The Emerging Roles of Extracellular Vesicles in Osteosarcoma

Extracellular vesicles (EVs) are heterogeneous nanosized vesicles that are constitutively released by virtually all types of cells. They have been isolated in almost all body fluids. EVs cargo consists of various molecules (nucleic acids, proteins, lipids, and metabolites), that can be found on EVs surface and/or in their lumen. EVs structure confer stability and allow the transfer of their cargo to specific cell types over a distance. EVs play a critical role in intercellular communication in physiological and pathological settings. The broadening of knowledge on EVs improved our comprehension of cancer biology as far as tumor development, growth, metastasis, chemoresistance, and treatment are concerned. Increasing evidences suggest that EVs have a significant role in osteosarcoma (OS) development, progression, and metastatic process. The modulation of inflammatory communication pathways by EVs plays a critical role in OS and in other bone-related pathological conditions such as osteoarthritis and rheumatoid arthritis. In this review we describe the emerging data on the role of extracellular vesicles in osteosarcoma and discuss the effects and function of OS-derived EVs focusing on their future applicability in clinical practice

New advances in the study of bone tumors: A lesson from the 3D environment

Bone primary tumors, such as osteosarcoma, are highly aggressive pediatric tumors that in 30% of the cases develop lung metastasis and are characterized by poor prognosis. Bone is also the third most common metastatic site in patients with advanced cancer and once tumor cells become homed to the skeleton, the disease is usually considered incurable, and treatment is only palliative. Bone sarcoma and bone metastasis share the same tissue microenvironment and niches. 3D cultures represent a new promising approach for the study of interactions between tumor cells and other cellular or acellular components of the tumor microenvironment (i.e., fibroblasts, mesenchymal stem cells, bone ECM). Indeed, 3D models can mimic physiological interactions that are crucial to modulate response to soluble paracrine factors, tumor drug resistance and aggressiveness and, in all, these innovative models might be able of bypassing the use of animal-based preclinical cancer models. To date, both static and dynamic 3D cell culture models have been shown to be particularly suited for screening of anticancer agents and might provide accurate information, translating in vitro cell cultures into precision medicine. In this mini-review, we will summarize the current state-of-the-art in the field of bone tumors, both primary and metastatic, illustrating the different methods and techniques employed to realize 3D cell culture systems and new results achieved in a field that paves the way toward personalized medicine

Extracellular nanovesicles secreted by human osteosarcoma cells promote angiogenesis

Angiogenesis involves a number of different players among which extracellular nanovesicles (EVs) have recently been proposed as an efficient cargo of pro-angiogenic mediators. Angiogenesis plays a key role in osteosarcoma (OS) development and progression. Acidity is a hallmark of malignancy in a variety of cancers, including sarcomas, as a result of an increased energetic metabolism. The aim of this study was to investigate the role of EVs derived from osteosarcoma cells on angiogenesis and whether extracellular acidity, generated by tumor metabolism, could influence EVs activity. For this purpose, we purified and characterized EVs from OS cells maintained at either acidic or neutral pH. The ability of EVs to induce angiogenesis was assessed in vitro by endothelial cell tube formation and in vivo using chicken chorioallantoic membrane. Our findings demonstrated that EVs derived from osteosarcoma cells maintained either in acidic or neutral conditions induced angiogenesis. The results showed that miRNA and protein content of EVs cargo are correlated with pro-angiogenic activity and this activity is increased by the acidity of tumor microenvironment. This study provides evidence that EVs released by human osteosarcoma cells act as carriers of active angiogenic stimuli that are able to promote endothelial cell functions relevant to angiogenesis

Role of citrate in pathophysiology and medical management of bone diseases

Citrate is an intermediate in the \u201cTricarboxylic Acid Cycle\u201d and is used by all aerobic organisms to produce usable chemical energy. It is a derivative of citric acid, a weak organic acid which can be introduced with diet since it naturally exists in a variety of fruits and vegetables, and can be consumed as a dietary supplement. The close association between this compound and bone was pointed out for the first time by Dickens in 1941, who showed that approximately 90% of the citrate bulk of the human body resides in mineralised tissues. Since then, the number of published articles has increased exponentially, and considerable progress in understanding how citrate is involved in bone metabolism has been made. This review summarises current knowledge regarding the role of citrate in the pathophysiology and medical management of bone disorders

The microfluidic trainer: Design, fabrication and validation of a tool for testing and improving manual skills

Microfluidic principles have been widely applied for more than 30 years to solve biological and micro-electromechanical problems. Despite the numerous advantages, microfluidic devices are difficult to manage as their handling comes with several technical challenges. We developed a new portable tool, the microfluidic trainer (MT), that assesses the operator handling skills and that may be used for maintaining or improving the ability to inject fluid in the inlet of microfluidic devices for in vitro cell culture applications. After several tests, we optimized the MT tester cell to reproduce the real technical challenges of a microfluidic device. In addition to an exercise path, we included an overfilling indicator and a correct infilling indicator at the inlet (control path). We manufactured the MT by engraving a 3 mm-high sheet of methacrylate with 60W CO2 laser plotter to create multiple capillary paths. We validated the device by enrolling 21 volunteers (median age 33) to fill both the MT and a commercial microfluidic device. The success rate obtained with MT significantly correlated with those of a commercial microfluidic culture plate, and its 30 min-continuous use for three times significantly improved the performance. Overall, our data demonstrate that MT is a valid assessment tool of individual performances in using microfluidic devices and may represent a low-cost solution to training, improve or warm up microfluidic handling skills

