David W. Grainger

Introduction: Early open fracture management aims to minimise the risk of complications. For the most severe open fracture wounds, multiple irrigation and debridement surgeries are required to overcome severe wound contamination, to reassess the evolving tissue injury or to temporise and plan further surgery. When multiple irrigation and debridement surgeries are needed, uncertainty remains about how the open fracture wound should be managed to best minimise complications. The primary aim of this trial is to compare the antibiotic cement bead pouch vs negative pressure wound therapy in the management of patients with severe open tibia fracture wounds. Methods and analysis: BvV is a multicentre, pragmatic, parallel arm randomised controlled trial that aims to enrol 312 adult patients admitted to a participating centre with a severe open tibia fracture requiring multiple irrigation and debridement surgeries. Participants will be randomly allocated on a 1:1 basis to either antibiotic cement bead pouch or negative pressure wound therapy. The primary outcome will be a composite outcome to evaluate clinical status 6 months after randomisation. Using the win ratio approach, we will hierarchically assess the composite outcome in the following order: (i) all-cause mortality, (ii) injury-related amputation of the lower extremity, (iii) unplanned reoperation to manage wound complications, an infection or promote fracture healing and (iv) clinical fracture healing assessed using the Functional IndeX for Trauma (FIX-IT) instrument. Ethics and dissemination: The BvV trial has been approved by a central institutional review board (IRB) (Advarra) for clinical sites in the USA, the ethics board at the coordinating centre at McMaster University (Hamilton Integrated Research Ethics Board), and participating sites not using the central institutional IRB (Fraser Health Research Ethics Board, The University of British Columbia Clinical Research Ethics Board, Newfoundland and Labrador Health Research Ethics Board, University of Manitoba Biomedical Research Ethics Board). Additional clinical sites who are in the start-up phase, as well as any new selected clinical sites, will obtain local approvals prior to initiating trial activities. This will include a clinical site in the UK who is in the process of obtaining the necessary approvals. Recruitment began in November 2023. Both interventions are frequently used to manage severe open fracture wounds, ensuring that the trial results can be easily transitioned into clinical practice. The results of this trial will be disseminated to national and international partners through peer-reviewed publications, academic conferences and stakeholder engagement activities. Trial registration number: NCT05615844 .

Having access to high‐quality cell populations is essential for biomedical research, diagnosis, prognosis, and therapeutic applications. Traditional enzymatic methods, such as trypsinization, remain widely used to detach cells from supporting material surfaces, though they often compromise cell surface integrity, viability and functionality. To address these limitations, diverse strategies have emerged that enable a much gentler release of cells from material surfaces. The use of external physical stimuli (like shear stresses, light, temperature, magnetic fields), chemical stimuli (based on changes in pH or ligand‐exchange based detachment) and biological stimuli (like aptamers and nucleic acid sequences) have been explored for the purpose of non‐invasive cell detachment. This review discusses the principles, mechanisms, advantages, and limitations of these most diverse cell detachment technologies. By providing this comprehensive perspective, we hope to guide researchers in selecting the most suitable techniques for their specific needs and to inspire further innovation in this vital biomedical area.

Computer simulations play an important role in a range of biomedical engineering applications. Thus, it is important that biomedical engineering students engage with modeling in their undergraduate education and establish an understanding of its practice. In addition, computational tools enhance active learning and complement standard pedagogical approaches to promote student understanding of course content. Herein, we describe the development and implementation of learning modules for computational modeling and simulation (CM&S) within an undergraduate biomechanics course. We developed four CM&S learning modules that targeted predefined course goals and learning outcomes within the febio studio software. For each module, students were guided through CM&S tutorials and tasked to construct and analyze more advanced models to assess learning and competency and evaluate module effectiveness. Results showed that students demonstrated an increased interest in CM&S through module progression and that modules promoted the understanding of course content. In addition, students exhibited increased understanding and competency in finite element model development and simulation software use. Lastly, it was evident that students recognized the importance of coupling theory, experiments, and modeling and understood the importance of CM&S in biomedical engineering and its broad application. Our findings suggest that integrating well-designed CM&S modules into undergraduate biomedical engineering education holds much promise in supporting student learning experiences and introducing students to modern engineering tools relevant to professional development.

Immune-related applications of mesenchymal stromal cells (MSCs) in cell therapy seek to exploit immunomodulatory paracrine signaling pathways to reduce inflammation. A key MSC therapeutic challenge is reducing patient outcome variabilities attributed to insufficient engraftment/retention of injected heterogenous MSCs. To address this, we propose directly transplantable human single-cell-derived clonal bone marrow MSC (cBMSC) sheets. Cell sheet technology is a scaffold-free tissue engineering strategy enabling scalable production of highly engraftable cell constructs retaining endogenous cell-cell and -matrix interactions, important to cell function. cBMSCs, as unique MSC subset populations, facilitate rational selection of therapeutically relevant MSC clones from donors. Here, we combine human cBMSCs with cell sheet technology, demonstrating cell sheet fabrication as a method to significantly upregulate the expression of immunomodulatory molecules IL-10, IDO-1, and PTGES2 across GMP-grade hcBMSC lines and whole hBMSCs compared to respective conventional cell suspensions. When treated with carbenoxolone, a gap junction inhibitor, cell sheets downregulate IL-10 and IDO-1 expression, implicating functional roles for intercellular sheet interactions. Beyond producing directly transferable multi-cellular hcBMSC constructs, cell sheet technology amplifies hcBMSC expression of immunomodulatory factors important to therapeutic action. Additionally, this work demonstrates the importance of cell-cell interactions as a tissue engineering design criterion to enhance consistent MSC functions.

