Engineering biological gradients

Biological gradients profoundly influence many cellular activities, such as adhesion, migration, and differentiation, which are the key to biological processes, such as inflammation, remodeling, and tissue regeneration. Thus, engineered structures containing bioinspired gradients can not only support a better understanding of these phenomena, but also guide and improve the current limits of regenerative medicine. In this review, we outline the challenges behind the engineering of devices containing chemical-physical and biomolecular gradients, classifying them according to gradient-making methods and the finalities of the systems. Different manufacturing processes can generate gradients in either in-vitro systems or scaffolds, which are suitable tools for the study of cellular behavior and for regenerative medicine; within these, rapid prototyping techniques may have a huge impact on the controlled production of gradients. The parallel need to develop characterization techniques is addressed, underlining advantages and weaknesses in the analysis of both chemical and physical gradients

Multifunctional platform based on electrospun nanofibers and plasmonic hydrogel. A smart nanostructured pillow for near-infrared light-driven biomedical applications

Multifunctional nanomaterials with the ability to respond to near-infrared (NIR) light stimulation are vital for the development of highly efficient biomedical nanoplatforms with a polytherapeutic approach. Inspired by the mesoglea structure of jellyfish bells, a biomimetic multifunctional nanostructured pillow with fast photothermal responsiveness for NIR light-controlled on-demand drug delivery is developed. We fabricate a nanoplatform with several hierarchical levels designed to generate a series of controlled, rapid, and reversible cascade-like structural changes upon NIR light irradiation. The mechanical contraction of the nanostructured platform, resulting from the increase of temperature to 42 °C due to plasmonic hydrogel-light interaction, causes a rapid expulsion of water from the inner structure, passing through an electrospun membrane anchored onto the hydrogel core. The mutual effects of the rise in temperature and water flow stimulate the release of molecules from the nanofibers. To expand the potential applications of the biomimetic platform, the photothermal responsiveness to reach the typical temperature level for performing photothermal therapy (PTT) is designed. The on-demand drug model penetration into pig tissue demonstrates the efficiency of the nanostructured platform in the rapid and controlled release of molecules, while the high biocompatibility confirms the pillow potential for biomedical applications based on the NIR light-driven multitherapy strategy

Multiscale multifactorial approaches for engineering tendon substitutes

The physiology of tendons and the continuous strains experienced daily make tendons very prone to injury. Excessive and prolonged loading forces and aging also contribute to the onset and progression of tendon injuries, and conventional treatments have limited efficacy in restoring tendon biomechanics. Tissue engineering and regenerative medicine (TERM) approaches hold the promise to provide therapeutic solutions for injured or damaged tendons despite the challenging cues of tendon niche and the lack of tendon-specific factors to guide cellular responses and tackle regeneration. The roots of engineering tendon substitutes lay in multifactorial approaches from adequate stem cells sources and environmental stimuli to the construction of multiscale 3D scaffolding systems. To achieve such advanced tendon substitutes, incremental strategies have been pursued to more closely recreate the native tendon requirements providing structural as well as physical and chemical cues combined with biochemical and mechanical stimuli to instruct cell behavior in 3D architectures, pursuing mechanically competent constructs with adequate maturation before implantation.Authors acknowledge the project “Accelerating tissue engineering and personalized medicine discoveries by the integration of key enabling nanotechnologies, marinederived biomaterials and stem cells,” supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). Authors acknowledge the H2020 Achilles Twinning Project No. 810850, and also the European Research Council CoG MagTendon No. 772817, and the FCT Project MagTT PTDC/CTM-CTM/ 29930/2017 (POCI-01-0145-FEDER-29930

Smart plasmonic hydrogels based on gold and silver nanoparticles for biosensing application

The importance of having a fast, accurate, and reusable track for detection has led to an increase investigation in the field of biosensing. Optical biosensing using plasmonic nanoparticles, such as gold and silver, introduces localized surface plasmon resonance (LSPR) sensors. LSPR biosensors are progressive in their sensing precision and detection limit. Also, the possibility to tune the sensing range by varying the size and shape of the particles has made them extremely useful. Hydrogels being hydrophilic 3D networks can be beneficial when used as matrices, because of a more efficient biorecognition. Stimuli-responsive hydrogels can be great candidates, as their response to a stimulus can increase recognition and detection. This article highlights recent advances in combining hydrogels as a matrix and plasmonic nanoparticles as sensing elements. The end capability and diversity of these novel biosensors in different applications in the near future are discussed

