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The objective of the study was to investigate the safety profile of high-risk micro-endomyocardial biopsy (micro-EMB) compared to conventional EMB in a large animal model. Twenty pigs were subjected to a maximum of 30 consecutive biopsies, including sampling from the free ventricular wall, with either micro-EMB (n = 10) or conventional EMB (n = 10). There were no major complications in the micro-EMB group (0/10), compared to six major complications in the EMB group (6/10; p = 0.003). Survival analysis further highlighted these differences (p = 0.004). There were significantly higher volumes of pericardial effusion in the EMB group (p = 0.01). The study shows a safety advantage of micro-EMB compared to standard EMB in the experimental high-risk circumstances investigated in this animal study. These results indicate enhanced possibilities to collect samples from sensitive areas by using the micro-EMB technique instead of standard EMB.

Endomyocardial biopsy is a valuable tool in cardiac diagnostics but is limited by low diagnostic yield and significant complication risks. Meanwhile, recent developments in transcriptomic and proteomic technologies promise a wealth of biological data from minimal tissue samples. To take advantage of the minimal tissue amount needed for molecular analyses, we have developed a sub-millimeter endovascular biopsy device, considerably smaller than current clinical equipment, and devised a low-input RNA-sequencing protocol for analyzing small tissue samples. In in vivo evaluation in swine, 81% of biopsy attempts (n = 157) were successful. High quality RNA-sequencing data was generated from 91% of the sequenced cardiac micro-biopsy samples (n = 32). Gene expression signatures of samples taken with the novel device were comparable with a conventional device. No major complications were detected either during procedures or during 7 days’ follow-up, despite acquiring a relatively large number of biopsies (median 30) in each animal. In conclusion, the novel device coupled with RNA-sequencing provides a feasible method to obtain molecular data from the myocardium. The method is less traumatic and has a higher flexibility compared to conventional methods, enabling safer and more targeted sampling from different parts of the myocardium.

We present a new type of microbiopsy tool (MBT) an order of magnitude smaller than commercially available biopsy catheters that, together with a trans-vessel wall catheter (Extroducer) successfully samples soft tissues with significantly less trauma to the tissue than commercial catheters. The MBT is mounted on a Nitinol wire. It features a gripping action that is actuated by the relative motion inside the Extroducer and has demonstrated repeated successful tissue sampling of approximately 500–1000 cells in ex-vivo tissue. This new catheter system can potentially allow super-selective, minimally invasive tissue sampling and transcriptomic analysis from hard to reach areas.

Purpose In mechanical thrombectomy (MT) for ischemic stroke, endothelial cells (ECs) from intracranial blood vessels adhere to the stent retriever device and can be harvested. However, understanding the molecular biology and the role of the endothelium in different pathological conditions remains insufficient. The purpose of the study was to characterize and analyze the molecular aspect of harvested ECs using cell culture and transcriptomic techniques in an MT swine model relevant to clinical ischemic stroke. Methods In swine, preformed thrombi were injected into the external carotid and subclavian arteries to occlude their branches. MT was performed according to clinical routine. The stent retriever device and thrombus were treated with cell dissociation buffer. The resulting cell suspension was analyzed by immunohistochemistry and was cultured. Cultured cells were analyzed using single-cell RNA sequencing (scRNA-seq) after fluorescence-activated cell sorting (FACS). Results A total number of 37 samples were obtained containing CD31-positive cells. Cell culture was successful in 90% of samples, and the cells expressed multiple typical EC protein markers. Eighty-nine percent of the sorted cells yielded high-quality transcriptomes, and single-cell transcriptomes from cultured cells showed that they expressed typical endothelial gene patterns. Gene expression analysis of ECs from an occluded artery did not show distinctive clustering into subtypes. Conclusion ECs harvested during MT can be cultured and analyzed using single-cell transcriptomic techniques. This analysis can be implemented in clinical practice to study the EC gene expression of comorbidities, such as hypertension, diabetes mellitus, and metabolic syndrome, in patients suffering from acute ischemic stroke.

Glioblastoma multiforme (GBM) is the most common and most severe form of malignant gliomas. The prognosis is poor with current combinations of pharmaceutical, radiotherapy, and surgical therapy. A continuous search for new treatments has therefore been ongoing for many years. Therapy with tumor-infiltrating lymphocytes (TILs) is a clinically promising strategy to treat various cancers, including GBM. An endovascular intraarterial injection of TILs as a method of delivery may, instead of intravenous infusion, result in better retention of effector cells within the tumor. Prior to clinical trials of intra-arterial injections with any cells, preclinical safety data with special emphasis on embolic–ischemic events are necessary to obtain. We used native rabbits as a model for intra-arterial injections with routine clinical catheter material and a clinical angiography suite. We selectively infused a total dose of 20 million activated T cells at a cell concentration of 4,000 cells/ml over 8 min of injection time. The rabbits were evaluated for ischemic lesions by 9.4 T magnetic resonance imaging (MRI) ( n = 6), and for tracking of injected cells, single-photon emission computed tomography/computed tomography (SPECT/CT) was used ( n = 2). In this study, we show that we can selectively infuse activated T cells to a CNS volume of 3.5 cm3 (estimated from the volumetric MRI) without catastrophic embolic– ischemic adverse events. We had one adverse event with a limited basal ganglia infarction, probably due to catheter-induced mechanical occlusion of one of the lateral lenticulostriatal arteries. The cells pass through the native brain without leaving SPECT signals. The cells then, over the first hours, end up in the liver to a large extent and to a lesser degree by the spleen, pancreas, and kidneys. Virtually no uptake could be detected in the lungs. This indicates a difference in biodistribution as opposed to other cell types when infused intravenously.

