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Scaffolds are important physical substrates for cell attachment, proliferation and differentiation. Multiple factors could influence the optimal design of scaffolds for a specific tissue, such as the geometry, the materials used to modulate cell proliferation and differentiation, its biodegradability and biocompatibility. The optimal design of a scaffold for a specific tissue strongly depends on both materials and manufacturing processes. Previous studies of human adipose-derived stem cells (hADSCs) seeded on poly(e-caprolactone) (PCL)/graphene scaffolds have proved that the addition of small concentrations of graphene to PCL scaffolds improves cell proliferation. Based on such results, this paper further investigates, for the first time, both in vitro and in vivo characteristics of 3D printed PCL/graphene scaffolds. Scaffolds were evaluated from morphological, biological and short term immune response points of view. Results show that the produced scaffolds induce an acceptable level of immune response, suggesting high potential for in vivo applications. Finally, the scaffolds were used to treat a rat calvaria critical size defect with and without applying micro electrical stimulation (10 μA). Quantification of connective and new bone tissue formation and the levels of ALP, RANK, RANKL, OPG were considered. Results show that the use of scaffolds containing graphene and electrical stimulation seems to increase cell migration and cell influx, leading to new tissue formation, well-organized tissue deposition and bone remodelling.

Background Augmenting repairs with extracellular matrix–based scaffolds is a common option for rotator cuff tears. In this study, a new collagen scaffold was assessed for its efficacy in augmenting rotator cuff repair. Methods The collagen scaffold was assessed in vitro for cytocompatibility and retention of tenocyte phenotype using alamarBlue assays, fluorescent imaging, and real-time polymerase chain reaction. Immunogenicity was assessed in vitro by the activation of human monocytes. In vivo, by use of a modified rat rotator cuff defect model, supraspinatus tendon repairs were carried out in 40 animals. Overlay augmentation with the collagen scaffold was compared with unaugmented repairs. At 6 and 12 weeks postoperatively, the repairs were tested biomechanically to evaluate repair strength, as well as histologically to assess quality of healing. Results The collagen scaffold supported human tendon-derived cell growth in vitro, with cells demonstrating proliferation and appearing morphologically tenocytic over the experimental period. No immunogenic responses were provoked compared with suture material control. In vivo, augmentation with the scaffold improved the histologic scores at 12 weeks (8.4 of 15 vs 6.4 of 15, P = .032). However, no significant difference was detected with mechanical testing. Conclusion The new collagen scaffold was supportive of cell growth in vitro and generated a minimal acute inflammatory response. In vivo, we observed an improvement in the histologic appearance of the repair at 12 weeks. However, a meaningful increase in biomechanical strength was not achieved. Further modification and improvement of the scaffold are required prior to consideration for clinical use.

Cell-cell communication plays a crucial role in bone development and maintenance, in health and disease. Our knowledge of the signalling pathways that regulate the communication of osteoblasts, osteoclasts and osteocytes is improving with time, giving us a better understanding of the regulation of the bone remodelling process. Bone cell communication has wider significance than the local tissue environment, however, with bone derived factors playing a role in whole-body homeostasis, including energy metabolism and kidney function. Similarly, there are a range of systemic conditions which affect the maintenance of bone mass. Understanding these complex interactions, the autocrine, paracrine and endocrine signalling involved in the regulation of bone health is paramount to a better understanding of bone disease, and ultimately developing targets for pharmaceutical intervention.

