To learn about the important connection between mechanical engineering and materials science, we turned to five experts with backgrounds in both fields for insight. Following are their perspectives on how the two disciplines informed their careers, which types of design challenges can be solved with materials information, and how ASM can improve that connection by leading with a “unity of disciplines” approach.

Using a physical vapor deposition process to manufacture medical device components reduces post-processing time and improves materials properties. This article addresses metallic sputter deposition technologies for Nitinol medical devices.

To learn what makes entrepreneurs in materials science tick, we turned to seven of ASM’s inventors and business founders for insight. Following are their perspectives on how they got started, lessons they learned along the way, what ASM can do to support innovators, and advice for the next generation of STEM entrepreneurs.

From its inception, this company’s mission was to improve upon current cardiovascular device limitations: their surface characteristics and its constituent materials. The first goal aimed to optimize material-host interaction at the molecular level and the second was to enhance the biomechanical properties of current materials used to build these devices.

Purpose: To establish a reproducible laboratory test to evaluate prospective vascular biomaterials with respect to their thromboinflammatory properties by examining fibrinogen, platelet, and monocyte binding. Endothelial migration onto these surfaces was used as an index of vascular healing.

Methods: To evaluate biomaterials for potential thrombogenicity and inflammation, binding assays of radiolabeled human fibrinogen, platelets, and monocytes were performed on standard pieces of vascular biomaterials, including metals and polymeric and ceramic-coated materials. Using an established in vitro endothelial cell migration model, the relative migration rate of cultured human aortic endothelial cells onto these vascular biomaterials was measured and compared. The fibrinogen, platelet, and monocyte binding results were combined along with the migration results to create an overall score of biocompatibility.

Results: A significant direct relation of platelet and monocyte binding to the amount of adsorbed fibrinogen was observed. In contrast, migration rates of cultured human aortic endothelial cells onto the same biomaterial surfaces were found to be inversely related the amount of bound fibrinogen. Among the materials tested, stainless steel received the highest score of biocompatibility, while turbostratic carbon scored the lowest.

Conclusions: Fibrinogen, platelet, and monocyte binding levels, as well as endothelial migration rates onto vascular material surfaces, provide a basis for evaluating thrombogenicity, inflammatory potential, and endothelialization in the laboratory prior to in vivo testing.

Background—

Stent luminal surface characteristics influence surface endothelialization. We hypothesize that luminal stent microgrooves created in the direction of coronary flow accelerate endothelial cell migration, resulting in lower levels of neointimal formation.

Methods and Results—

Surface coverage efficiency was evaluated in vitro by allowing human aortic endothelial cells (HAEC) to migrate onto microgrooved (G) or smooth (NG) surfaces. HAEC functionality was assessed by proliferation rate, apoptosis rate, nitric oxide production, and inflammatory markers TNF-α and VCAM-1 expression. Early endothelialization and restenosis studies were performed using the porcine coronary injury model. Stainless steel stents of identical design with (GS) and without (NGS) luminal microgrooves were used. The commercially available Multi-Link Vision (MLVS) stent of identical design was used as a control. The degree of GS and NGS surface endothelialization was compared at 3 days. Biocompatibility and tissue response outcomes were evaluated at 28 days. The in vitro study demonstrated that at 7 days the presence of surface microgrooves increased HAEC migration distance >2-fold. Cell proliferation rate and nitric oxide production were increased and apoptosis rate was decreased. There was no difference in inflammatory marker expression. At 3 days, coronary artery stent endothelialization was significantly increased in GS compared with NGS (81.3% versus 67.5%, P=0.0002). At 28 days, GS exhibited lower neointimal thickness compared with either NGS (21.1%, P=0.011) or MLVS (40.8%, P=0.014).

Conclusion—

Parallel microgrooves on coronary stent luminal surfaces promote endothelial cell migration and positively influence endothelial cell function, resulting in decreased neointimal formation in the porcine coronary injury model.