The trans-vessel wall device (TW-device) is a new endovascular tool for precise and safe delivery of various payloads (cells, viral, modified RNA, chemotherapy, growth factors) in oncology and regenerative medicine. The twofold aim of this study was to assess cell engraftment and tumor growth using the TW-device for endovascular transplantation and to evaluate its ability to directly access solid tumors. We used the VX2 model in the rabbit kidney to compare percutaneously implanted fresh VX2 cells with TW-device injections of cryopreserved VX2 cells. We demonstrated the feasibility of endovascular transplantation (n = 7) of tumor cells, achieving a 57.1% engraftment rate despite cryopreservation, comparable with 70% for percutaneous delivery of fresh cells (n = 10). Re-access using the TW-device was 100% successful (n = 11) with super-selective intratumoral contrast administration without complications. In conclusion, endovascular transplantation of VX2 cells using the TW-device resulted in proliferating cell grafts in the rabbit kidney establishing functional proof that cells indeed survive handling, preparation, and device passage. We also show the TW-device is able to access solid tumor parenchyma allowing precise intraparenchymal administration.This proof-of-concept study open up possibilities for repeated direct parenchymal injections via the endovascular route in any hard to reach organ.

Biocompatibility of medical implants poses a significant challenge in medical technology. Neural implants, integral to curative therapies, initially exhibit efficacy but can lead to unforeseen long-term side effects. The material composition and dimensions of implants are critical factors influencing their biocompatibility within brain tissue. Typically, neural implants are identified as foreign entities by the patient's immune system, triggering persistent inflammation and severe adverse effects. In this study, we investigate the host response in mouse brain tissue of implanted microscale constructs measuring 0.1 x 0.1 x 1 mm3 fabricated from common microfabrication materials. Magnetic Resonance Imaging (MRI) analysis reveals rapid recovery of brain parenchyma at 6 week interval post-implantation, accompanied by negligible or mild adverse immune responses during the experimental period. Histological assessments and cell marker stainings targeting astroglia, macrophages, and microglia demonstrate minimal impacts of the microconstructs on mouse brain tissue throughout the 24-week implantation period. Our findings indicate that untethered microimplants of this scale may have potential applications in medical technology and medical treatment for various brain diseases. In summary, this study supports the development of potentially biocompatible brain microimplants that could be useful for the long-term management of chronic brain disorders.

Heart failure has a poor prognosis and no curative treatment exists. Clinical trials are investigating gene- and cell-based therapies to improve cardiac function. The safe and efficient delivery of these therapies to solid organs is challenging. Herein, we demonstrate the feasibility of using an endovascular intramyocardial delivery approach to safely administer mRNA drug products and perform cell transplantation procedures in swine. Using a trans-vessel wall (TW) device, we delivered chemically modified mRNAs (modRNA) and mRNA-enhanced mesenchymal stromal cells expressing vascular endothelial growth factor A (VEGF-A) directly to the heart. We monitored and mapped the cellular distribution, protein expression, and safety tolerability of such an approach. The delivery of modRNA-enhanced cells via the TW device with different flow rates and cell concentrations marginally affect cell viability and protein expression in situ. Implanted cells were found within the myocardium for at least 3 days following administration, without the use of immunomodulation and minimal impact on tissue integrity. Finally, we could increase the protein expression of VEGF-A over 500-fold in the heart using a cell-mediated modRNA delivery system compared with modRNA delivered in saline solution. Ultimately, this method paves the way for future research to pioneer new treatments for cardiac disease.

