The Novel X-Ray Visible Zein-Based Non-adhesive Precipitating Liquid Embolic HEIE1_2017: An Exploratory Study.

PURPOSE: To investigate the novel zein-based non-adhesive precipitating liquid embolic HEIE1_2017. MATERIALS AND METHODS: Zein-based liquid embolics are an own class of embolization material. In this study, HEIE1_2017, a novel zein-based liquid embolic, was investigated. Visibility was assessed in vitro in CT and MRI phantoms, embolization characteristics were assessed in vivo in the kidneys of 12 pigs. Components of HEIE1_2017 were zein as occlusion material, ethanol as solvent, and iodized oil as radiopaque material. HEIE1_2017 was used in pure (HEI-PURE) and manually modified (HEI-MOD) form and compared with 6% ethylene vinyl alcohol copolymer (EVOH). Different radiological methods (CT, MRI, DSA, cone-beam CT, and micro-CT) and histopathologic analyses were applied to compare visibility and vascular occlusion patterns. RESULTS: In CT phantoms, all embolics were definitely visible as hyperdense materials. In MRI phantoms, signal-to-noise ratio was highest for HEI-PURE, followed by HEI-MOD and EVOH. In all kidneys, embolization procedures were technically successful and without complications. In DSA, all embolics were definitely visible during and after embolization. Only EVOH caused substantial artifacts in cone-beam CT and CT. In micro-CT and histopathology, HEI-PURE showed a homogeneous occlusion from segmental arteries to glomerular capillaries. HEI-MOD demonstrated the deepest vascular penetration (up to the level of peritubular capillaries), but with an inhomogeneous distribution. For EVOH, there was inhomogeneous vascular occlusion from segmental arteries to glomerular capillaries. CONCLUSION: HEIE1_2017 is a promising novel zein-based liquid embolic. Further preclinical and clinical studies with higher case numbers and long-term follow-up are needed to further assess the value of this embolic material.

In vivo characterization of a new type of biodegradable starch microsphere for transarterial embolization.

Transarterial embolization is an established minimally invasive treatment for solid tumors. Unintended inflammation, foreign body reactions and ischemia-triggered neoangiogenesis are clinical drawbacks of permanent embolic materials. The aim of the current study was to characterize a new type of biodegradable starch microsphere with regard to angiographic and histopathological features such as patterns of acute arterial occlusion as well as induction of tissue necrosis, microsphere biodegradation, and inflammation and foreign body reactions during follow-up. Key characteristics of both biodegradable prototypes (L1 and L2; prototype groups) were as follows: microspheres are biodegradable by serum α-amylase, produced from chemically crosslinked potato starch to different extents, in a diameter range of ∼300-800 µm, differing in size distribution and featuring a microsphere deformation of ∼1%. In vivo transarterial embolization with L1 and L2, while applying clinical standard techniques, was performed and compared with clinically established permanent microspheres (Embosphere®500-700 and Embosphere®700-900; control groups). Twenty-four pig kidneys were embolized with the different embolic materials by following the study protocol, and there were no technical failures or complications. Parenchymal necrosis with interstitial calcification was observed in all kidneys independent of the type of embolic material used. Compared with the permanent embolic materials, biodegradable microspheres showed complete (L1) or partial (L2) biodegradation within one week after transarterial embolization, and induced a comparable (L1) or a lower (L2) degree of arterial wall necrosis and a lower degree of inflammation and foreign body reactions. In conclusion, the presented new type of biodegradable microsphere is promising, and could be further evaluated in terms of clinical translation.