SIR 2024
Embolization
Julien Namur, PhD
Director of study
Archimmed, France
Financial relationships: Full list of relationships is listed on the CME information page.
Jean-Pierre Saint-Maurice, MD
Neuroradiology
AP-HP hôpital Lariboisière, France
Disclosure information not submitted.
Saida Homayra Ghegediban, MS
Research engineer
Archimmed, France
Disclosure information not submitted.
Laurence Moine, PhD
CNRS research director
UMR CNRS 8612, Institut Galien Paris-Saclay, France
Disclosure information not submitted.
To develop resorbable embolization microspheres (REM) with adjustable time of resorption and check their performances as a transient embolic agent.
Materials and Methods: REM were made from polyethylene glycol, methacrylic monomer and hydrolytic resorbable crosslinker by suspension polymerization. Three crosslinkers (CL1, CL2 and CL3) containing different ratios of lactide, glycolide and caprolactone were prepared by ring-opening polymerization to get 3 degradation times. REM were sieved into 5 size ranges from 40-80 µm to 700-900 µm. In vitro, size distribution, suspension time, deliverability in catheters, and degradation time (PBS, 37°C) of sterile REM were checked. In vivo, arterial distribution and recanalization time were analyzed for different sizes of CL1-REM. Embolization of branches of the renal artery was performed in 4 sheep with REM or non-degradable Embosphere® (ES). Three animals were sacrificed at the end of the procedure. One animal underwent angiography to check for vessel patency at 24 h and 72 h, then sacrificed. Histopathology analysis was performed at termination point for all animals
Results:
REM were within the targeted size for > 90 % of microspheres. Suspension was optimal in 60/40 saline/contrast mixture and lasted ≥ 5 min. Injection of REM below 500 µm was graded smooth in microcatheters with an inner diameter (ID) down to 0.019". REM 500-700 and 700-900 were injectable in catheters with ID ≥ 0.022'' and ≥ 0.041'' respectively. Complete degradation time of CL1-REM was 24 h (15 % of mass loss at 6 h), regardless of diameter. CL2-REM and CL3-REM were completely degraded respectively in 3 days (18 % at D1) or in 14 days (12 % at D3, 30 % at D7). The arterial distribution in kidney was not significantly different between CL1-REM 300-500 and ES 300-500 (p=0.297) while CL1-REM 700-900 located more proximally (p< 0.001). Hepatic and renal vessels embolized with CL1-REM 40-80 and 300-500 showed complete recanalization at 24 h, in accordance with the in vitro degradation time. No trace of embolic material was found in histology of liver and kidney. Ischemic lesions were evidenced in the two organs.
Conclusion:
Resorbable embolization microspheres calibrated within the target size ranges were obtained. Degradation of REM was tunable between 24 h to 2 weeks by adjusting the crosslinker composition. Vascular distribution of CL1-REM was not significantly different from Embosphere® of similar size. REM degradation and effective recanalization of occluded vessels were confirmed in vivo. A 24 h degradation time was sufficient to induce ischemic damage in the sheep model.