Inherent to any stenting procedure is the prescription of dual antiplatelet therapy (DAPT) to reduce the platelet response. Clinical guidelines recommend 6–12 months of DAPT, depending on stent type, clinical picture and patient factors. Our hypothesis is that a nanostructured noble metal coating has the potential to reduce protein deposition and platelet activation. These effects would reduce subsequent thrombo-inflammatory reactions, potentially mitigating the need for an extensive DAPT in the acute phase. Here, a noble metal nanostructure coating on stents is investigated. Twelve pigs underwent endovascular implantation of coated and non-coated stents for paired comparisons in a blinded study design. The non-coated control stent was placed at the contralateral corresponding artery. Volumetric analysis of angiographic data, performed by a treatment blinded assessor, demonstrated a significant thrombus reduction for one of the coatings compared to control. This effect was already seen one hour after implantation. This finding was supported by in vitro data showing a significant reduction of coagulation activation in the coated group. This novel coating shows promise as an implant material addition and could potentially decrease the need for DAPT in the early phases of stent implementation.

A simple incision procedure in a blood vessel makes the entire vascular system accessible. Through contrast injection and X-ray visualization, the vascular tree can be mapped and navigated through manual manipulation of thin tubes and wires. This utilization of the vasculature as internal pathways is commonly referred to as the endovascular technique. This technique can be used to deliver implants and drugs, retrieve problematic lesions or objects from the vasculature, or take tissue samples. Compared to open surgery, the advantage of this technique lies in the reduced invasiveness, ideally only leaving a small incision scar at the point of entry. Some interventions, however, are still associated with certain risks, requiring medication or complicating further interventions. The development of sequencing technologies presents an opportunity to improve and miniaturize devices, reducing invasiveness. This thesis aims to mitigate these risks and capitalize on the potential of next generation sequencing through microfabrication technologies, producing devices that are less invasive than current methods or that enable a new procedure.

Initially, the aspect of endovascular heart biopsy is covered. The first work presents the fabrication and in vivo evaluation of a nitinol-based catheter device designed for extracting myocardial tissue. The device is fabricated through picosecond laser machining of nitinol tubes and wires, producing a device that is substantially smaller than what is currently used. The samples are evaluated and compared to samples extracted with conventional devices through RNA-Sequencing, verifying the proof of concept. The second work further emphasizes the device's functionality by evaluating it in a disease model of endomyocardial infarction. Tissue that is affected by the infarct and surrounding healthy tissue is extracted and compared in terms of its genetic expression. This comparison reveals a genetic discrepancy between the sick and healthy tissue, verifying the potential of using the device with RNA-sequencing for diagnostic purposes. The third work evaluates the safety aspects of the novel device in a head-to-head comparison with a conventional device. The study reveals a clear benefit of using the smaller device in terms of the complication rate during the procedure.

The fourth work presents the fabrication and in vivo evaluation of another nitinol based catheter device designed for endothelial cell sampling. The device is fabricated through two-photon polymerization technologies, producing sub-mm brush structures mounted on a nitinol wire. Currently, there are no devices in clinical use that are capable of exclusively extracting endothelial cells. The novel device presents a solution for selective interaction with the innermost layer of the blood vessel. It represents an important step toward sampling endothelial cells for diagnostic and research purposes.

The fifth and sixth works collectively present two different aspects of a third nitinol based catheter device designed to sample tissue from soft organs anywhere in the body. The device is fabricated using laser micromachining, grinding, and two-photon polymerization. The work is separated in terms of the in vivo evaluation and the technical solution. The technical aspects of the device are examined in terms of force generation in miniaturized catheter systems and the problems that arise in terms of mechanical scaling. These problems are solved by attaching pistons along the wire surface coupled with applied pressure to increase the force generated. The sampling with this device is realized, similar to the fourth work, with sub-mm brushes mountedon the wire. In vivo evaluation of this device reveals successful sampling of minute tissue quantities from the liver and kidney, in the size range of 10-100 cells per sample.

The seventh work presents the in vivo and in vitro performance of a nanostructure coating on nitinol-based stents. Patients with a stent implant are prescribed an extensive medication regimen to counteract the metal implant's effects on the blood and surrounding tissue. This issue is being continuously targeted by new stent platforms, either with a drug-eluting polymer layer or by being resorbable by the body or through various other means. These implants all have a transient behavior, resulting in different issues over time. Paper VII presents an alternative approach to this problem by instead applying a nanostructure coating that is designed to interact with the blood to a much lesser degree, as demonstrated by CT-angiography and the measurement of multiple biomarkers.

