The novel coronavirus SARS-CoV-2, the pathogen responsible for the rapidly growing outbreak of coronavirus disease (COVID-19), is causing widespread concerns and fear, due to its extremely high contagiousness and the potential risk of developing pneumonia.Global research efforts have been devoted to investigating the molecular mechanism of virus pathogenesis, in order to develop effective drugs or vaccines to tackle the on-going pandemic.Several experiments related to SARS-CoV-2 proteins or for testing potential drugs for the treatment of viral infections are currently being carried out.In the present review, innovative approaches for advanced characterization based on large machines of physics, making use of Synchrotron radiation and Neutron beams, are discussed.

The breakdown of intestinal anastomosis is a serious postsurgical complication. The worst complication is anastomotic leakage, resulting in contaminated peritoneal cavity, sepsis, multi-organ failure and even death. In problematic locations like the rectum, the leakage rate has not yet fallen below 10 %. Such a life-threatening condition is the result of impaired healing in the anastomotic wound. It is still vital to find innovative strategies and techniques in order to support regeneration of the anastomotic wound. This paper reviews the surgical techniques and biomaterials used, tested or published. Electrospun nanofibers are introduced as a novel and potential material in gastrointestinal surgery. Nanofibers possess several, unique, physical and chemical properties, that may effectively stimulate cell proliferation and collagen production; a key requirement for the healed intestinal wound.

Bone regeneration is a long-term process requiring proper scaffolding and drug delivery systems. The current study delivers a three-dimensional (3D) scaffold prepared by blend centrifugal spinning loaded with the osteogenic supplements (OS) β-glycerol phosphate, ascorbate-2-phosphate and dexamethasone. The OS were successfully encapsulated into a fibrous scaffold and showed sustained release for 30 days. Furthermore, biological testing showed the osteoinductive properties of the scaffolds on a model of human mesenchymal stem cells and stimulatory effect on a model of osteoblasts. The osteoinductive properties were further proved in vivo in critical size defects of rabbits. The amount of bone trabecules was bigger compared to control fibers without OS. The results indicate that due to its long-term drug releasing properties, single step fabrication process and 3D structure, the system shows ideal properties for use as a cell-free bone implant in tissue-engineering.

The biofunctionalization of scaffolds for tissue engineering is crucial to improve the results of regenerative therapies. This study compared the effect of platelet-functionalization of 2D electrospun and 3D centrifugal spun scaffolds on the osteogenic potential of hMSCs. Scaffolds prepared from poly-epsilon-caprolactone, using electrospinning and centrifugal spinning technology, were functionalized using five different concentrations of platelets. Cell proliferation, metabolic activity and osteogenic differentiation were tested using hMSCs cultured in differential and non-differential medium. The porous 3D structure of the centrifugal spun fibers resulted in higher cell proliferation. Furthermore, the functionalization of the scaffolds with platelets resulted in a dose dependent increase in cell metabolic activity, proliferation and production of an osteogenic marker alkaline phosphatase. The effect was further promoted by culture in an osteogenic differential medium. The increase in combination of both platelets and osteogenic media shows an improved osteoinduction by platelets in environments rich in inorganic phosphate and ascorbate. Nevertheless, the results of the study showed that the optimal concentration of platelets for induction of hMSC osteogenesis is in the range of 900-3000 x 10(9) platelets/L. The study determines the potential of electrospun and centrifugal spun fibers with adhered platelets, for use in bone tissue engineering.