Introduction Endomyocardial biopsy (EMB) is the gold standard for diagnosis of several cardiac diseases, yet its use is limited by low diagnostic yield and significant complication risks. The size of the current devices allows only limited steering to different parts of the ventricle walls. In transplant monitoring, repeated biopsies with the current devices can cause scarring that makes it increasingly difficult to obtain adequate samples. We hypothesised that several of the shortcomings of EMB can be avoided with a smaller and more steerable device. Further, we hypothesised that the novel sampling procedure could be coupled to a low-input molecular analysis method, such as RNA-sequencing (RNA-seq), to provide molecular characterisation of the tissue without the need of large biopsy samples. Purpose To develop an EMB device with significantly smaller dimensions, for future use in diagnostics and research investigations. Specific aims were to test feasibility and safety of the procedure, as well as the quality of the generated molecular data. Methods 65 “micro biopsy” (micro-EMB) device prototypes were designed and evaluated in-house. The prototypes were evaluated either in an ex-vivo simulator or in acute non-survival pig experiments (n=23). Once the final device design was reached, an in vivo trial was set up using six naive Yorkshire farm pigs. Micro-EMB, conventional EMB, skeletal muscle and blood samples were collected for RNA-seq characterisation and comparison. In half of the animals (n=3), micro-EMB was the only intervention in order to prioritise safety evaluations. The animals were monitored for one week. Results The final device design has an outer diameter (OD) of 0.4 mm, compared to a conventional 11 mm device (in the opened position), Fig 1A. The device can be directed to different parts of the myocardium in both ventricles. In the in vivo evaluation in swine, 81% of the biopsy attempts (n=157) were successful. High quality RNA-seq data was generated from 91% of the sequenced heart micro-biopsy samples (n=32). The gene expression signatures of samples taken with the novel device were comparable with samples taken with a conventional device, Fig 1B. No major complications were detected either during periprocedural monitoring or during the follow-up. The tissue mark after micro-biopsy was markedly smaller than after conventional endomyocardial biopsy. A) Bioptome dimensions. B) RNA-seq data. Conclusions Our preliminary data suggest that the novel submillimeter biopsy device, coupled with RNA-seq, provides a feasible method to obtain molecular data from the myocardium. The method is less traumatic and has a higher flexibility compared to conventional methods, enabling safer and more specific sampling from different parts of the myocardium. In the long term, the procedure could open unprecedented diagnostic and research possibilities. Future studies should be directed to establish the capabilities of the novel method in a relevant disease model. Acknowledgement/Funding Family Erling Persson Foundation. The Söderberg foundations. KID (Karolinska Institutet). The 4D project. Stockholm county council. Astra Zeneca.

OBJECTIVES With the emergence of targeted cell transplantation and gene therapy, there is a need for minimally invasive tissue access to facilitate delivery of therapeutic substrate. The objective of this study was to demonstrate the suitability of an endovascular device which is able to directly access tissue and deliver therapeutic agent to the heart, kidney and pancreas without need to seal the penetration site. METHODS In vivo experiments were performed in 30 swine, including subgroups with follow-up to evaluate complications. The previously described trans-vessel wall (VW) device was modified to be sharper and not require tip detachment to seal the VW. Injections into targets in the heart (n = 13, 24-h follow-up n = 5, 72-h follow-up n = 3), kidney (n = 8, 14-day follow-up n = 3) and pancreas (n = 5) were performed. Some animals were used for multiple organ injections. Follow-up consisted of clinical monitoring, angiography and necropsy. Transvenous (in heart) and transarterial approaches (in heart, kidney and pancreas) were used. Injections were targeted towards the subepicardium, endomyocardium, pancreas head and tail, and kidney subcapsular space and cortex. RESULTS Injections were successful in target organs, visualized by intraparenchymal contrast on fluoroscopy and by necropsy. No serious complications (defined as heart failure or persistent arrhythmia, haemorrhage requiring treatment or acute kidney injury) were encountered over a total of 157 injections. CONCLUSIONS The trans-VW device can achieve superselective injections to the heart, pancreas and kidney for delivery of therapeutic substances without tip detachment. All parts of these organs including the subepicardium, pancreas tail and renal subcapsular space can be efficiently reached.

Interventional treatment regimens have increased the demand for accurate understanding of the progression of injury in acute ischemic stroke. However, conventional animal models severely inhibit collateral blood flow and mimic the malignant infarction profile not suitable for treatment. The aim of this study was to provide a clinically relevant profile of the emergence and course of ischemic injury in cases suitable for acute intervention, and was achieved by employing a M2 occlusion model (M2CAO) that more accurately simulates middle cerebral artery (MCA) occlusion in humans. Twenty-five Sprague-Dawley rats were subjected to Short (90 min), Intermediate (180 min) or Extended (600 min) transient M2CAO and examined longitudinally with interleaved diffusion-, T2- and arterial spin labeling perfusion-weighted magnetic resonance imaging before and after reperfusion. We identified a rapid emergence of cytotoxic edema within tissue regions undergoing infarction, progressing in several distinct phases in the form of subsequent moderation and then reversal at 230 min (p < 0.0001). We identified also the early emergence of vasogenic edema, which increased consistently before and after reperfusion (p < 0.0001). The perfusion of the penumbra correlated more strongly to the perfusion of adjacent tissue regions than did the perfusion of regions undergoing infarction (p = 0.0088). This was interpreted as an effect of preserved collateral blood flow during M2CAO. Accordingly, we observed only limited recruitment of penumbra regions to the infarction core. However, a gradual increase in infarction size was still occurring as late as 10 hours after M2CAO. Our results indicate that patients suffering MCA branch occlusion stand to benefit from interventional therapy for an extended time period after the emergence of ischemic injury.

Endothelial cell sampling coupled with transcriptomic analysis in a swine model of mechanical thrombectomy