Med ett snitt i ett blodkärl tillgängliggörs hela kärlsystemet. Genom kontrastinjektion och röntgenvisualisering kan man kartlägga och navigera kärlträdet med hjälp av manuell manipulation av tunna rör och trådar. Användandet av kärlträdet som interna vägar kallas i dagligt tal för den endovaskulära tekniken. Med denna teknik kan man leverera implantat och mediciner, extrahera problematiska lesioner eller objekt, eller ta vävnadsprover. Jämfört med öppen kirurgi så är fördelen med denna teknik den minskade invasiviteten, där ett litet sår vid ingången till kärlträdet är det enda som återstår, i idealfallet. Vissa procedurer är dock fortfarande förknippade med vissa risker som kräver medicinering eller som försvårar vidare behandlingar. Utvecklingen av sekvenseringstekniker möjliggör förbättring och miniatyrisering av verktyg och på så sätt en minskning av dess invasivitet. Denna avhandling ämnar att minska riskerna som förknippas med endovaskulära procedurer och att kapitalisera på potentialen som sekvensering representerar. Genom tekniker för mikrofabrikation tillverkas verktyg som är mindre invasiva än nuvarande metoder eller som möjliggör en ny procedur.

Inledningsvis kommer endovaskulär hjärtbiopsi att beskrivas. Det första arbetet presenterar tillverkningen och in vivo-utvärderingen av ett nitinol-baserat kateterverktyg designat för att extrahera vävnad från myokardiet. Verktyget är tillverkat med laserbearbetning av nitinolrör och trådar, med hjälp av en pikosekundlaser. Verktyget är avsevärt mindre än de som används kliniskt idag. Proverna som tas utvärderas och jämförs med prover som tas med konventionella verktyg genom RNA-Sekvensering, där konceptets genomförbarhet bevisas. Det andra arbetet fördjupar utvärderingen av verktygets funktionalitet genom att utvärdera det i en sjukdomsmodell, specifikt en modell av hjärtinfarkt. Vävnad som påverkas av infarkten och omkringliggande, frisk vävnad extraheras med verktyget och dess genuttryck jämförs. Denna jämförelse avslöjar en genetisk diskrepans mellan sjuk och frisk vävnad, vilket verifierar potentialen med att använda RNA-sekvensering för diagnostik. Det tredje arbetet utvärderar säkerhetsaspekterna hos det nya verktyget genom en direkt jämförelse med det konventionella verktyget. Studien visar på en klar fördel i att använda det nya verktyget med avseende på incidensen av komplikationer under proceduren.

Det fjärde arbetet presenterar tillverkningen och in vivo-utvärderingen av ytterligare ett nitinol-baserat kateterverktyg designat för att provtagning av endotelceller. Verktyget tillverkas med hjälp av tvåfotonpolymerisering, där sub-mm borststrukturer tillverkas och monteras på nitinoltråd. För närvarande finns inga verktyg i kliniskt bruk som klarar att selektivt extrahera endotelceller. Det nya verktyget presenterar en lösning för att selektivt interagera med det innersta lagret av blodkärlet och motsvarar ett viktigt steg mot provtagning av endotelceller för diagnostiska syften och för forskning.

Det femte och sjätte arbetet presenterar två aspekter av ett tredje nitinol-baserat kateterverktyg designat för att ta prover från mjuka organ i kroppen. Verktyget tillverkas med laserbearbetning, slipning och tvåfotonpolymerisering. Arbetena är separerade i in vivo-utvärderingen och den tekniska lösningen. De tekniska aspekterna av verktyget utvärderas vad gäller kraftgenerering hos miniatyriserade kateter-system och de problem som uppstår med mekanisk skalning. Dessa problem löses genom att tillsätta pistonger längs tråden och applicera ett tryck för att öka kraftgenereringen. Provtagningsmekanismen liknar den som presenteras i det fjärde arbetet, där liknande sub-mm borststrukturer tillsatts på en tråd. In vivo-utvärdering av verktyget visar på framgångsrik provtagning från lever och njure, i storleksordningen 10-100 celler per prov.

