Characterisation of porous knitted titanium for replacement of intervertebral disc nucleus pulposus

Abstract

Effective restoration of human intervertebral disc degeneration is challenged by numerous limitations of the currently available spinal fusion and arthroplasty treatment strategies. Consequently, use of artificial biomaterial implant is gaining attention as a potential therapeutic strategy. Our study is aimed at investigating and characterizing a novel knitted titanium (Ti6Al4V) implant for the replacement of nucleus pulposus to treat early stages of chronic intervertebral disc degeneration. Specific knitted geometry of the scaffold with a porosity of 67.67 ± 0.824% was used to overcome tissue integration failures. Furthermore, to improve the wear resistance without impairing original mechanical strength, electro-polishing step was employed. Electro-polishing treatment changed a surface roughness from 15.22 ± 3.28 to 4.35 ± 0.87 µm without affecting its wettability which remained at 81.03 ± 8.5°. Subsequently, cellular responses of human mesenchymal stem cells (SCP1 cell line) and human primary chondrocytes were investigated which showed positive responses in terms of adherence and viability. Surface wettability was further enhanced to super hydrophilic nature by oxygen plasma treatment, which eventually caused substantial increase in the proliferation of SCP1 cells and primary chondrocytes. Our study implies that owing to scaffolds physicochemical and biocompatible properties, it could improve the clinical performance of nucleus pulposus replacement.

The Influence of Selective Laser Melting (SLM) Process Parameters on In-Vitro Cell Response

“…The topography changes of titanium surfaces were not observed under high magnifications above ×30,000 on untreated discs fabricated with different laser parameters. Tendulkar et al [ 58 ] reported intervertebral disc made from titanium wire with Ra around 15 µm and contact angle almost 90° which remained almost unchanged after electro-polishing, while Ra parameter decreased around 3 times. In our study the 4–6-fold decrease in the surface energy of the titanium discs with the simultaneous lack of improvement of parameter Ra resulted from thermal treatments in 600 °C for 1 h. Furthermore annealing changed the contact angle to more hydrophilic values equal 90° and 72° after treatment in vacuum and oxygen atmosphere, respectively.…”

Usefulness of Mesenchymal Cell Lines for Bone and Cartilage Regeneration Research

“…Nowadays, a high number of MSC lines that display specific characteristics and differentiation capabilities have been generated and are valuable tools as part of models of disease and tissue repairing strategies. Different MSC lines have been employed for testing [17,[20][21][22][23][24][25] or producing [26,27] engineered scaffolds for skeletal applications, and for both investigating the MSC differentiation process [28][29][30][31][32][33][34] and finding new ways to improve it [35][36][37][38][39]. Additionally, these cell lines have also been used for analyzing functional makers [19,40] or even for exploring their roles in different diseases, such as osteoarthritis [41,42].…”

Exogenous Delivery of Link N mRNA into Chondrocytes and MSCs—The Potential Role in Increasing Anabolic Response

“…Biocompatibility is a fundamental prerequisite for any biomaterial to be used in tissue engineering. Thus, a knitted titanium scaffold, which showed in our previous studies a high biocompatibility, was used as an example for the 3D cultivation of cells for potential application in IVD treatment [23]. SCP1 cells and primary human chondrocytes were seeded on these biocompatible knitted titanium scaffolds and the transfectability of these cells was analyzed using lipoplexes-containing Lipofectamine 2000 and 1 µg eGFP mRNA.…”

“…Consequently, in this study, we analyzed a combined approach of synthetic Link N mRNA delivery together with knitted titanium scaffold as a promising strategy for improving and supporting the reparative processes for the treatment of joint tissues. Previously, our group demonstrated that knitted titanium scaffold, which was aimed for IVD nucleus pulposus replacement, supports cell attachment, growth of human primary chondrocytes as well as SCP1 cells in vitro [23]. Importantly, the 3D architecture of the porous knitted titanium scaffold is expected to play a role in maintaining space, which is necessary for tissue integration upon implantation in vivo.…”

“…Cell were expanded in culture medium (α-MEM (minimal essential medium; GIBCO, Darmstadt, Germany)), 10% FCS (GIBCO, Darmstadt, Germany), and 1% penicillin/streptomycin (Merck, Darmstadt, Germany) 10,000 units/mL penicillin and 10 mg/mL streptomycin) in a cell incubator at 37 °C and 5% CO 2 [37]. The isolation of primary human chondrocytes was performed as previously described [23]. Briefly, chondrocytes were isolated from donated femoral condyle tissues (donor number N = 23; sex m/f = 10/13, respectively; age = 74.86 ± 8.15 years) (BG Klinik, Tübingen) by collagenase (1500 U/mL, GIBCO, Darmstadt, Germany) digestion, and expanded in culture medium (DMEM/Ham’s F12 (1:1), 10% FCS, 1% penicillin/streptomycin, 50 µM L-ascorbate-2-phosphate (Merck, Darmstadt, Germany) at 37 °C and 5% CO 2 .Different donor samples (N ≥ 3)with passage number 2 were used for each experiment.…”