Evaluation of expansion and crossing profile characteristics of micro laser powder bed fusion-manufactured coronary stents in a rat model.

Micro-laser powder bed fusion (µ-LPBF) technology holds significant potential for fabricating coronary stents tailored to an individual's anatomy, potentially addressing the issue of in-stent restenosis (ISR). Despite several studies on µ-LPBF stents, no experimental work has investigated their implantability in a rat model. This pilot study fabricated two types of µ-LPBF stents from 316 L stainless steel (316 L SS) and cobalt-chromium (CoCr) and assessed their implantability in the rat abdominal aorta through post-mortem experiments and one in vivo implantation of a 316 L SS stent. Expansion behavior was evaluated in vitro through free expansion tests and within healthy and 70% stenosed artificial arteries. We demonstrated successful implantation of µ-LPBF stents in the rat aorta. Both stent types showed sufficient deliverability and could be advanced through the femoral artery to the abdominal aorta without fracturing. The stents maintained their integrity under external tissue compression, as evidenced by histological and µCT images. Greater expansion was observed in 316 L SS stents compared to CoCr stents in both in vitro and in vivo experiments. Non-uniform expansion was observed for both µ-LPBF stent types, with post-mortem and artificial arteries experiments showing an opposite pattern to the 'dog bone' phenomenon. These results demonstrate the feasibility of µ-LPBF stent fabrication and successful implantation in rats, highlighting the potential of µ-LPBF as a promising approach for producing personalized stents or stents with fully customized geometries.