The rapid development of new materials and their application in an extremely wide variety of research and technological fields has lead to the request of increasingly sophisticated characterization methods. In particular residual stress measurements by neutron diffraction, small angle scattering of X-rays and neutrons, as well as 3D imaging techniques with spatial resolution at the micron or even sub-micron scale, like micro-and nano-computerized tomography, have gained a great relevance in recent years.Residual stresses are autobalancing stresses existing in a free body not submitted to any external surface force. Several manufacturing processes, as well as thermal and mechanical treatments, leave residual stresses within the components. Bragg diffraction of X-rays and neutrons can be used to determine residual elastic strains (and then residual stresses by knowing the material elastic constants) in a non-destructive way. Small Angle Scattering of neutrons or X-rays, complementary to Transmission Electron Microscopy, allows the determination of structural features such as volume fraction, specific surface and size distribution of inhomogeneities embedded in a matrix, in a huge variety of materials of industrial interest. X-ray microtomography is similar to conventional Computed Tomography employed in Medicine, allowing 3D imaging of the investigated samples, but with a much higher spatial resolution, down to the sub-micron scale. Some examples of applications of the experimental techniques mentioned above are described and discussed.

Bone and cartilage are tissues of a three-dimensional (3D) nature. Therefore, scaffolds for their regeneration should support cell infiltration and growth in all 3 dimensions. To fulfill such a requirement, the materials should possess large, open pores. Centrifugal spinning is a simple method for producing 3D fibrous scaffolds with large and interconnected pores. However, the process of bone regeneration is rather complex and requires additional stimulation by active molecules. In the current study, we introduced a simple composite scaffold based on platelet adhesion to poly-ε-caprolactone 3D fibers. Platelets were used as a natural source of growth factors and cytokines active in the tissue repair process. By immobilization in the fibrous scaffolds, their bioavailability was prolonged. The biological evaluation of the proposed system in the MG-63 model showed improved metabolic activity, proliferation and alkaline phosphatase activity in comparison to nonfunctionalized fibrous scaffold. In addition, the response of cells was dose dependent with improved biocompatibility with increasing platelet concentration. The results demonstrated the suitability of the system for bone tissue.

In the last decades, very significant advances have been made for what concerns bone and joint substitution and in the repair and regeneration of bone defects. Though some strong requirements are still to be met, biomaterials for these purposes have known an impressive evolution, for what concerns their mechanical behaviour, their bioresorbability and finally their capability to generate new bone tissue in a stable way in long periods. The validation of such materials necessarily depends on a suitable characterization of their properties. In this article a brief review of some works in this field, carried out by the authors’ research group, is presented. It was shown in particular how advanced experimental methods, such as synchrotron radiation µCT and synchrotron radiation diffraction can offer very important information, can be not only complementary methods to more standard techniques (electron microscopy, X-ray diffraction), but can also offer the possibility to measure parameters that cannot be obtained otherwise.

Herein we describe the core/shell centrifugal spinning process to deliver susceptible bioactive molecules.

3D materials supporting cell adhesion, infiltration and proliferation are crucial for bone tissue engineering. In the current study we combined PCL fibers prepared using centrifugal spinning with adhered liposomes filled with platelet lysate as a natural source of growth factors. The scaffold was seeded with MG-63 cells and tested in vitro as a potential drug delivery system for bone tissue engineering.

Background: The macroscopic structure of bone has been traditionally studied through x-ray radiography or x-ray tomography. However, the resolution limits of these techniques do not enable the reconstruction of the composite bone architecture at the nanometer level. Compared with histomorphometry, x-ray micro-CT has shown its efficiency in providing nondestructive and rapid 3D images and measurements on bone microstructure. Micro-CT higher resolution has been achieved with synchrotron radiation-based computed microtomography (SR mu CT).Purpose: The aim of this study was a histological and SRmCT analysis of 2 porous titanium implants.Materials and Methods: Two direct laser metal forming titanium implants were inserted in the posterior maxilla of a patient and retrieved after 2 months. One of these implants was treated to obtain thin ground sections, whereas the other underwent a SRmCT evaluation.Results: The histological results, showing that the implant surface presented superficial debris and particle inclusions in the surrounding tissue close to the bone area, were confirmed by micro-CT investigations.Conclusions: SRmCT allowed high resolution with good sample penetration and depth of focus and an evaluation of the relative arrangement of structures that cannot be determined by 2D imaging. (Implant Dent 2013;22:175-181)

