Electromagnetically enhanced coating of a sintered titanium grid with human SAOS-2 osteoblasts and extracellular matrix

In Vitro Production of Calcified Bone Matrix onto Wool Keratin Scaffolds via Osteogenic Factors and Electromagnetic Stimulus

Pulsed electromagnetic field (PEMF) has drawn attention as a potential tool to improve the ability of bone biomaterials to integrate into the surrounding tissue. We investigated the effects of PEMF (frequency, 75 Hz; magnetic induction amplitude, 2 mT; pulse duration, 1.3 ms) on human osteoblast-like cells (SAOS-2) seeded onto wool keratin scaffolds in terms of proliferation, differentiation, and production of the calcified bone extracellular matrix. The wool keratin scaffold offered a 3D porous architecture for cell guesting and nutrient diffusion, suggesting its possible use as a filler to repair bone defects. Here, the combined approach of applying a daily PEMF exposure with additional osteogenic factors stimulated the cells to increase both the deposition of bone-related proteins and calcified matrix onto the wool keratin scaffolds. Also, the presence of SAOS-2 cells, or PEMF, or osteogenic factors did not influence the compression behavior or the resilience of keratin scaffolds in wet conditions. Besides, ageing tests revealed that wool keratin scaffolds were very stable and showed a lower degradation rate compared to commercial collagen sponges. It is for these reasons that this tissue engineering strategy, which improves the osteointegration properties of the wool keratin scaffold, may have a promising application for long term support of bone formation in vivo.

The Use of Pulsed Electromagnetic Fields to Promote Bone Responses to Biomaterials In Vitro and In Vivo

Implantable biomaterials are extensively used to promote bone regeneration or support endosseous prosthesis in orthopedics and dentistry. Their use, however, would benefit from additional strategies to improve bone responses. Pulsed Electromagnetic Fields (PEMFs) have long been known to act on osteoblasts and bone, affecting their metabolism, in spite of our poor understanding of the underlying mechanisms. Hence, we have the hypothesis that PEMFs may also ameliorate cell responses to biomaterials, improving their growth, differentiation, and the expression of a mature phenotype and therefore increasing the tissue integration of the implanted devices and their clinical success. A broad range of settings used for PEMFs stimulation still represents a hurdle to better define treatment protocols and extensive research is needed to overcome this issue. The present review includes studies that investigated the effects of PEMFs on the response of bone cells to different classes of biomaterials and the reports that focused on in vivo investigations of biomaterials implanted in bone.

Effects of Build Orientation on Surface Morphology and Bone Cell Activity of Additively Manufactured Ti6Al4V Specimens

Additive manufacturing of lightweight or functional structures by selective laser beam (SLM) or electron beam melting (EBM) is widespread, especially in the field of medical applications. SLM and EBM processes were applied to prepare Ti6Al4V test specimens with different surface orientations (0°, 45° and 90°). Roughness measurements of the surfaces were conducted and cell behavior on these surfaces was analyzed. Hence, human osteoblasts were seeded on test specimens to determine cell viability (metabolic activity, live-dead staining) and gene expression of collagen type 1 (Col1A1), matrix metalloprotease (MMP) 1 and its natural inhibitor, TIMP1, after 3 and 7 days. The surface orientation of specimens during the manufacturing process significantly influenced the roughness. Surface roughness showed significant impact on cellular viability, whereas differences between the time points day 3 and 7 were not found. Collagen type 1 mRNA synthesis rates in human osteoblasts were enhanced with increasing roughness. Both manufacturing techniques further influenced the induction of bone formation process in the cell culture. Moreover, the relationship between osteoblastic collagen type 1 mRNA synthesis rates and specimen orientation during the building process could be characterized by functional formulas. These findings are useful in the designing of biomedical applications and medical devices.

A case of successful interaction between cells derived from human ovarian follicular liquid and gelatin cryogel for biotech and medical applications

Significant research efforts have been undertaken in the last decade to develop specific cell-based therapies and, in particular, adult multipotent mesenchymal stem cells (MSCs) hold great promise toward such regenerative strategies. Bio-materials have been widely used in reconstructive bone surgery to heal critical-size bone defects due to trauma, tumor resection, and tissue degeneration. In particular, gelatin cryogel scaffolds are promising new biomaterials owing to their biocompatibility. There is an increasing demand for MSC-based regenerative approaches in the musculoskeletal system. Combining stem cells with biomaterial scaffolds provides a promising strategy for tissue engineering. Our previous studies showed the possibility to obtain MSCs from the human ovarian follicular liquid (FL) that is usually wasted during in vitro fertilization (IVF). In this study, we tested the ability of these FL cells to grow on gelatin cryogel in comparison with MSCs derived from human bone marrow. Samples and controls were analyzed with confocal and scanning electron microscopes. Results demonstrated that FL cells could grow on the biomaterial not only on the top but also in the layers below till 60 µm of deepness. Data suggested that the observed cells were mesenchymal since positive for vimentin and CD-44, typical MSC markers. Successful growth of putative MSCs derived from follicular liquid on 3D gelatin cryogel opens potential developments in biotech and medical applications.

Ultrasound stimulus to enhance the bone regeneration capability of gelatin cryogels

In the present study, gelatin-based cryogels have been seeded with human SAOS-2 osteoblasts. In order to overcome the drawbacks associated with in vitro culture systems, such as limited diffusion and inhomogeneous cell-matrix distribution, this work describes the application of ultrasounds (average power, 149 mW; frequency, 1.5 MHz) to physically enhance the cell culture in vitro. The results indicate that the physical stimulation of cell-seeded gelatin-based cryogels upregulates the bone matrix production.

Biological effects of ultrasound stimulus on cells derived from human ovarian follicular liquid

Low-Intensity Pulsed Ultrasound Stimulus (LIPUS) accelerates the bone fracture healing in animal models and in clinical studies. In this work, according to the literature, we have chosen the mesenchymal stem cells (MSCs) as precursors of bony tissue, in particular the MSCs derived from the human ovarian follicular liquid (FL), and we have investigated the effects of ultrasounds on their proliferation. We tested two different durations of ultrasound stimulus (2 and 5 min) and compared these data to the control without ultrasound treatment. To quantify the proliferation of these putative MSCs, we used the BrdU incorporation assay: in comparison with the control, the results showed that 5 min of ultrasound stimulus significantly increased the percentage number of cells in intensive proliferative activity; on the other hand, there was no significant difference using 2 min of stimulation, hypothetically because the transmitted energy was not sufficient to stimulate the cells and to consequently enhance their proliferation. In conclusion, the effects of LIPUS on putative MSCs derived from ovarian follicular liquid show potential developments in biotech or medical applications.

Scaffold/Extracellular matrix hybrid constructs for bone-tissue engineering

The limited natural ability of the body to fully repair large bone defects often necessitates the implantation of a replacement material to promote healing. While the current clinical strategies to address such bone defects generally carry associated limitations, bone-tissue engineering approaches seek to minimize any adverse effects and facilitate complete regeneration of the lost tissue. Of particular interest are hybrid constructs that incorporate multiple components found within the native bone matrix to enhance the osteogenicity of biocompatible materials, which might otherwise be non-osteogenic. This Progress Report will focus on such hybrid constructs that incorporate multiple components from native bone matrix for bone-tissue engineering and will highlight the synthesis and characterization of the hybrid constructs, cellular attachment and proliferation within the constructs, in vitro osteogenicity of the constructs, and the biological response to in vivo implantation of the constructs at ectopic and orthotopic sites.