Acer velutinum Bioss. (velvet maple) seedlings are more tolerant to water deficit than Alnus subcordata C.A. Mey. (Caucasian alder) seedlings

Drought stress is a major environmental factor limiting plant growth. Selection of drought-tolerant plants is of critical importance in vegetation restoration and forestation programs. Alnus subcordata and Acer velutinum are two valuable, dominant, and endemic species in the Hyrcanian forests. There are fast-growing species and significant diffuse-porous hardwood in afforestation and reforestation. One-year old seedlings of both species were exposed to four water shortage treatments (100, 75, 50 and 25% of field capacity (FC) chosen as control, mild, moderate, and severe) for 12 weeks. Thereafter, their morphological characteristics such as height and basal area, total and organs biomass (root, stem, and leaf), leaf area (LA), specific leaf area (SLA), leaf area ratio (LAR), as well as physiological and biochemical characteristics such as relative water content (RWC), content of chlorophyll, free proline and malondialdehyde (MDA), and superoxide dismutase (SOD) and peroxidase (POD) activity were measured. The results showed that when exposed to reduced water availability, plants’ height, basal diameter, total and organs biomass, LA, LAR, RWC and chlorophyll content decreased, but their proline concentration, MDA content, SOD, and POD activity increased in both species. The root to shoot ratio (R/S) and root mass ratio (RMR) increased at 50 and 25% FC treatments in A. subcordata, whereas no significant difference was found in A. velutinum under drought treatments. SLA increased significantly at 50% FC in A. velutinum and decreased in A. subcordata under drought treatments compared to control treatment. A. velutinum showed more proline content, RWC, POD, and lower increase in MDA content than A. subcordata under moderate treatment. Therefore, A. velutinum appears to possess a better mechanism to cope drought stress. The drought tolerance of A. velutinum may enhance its potential for climatic adaptations under drier conditions with the ongoing climatic change

Big bottlenecks in cardiovascular tissue engineering.

Although tissue engineering using human-induced pluripotent stem cells is a promising approach for treatment of cardiovascular diseases, some limiting factors include the survival, electrical integration, maturity, scalability, and immune response of three-dimensional (3D) engineered tissues. Here we discuss these important roadblocks facing the tissue engineering field and suggest potential approaches to overcome these challenges

Engineering of pulmonary surfactant corona on inhaled nanoparticles to operate in the lung system

Exposure of inhaled nanoparticles (NPs) to the deep lung tissue results in the adsorption of pulmonary surfactant (PSf) on the surface of NPs and the formation of a biomolecular corona. The adsorption of the peculiar phospholipids (PLs) and surfactant proteins (SPs) provides NPs with a new bio-identity, which likely changes their corresponding interactions with cells and other bio-systems. Exploring the interaction of NPs with the PSf film at the alveolar air-fluid interface can provide valuable insights into the role of biofluids in the cellular uptake of NPs and their nanotoxic effects. Wrapping biomembranes around NPs and the formation of lipoprotein corona regulate viscoelastic changes, NP insertion into the membrane, and cellular uptake of NPs. In this review, a concise overview has been presented on the engineering of PSf on inhaled NPs to operate in lung environment. First, the physiological barriers in the pulmonary delivery of NPs and approaches to regulating their pulmonary fate are introduced and rationalized. Next, a short description is given on the different sources used for exploring the interfacial performance of inhaled NPs in vitro. A discussion is then presented on SP corona formation on the surface of inhaled NPs, coronal proteome/lipidome in respiratory tract lining fluid (RTLF), regulation of NP aggregation and surfactant flow characteristics, PSf corona and its functional role in the cellular uptake of NPs, followed by explanations on the clinical correlations of PSf corona formation/inhibition on the surface of NPs. Finally, the challenges and future perspectives of the field have been discussed. This review can be harnessed to exploit PSf for the development of safe and bio-inspired pulmonary drug delivery strategies.</p

Mass Spectrometry, Structural Analysis, and Anti-Inflammatory Properties of Photo-Cross-Linked Human Albumin Hydrogels

Albumin-based hydrogels offer unique benefits such as biodegradability and high binding affinity to various biomolecules, which make them suitable candidates for biomedical applications. Here, we report a non-immunogenic photocurable human serum-based (HSA) hydrogel synthesized by methacryloylation of human serum albumin by methacrylic anhydride (MAA). We used matrix-assisted laser desorption ionization-time-of-flight mass spectrometry, liquid chromatography-tandem mass spectrometry, as well as size exclusion chromatography to evaluate the extent of modification, hydrolytic and enzymatic degradation of methacrylated albumin macromer and its cross-linked hydrogels. The impacts of methacryloylation and cross-linking on alteration of inflammatory response and toxicity were evaluated in vitro using brain-derived HMC3 macrophages and Ex-Ovo chick chorioallantoic membrane assay. Results revealed that the lysines in HSA were the primary targets reacting with MAA, though modification of cysteine, threonine, serine, and tyrosine, with MAA was also confirmed. Both methacrylated HSA and its derived hydrogels were nontoxic and did not induce inflammatory pathways, while significantly reducing macrophage adhesion to the hydrogels; one of the key steps in the process of foreign body reaction to biomaterials. Cytokine and growth factor analysis showed that albumin-based hydrogels demonstrated anti-inflammatory response modulating cellular events in HMC3 macrophages. Ex-Ovo results also confirmed the biocompatibility of HSA macromer and hydrogels along with slight angiogenesis-modulating effects. Photocurable albumin hydrogels may be used as a non-immunogenic platform for various biomedical applications including passivation coatings

