Ultrasound‐guided hepatic portal vein injection is not a reproducible technique for delivery of cell therapies to the liver in mice

Abstract

AbstractAimsOur aim was to determine if ultrasound‐guided HPV injection in mice would provide reproducible and reliable results, as is currently obtained via open laparotomy techniques, and offer a surgical refinement to emulate islet transplantation in humans.MethodsFluorescent‐polymer microparticles (20 μm) were injected (27G‐needle) into the HPV via open laparotomy (n = 4) or under ultrasound‐guidance (n = 4) using an MX550D‐transducer with a Vevo3100‐scanner (FUJIFILM VisualSonics, Inc.). Mice were culled 24‐h post injection; organs were frozen, step sectioned (10 μm‐slices) and 10 sections/mouse (50 μm‐spacing) were quantified for microparticles in the liver and other organs by fluorescent microscopy.ResultsMurine HPV injection, via open laparotomy‐route, resulted in widespread distribution of microparticles in the liver, lungs and spleen; ultrasound‐guided injection resulted in reduced microparticle delivery (p < 0.0001) and microparticle clustering in distinct areas of the liver at the site of needle penetration, with very few/no microparticles being seen in lung and spleen tissues, hypothesised to be due to flow into the body cavity: liver median (interquartile range) 4.15 (0.00–4.15) versus 0.00 (0.00–0.00) particle‐count mm−2, respectively.ConclusionsUltrasound‐guided injection results in microparticle clustering in the liver, with an overall reduction in microparticle number when compared to open laparotomy HPV injection, and high variability in microparticle‐counts detected between mice. Ultrasound‐guided injection is not currently a technique that can replace open laparotomy HPV of islet transplantation in mice.