Mesenchymal stem cells deriving from dental pulp differentiate into osteoblasts capable of producing bone. In previous studies, we extensively demonstrated that, when seeded on collagen I scaffolds, these cells can be conveniently used for the repair of human mandible defects. Here, we assess the stability and quality of the regenerated bone and vessel network 3 years after the grafting intervention, with conventional procedures and in-line holotomography, an advanced phase-imaging method using synchrotron radiation that offers improved sensitivity toward low-absorbing structures. We found that the regenerated tissue from the graft sites was composed of a fully compact bone with a higher matrix density than control human alveolar spongy bone from the same patient. Thus, the regenerated bone, being entirely compact, is completely different from normal alveolar bone. Although the bone regenerated at the graft sites is not of the proper type found in the mandible, it does seem to have a positive clinical impact. In fact, it creates steadier mandibles, may well increase implant stability, and, additionally, may improve resistance to mechanical, physical, chemical, and pharmacological agents.

Bone is a complex dynamic tissue undergoing a continuous remodeling process. Gravity is a physical force playing a role in the remodeling and contributing to the maintenance of bone integrity. This article reports an investigation on the alterations of the bone microarchitecture that occurred in wild type (Wt) and pleiotrophin-transgenic (PTN-Tg) mice exposed to a near-zero gravity on the International Space Station (ISS) during the Mice Drawer System (MDS) mission, to date, the longest mice permanence (91 days) in space. The transgenic mouse strain over-expressing pleiotrophin (PTN) in bone was selected because of the PTN positive effects on bone turnover. Wt and PTN-Tg control animals were maintained on Earth either in a MDS payload or in a standard vivarium cage. This study revealed a bone loss during spaceflight in the weight-bearing bones of both strains. For both Tg and Wt a decrease of the trabecular number as well as an increase of the mean trabecular separation was observed after flight, whereas trabecular thickness did not show any significant change. Non weight-bearing bones were not affected. The PTN-Tg mice exposed to normal gravity presented a poorer trabecular organization than Wt mice, but interestingly, the expression of the PTN transgene during the flight resulted in some protection against microgravity's negative effects. Moreover, osteocytes of the Wt mice, but not of Tg mice, acquired a round shape, thus showing for the first time osteocyte space-related morphological alterations in vivo. The analysis of specific bone formation and resorption marker expression suggested that the microgravity-induced bone loss was due to both an increased bone resorption and a decreased bone deposition. Apparently, the PTN transgene protection was the result of a higher osteoblast activity in the flight mice.

Stem cell based tissue engineering therapies involve the administration of manipulated stem cell populations with the purpose of repairing and regenerating damaged or diseased tissue. Currently available methods of monitoring transplanted cells are quite limited. The monitoring of stem cell therapy outcomes requires the development of non-destructive strategies capable to identify the location, magnitude, and duration of cellular survival and fate. The recent development of imaging techniques offers great potential to address these critical issues by non-invasively tracking the fate of the transplanted cells. This chapter offers a focused presentation of some examples of the use of imaging techniques connected to the nanotechnological world in research areas related to stem cells. In particular, investigations concerning human stem cell treatment of Duchenne muscular dystrophy in animal models, cellular therapy to generate new myocardium in infarcted rat heart, bioscaffolds for cell proliferation driving to form bone tissue will be discussed. Tissue engineering and regenerative medicine represent an emerging research area that promises new therapeutic techniques for the repair and replacement of tissues and organs that have lost functions due to ageing, disease, damage, and congenital defects (Langer & Vacanti, 1999; Atala, 2005; Jones & Hench, 2003). Clinical applications have already begun to repair a wide variety of tissues, such as blood, skin, cornea, cartilage, and bone. Imaging techniques are playing an increasingly important role in the rigorous characterization of biomaterial properties and function. Sophisticated 2D imaging technologies have been developed to complement histological evaluation and probe complex biological events occurring at the interface between tissues and biomaterials (Boskey & Pleshko Camacho, 2007; Campbell & Kim, 2007). However, there is a clear need for high resolution 3D imaging technologies that reveal the spatial distribution of regenerated tissues forming in vitro and in vivo conditions. Moreover, for regeneration of vascularized tissues such as bone or muscle, the ability to quantify 3D vascular in-growth would be tremendously valuable, particularly for studies exploring the potential to enhance regeneration via therapeutic angiogenesis strategies (Silva & Mooney, 2007). The imaging modality that has been most extensively applied for this purpose, particularly for bone tissue engineering studies (Mastrogiacomo et al., 2004;