Thermoactive Smart Electrospun Nanofibers

The recent burst of research on smart materials is a clear evidence of the growing interest of the scientific community, industry, and society in the field. The exploitation of the great potential of stimuli-responsive materials for sensing, actuation, logic, and control applications is favored and supported by new manufacturing technologies, such as electrospinning, that allows to endow smart materials with micro- and nanostructuration, thus opening up additional and unprecedented prospects. In this wide and lively scenario, this article systematically reviews the current advances in the development of thermoactive electrospun fibers and textiles, sorting them, according to their response to the thermal stimulus. Hence, several platforms including thermoresponsive systems, shape memory polymers, thermo-optically responsive systems, phase change materials, thermoelectric materials, and pyroelectric materials, are described and critically discussed. The difference in active species and outputs of the aforementioned categories is highlighted, evidencing the transversal nature of temperature stimulus. Moreover, the potential of novel thermoactive materials are pointed out, revealing how their development could take to utmost interesting achievements

3D Tissue Modelling of Skeletal Muscle Tissue

Skeletal muscle tissue exhibits endogenous ability to regenerate. However, the self-repair mechanism is restricted only to small damages. The increasing number of extensive injuries of skeletal muscles due to various accidents, more active life-style or cancer resection, combined with the shortcomings of the conventional treatment procedures, creates demand for new, more advanced solutions. Muscle tissue engineering (TE) appears as a promising strategy for fabrication of tissue substitutes from biomaterials, cells and bioactive factors, alone or combined. In this chapter, we present current state of the art of regeneration and engineering of skeletal muscle tissue. The chapter begins with a brief introduction to structure and functions of skeletal muscle tissue, followed by discussion of cells with potential for repair of muscle injuries and dysfunctions. Next, we provide an overview of natural and synthetic biomaterials used in skeletal muscle TE, as well as description of techniques used to process the biomaterials into scaffolds. We also highlight the importance of mechanical and electrical stimulation during in vitro culture and their effect on cell differentiation and maturation. Last but not least, the latest results of in vivo studies are reported. The chapter is concluded with a short summary and outlook on future developments

Infections or Vaccines Associated with Finkelstein-Seidlmayer Vasculitis: Systematic Review.

Finkelstein-Seidlmayer vasculitis, also referred to as acute hemorrhagic edema of young children, is a rare small-vessel leukocytoclastic vasculitis. This condition is skin-limited, mainly affects infants up to 2 years of age and spontaneously remits. It has been suggested that an infection or a vaccine precede (by ≤ 14 days) this vasculitis. To better understand the interplay between infections or vaccines and Finkelstein-Seidlmayer vasculitis, we utilized the data contained in the Acute Hemorrhagic Edema BIbliographic Database AHEBID. The database, initiated in 2019, is being regularly updated, encompasses the entire original literature on Finkelstein-Seidlmayer vasculitis published after the original description and is attainable on request. The possible existence of an infectious or a vaccine precursor was addressed in 447 cases. Most cases were preceded by an infection (N = 384; 86%), by a vaccination (N = 20; 4.4%), or both an infection and a vaccination (N = 17; 3.8%). No precursor was reported in the remaining cases (N = 26; 5.8%). Two distinct infections preceded the onset of the vasculitis in 11 of the 381 cases with infection-associated Finkelstein-Seidlmayer vasculitis. The following infectious precursors were reported: upper respiratory tract infection (N = 292); acute gastroenteritis (N = 40); a benign febrile infection (N = 36); lower respiratory tract infection (N = 22); further infections (N = 8). The temporal relationship between the infectious precursor and the onset of the skin eruption was detailed in 336 cases: 54 cases developed before resolution and 282 after resolution of the infection. In conclusion, most cases of Finkelstein-Seidlmayer vasculitis are preceded by an infection. In a minority of cases, this skin vasculitis develops before resolution of the infection. In most cases, however, this vasculitis develops after resolution of the infection. More rarely, this vasculitis is preceded by a vaccination

Nanotechnology-assisted RNA delivery. From nucleic acid therapeutics to COVIDvaccines

In recent years, the main quest of science has been the pioneering of the groundbreaking biomedical strategies needed for achieving a personalized medicine. Ribonucleic acids (RNAs) are outstanding bioactive macromolecules identified as pivotal actors in regulating a wide range of biochemical pathways. The ability to intimately control the cell fate and tissue activities makes RNA-based drugs the most fascinating family of bioactive agents. However, achieving a widespread application of RNA therapeutics in humans is still a challenging feat, due to both the instability of naked RNA and the presence of biological barriers aimed at hindering the entrance of RNA into cells. Recently, material scientists’ enormous efforts have led to the development of various classes of nanostructured carriers customized to overcome these limitations. This work systematically reviews the current advances in developing the next generation of drugs based on nanotechnology-assisted RNA delivery. The features of the most used RNA molecules are presented, together with the development strategies and properties of nanostructured vehicles. Also provided is an in-depth overview of various therapeutic applications of the presented systems, including coronavirus disease vaccines and the newest trends in the field. Lastly, emerging challenges and future perspectives for nanotechnology-mediated RNA therapies are discussed