Hyaluronan: an overview.

Hyaluronic acid (HA) is a polyanionic natural polymer occurring as a linear polysaccharide composed of glucuronic acid and N-acetylglucosamine repeats. Hyaluronic acid has a wide range of applications with its excellent physicochemical properties such as biodegradability, biocompatibility, non-toxicity, non-immunogenicity and serves as an excellent tool in biomedical applications such as osteoarthritis surgery, ocular surgery, plastic surgery, tissue engineering and drug delivery. This work provides an overview on hyaluronic acid, its chemistry and biochemistry and its medical applications.

On-chip recapitulation of the tumor microenvironment: A decade of progress.

One of the hurdles to the development of new anticancer therapies is the lack of in vitro models which faithfully reproduce the in vivo tumor microenvironment (TME). Understanding the dynamic relationships between the components of the TME in a controllable, scalable, and reliable setting would indeed support the discovery of biological targets impacting cancer diagnosis and therapy. Cancer research is increasingly shifting from traditional two-dimensional (2D) cell culture toward three-dimensional (3D) culture models, which have been demonstrated to increase the significance and predictive value of in vitro data. In this scenario, microphysiological systems (also known as organs-on-chip) have emerged as a relevant technological platform enabling more predictive investigation of cell-cell and cell-ECM interplay in cancer, attracting a significant research effort in the last years. This review illustrates one decade of progress in the field of tumor-microenvironment-on-chip (TMOC) approaches, exploiting either cell-laden microfluidic chambers or microfluidic confined tumor spheroids to model the TME. TMOCs have been designed to recapitulate several aspects of the TME, including tumor cells, the tumor-associated stroma, the immune system, and the vascular component. Significantly, the last aspect has emerged for its pivotal role in orchestrating cellular interactions and modulating drug pharmacokinetics on-chip. A further advancement has been represented by integration of TMOCs into multi-organ microphysiological systems, with the final aim to follow the metastatic cascade to target organs and to study the effects of chemotherapies at a systemic level. We highlight that the increased degree of complexity achieved by the most advanced TMOC models has enabled scientists to shed new light on the role of microenvironmental factors in tumor progression, metastatic cascade, and response to drugs.

A novel extrusion-based 3D bioprinting system for skeletal muscle tissue engineering.

Three-dimensional (3D) bioprinting is an emerging technology, which turned out to be an optimal tool for tissue engineering approaches. To date, different printing systems have been developed. Among them, the extrusion-based approach demonstrated to be the most suitable for skeletal muscle tissue engineering, due to its ability to produce and deposit printing fibers in a parallel pattern that well mimic the native skeletal muscle tissue architecture. In tissue bioengineering, a key role is played by biomaterials, which must possess the key requisite of 'printability'. Nevertheless, this feature is not often well correlated with cell requirements, such as motives for cellular adhesion and/or absorbability. To overcome this hurdle, several efforts have been made to obtain an effective bioink by combining two different biomaterials in order to reach a good printability besides a suitable biological activity. However, despite being efficient, this strategy reveals several outcomes limitations. We report here the development and characterization of a novel extrusion-based 3D bioprinting system, and its application for correction of volumetric muscle loss (VML) injury in a mouse model. The developed bioprinting system is based on the use of PEG-Fibrinogen, a unique biomaterial with excellent biocompatibility, well-suited for skeletal muscle tissue engineering. With this approach, we obtained highly organized 3D constructs, in which murine muscle progenitors were able to differentiate into muscle fibers arranged in aligned bundles and capable of spontaneously contracting when culturedin vitro. Furthermore, to evaluate the potential of the developed system in future regenerative medicine applications, bioprinted constructs laden with either murine or human muscle progenitors were transplanted to regenerate theTibialis Anteriormuscle of a VML murine model, one month after grafting.

Response to the 2009 influenza A(H1N1) pandemic in Italy.

In Italy, the arrival of the 2009 pandemic influenza A(H1N1) virus triggered an integrated response that was mainly based on the 2006 National Pandemic Preparedness and Response Plan. In this article we analyse the main activities implemented for epidemiological surveillance, containment and mitigation of the pandemic influenza and the lesson learned from this experience. Overall, from week 31 (27 July ­ 2 August) of 2009 to week 17 (26 April ­ 2 May) of 2010, we estimate that there were approximately 5,600,000 cases of influenza-like illness (ILI) who received medical attention (with almost 2,000 laboratory-confirmed cases of pandemic influenza from May to October 2009). A total of 1,106 confirmed cases were admitted to hospital for serious conditions, of whom 532 were admitted to intensive care units. There were 260 reported deaths due to pandemic influenza. Approximately 870,000 first doses of the pandemic vaccine were administered, representing a vaccine coverage of 4% of the target population. One of the possible reasons for the low uptake of the pandemic vaccine in the target population could be the communication strategy adopted, for both the general population and healthcare workers, which turned out to be a major challenge. Active involvement of all health professionals (at local, regional and national level) in influenza pandemic preparedness and response should be encouraged in the future.

