Explore the vast range of titles available.

In vivo evaluation of biomaterials largely relies on histology to assess biocompatibility and foreign body responses. While effective for capturing end‐stage outcomes, these methods offer limited insight into the cellular mechanisms driving tissue remodeling, hindering efforts to rationally design better biomaterials. Transcriptomics has revolutionized our understanding of gene activity driving cellular function, yet remains underutilized in biomaterial evaluation. Recent advances in high‐resolution spatial transcriptomics now enable precise mapping of gene expression within tissue, offering detailed insight into cellular states and spatial organization. To align biomaterial research with advances in spatial biology, we develop a bioinformatics workflow for the Xenium platform to analyze in vivo responses to implanted materials. Applying this workflow to evaluate electrospun polycaprolactone (PCL) scaffolds implanted subcutaneously in mice, we identify spatially distinct macrophage and fibroblast subpopulations with unique gene expression profiles. Spatial analyses show shared phenotypic features between co‐localized macrophages and fibroblasts, oriented from the scaffold body to its surface. Gene ontology linked these spatial transitions to functional roles, with immune cell recruitment occurring within the scaffold and fibrosis at the surface. These transitions were not detectable by histology, highlighting spatial transcriptomics as a powerful approach for uncovering cellular dynamics and enabling better biologically‐informed design of biomaterials. This work establishes a standardized, high‐resolution spatial transcriptomics workflow for characterizing host responses to biomaterial implants. Using the 10× Xenium platform, the pipeline integrates spatial mapping, subclustering, and functional enrichment to resolve immune and stromal cell organization at single‐cell resolution, enabling reproducible, systems‐level evaluation of biomaterial performance and biocompatibility.

Multifunctional nanocarriers (MNCs) promise to improve therapeutic outcomes by combining multiple classes of molecules into a single nanostructure, enhancing active targeting of therapeutic agents and facilitating new combination therapies. However, nanocarrier platforms currently approved for clinical use can still only carry a single therapeutic agent. The complexity and escalating costs associated with the synthesis of more complex MNCs have been major technological roadblocks in the pathway for clinical translation. Here, we show that plasma polymerized nanoparticles (PPNs), synthesised in reactive gas discharges, can bind and effectively deliver multiple therapeutic cargo in a facile and cost-effective process compatible with up scaled commercial production. Delivery of siRNA against vascular endothelial growth factor (siVEGF) at extremely low concentrations (0.04 nM), significantly reduced VEGF expression in hard-to-transfect cells when compared with commercial platforms carrying higher siRNA doses (6.25 nM). PPNs carrying a combination of siVEGF and standard of care Paclitaxel (PPN-Dual) at reduced doses (< 100 µg/kg) synergistically modulated the microenvironment of orthotopic breast tumors in mice, and significantly reduced tumor growth. We propose PPNs as a new nanomaterial for delivery of therapeutics, which can be easily functionalised in any laboratory setting without the need for additional wet-chemistry and purification steps.

Minimally invasive interventions using drug‐eluting stents or balloons are a first‐line treatment for certain occlusive cardiovascular diseases, but the major long‐term cause of failure is neointimal hyperplasia (NIH). The drugs eluted from these devices are non‐specific anti‐proliferative drugs, such as paclitaxel (PTX) or sirolimus (SMS), which do not address the underlying inflammation. MCC950 is a selective inhibitor of the NLRP3‐inflammasome, which drives sterile inflammation commonly observed in NIH. Additionally, in contrast to broad‐spectrum anti‐inflammatory drugs, MCC950 does not compromise global immune function due this selective activity. In this study, MCC950 is found to not impact the viability, integrity, or function of human coronary endothelial cells, in contrast to the non‐specific anti‐proliferative effects of PTX and SMS. Using an in vitro model of NLRP3‐mediated inflammation in murine macrophages, MCC950 reduced IL‐1β expression, which is a key driver of NIH. In an in vivo mouse model of NIH in vascular grafts, MCC950 significantly enhanced re‐endothelialization and reduced NIH compared to PTX or SMS. These findings show the effectiveness of a targeted anti‐inflammatory drug‐elution strategy with significant implications for cardiovascular device intervention. Current drug eluting vascular devices releasing paclitaxel and sirolimus prevent growth of key vascular cells but fail to promote vessel healing (endothelialization), resulting in poor long‐term reduction of vessel narrowing (neointimal hyperplasia). In contrast, highly selective anti‐inflammatory MCC950 promotes rapid healing of the blood vessel and reduces vessel narrowing.