Perfused Platforms to Mimic Bone Microenvironment at the Macro/Milli/Microscale: Pros and Cons

As life expectancy increases, the population experiences progressive ageing. Ageing, in turn, is connected to an increase in bone-related diseases (i.e., osteoporosis and increased risk of fractures). Hence, the search for new approaches to study the occurrence of bone-related diseases and to develop new drugs for their prevention and treatment becomes more pressing. However, to date, a reliable in vitro model that can fully recapitulate the characteristics of bone tissue, either in physiological or altered conditions, is not available. Indeed, current methods for modelling normal and pathological bone are poor predictors of treatment outcomes in humans, as they fail to mimic the in vivo cellular microenvironment and tissue complexity. Bone, in fact, is a dynamic network including differently specialized cells and the extracellular matrix, constantly subjected to external and internal stimuli. To this regard, perfused vascularized models are a novel field of investigation that can offer a new technological approach to overcome the limitations of traditional cell culture methods. It allows the combination of perfusion, mechanical and biochemical stimuli, biological cues, biomaterials (mimicking the extracellular matrix of bone), and multiple cell types. This review will discuss macro, milli, and microscale perfused devices designed to model bone structure and microenvironment, focusing on the role of perfusion and encompassing different degrees of complexity. These devices are a very first, though promising, step for the development of 3D in vitro platforms for preclinical screening of novel anabolic or anti-catabolic therapeutic approaches to improve bone health

Strontium Functionalization of Biomaterials for Bone Tissue Engineering Purposes: A Biological Point of View

Strontium (Sr) is a trace element taken with nutrition and found in bone in close connection to native hydroxyapatite. Sr is involved in a dual mechanism of coupling the stimulation of bone formation with the inhibition of bone resorption, as reported in the literature. Interest in studying Sr has increased in the last decades due to the development of strontium ranelate (SrRan), an orally active agent acting as an anti-osteoporosis drug. However, the use of SrRan was subjected to some limitations starting from 2014 due to its negative side effects on the cardiac safety of patients. In this scenario, an interesting perspective for the administration of Sr is the introduction of Sr ions in biomaterials for bone tissue engineering (BTE) applications. This strategy has attracted attention thanks to its positive effects on bone formation, alongside the reduction of osteoclast activity, proven by in vitro and in vivo studies. The purpose of this review is to go through the classes of biomaterials most commonly used in BTE and functionalized with Sr, i.e., calcium phosphate ceramics, bioactive glasses, metal-based materials, and polymers. The works discussed in this review were selected as representative for each type of the above-mentioned categories, and the biological evaluation in vitro and/or in vivo was the main criterion for selection. The encouraging results collected from the in vitro and in vivo biological evaluations are outlined to highlight the potential applications of materials’ functionalization with Sr as an osteopromoting dopant in BTE

Simultaneous sinus lift and implant placement using lateral approach in atrophic posterior maxilla with residual bone height of 5 mm or less. A systematic review

Aim To test both success and survival rate of implant placed simultaneously with sinus lift in atro-phic posterior maxilla with a residual bone height of less than 5 mm. Materials and methods A computer search strategy was developed for the following electronic databases: MEDLINE/ PubMed and EMBASE. All the relevant articles were screened involving controlled clinical trials, randomized clinical trials, prospective cohort studies. Results The selection process yielded 12 studies, published between 1999 and 2016, 6 of which were prospective, 1 was a randomized controlled trial, 5 were controlled studies. Conclusions Within the limitation of this systematic review, the qualitative data analysis revealed that the survival rate of implants placed in grafted sinus ranged from 61% to 100%; on the other hand, the success rate ranged between 75.3% to 94.8%. No significant differences were detected regarding different grafting materials used. In order to understand if the one-stage pro-cedure is an effective and predictable surgical alternative in critically resorbed maxillae, larger and well designed clinical trials are needed

Simultaneous sinus lift and implant placement using lateral approach in atrophic posterior maxilla with residual bone height of 5 mm or less. A systematic review

Aim To test both success and survival rate of implant placed simultaneously with sinus lift in atro-phic posterior maxilla with a residual bone height of less than 5 mm. Materials and methods A computer search strategy was developed for the following electronic databases: MEDLINE/ PubMed and EMBASE. All the relevant articles were screened involving controlled clinical trials, randomized clinical trials, prospective cohort studies. Results The selection process yielded 12 studies, published between 1999 and 2016, 6 of which were prospective, 1 was a randomized controlled trial, 5 were controlled studies. Conclusions Within the limitation of this systematic review, the qualitative data analysis revealed that the survival rate of implants placed in grafted sinus ranged from 61% to 100%; on the other hand, the success rate ranged between 75.3% to 94.8%. No significant differences were detected regarding different grafting materials used. In order to understand if the one-stage pro-cedure is an effective and predictable surgical alternative in critically resorbed maxillae, larger and well designed clinical trials are needed