[Antibiotic-resistance in Italy: activity of the first year of the surveillance project AR-ISS]. / Antibiotico-resistenza in Italia: un anno di attività del progetto di sorveglianza AR-ISS.

The antibiotic resistance surveillance project AR-ISS, started in 2001, is based on a network of 62 sentinel microbiological laboratories throughout the country. The laboratories collect and transmit data to the Istituto Superiore di Sanità on the antibiotic susceptibility of bloodstream isolates of 7 species: Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus faecalis/faecium, Klebsiella pneumoniae/oxytoca ed Escherichia coli. They also send selected bacterial strains for further characterization. Results of the first year of surveillance are presented and are compared with data from the previous study EARSS-Italia and from other European countries. Oxacillin resistance in S. aureus appears to be stable, however, it remains one of the highest in Europe (41,5%). No strain with intermediate susceptibility or resistance to vancomycin has been isolated. In S. pneumoniae, the level of penicillin resistance is moderate (10,8%), but macrolide resistance has increased greatly (37,6% versus 28,6% of the previous study), following a tendency common to several European countries. Unexpectedly, vancomycin resistance in E. faecium was found to be 18%, the highest in Europe. Presumptive ESBL production in Gram-negative organisms can be estimated at 20% in Klebsiella and 1% in E. coli. Ampicillin and ciprofloxacin resistance in E. coli (respectively 50% and 18%) are among the highest in Europe. In conclusion, the rate of antibiotic resistance in the species studied is worrisome and requires continuing monitoring. Although some activities of AR-ISS need improvements, the surveillance has the potentiality to produce relevant and representative data about antibiotic resistance in Italy that can be used for comparison at the European level.

Combined additive manufacturing approaches in tissue engineering.

Advances introduced by additive manufacturing (AM) have significantly improved the control over the microarchitecture of scaffolds for tissue engineering. This has led to the flourishing of research works addressing the optimization of AM scaffolds microarchitecture to optimally trade-off between conflicting requirements (e.g. mechanical stiffness and porosity level). A fascinating trend concerns the integration of AM with other scaffold fabrication methods (i.e. "combined" AM), leading to hybrid architectures with complementary structural features. Although this innovative approach is still at its beginning, significant results have been achieved in terms of improved biological response to the scaffold, especially targeting the regeneration of complex tissues. This review paper reports the state of the art in the field of combined AM, posing the accent on recent trends, challenges, and future perspectives.

Graded porous polyurethane foam: a potential scaffold for oro-maxillary bone regeneration.

Bone tissue engineering applications demand for biomaterials offering a substrate for cell adhesion, migration, and proliferation, while inferring suitable mechanical properties to the construct. In the present study, polyurethane (PU) foams were synthesized to develop a graded porous material-characterized by a dense shell and a porous core-for the treatment of oro-maxillary bone defects. Foam was synthesized via a one-pot reaction starting from a polyisocyanate and a biocompatible polyester diol, using water as a foaming agent. Different foaming conditions were examined, with the aim of creating a dense/porous functional graded material that would perform at the same time as an osteoconductive scaffold for bone defect regeneration and as a membrane-barrier to gingival tissue ingrowth. The obtained PU was characterized in terms of morphological and mechanical properties. Biocompatibility assessment was performed in combination with bone-marrow-derived human mesenchymal stromal cells (hBMSCs). Our findings confirm that the material is potentially suitable for guided bone regeneration applications.

Antimicrobial resistance in Italy: preliminary results from the AR-ISS project.

Antimicrobial resistance represents a critical problem in human medicine today, from both clinical and economic points of view. In 1999, the Council of the European Union included antibiotic resistance among the public health priorities in the Community, and a resolution entitled 'A strategy against the microbial threat' was issued (1). According to this document, the establishment or strengthening of a surveillance system for the collection of reliable and comparable data on a national and international scale is one of the main interventions needed to control and prevent antibiotic resistance. Surveillance systems should also integrate data about the use and prescription of antibiotics (2).

Current trends in the design of scaffolds for computer-aided tissue engineering.

Advances introduced by additive manufacturing have significantly improved the ability to tailor scaffold architecture, enhancing the control over microstructural features. This has led to a growing interest in the development of innovative scaffold designs, as testified by the increasing amount of research activities devoted to the understanding of the correlation between topological features of scaffolds and their resulting properties, in order to find architectures capable of optimal trade-off between often conflicting requirements (such as biological and mechanical ones). The main aim of this paper is to provide a review and propose a classification of existing methodologies for scaffold design and optimization in order to address key issues and help in deciphering the complex link between design criteria and resulting scaffold properties.