Refractory Metal Coated Alumina Foams as Support Material for Stem Cell and Fibroblasts Cultivation.

Georg Hasemann,Heike Walles,Manja Krüger,Michael Scheffler,Ulf Betke

doi:10.3390/ma14112813

Abstract

Ceramics are widely used as implant materials; however, they are brittle and may emit particles when used in these applications. To overcome this disadvantage, alumina foams, which represent a 3D cellular structure comparable to that of human trabecular bone structures, were sputter coated with platinum, tantalum or titanium and modified with fibronectin or collagen type I, components of the extracellular matrix (ECM). To proof the cell material interaction, the unmodified and modified materials were cultured with (a) mesenchymal stem cells being a perfect indicator for biocompatibility and releasing important cytokines of the stem cell niche and (b) with fibroblasts characterized as mediators of inflammation and therefore an important cellular component of the foreign body reaction and inflammation after implantation. To optimize and compare the influence of metal surfaces on cellular behavior, planar glass substrates have been used. Identified biocompatible metal surface of platinum, titanium and tantalum were sputtered on ceramic foams modified with the above-mentioned ECM components to investigate cellular behavior in a 3D environment. The cellular alumina support was characterized with respect to its cellular/porous structure and niche accessibility and coating thickness of the refractory metals; the average cell size was 2.3 mm, the average size of the cell windows was 1.8 mm, and the total foam porosity was 91.4%. The Pt, Ti and Ta coatings were completely dense covering the entire alumina foam surface. The metals titanium and tantalum were colonized very well by the stem cells without a coating of ECM components, whereas the fibroblasts preferred components of the ECM on the alumina foam surface.

Highlights

Artificial prosthesis have been successfully implanted in the human body for many years and improve mobility, vitality and the quality of life of many patients
Open cellular alumina foams were sputter coated with titanium, platinum and tantalum to obtain dense, approximately 100 nm thick metallic layers, and they were cultivated with mesenchymal stem cells or fibroblasts; the alumina foams were modified with extracellular matrix (ECM)
Fibroblasts have a somewhat lower proliferation rate on the metal-coated and unmodified planar substrates, while the proliferation rate of the stem cells is somewhat lower at the ECM modified planar substrate, both over time

Summary

Introduction

Artificial prosthesis have been successfully implanted in the human body for many years and improve mobility, vitality and the quality of life of many patients. Materials available for total hip arthroplasty (THA) are for examples metal-on-highlycross-linked-polyethylene (MoP), ceramic-on-highly-cross-linked-polyethylene (CoP), metal-on-metal (MoM) and ceramic-on-ceramic (CoC) bearing couples They show good bio- and cell compatibility. Ti-Al-V [6,7], Ti-Mo-Zr-Al [8], Co-Cr-Mo [9,10] and porous Ta [11,12] implants possess very good bio- and cell compatibility [6] and are used in a large variety of implant applications, i.e., as hip, shoulder or dental implants Even these implant “workhorses” may promote inflammation and fibrous tissue reactions due to metal ion release. Special implant treatment such as Plasma Immersion Ion Implantation (PIII) may help to avoid fibrosis and a heavy foreign body reaction of the immune system on implants and implant materials [14]

Methods

Results

Conclusion