Cell–Material Interactions in Direct Contact Culture of Endothelial Cells on Biodegradable Iron-Based Stents Fabricated by Laser Powder Bed Fusion and Impact of Ion Release

Abstract

Additive manufacturing is a promising technology for the fabrication of customized implants with complex geometry. The objective of this study was to investigate the initial cell−material interaction of degradable Fe-30Mn-1C-0.02S stent structures in comparison to conventional 316L as a reference, both processed by laser powder bed fusion. FeMn-based alloys have comparable mechanical properties with clinically applied AISI 316L for a corrosion-resistant stent material. Different corrosion stages of the as-built Fe-30Mn-1C-0.02S stent surfaces were simulated by pre-conditioning in DMEM under cell culture conditions for 2 h, 7 days, and 28 days. Human umbilical vein endothelial cells (HUVECs) were directly seeded onto the pre-conditioned samples, and cell viability, adherence, and morphology were analyzed. These studies were accompanied by measurements of iron and manganese ion release and Auger electron spectroscopy to evaluate the influence of corrosion products and degradation on the cells. In the initial phase (2 h of preconditioning), HUVECs were able to attach but the cell number decreased over the cultivation period of 14 days and the CD31 staining pattern of intercellular contacts was disordered. At later time points of corrosion (7 and 28 days of pre-conditioning), CD31 staining was distinctly located at the intercellular contacts, and the cell density increased after seeding and was stable for up to 14 days. Formation of a complex degradation layer, which had a composition and thickness dependent on the pre-conditioning time, led to a reduced ion release and finally showed a positive effect on cell survival. Concluding, our data suggest the suitability of Fe-30Mn-1C-0.02S for in vivo applications.

FeMn with Phases of a Degradable Ag Alloy for Residue-Free and Adapted Bioresorbability

“…Since, during degradation, the released ions react and form corrosion products, the consideration of the biocompatibility of single elements is not sufficient, and corrosion products generated in the complex environment of the living organism must be considered. Investigations of biocompatibility, even in vivo, consider the good biocompatibility of FeMn [ 13 , 19 , 27 , 28 , 29 , 30 , 31 ].…”

“…The released ions can form phosphates which deposit on the surface. Compounds with Fe and Mn are present on the surface, but the degradation can proceed further since exchange with the electrolyte is still possible [ 16 , 19 , 30 , 44 ]. In contrast, Ca-Phosphate (P), originating from the electrolyte, creates an inhibiting layer deteriorating the degradation rate [ 13 , 19 , 28 , 30 , 36 , 45 ].…”

Preparation and Properties of Iron Nanoparticle-Based Macroporous Scaffolds for Biodegradable Implants

“…In this case, the formed hydroxide (OH − ) ions interact with the Fe 2+ ions released into the solution, resulting in iron (II) hydroxide followed by the conversion to iron (III) hydroxide in the presence of water and air oxygen. Numerous Materials 2022, 15, 4900 2 of 14 studies on cytotoxicity and biocompatibility testify to the possibility of the use of Fe-based materials as biodegradable implants [23][24][25][26].…”

The Study on Resolution Factors of LPBF Technology for Manufacturing Superelastic NiTi Endodontic Files

“…Due to the absence of research dedicated to the manufacturing of NiTi Self-Adjusting Files by LPBF technology, it is worth mentioning alternative micro-scale devices that received increased attention. Several works were dedicated to the investigation of the feasibility of printing stents for coronary vessels from Co-Cr [ 18 ], titanium [ 11 ], steel [ 19 ], and NiTi [ 20 ], which previously were made using laser cutting methods from hollow tubes [ 21 ]. It was demonstrated that resolution, surface finish, and layer bonding dramatically impact the stent performance [ 18 , 19 , 20 ].…”

“…Several works were dedicated to the investigation of the feasibility of printing stents for coronary vessels from Co-Cr [ 18 ], titanium [ 11 ], steel [ 19 ], and NiTi [ 20 ], which previously were made using laser cutting methods from hollow tubes [ 21 ]. It was demonstrated that resolution, surface finish, and layer bonding dramatically impact the stent performance [ 18 , 19 , 20 ]. In terms of Nickel-Titanium alloy, both superelasticity and shape memory effect are used for stents to decrease their volume during placement with subsequent extension under temperature influence and to impart a constant load on the walls of the vessel respectively.…”