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

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.

Alumina applied in bone regeneration: Porous α-alumina and transition alumina

“…In vitro human osteoblast-like MG-63 cell culture, adhesion, and proliferation [50] Nanoporous α-alumina -Cell adhesion, viability, and osteogenic potential pre-osteoblastic MC3T3-E1 cell [51] Porous alumina Calcium phosphate and strontium ion - [52] α-alumina particle Hydroxyapatite/poly-εcaprolactone composite Dermal fibroblast normal human, neonatal (HDFn) cell culture and viability [53] Porous α-alumina Fluorapatite + TiO 2 composite - [54] Porous alumina Coated with platinum, titanium, and tantalum Cell behavior fibroblast and hematopoietic stem cell (HSC) [55] Nano alumina powder Hydroxyapatite Cell culture and plasma protein adsorption [56] Porous alumina Hydroxyapatite - [57] Nano γ-alumina Silk fibroin/chitosan composite In vitro biodegradation and biomineralization [58] stability in wet physiological environments [41,42]. These factors are important because the human body possesses a highly corrosive environment.…”