Endovascular endothelial cell biopsy - a systematic review.

Background: Endovascular endothelial cell biopsy (ECBx) allows direct sampling of endothelial cells (ECs) and subsequent assessment of EC function in patients. Our systematic review aims to summarise the current literature describing protocols to obtain and analyse EC and obtain pooled estimates of success rate and EC numbers obtained with different techniques in different populations. Materials and methods: Studies were identified on Medline using the terms 'endothelial cell' AND 'biopsy' AND 'humans'. All primary research involving EC biopsy was included, while animal studies or non-primary research studies were excluded from the review. The data was integrated into a narrative review and the study was registered with PROSPERO (CRD42022278551). Results: Of all journal articles identified (n=784), 51 articles were included in this review. Most studies (n=46) used a J wire for EC sampling from blood vessels in the arm (superficial arm veins [n=30], brachial artery [n=3], radial artery [n=4]). The pooled success rate was 91±15%. The average yield was 1,058±893 cells per biopsy, with variability depending on procedural factors such as wire placement, depth and technique. No significant complications were reported. Several analytical techniques were used to evaluate the isolated ECs with the most common technique being immunofluorescence (n=36). Risk of bias assessment and statistical analysis not performed due to heterogeneity of data and variability in reporting. Conclusions: Endothelial cells can be obtained with a variety of techniques with a high success rate and minimal complications. This review highlights novel research opportunities provided by ECBx.