This study presents a versatile perfusion bioreactor system designed to evaluate endothelialization on electrospun polycaprolactone (PCL)–gelatin vascular grafts under controlled flow conditions that mimic physiological and pathological shear stress. The bioreactor enables direct assessment of endothelial cell behavior on 3D graft structures, providing a more physiologically relevant platform compared to traditional static cultures. Electrospun PCL–gelatin grafts demonstrate uniform endothelial cell coverage when exposed to physiological shear stress (>10 dyn cm−2), with cells displaying alignment in the direction of flow. Under these conditions, endothelial cells upregulate endothelial nitric oxide synthase and platelet endothelial cell adhesion molecule‐1, markers associated with vascular homeostasis, anti‐inflammatory activity, and enhanced endothelial migration. In contrast, grafts subjected to pathological shear stress (<5 dyn cm−2) exhibit increased expression of intercellular adhesion molecule‐1, promoting monocyte adhesion and a proinflammatory response. These findings highlight the importance of physiological flow dynamics in regulating endothelial function and demonstrate the value of this bioreactor system as a platform prior to preclinical evaluation of vascular grafts. By providing a more accurate in vitro model, this system may accelerate the development of bioengineered vascular grafts with improved clinical outcomes. Traditional static culture provides limited physiological relevance for evaluation of vascular grafts. A perfusion bioreactor system can provide more accurate in vitro model for evaluation of vascular grafts, exposing endothelial cells on 3D structure to physiological or pathological shear stress. Endothelial cells under physiological shear stress demonstrate anti‐inflammatory activity, while cells exposed to pathological shear stress exhibit proinflammatory characteristics.

Skeletal myofibers naturally regenerate after damage; however, impaired muscle function can result in cases when a prominent portion of skeletal muscle mass is lost, for example, following traumatic muscle injury. Volumetric muscle loss can be modeled in mice using a surgical model of muscle ablation to study the pathology of volumetric muscle loss and to test experimental treatments, such as the implantation of acellular scaffolds, which promote de novo myogenesis and angiogenesis. Here we provide step-by-step instructions to perform full-thickness surgical ablation, using biopsy punches, and to remove a large volume of the tibialis anterior muscle of the lower limb in mice. This procedure results in a reduction in muscle mass and limited regeneration capacity; the approach is easy to reproduce and can also be applied to larger animal models. For therapeutic applications, we further explain how to implant bioscaffolds into the ablated muscle site. With adequate training and practice, the surgical procedure can be performed within 30 min. Key points A surgical procedure for the full-thickness surgical ablation of ~20–60% of the mouse tibialis anterior using a commercial 2–3-mm biopsy punch allows the ablation size to be customized. The model is representative of skeletal muscle loss. The surgically ablated muscles’ uniform geometry does not fully reproduce the complexity of traumatic muscle injury, which includes other injuries associated with trauma to the bone, nerves or tendons. This protocol covers the surgical ablation of muscle tissue in mice, as a reproducible model of volumetric muscle loss, and the implantation of therapeutic bioscaffolds to induce myogenesis and angiogenesis.

Current synthetic vascular grafts are not suitable for use in low-diameter applications. Silk fibroin is a promising natural graft material which may be an effective alternative. In this study, we compared two electrospun silk grafts with different manufacturing processes, using either water or hexafluoroisopropanol (HFIP) as solvent. This resulted in markedly different Young’s modulus, ultimate tensile strength and burst pressure, with HFIP spun grafts observed to have thicker fibres, and greater stiffness and strength relative to water spun. Assessment in a rat abdominal aorta grafting model showed significantly faster endothelialisation of the HFIP spun graft relative to water spun. Neointimal hyperplasia in the HFIP graft also stabilised significantly earlier, correlated with an earlier SMC phenotype switch from synthetic to contractile, increasing extracellular matrix protein density. An initial examination of the macrophage response showed that HFIP spun conduits promoted an anti-inflammatory M2 phenotype at early timepoints while reducing the pro-inflammatory M1 phenotype relative to water spun grafts. These observations demonstrate the important role of the manufacturing process and physical graft properties in determining the physiological response. Our study is the first to comprehensively study these differences for silk in a long-term rodent model.