Translational impact assessment is key to selecting those biomedical research discoveries most likely to be converted into viable new products to improve human health. However, metrics for translational success are variable, are not limited to commercial success, and may not be relevant to every case or institution. Societal impact is a top translational priority in a globalized society.

Self-assembled monolayers (SAMs) of perfluoroalkanethiols [CF3(CF2)xCH2CH2SH (x = 3, 5, 7, and 9)] on gold were characterized by x-ray photoelectron spectroscopy (XPS), near edge x-ray absorption fine structure (NEXAFS), and static time-of-flight secondary ion mass spectrometry (ToF-SIMS). Perfluoroalkanethiols of several chain lengths were synthesized using a known hydride reduction method for transforming commercially available perfluoroalkyliodides to corresponding perfluoroalkanethiols. This strategy provides improved product yields compared to other known routes based on hydrolysis from the common thioacetyl perfluoroalkyl intermediate. Angle-dependent XPS analysis revealed that CF3(CF2)xCH2CH2SH (x = 5, 7, and 9; F6, F8, and F10, respectively) SAMs on gold exhibited significant enrichment of the terminal CF3 group at the outer monolayer surface with the sulfur present as a metal-bound thiolate located at the monolayer-gold interface. XPS of the CF3(CF2)3CH2CH2SH (F4) monolayer revealed a thin film with a significant (>50%) amount of hydrocarbon contamination consistent with poorly organized monolayers, while the longest thiol (F10) showed XPS signals attributed to substantial ordering and anisotropy. ToF-SIMS spectra from all four SAMs contained molecular ions representative of the particular perfluorinated thiol used to prepare the monolayer. NEXAFS methods were used to determine degrees of ordering and average tilt for molecules comprising monolayers. The SAMs prepared from the longest (F10) thiols exhibited the highest degree of ordering with the molecular axis nearly perpendicular to the gold surface. The degree of ordering decreased significantly with decreasing length of the perfluorocarbon tail.

Mesenchymal stromal cells (MSCs) represent a promising treatment for immune-related diseases due to their diverse immunomodulatory paracrine functions. However, progress of culture-expanded MSCs is hindered by inconsistent cell function, poor localization, and insufficient retention when administered as suspended cell injections, thus placing spatiotemporal dosing constraints on therapeutic functions. To address these limitations, we introduce the combination of in vitro interferon-gamma (IFN-γ) priming, a key stimulator of MSC immunosuppressive potency, and thermoresponsive cultureware to harvest cultured MSCs as directly transplantable scaffold-free immunosuppressive cell sheets. Here, we demonstrate that MSC sheets produced with IFN-γ priming upregulate expression of immunosuppressive factors indoleamine 2,3-dioxygenase (IDO-1), interleukin-10 (IL-10), programmed death ligand-1 (PD-L1), and prostaglandin E2 (PGE2) in both dose- and duration-dependent manners. In addition, IFN-γ primed MSC sheets showed increased ability to inhibit T-cell proliferation via indirect and direct contact, specifically related to increased IDO-1 and PGE2 concentrations. Furthermore, this study’s use of human clinical-grade single-cell-derived clonal bone marrow-derived MSCs, contributes to the future translatability and clinical relevancy of the produced sheets. Ultimately, these results present the combination of IFN-γ priming and MSC sheets as a new strategy to improve MSC-mediated treatment of localized inflammatory diseases.

A focal advantage of cell sheet technology has been as a scaffold-free three-dimensional (3D) cell delivery platform capable of sustained cell engraftment, survival, and reparative function. Recent evidence demonstrates that the intrinsic cell sheet 3D tissue-like microenvironment stimulates mesenchymal stem cell (MSC) paracrine factor production. In this capacity, cell sheets not only function as 3D cell delivery platforms, but also prime MSC therapeutic paracrine capacity. This study introduces a “cell sheet multilayering by centrifugation” strategy to non-invasively augment MSC paracrine factor production. Cell sheets fabricated by temperature-mediated harvest were first centrifuged as single layers using optimized conditions of rotational speed and time. Centrifugation enhanced cell physical and biochemical interactions related to intercellular communication and matrix interactions within the single cell sheet, upregulating MSC gene expression of connexin 43, integrin β1, and laminin α5. Single cell sheet centrifugation triggered MSC functional enhancement, secreting higher concentrations of pro-regenerative cytokines vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), and interleukin-10 (IL-10). Subsequent cell sheet stacking, and centrifugation generated cohesive, bilayer MSC sheets within 2 h, which could not be accomplished within 24 h by conventional layering methods. Conventional layering led to H1F-1α upregulation and increased cell death, indicating a hypoxic thickness limitation to this approach. Comparing centrifuged single and bilayer cell sheets revealed that layering increased VEGF production 10-fold, attributed to intercellular interactions at the layered sheet interface. The “MSC sheet multilayering by centrifugation” strategy described herein generates a 3D MSC-delivery platform with boosted therapeutic factor production capacity.