIR spectrometers in diffuse reflection mode (1158–2169 nm) to (i) discriminate infant milk formula (IMF) powder samples (n = 500) by storage time (0–12 months) and to (ii) predict IMF powder particle size parameters. Reference particle size parameters were determined using laser-light-scattering. Fast Fourier transform (FFT) and wavelet transform (WT) denoising methods were employed on micro NIR spectra to remove noise and enhance spectral features. Partial least square discriminant analysis (PLS-DA) and partial least squares regression (PLSR) modelling approaches were used to discriminate IMF by storage time and predict powder particle size, respectively. The models developed using the micro NIR denoised spectra had correct identifications (CI p ) of 89–100% for IMF storage time discrimination and RPDPs of 2.29–2.98 for particle size prediction, which were comparable to the model performances achieved using the benchtop NIR spectra (CI p values of 81.3–100% for IMF storage time discrimination and RPDPs of 2.08–3.07 for particle size prediction). This study demonstrated that the potential of micro NIR spectroscopy combined with chemometrics and denoising methods as a suitable process analytical technology (PAT) tool for IMF powder storage time discrimination and particle size prediction along the IMF distribution chain from production to consumer. • Benchtop and micro NIR models can assess IMF powder storage time and particle size. • IMF powder storage time was discriminated using PLS-DA modelling. • IMF powder particle size was predicted using PLSR modelling. • FFT and WT denoising methods are suitable to remove micro NIR spectral noise. • Micro NIR models had overall better performance than benchtop NIR models.

The Impact of Burr Hole Device and Lead Design on Deep Brain Stimulation Lead Stability in Benchtop and Ovine Models

Background and ObjectivesA market-released deep brain stimulation (DBS) lead and burr hole device (BHD) have been used for more than ten years to provide stable DBS therapy using leads with four equally distributed cylindrical electrodes along the distal lead length. Newer directional leads cluster segmented electrodes at the center of the electrode array. This work tests the hypothesis that improved chronic translational and rotational stability through enhanced BHD design may ensure that these newer directional electrodes remain in a stable orientation near the stimulation target to maintain therapy and maximize opportunities to adjust therapy, if needed. Materials and MethodsA new DBS lead system (commercially available in the United States and termed “new” throughout the manuscript) has been developed, and a combination of bench testing (45 product samples tested) and chronic sheep studies (17 animals followed for 13.5 weeks on average) was conducted to test the hypothesis that design changes incorporated into the new DBS system further stabilize the position and orientation of a DBS lead tip compared with a legacy DBS system. ResultsThe new DBS system demonstrated a 55% relative improvement in chronic lead tip stability compared with the legacy DBS system with over a decade of clinical use. In a bench test, the new system required 79% more applied torque and 203% more lead body revolutions to rotate the lead in the BHD than the legacy system that was not designed to offer rotational stability. ConclusionsThese measurements quantitatively demonstrate that DBS system design can positively improve lead translational and rotational stability and show that system design is an important consideration for future product development.

Matched template analysis of continuous wave laser for space debris ranging application

The growth of human-made space debris, sharing the same Earth’s orbital space as active satellites, is a worrying environmental condition. Precise tracking and orbital modelling of space debris are vital to predict potential future collisions with active satellites. This paper investigates a continuous-wave laser ranging method where a bench-top experiment models the reflected amplitude modulated optical signal from a space debris target. The optical signal is digitised and stored to undergo post-digital signal processing using a parameter estimation matched filter approach to estimate the time-varying delay between the target debris and the observing telescope. The experiment investigated two different detection methods, the direct detection of the optical signal and the coherent detection where the optical signal is amplified with a bright local oscillator before signal detection. The experimental results show that the coherent detection method can provide a more precise time-varying delay estimate than the direct detection method due to the improved signal-to-noise ratio. The experimental results also show improved precision in the parameter estimation when using larger portions of the acquired signal’s time series. The experimental results were used to model for a potential space debris application. For example, assuming the received signal power from the target debris is approximately 3.5fW, the time-varying delay of the target debris using the coherent detection method can be estimated with a precision of 1m/s using 2.5s of the acquired signal time series. This is well within the expected minimum time series that can be collected from a space debris target from a single flyover at the telescope site.

