For evaluation of orthopaedic biomaterials the closest hostile-like in vitro environments are desirable with relevant control of chemical, biological, mechanical etc. parameters. For faster screening and reduction of time and costs, combination of different critical key parameters in minimal tests is needed. New trends also favour minimisation of in vivo (2010/63/EC, towards replacement technology) and clinical tests (2001/20/EC, 2005/28/EC) for new products yet not compromising risks. Biomaterials manufacturers also are interested in shortening of the time-to-market keeping conformity to essential requirements and withstanding the simulated “worst case” conditions (2003/94/EC). Here we show the new approach of the creation of conditions closest to real life and applications, based on scientifically designed and optimised models, aiming on predictive outputs. With new device and designed protocols, several biomaterials for orthopaedic applications were analysed: titanium, biodegradable fibrous scaffolds and hydrogels. Creation of several favourable conditions for different tissues type formation took place on the surface of the porous titanium specimen. Such conditions could be designed for measurement of the cells proliferation and e.g. simultaneous bacterial adhesion with rather high precision. The method has been compared in independent laboratories for hydrogels with other measuring techniques and shown the benefits of the method especially in more precise control of biomechanical cues. It was observed that significant amount of data are containing in the recorded signals which underlines the importance of correct and holistic data post-processing. The protocols can be furthermore tailored to simulate different conditions, such as for specific positions in tibia, or humeral etc., and combined with patient-specific biomechanics (soft tissues) for customised implant design. The financial support from the Finnish Agency of Innovation (Tekes) is gratefully acknowledged.

Author has no competing financial or conflicting interests.

Bone tissue engineering is a promising strategy to treat the huge number of bone fractures caused by progressive population ageing and diseases i.e., osteoporosis. The bioactive and biomimetic materials design modulating cell behaviour can support healthy bone tissue regeneration. In this frame, type I collagen and hydroxyapatite (HA) have been often combined to produce biomimetic scaffolds. In addition, mesoporous bioactive glasses (MBGs) are known for their ability to promote the deposition of HA nanocrystals and their potential to incorporate and release therapeutic ions. Furthermore, the use of 3D printing technologies enables the effective design of scaffolds reproducing the natural bone architecture. This study aims to design biomimetic and bioactive 3D printed scaffolds that mimic healthy bone tissue natural features in terms of chemical composition, topography and biochemical cues. Optimised collagenous hybrid systems will be processed by means of extrusion 3D printing technologies to obtain high resolution bone-like structures. Protocols of human co-cultures of osteoblasts and osteoclasts will be developed and used to test the 3D scaffolds. Type I collagen has been combined with rod-like nano-HA and strontium containing MBGs (micro- and nano-sized particles) in order to obtain hybrid systems resembling the composition of native bone tissue. A comprehensive rheological study has been performed to investigate the potential use of the hybrid systems as biomaterial inks. Mesh-like structures have been obtained by means of extrusion-based technologies exploiting the freeform reversible embedding of suspended hydrogels (FRESH) approach. Different crosslinking methods have been tested to improve final constructs mechanical properties. Both crosslinked and non-crosslinked biomaterials were cultured with human osteoblasts and osteoclasts to assay the hybrid matrix biocompatibility as well as its influence on cell behaviour. Homogeneous hybrid systems have been successfully developed and characterised, proving their suitability as biomaterial inks for 3D printing technologies. Mesh-like structures have been extruded in a thermo-reversible gelatine slurry, exploiting the sol-gel transition of the systems under physiological conditions. Covalent bonds between collagen molecules have been promoted by genipin treatment, leading to a significant increase in matrix strength and stability. The collagen methacrylation and the further UV-crosslinking are under investigation as alternative promising method to reinforce the 3D structure during the printing process. Biological tests showed the potential of the developed systems especially for genipin treated samples, with a significant adhesion of primary cells. Collagenous hybrid systems proved their suitability for bioactive 3D printed structures design for bone tissue engineering. The multiple stimuli provided by the scaffold composition and structure will be investigated on both direct and indirect human osteoblasts and osteoclasts co-culture, according to the developed protocols

Protocols for processing of tissue from arthroplasty infections vary and might affect the recovery of bacteria. We compared homogenization, bead beating and enzymatic disruption for recovery of live bacteria from tissue samples. Suspensions of Staphylococcus aureus and Escherichia coli were prepared as controls. Three samples were taken from each and the first was bead beaten, the second homogenized, and Proteinase K was added for 10 and 30 minutes to the third sample before culturing. In addition, artificially inoculated pork tissue and known infected human tissue samples were processed by either homogenization or bead beating prior to cultures and results were compared. Number of cycles of bead beating and homogenization and duration of Proteinase K treatment had significant effects. Bead beating for 2 and 4 cycles reduced the yield of S.aureus to 52% and 20% of control, and E.coli to 33% and 8%. Homogenization for 2 and 4 cycles reduced S.aureus to 86% and 65% of control, and E.coli to 90% and 87%. Proteinase K for 10 minutes and 30 minutes reduced the yield of S.aureus to 75% and 33% of control, and E.coli to 91% and 49% respectively. Inoculated Pork tissue showed a reduction in S.aureus recovery of 90% for bead beating compared to homogenization, and 80% in the case of E.coli. Bead beating of infected human tissue samples reduced the yield by 58% compared to homogenization. Bead-beating is a common recommended method of processing tissue from arthroplasty cases. However, even though it produces a homogeneous sample, it does so at the cost of significant loss of viable bacteria. Homogenization and 10 minutes of Proteinase K incubation are almost equivalent, but the homogenizer is preferred being more controllable and cheaper. This should help to define guidelines for diagnosing infections using tissue samples