Nanoporous metals for biodegradable implants: Initial bone mesenchymal stem cell adhesion and degradation behavior

Abstract

Nanostructured Fe-Mn and Fe-Mn-Zn metal scaffolds were generated through a well-controlled selective leaching process in order to fulfill the growing demand for adjustable degradation rates and improved cellular response of resorbable materials. Mouse bone marrow mesenchymal stem cells (D1 ORL UVA) were seeded onto eleven, carefully chosen nanoporous surfaces for 24 h in vitro. Using a combination of fluorescence microscopy, scanning electron microscopy (SEM), and an MTS assay, it was discovered that scaffolds with nanoscale roughened surfaces had increased cell attachment by up to 123% compared to polished smooth Fe-Mn surfaces. Significant cell spreading and construction of cell multilayers were also apparent after 24 h, suggesting better adhesion. Additionally, static electrochemical polarization experiments revealed an improvement of up to 26% in the actual rate of biodegradation for Fe-Mn surface-modified materials. However, any residual concentration of zinc after leaching was shown to slightly increase corrosion resistance. The results demonstrate that selectively leached, nanostructured Fe-Mn surfaces have the potential of being tailored to a diverse set of transient implant scenarios, while also effectively boosting overall biocompatibility, initial cell attachment, and degradation rate. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1747-1758, 2016.

In Vivo Evaluation of Biodegradability and Biocompatibility of Fe30Mn Alloy

“…Substantial variability in the thickness of the corrosion layer was noted around the implants, and resorption appeared slower than expected in comparison to previous in vitro study demonstrating a corrosion rate of 0.0905 mm/year for Fe30Mn immersed in phosphate-buffered saline. 16 It has been demonstrated that corrosion rates vary substantially depending on anatomical locations and species, and on local differences such as blood flow, protein content, pH and temperature. 3,4,6,7,13,21 The in vivo resorption rate of Fe30Mn was not determined in this study as the resorption of Fe30Mn wires was not apparent radiographically, and the residual core wire and corrosion layer could not be consistently differentiated on histological sections.…”

“…9,12,14 In this context, recent in vitro and in vivo studies investigated different compositions of iron-manganese alloys with intermediate degradation rate compared with pure iron and magnesium alloys, that may carry a greater potential for temporary internal fixation during fracture healing. 10,11,15,16 Iron-manganese alloy containing 35 wt% manganese 9 was found to have magnetic and mechanical properties close to 316L stainless steel (SS), 17 adequate ductility, and an in vitro corrosion rate three times higher than pure iron. 9,14,15 The purpose of this study was to evaluate the biodegradability and biocompatibility of an iron and manganese alloy containing 30 wt% manganese and 70 wt% iron (Fe30Mn) in bone in an in vivo rat model.…”

“…9,14,15 The purpose of this study was to evaluate the biodegradability and biocompatibility of an iron and manganese alloy containing 30 wt% manganese and 70 wt% iron (Fe30Mn) in bone in an in vivo rat model. Considering the results of three preliminary in vitro studies, 11,15,16 we hypothesized that the novel absorbable wire would demonstrate substantial resorption in vivo over a period of 6 months, and would not elicit any local or systemic adverse reaction.…”

Challenges and Opportunities for Integrating Dealloying Methods into Additive Manufacturing

“…Constructing an implant that will provide both adequate mechanical support upon implantation and degrade quickly enough to transfer the load to surrounding tissue is difficult, but one promising solution is to use metal scaffolds with significant porosity. Heidan and colleagues saw increased cell attachment on the nanoporous surfaces of a dealloyed Fe-Mn scaffold and measured an improved degradation rate due to the increased surface area for medium attack [ 55 ]. AM has already been demonstrated as an effective process for printing customized implants [ 56 ] and incorporating dealloying into the production process will enable the production of nanoporous and nanocomposite biomedical implants with the necessary material properties to improve performance and patient outcomes.…”

Development of an electrospun polycaprolactone/silk scaffold for potential vascular tissue engineering applications

“…14,15 Besides, the scaffold material should have biodegradable matched with tissue growth in vivo. 16,17 Furthermore, the scaffolds should provide robust mechanical properties to avert bursting and leaking by themselves during implantation, 18 as well as to withstand blood pressure after implantation. Although vascular scaffolds, such as expanded polytetrafluoroethylene (ePTFE) and Dacron, have been successfully used in clinical practice.…”