Swarming microrobotic platform enables aneurysm embolization with high fifilling ratio | Multidisciplinary

Researchers from the Chinese University of Hong Kong (CUHK) have developed a swarming microrobotic platform for aneurysm embolization, overcoming the limitation of incomplete aneurysm occlusion with current treatment options in cases of rapid blood flow.

Aneurysms are balloon-like bulges caused by weakening of the blood vessel wall. Their rupture can lead to life-threatening internal bleeding, with a high mortality rate of >40 percent. [Sci Adv 2023;doi:10.1126/sciadv.adf9278]

Embolization is a minimally invasive procedure to reduce bleeding risk by filling the aneurysm sac with embolic materials (eg, metallic coils, polymeric spheres, gelling solution). In cases of incomplete aneurysm occlusion, however, fragmentation and subsequent leakage of embolic materials may result in nontargeted occlusion of distal blood vessels.

“Therefore, an effective embolization strategy with better filling controllability, endovascular environment compatibility and clinical performance is urgently desired,” wrote the researchers. “The use of active microrobots as embolic agents has emerged as an inspiring embolization strategy, which can fill targeted aneurysms completely while avoiding unintended blockage of nontargeted blood vessels.”

The swarming microrobotic platform is a micro-sized sphere consisting of a pH-responsive, self-healing hydrogel matrix, magnetic nanoparticles and imaging dopants. Embolization using this novel platform consists of four stages:

Stage I: Placement of a catheter at the aneurysm neck through real-time imaging guidance;
Stage II: Microgel deployment and aggregation in the aneurysm sac directed by a magnetic field;
Stage III: Injection of an acidic buffer solution to activate on demand embolization by triggering the formation of inter- or intra-molecular hydrogen bonds;
Stage IV: Catheter removal.

The microgel’s self-adhesive property allows welding, thus preventing leakage and fragmentation of embolic materials. “The welded microgel exhibits excellent stability in physiological environment for at least half a year, with satisfactory bio- or haemo-compatibility,” pointed out the researchers.

“We demonstrated efficient and selective accumulation of microgel in the aneurysm sac [without unintended leakage], and a filling ratio of >95 percent can be achieved even under dynamic blood flow with a mean velocity of up to 20 cm/s,” they added.

Other potential applications of the swarming microrobotic platform include bleeding control in other organs, as well as noninvasive, efficient, safe and personalized treatment of various aneurysm-related diseases. Further preclinical and clinical studies will be conducted.

“This new embolization technology illustrates the value of collaborative research between medicine and engineering,” commented Professor Simon Yu of the Department of Imaging and Interventional Radiology, CUHK. “There is great potential for further development and application of magnetic and image-guided microrobots in endovascular interventional treatments.”

“Further research will be conducted to develop micro- and nano-robot swarms with better in vivo imaging and remote control,” added Professor Zhang Li of the Department of Mechanical and Automation Engineering, CUHK.