Migration, Matrix Production and Lamellar Bone Formation of Human Osteoblast-Like Cells in Porous Titanium Implants

Abstract

The goal of this study was to characterize growth, mineralization and bone formation of osteoblast-like cells in titanium pore channels of defined diameter. Titanium implants with continuous drill channels of diameters of 300, 400, 500, 600 and 1,000 µm were inserted into human osteoblast-like cell cultures. The ingrowth of the cells into the drill channels was investigated by transmitted-light microscopy and scanning electron microscopy. Immunofluorescence and histological analysis of 15-channel sections of each diameter were used to investigate the growth behavior and the matrix protein patterns. Mineralization was evidenced by Alizarin red staining and high-resolution microradiography. The ingrowth of human osteoblast-like cells in the drill channels occurred in a sequence of four characteristic stages. In stage 1, osteoblast precursor cells adhered to the wall of the channel and migrated three-dimensionally into the channel by forming foot-like protoplasmic processes. For all 15 sample drill channels that were investigated, the cell ingrowth over 20 days amounted on average to 793 µm (± 179) into 600-µm-diameter channels, where they migrated significantly faster than in all the other channels. In stage 2, approximately on day 5–7, the osteoblast-like cells began to anchor on the substrate wall by matrix proteins and to build up a dense network of matrix proteins in the drill channel. The mineralization of the extracellular matrix, while depending on cell stimulation, was initiated in stage 3, on average after 4 weeks. In drill channels of a diameter of 1,000 µm the cell growth was incomplete and no mineralization was found by radiological assessment. Starting in week 6, in the drill channels of diameters ranging from 300 to 600 µm, the network of extracellular matrix proteins and osteoblast-like cells began to form an osteon-like structure. Neither the highly developed migration behavior of osteoblastic cells nor the reorganization from a fiber-like matrix to a lamellar structure have so far been described for cell cultures.

Paired evaluation of calvarial reconstruction with prototyped titanium implants with and without ceramic coating

“…Several studies have demonstrated these properties either with osteoblast cultures 5,20 or with in vivo experiments 3,4,11 .…”

Surface Modification of Titanium Plate with Anodic Oxidation and Its Application in Bone Growth

“…Therefore, in order to obtain osseointegration, the surgical cavity must be prepared with the least injury possible [15,50,58]. In order to cause minimal damage to the surrounding bone tissues, in the present study, bone perforation was performed using burs of increasingly larger diameters, and under constant saline irrigation.…”

Porous Titanium by Powder Metallurgy for Biomedical Application: Characterization, Cell Citotoxity and in vivo Tests of Osseointegration

“…Furthermore, it may influence the early formation of fibrin clots, platelet activation and the production of growth factors related to bone tissue, thereby interfering directly in cell recruitment, adhesion, proliferation and differentiation [24]. Evidence suggests that the mechanism by which the topography of Ti influences the differentiation of osteoblasts is related to the pathways of phospholipase A2, protein kinase A and integrin.…”

“…Numerous studies have shown that implant porosity promotes positive results in bone neoformation in vivo [4,5,[8][9][10]22,23], since it increases the contact area between the biomaterials and bone tissue [4,22], resulting in improved implant stability over time, as well as accelerating the process of osseointegration [24]. Concomitantly, various studies have shown that the implant surface can alter the metabolism and phenotypic expression of osteoblastic cells [22,23,25].…”

“…Osteoblasts in culture were capable of covering distances of 600m in diameter to populate a channel in a Ti sample, forming cell bridges [24]. In channels 300µm in diameter, a single cell was capable of creating extensions side to side by filopodia.…”