Juvenile Paget’s disease (JPD) is a rare recessively-inherited bone dysplasia. The great majority of cases described to date have had homozygous mutations in TNFRSF11B, the gene encoding osteoprotegerin. We describe a boy who presented with recurrent clavicular fractures following minor trauma (8 fractures from age 2 to 11). He was of normal height and despite mild lateral bowing of the thighs and anterior bowing of the shins he remained physically active. Abnormal modelling was noted in ribs and humeri on clavicular radiographs, and a skeletal survey at the age of 7 showed generalised diaphyseal expansion of the long bones with thickening of the periosteal and endosteal surfaces of the cortices. On biochemical evaluation, serum alkaline phosphatase was noted to be persistently elevated. The diagnosis of JPD was confirmed by the finding of compound heterozygous mutations in TNFRSF11B: a maternally-inherited A > G missense mutation at position 1 of the first amino acid codon (previously reported) and a paternally-inherited splice acceptor site mutation in intron 3 at a highly conserved position (not previously reported). Bioinformatics analysis suggested both mutations were disease-causing. Compound heterozygote mutations in TNFRSF11B causing JPD have been previously reported only once – in a boy who also had a relatively mild skeletal phenotype. The milder features may lead to delay in diagnosis and diagnostic confusion with other entities, but the extraskeletal features of JPD may nonetheless develop.

Most patients with juvenile Paget's disease (JPD) are homozygous for mutations in the gene TNFRSF11B that result in deficiency of osteoprotegerin (OPG) - a key regulator of bone turnover. So far, about 10 different OPG mutations have been described. The current study presents two novel OPG mutations in JPD patients. Patient 1 was diagnosed at the age of 9months when he presented with inability to sit up, slow growth, marked bone pain and very high levels of serum alkaline phosphatase. Patient 2 presented a milder phenotype. He was initially diagnosed with osteogenesis imperfecta, and although he had numerous fractures and bone deformity, he was still independently mobile at the age of 19years, when a diagnosis of JPD was confirmed. Sequence analysis of DNA samples from the patients determined two novel homozygous mutations in TNFSRF11B. Patient 1 (severe phenotype) had a large (245-251kbp) homozygous deletion beginning in intron 1 that resulted in loss of 4 of the 5 exons of TNFSRF11B, including the whole ligand-binding domain. Patient 2 had a homozygous missense mutation resulting in a Thr>Pro change in exon 2 of TNFSRF11B that is predicted to disrupt the OPG ligand-binding domain. Taken in conjunction with other published cases, these results are consistent with the hypothesis that the most severe phenotypes in JPD are seen in patients with major gene deletions or mutations affecting cysteine residues in the ligand-binding domain.

Tissue engineered scaffolds are an integral part of future regenerative efforts, whether as carriers for stem cells and growth factors, or as acellular supports on their own. These scaffolds will be inserted at the site of injury, aim to provide temporary mechanical support and promote appropriate cell attachment and growth. Millions of dollars are spent on the development of biomaterial scaffolds, with many put into animal studies and clinical use without proper evaluation, often leading to unfavourable outcomes and associated patient morbidity.We exposed two novel scaffolds designed for use in tendon regeneration to a series of in vitro tests, the first a decellularised extracellular matrix (ECM), the second a silk-like material. SEM images were taken to evaluate scaffold nanostructure. Primary human dendritic cells were exposed to scaffolds, with FACS analysis of cell-surface activation markers determining scaffold immunogenicity. Growth of primary tenocytes was analysed using live-dead staining and alamarBlue® fluorescence, for cytocompatability. While, phenotypic retention was assessed through real-time PCR analysis of tenocytic genes.The decellularised ECM demonstrated low activation in the dendritic cell assay, suggesting low immunogenicity. The cytocompatability assays and real-time PCR analyses suggested that the material was indeed suitable for cell growth and differentiation. However, during the third biological repeat, no cells grew on the material, nor did they on the fourth and fifth repeat. In retrospect it appears that following the second repeat a new batch was tested, with very different properties to the first, which accounted for the reduced cytocompatability.The silk-like material produced some of the most repeatable and promising results with the cytocompatability and real-time PCR analyses, while the SEM demonstrated intertwined fibres suitable for cell alignment. However, the immunogenicity assay demonstrated that this material invoked high activation of the primary human dendritic cells, suggesting the material would be unsuitable for in vivo implantation.These studies have highlighted that without stringent testing in vitro, great time and expense would have been spent taking these materials forward for animal studies and potentially clinical studies, when clearly they are not suitable for these in their current incarnation.