Diseases with the highest burden for society such as stroke, myocardial infarction, pulmonary embolism, and others are due to blood clots. Preclinical and clinical techniques to study blood clots are important tools for translational research of new diagnostic and therapeutic modalities that target blood clots. In this study, we employed a three-dimensional (3D) printed middle cerebral artery model to image clots under flow conditions using preclinical imaging techniques including fluorescent whole-body imaging, magnetic resonance imaging (MRI), and computed X-ray microtomography (microCT). Both liposome-based, fibrin-targeted, and non-targeted contrast agents were proven to provide a sufficient signal for clot imaging within the model under flow conditions. The application of the model for clot targeting studies and thrombolytic studies using preclinical imaging techniques is shown here. For the first time, a novel method of thrombus labeling utilizing barium sulphate (Micropaque^®) is presented here as an example of successfully employed contrast agents for in vitro experiments evaluating the time-course of thrombolysis and thus the efficacy of a thrombolytic drug, recombinant tissue plasminogen activator (rtPA). Finally, the proof-of-concept of in vivo clot imaging in a middle cerebral artery occlusion (MCAO) rat model using barium sulphate-labelled clots is presented, confirming the great potential of such an approach to make experiments comparable between in vitro and in vivo models, finally leading to a reduction in animals needed.

Detecting and characterizing microplastics within biological tissues remains analytically challenging due to their small size, complex composition, and the heterogeneous nature of biological matrices. Existing methods often rely on destructive sample preparation or only provide partial information, highlighting the need for advanced techniques that can simultaneously resolve both the structural and chemical features of microplastics in situ. To address this gap, we introduce a multimodal analytical approach that integrates micro-computed tomography (μCT), which enables non-invasive volumetric imaging of the tissue with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to detect microplastics based on their metal markers. Rat tissue was spiked with polyethylene terephthalate (PET) microplastics, and results showed that μCT imaging alone was insufficient for definitively determining microplastics. However, PET contained several elements, such as antimony and cobalt, and it was possible to detect PET microplastics using LA-ICP-MS based on those metal markers. Furthermore, the developed workflow combining μCT and LA-ICP-MS enabled volumetric segmentation of microplastic reconstruction based on their 3D distribution and evaluation of their size distribution. The results demonstrate that integrating LA-ICP-MS spatial element mapping of PET metal markers facilitates precise validation and segmentation of microplastic locations within tissue on μCT. The proposed protocol was evaluated against a reference size distribution method, addressing the associated detection limitations. Overall, this dual-modality approach provides a proof of concept for microplastic detection in biological tissues by combining both structural and chemical analyses.

The aim of the study was to compare 4 modes of ischaemic cardioprotection using continuous prograde autologous blood perfusion of the coronary artery in two hypothermic modes (group A, B) or conventional protection by cooled Hartmann solution (group C) or cooled saline (group D) without perfusion of the graft. Male Wistar rats (n = 24) were divided into four groups (A–D). In groups A (22–25 °C) and B (4–8 °C), blood perfusion rate was 10 ml/h and the graft was placed in a water bath. Groups C, D were initially rinsed with cold (4–8 °C) Hartmann solution (C) and cold saline solution (D), next the graft was placed in a water bath of cold (4–8 °C) Hartmann solution (C) or saline solution (D). The observed time was 30 min after the implemented perfusion (A, B) or initial rinsing (C, D). At 30 min, hearts of all the groups were perfused for 10 min with prograde-autologous arterialized blood at room temperature. At perfusion minute 10, blood was collected for biochemical analysis (sample 1). Sample 2 involved blood from a portable syringe infusion pumps (in parallel with sample 1). Pairwise test differences between samples 1 and 2 were significant in all the groups as regards creatine kinase and lactate dehydrogenase values, sampling 1 values being always higher, while cardiac troponin I concentrations were non-significant in the same comparison. The heart rate during the final perfusion was identical in all the groups. Our study has demonstrated that all observed cardioprotection modes are useful for experimental heart grafting.

Enhancing the fibrinolysis efficacy of recombinant tissue plasminogen activators (r-tPA) may be achieved by increasing the blood plasminogen levels. This study evaluated the effect of plasminogen (PLG) addition to a clinically relevant alteplase (r-tPA) dose on fibrinolysis. Sixty nine Wistar albino rats were divided into 7 groups; control (n = 10), r-tPA 0.9 mg/kg (0.9r-tPA) (n = 10), r-tPA 0.9 mg/kg + PLG 8 IU/kg (0.9r-tPA+8PLG) (n = 10), r-tPA 0.9 mg/kg + PLG 16 IU/kg (0.9r-tPA+16PLG) (n = 10), r-tPA 0.6 mg/kg + PLG 8 IU/kg (0.6r-tPA+8PLG) (n = 10), r-tPA 0.6 mg/kg + PLG 16 IU/kg (0.6r-tPA+16PLG) (n = 10), and r-tPA 0.9 mg/kg + PLG 8 IU/kg (0.9r-tPA+8PLG60) (n = 9) with the PLG administered 60 min before the r-tPA administration. In all groups, systemic embolism was induced by application of three barium sulfate-labeled artificial clots in abdominal aorta. Artificial clots were visualized under micro-fluoroscopy, and radiographs were captured every 5 min during fibrinolytic/saline infusion. The measurement of clot area was used to calculate fibrinolysis rate (%/min) and the area under the curve (AUC; %*min). Results show that all PLG combinations enhanced fibrinolysis relative to untreated controls (p < 0.001). At the clinical 0.9 mg/kg dose, PLG supplementation significantly increased the fibrinolysis rate compared with r-tPA alone (r-tPA: 0.8 ± 0.5%/min; 8 IU/kg, p = 0.025; 16 IU/kg, p < 0.001), and this benefit was retained when PLG was administered 60 min in advance (p = 0.024). Differences between PLG doses were not statistically significant. Systemic plasminogen supplementation therefore enhances r-tPA-mediated fibrinolysis in vivo at a clinically relevant dose and regimen, without requiring catheter-directed delivery.