Det sjunde arbetet presenterar in vivo- och in vitro-utvärderingen av en nanostruktur-beläggning på nitinol-baserade stentar. Patienter med ett stentimplantat ordineras en extensiv medicinering för att kontra effekterna som implantatet har på blodet och omkringliggande vävnad. Nya stentplattformar utvecklas löpande för att kontra dessa effekter, exempelvis genom beläggningen av ett polymerlager som innehåller medicin, genom resorberbara implantat och många andra sätt. Dessa implantat har ett transient beteende som resulterar i olika problem på längre sikt. Det sjunde arbetet presenterar en alternativ lösning till dessa problem genom att applicera en nanostruktur-beläggning som är designat att interagera med blodet till en mindre grad. Detta demonstreras med CT-angiografi och mätningen av flertalet blodmarkörer.

Endothelial cells play an important role in several vascular diseases, and molecular analysis of these cells could provide valuable information on underlying tissue status. However, no clinically established procedure for harvesting endothelial cells exists. A micro-3D-printed device adapted for endovascular techniques to harvest endothelial cells for transcriptomic analysis is presented. In vivo evaluation in swine (n = 6) yielded tissue samples in 60 out of 65 cases, of which 80% show a substantial amount of tissue. The cytological evaluation indicates high selectivity towards endothelial cells, and RNA-sequencing shows gene expression signatures consistent with vascular tissue. It is found that there are no short-term safety risks compared to operation with a control wire of equal dimensions and acute complications are not detected. If translated to clinical use, the device could enable increased understanding of early-stage endothelial cell-mediated disease progression and earlier diagnosis of diseases such as atherosclerosis.

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. 

Endothelial cells lining blood vessels have phenotypic variations that indicate the health/disease status for a variety of conditions, including atherosclerosis and hypertension. Current sampling strategies lead to a high variation in the sampled amount, and we are not aware of sampling tools specifically targeting endothelial cells. Here, we present a new type of endovascular catheter for sampling of the blood vessel wall. The catheter is a 380 mu m nitinol tube over which 3D printed graters are threaded. The catheter is designed to be non-invasive during the axial motion and to interact with the blood vessel wall when rotated. Initial results indicate successful in-vivo sampling - with minimal blood contamination - of the wall of blood vessels less than 0.5 mm in diameter.

Micro-endomyocardial biopsy (micro-EMB) is a novel catheter-based biopsy technique, aiming to increase flexibility and safety compared to conventional EMB. The technique was developed and evaluated in healthy swine. Therefore, the ability to detect disease related tissue changes could not be evaluated. The aim of the present pilot study was to investigate the ability to detect disease related gene expression changes using micro-EMB. Myocardial infarction was induced in three swine by coronary artery balloon occlusion. Micro-EMB samples (n = 164) were collected before, during, and after occlusion. RNA-sequencing was performed on 85 samples, and 53 of these were selected for bioinformatic analysis. A large number of responding genes was detected from the infarcted area (n = 1911). The early responding genes (n = 1268) were mostly related to apoptosis and inflammation. There were fewer responding genes two days after infarction (n = 6), which were related to extra-cellular matrix changes, and none after 14 days. In contrast to the infarcted area, samples harvested from a non-infarcted myocardial region showed considerably fewer regulated genes (n = 33). Deconvolution analysis, to estimate the proportion of different cell types, revealed a higher proportion of fibroblasts and a reduced proportion of cardiomyocytes two days after occlusion compared to baseline (p < 0.02 and p < 0.01, respectively. S5 File). In conclusion, this pilot study demonstrates the capabilities of micro-EMB to detect local gene expression responses at an early stage after ischemia, but not at later timepoints.

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.