Myocardial micro-biopsy procedure for molecular characterization with increased precision and reduced trauma

Abstract

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 lowinput 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 RNAsequencing 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. Endomyocardial biopsy (EMB) is an established method for obtaining ventricular cardiac tissue for pathologic diagnosis and research, primarily for rejection monitoring after cardiac transplantation. EMB is also used in diagnosis of cardiomyopathies, infectious and neoplastic disease. Typically, the EMB device is inserted into the femoral vein or the right internal jugular vein and advanced to the right ventricle (RV), where samples are taken from the ventricular septum 1. The use of EMB is declining 2 , despite being the gold standard method for a number of diagnoses and being supported by cardiology organizations 1,3. This decline may be caused by an increasing use of non-invasive low-risk tests, low diagnostic yield, and complication risks. In fact, the diagnostic yield of EMB is low for many diseases 4. Moreover, the method has a significant complication risk, variably reported between 2.7% and 8.9% 1,2 .

Micro-biopsy for detection of gene expression changes in ischemic swine myocardium: A pilot study

“…(C) Fluoroscopy in posteroanterior view, showing sampling from apical (infarcted) and lateral (non-infarcted) regions (arrows). Panel A contains elements reproduced from Springer Nature [ 5 ] under Creative Commons License CC-BY 4.0.…”

“…The study was limited by relatively few replicates from each timepoint. It is known from our previous work that the inclusion rate of sequenced micro-EMB procedure is around 80%, due to small and extremely selective sampling, which has to be accounted for when preparing analyses [ 5 ]. The study was also limited by partly inaccurate sampling of infarcted and non-infarcted areas, which could potentially be addressed with supplemental endovascular guidance techniques.…”

“…All biopsies were obtained using a transfemoral approach, using the same technique as described previously [ 5 ]. In short, a 5 F or 7 F short sheath (Saint Jude Medical, Little Canada, MN, USA) was used to gain access to the femoral artery, and a standard 1.66 mm (5 F) or 1.33 mm (4 F) straight diagnostic catheter (Torcon NB advantage, Cook Medical, Bloomington, IN, USA) was used to access the LV.…”

“…We also devised a low-input RNA isolation protocol to enable RNA-sequencing (RNA-seq) analysis on small tissue samples. The technique was evaluated in swine, demonstrating reduced trauma and increased navigability compared to conventional methods, as well as good RNA-seq data quality [ 5 ]. However, the previous study was performed in healthy animals and did not assess the ability to detect gene expression changes related to disease.…”

“…To our knowledge, the novel micro-EMB technique is the first attempt to miniaturize a biopsy device specifically intended for low-input molecular analyses. Due to the dramatic reduction in tissue specimen size—over three orders of magnitude (from the conventional 10–40 mg to approximately 0.01 mg [ 5 , 10 ])—it remains unknown whether the tissue samples can be used to detect gene expression changes.…”