Enhanced Anticancer Activity of Hymenocardia acida Stem Bark Extract Loaded into PLGA Nanoparticles.

Hymenocardia acida (H. acida) is an African well-known shrub recognized for numerous medicinal properties, including its cancer management potential. The advent of nanotechnology in delivering bioactive medicinal plant extract with poor solubility has improved the drug delivery system, for a better therapeutic value of several drugs from natural origins. This study aimed to evaluate the anticancer properties of H. acida using human lung (H460), breast (MCF-7), and colon (HCT 116) cancer cell lines as well as the production, characterization, and cytotoxicity study of H. acida loaded into PLGA nanoparticles. Benchtop models of Saccharomyces cerevisiae and Raniceps ranninus were used for preliminary toxicity evaluation. Notable cytotoxic activity in benchtop models and human cancer cell lines was observed for H. acida crude extract. The PLGA nanoparticles loading H. acida had a size of about 200 nm and an association efficiency of above 60%, making them suitable to be delivered by different routes. The outcomes from this research showed that H. acida has anticancer activity as claimed from an ethnomedical point of view; however, a loss in activity was noted upon encapsulation, due to the sustained release of the drug.

RVEX: Right Ventricular External Device for Biomimetic Support and Monitoring of the Right Heart

AbstractRight ventricular (RV) failure remains a significant burden for patients with advanced heart failure, especially after major cardiac surgeries such as implantation of left ventricular assist devices. Device solutions that can assist the complex biological function of heart muscle without the disadvantages of bulky designs and infection‐prone drivelines remain an area of pressing clinical need, especially for the right ventricle. In addition, devices that incur contact between blood and artificial surfaces mandate long‐term use of blood‐thinning medications, carrying increased risks for the patients. This work describes the design of a biomimetic, elastic sleeve to support RV‐specific motion via tuned regional mechanical properties. The RV external device (RVEX) in computational models as well as benchtop models and ex vivo (i.e., explanted heart) setups are evaluated to characterize the device and predict functional benefit. Additionally, long‐term implantation potential is demonstrated in mice. Finally, the ability to sensorize the RVEX device to yield resistive self‐sensing capabilities to continuously monitor ventricular deformation, as demonstrated in benchtop experiments and in live animal surgeries, is proposed.

Current benchtop protocols are not appropriate for the evaluation of distraction-based growing rods: a literature review to justify a new protocol and its development

Although distraction-based growing rods (GR) are the gold standard for the treatment of early onset scoliosis, they suffer from high failure rates. We have (1) performed a literature search to understand the deficiencies of the current protocols, (2) in vitro evaluation of GRs using our proposed protocol and performed a finite element (FE) model validation, and (3) identified key features which should be considered in mechanical testing setups. PubMed, Embase, and Web of Science databases were searched for articles published on (a) in vivo animal, in vitro cadaveric, and biomechanical studies analyzing the use of GRs as well as (b) failure mechanisms and risk factors for GRs. Both FE and benchtop models of a proposed TGR test construct were developed and evaluated for two cases, long tandem connectors (LT), and side-by-side connectors (SBS). The test construct consisted of five polymer blocks representing vertebral bodies, joined with springs to simulate spinal stiffness. The superior and inferior blocks accepted the pedicle screw anchors, while the three middle blocks were floating. After the pedicle screws, rods, and connectors were assembled onto this construct, distraction was performed, mimicking scoliosis surgery. The resulting distracted constructs were then subjected to static compression-bending loading. Yield load and stiffness were calculated and used to verify/validate the FE results. From the literature search, key features identified as significant were axial and transverse connectors, contoured rods, and distraction, distraction being the most challenging feature to incorporate in testing. The in silico analyses, once they are validated, can be used as a complementing technique to investigate other anatomical features which are not possible in the mechanical setup (like growth/scoliosis curvature). Based on our experiment, the LT constructs showed higher stiffness and yield load compared to SBS (78.85N/mm vs. 59.68N/mm and 838.84N vs. 623.3N). The FE predictions were in agreement with the experimental outcomes (within 10% difference). The maximum von Mises stresses were predicted adjacent to the distraction site, consistent with the location of observed failures in vivo. The two-way approach presented in this study can lead to a robust prediction of the contributing factors to the in vivo failure.