The present contribution is concerned with a combined experimental and numerical design of graded cellular materials for multifunctional aerospace application performed in the context of an integrated research project funded by the European Commission. The primary objective is an exploration of the potential of functionally graded materials as sandwich cores for multifunctional application. With particulate advanced pore morphology (APM) foams and hollow spheres assemblies, two different types of particle-based cellular base materials are considered. Based on these constituent materials, functionally graded sandwich cores are designed in a combined numerical and experimental approach. Their properties and their performance in the desired application are investigated and optimized. The performance of the optimized material is compared to the performance of a non-graded sandwich core in the numerical simulation of a bird strike experiment. (C) 2012 Elsevier Ltd. All rights reserved.

Recently published reports have described possible cellular therapy approaches to regenerate muscle tissues using arterial route delivery. However, the kinetic of distribution of these migratory stem cells within injected animal muscular dystrophy models is unknown. Using living X-ray computed microtomography, we established that intra-arterially injected stem cells traffic to multiple muscle tissues for several hours until their migration within dystrophic muscles. Injected stem cells express multiple traffic molecules, including VLA-4, LFA-1, CD44, and the chemokine receptor CXCR4, which are likely to direct these cells into dystrophic muscles. In fact, the majority of intra-arterially injected stem cells access the muscle tissues not immediately after the injection, but after several rounds of recirculation. We set up a new, living, 3D-imaging approach, which appears to be an important way to investigate the kinetic of distribution of systemically injected stem cells within dystrophic muscle tissues, thereby providing supportive data for future clinical applications.

The recent introduction of stem cells in cardiology provides new tools in understanding the regenerative processes of the normal and pathological heart and has opened a search for new therapeutic strategies. Recent published reports have contributed to identifying possible cellular therapy approaches to generate new myocardium, involving transcoronary and intramyocardial injection of progenitor cells. However, one of the limiting factors in the overall interpretation of clinical results obtained by cell therapy is represented by the lack of three-dimensional (3D) high-resolution methods for the visualization of the injected cells and their fate within the myocardium. This work shows that X-ray computed microtomography may offer the unique possibility of detecting, with high definition and resolution and in ex vivo conditions, the 3D spatial distribution of rat cardiac progenitor cells, labelled with iron oxide nanoparticles, inside the infarcted rat heart early after injection. The obtained 3D images represent a very innovative progress as compared to experimental two-dimensional (2D) histological analysis, which requires time-consuming energies for image reconstruction in order to provide the overall distribution of rat clonogenic cells within the heart. Through microtomography, we were able to observe in 3D the presence of these cells within damaged cardiac tissue, with important structural details that are difficult to visualize by conventional bidimensional imaging techniques. This new 3D-imaging approach appears to be an important way to investigate the cellular events involved in cardiac regeneration and represents a promising tool for future clinical applications. Copyright (C) 2011 John Wiley & Sons, Ltd.

Advances in stem cell research have provided important understanding of the cell biology and offered great promise for developing new strategies for tissue regeneration. The beneficial effects of stem cell therapy depend also by the development of new approachs for the track of stem cells in living subjects over time after transplantation. Recent developments in the use of nanotechnologies have contributed to advance of the high-resolution in vivo imaging methods, including positron emission tomography (PET), single-photon emission tomography (SPECT), magnetic resonance (MR) imaging, and X-Ray computed microtomography (microCT). This review examines the use of nanotechnologies for stem cell tracking.