Models of arterial injury in rodents have been invaluable to our current understanding of vessel restenosis and play a continuing role in the development of endovascular interventions for cardiovascular disease. Mechanical distention of the vessel wall and denudation of the vessel endothelium are the two major modes of vessel injury observed in most clinical pathologies and are critical to the reproducible modelling of progressive neointimal hyperplasia. The current models which have dominated this research area are the mouse wire carotid or femoral injury and the rat carotid balloon injury. While these elicit simultaneous distension of the vessel wall and denudation of the luminal endothelium, each model carries limitations that need to be addressed using a complementary injury model. Wire injuries in mice are highly technical and procedurally challenging due to small vessel diameters, while rat balloon injuries require permanent blood vessel ligation and disruption of native blood flow. Complementary models of vascular injury with reproducibility, convenience, and increased physiological relevance to the pathophysiology of endovascular injury would allow for improved studies of neointimal hyperplasia in both basic and translational research. In this study, we developed a new surgical model that elicits vessel distention and endothelial denudation injury using sequential steps using microforceps and a standard needle catheter inserted via arteriotomy into a rat common carotid artery, without requiring permanent ligation of branching arteries. After 2 weeks post-injury this model elicits highly reproducible neointimal hyperplasia and rates of re-endothelialisation similar to current wire and balloon injury models. Furthermore, evaluation of the smooth muscle cell phenotype profile, inflammatory response and extracellular matrix within the developing neointima, showed that our model replicated the vessel remodelling outcomes critical to restenosis and those becoming increasingly focused upon in the development of new anti-restenosis therapies.

Although stem cell therapy has tremendous therapeutic potential, clinical translation of stem cell therapy has yet to be fully realized. Recently, patient comorbidities and lifestyle choices have emerged to be important factors in the efficacy of stem cell therapy. Tobacco usage is an important risk factor for numerous diseases, and nicotine exposure specifically has become increasing more prevalent with the rising use of electronic cigarettes. This review describes the effects of nicotine exposure on the function of various stem cells. We place emphasis on the differential effects of nicotine exposure and as well as in preclinical models. Further research on the effects of nicotine on stem cells will deepen our understanding of how lifestyle choices can impact the outcome of stem cell therapies.

Despite the therapeutic potential of mesenchymal stromal cells (MSC), there is limited understanding of optimal extracellular matrix (ECM) environments to manufacture these cells. We developed tissue chips to study the effects of multi-factorial ECM environments under manufacturable stiffness ranges and multi-component ECM compositions. Manufacturing qualities of cell expansion potential, immunomodulation, and differentiation capacity were examined. The results show stiffness effects, with 900 kPa substrates supporting higher proliferation and osteogenic differentiation, along with anti-inflammatory IL-10 expression, whereas 150 kPa substrates promoted adipogenic differentiation at 150 kPa, suggesting that optimal ECM environments may differ based on manufacturing goals. ECM biochemistries containing fibronectin and laminin further modulated MSC manufacturing qualities across various stiffnesses. Proteomic and transcriptomic analyses revealed unique ECM combinations that induced higher levels of angiogenic and immunomodulatory cytokines, compared to single factor ECMs. These findings demonstrate that optimized ECM environments enhance MSC manufacturing quality.

Background Induced pluripotent stem-cell derived endothelial cells (iPSC-ECs) can be generated from any somatic cell and their iPSC sources possess unlimited self-renewal. Previous demonstration of their proangiogenic activity makes them a promising cell type for treatment of ischemic injury. As with many other stem cell approaches, the low rate of in-vivo survival has been a major limitation to the efficacy of iPSC-ECs to date. In this study, we aimed to increase the in-vivo lifetime of iPSC-ECs by culturing them on electrospun polycaprolactone (PCL)/gelatin scaffolds, before quantifying the subsequent impact on their proangiogenic function. Methods iPSC-ECs were isolated and stably transfected with a luciferase reporter to facilitate quantification of cell numbers and non-invasive imaging in-vivo PCL/gelatin scaffolds were engineered using electrospinning to obtain woven meshes of nanofibers. iPSC-ECs were cultured on scaffolds for 7 days. Subsequently, cell growth and function were assessed in vitro followed by implantation in a mouseback subcutaneous model for 7 days. Results Using a matrix of conditions, we found that scaffold blends with ratios of PCL:gelatin of 70:30 (PG73) spun at high flow rates supported the greatest levels of iPSC-EC growth, retention of phenotype, and function in vitro. Implanting iPSC-ECs seeded on PG73 scaffolds in vivo improved their survival up to 3 days, compared to cells directly injected into control wounds, which were no longer observable within 1 h. Enhanced engraftment improved blood perfusion, observed through non-invasive laser Doppler imaging. Immunohistochemistry revealed a corresponding increase in host angiogenic mechanisms characterized by the enhanced recruitment of macrophages and the elevated expression of proangiogenic cytokines vascular endothelial growth factor and placental growth factor. Conclusions Knowledge of these mechanisms combined with a deeper understanding of the scaffold parameters influencing this function provides the groundwork for optimizing future iPSC-EC therapies utilizing engraftment platforms. The development of combined scaffold and iPSC-EC therapies could ultimately improve therapeutic angiogenesis and the treatment of ischemic injury.