Recent advances on the development of phantoms using 3D printing for imaging with CT, MRI, PET, SPECT, and ultrasound

Purpose: Printing technology, capable of producing three‐dimensional (3D) objects, has evolved in recent years and provides potential for developing reproducible and sophisticated physical phantoms. 3D printing technology can help rapidly develop relatively low cost phantoms with appropriate complexities, which are useful in imaging or dosimetry measurements. The need for more realistic phantoms is emerging since imaging systems are now capable of acquiring multimodal and multiparametric data. This review addresses three main questions about the 3D printers currently in use, and their produced materials. The first question investigates whether the resolution of 3D printers is sufficient for existing imaging technologies. The second question explores if the materials of 3D‐printed phantoms can produce realistic images representing various tissues and organs as taken by different imaging modalities such as computer tomography (CT), positron emission tomography (PET), single‐photon emission computed tomography (SPECT), magnetic resonance imaging (MRI), ultrasound (US), and mammography. The emergence of multimodal imaging increases the need for phantoms that can be scanned using different imaging modalities. The third question probes the feasibility and easiness of “printing” radioactive or nonradioactive solutions during the printing process. Methods: A systematic review of medical imaging studies published after January 2013 is performed using strict inclusion criteria. The databases used were Scopus and Web of Knowledge with specific search terms. In total, 139 papers were identified; however, only 50 were classified as relevant for this paper. In this review, following an appropriate introduction and literature research strategy, all 50 articles are presented in detail. A summary of tables and example figures of the most recent advances in 3D printing for the purposes of phantoms across different imaging modalities are provided. Results: All 50 studies printed and scanned phantoms in either CT, PET, SPECT, mammography, MRI, and US—or a combination of those modalities. According to the literature, different parameters were evaluated depending on the imaging modality used. Almost all papers evaluated more than two parameters, with the most common being Hounsfield units, density, attenuation and speed of sound. Conclusions: The development of this field is rapidly evolving and becoming more refined. There is potential to reach the ultimate goal of using 3D phantoms to get feedback on imaging scanners and reconstruction algorithms more regularly. Although the development of imaging phantoms is evident, there are still some limitations to address: One of which is printing accuracy, due to the printer properties. Another limitation is the materials available to print: There are not enough materials to mimic all the tissue properties. For example, one material can mimic one property—such as the density of real tissue—but not any other property, like speed of sound or attenuation

Control of dense collagen gel scaffolds for tissue engineering through measurement and modelling of hydraulic permeability

Among various natural biopolymers, type I collagen gels have demonstrated the highest potential as biomimetic scaffolds for tissue engineering (TE). However, the successful application of collagen gels requires a greater understanding of the relationship between their microstructure and physical-mechanical properties. Therefore, a precise method to modulate collagen gel microstructure in order to attain optimal scaffold properties for diverse biomedical applications is necessary. This dissertation describes a new approach to produce collagen gels with defined microstructures, quantified by hydraulic permeability ( k), in order to optimize scaffold properties for TE applications. It was hypothesized that the measurement of k can be used to study the role of microstructure in collagen gel properties, as well as cell function and cell-scaffold interactions. Applying increasing levels of plastic compression (PC) to the highly hydrated collagen gels resulted in an increase in collagen fibrillar density, reduced Happel model derived k values, increased gel stiffness, promoted MSC metabolic activity, osteogenic differentiation, and mineral deposition, while cell-induced gel contraction diminished. Thus, collagen gels with lower k and higher stiffness values exhibited greater potential for bone tissue engineering.Correlating between collagen gel microstructure, k, and fibroblast function within collagen gels indicated that increasing the level of PC yielded a reduction in pore size and an increase in fibril bundle diameter. Decrease in k values resulted in a decrease in gel contraction and an increase in cell metabolic activity. An increase in cell density accelerated contraction. Therefore, fibroblast function within collagen gels can be optimised by a balance between the microstructure, k, and cell seeding density.Developing a micromechanical model to measure experimental k of collagen gels during confined compression revealed the formation of a dense collagen lamella at the fluid expulsion boundary, thereby generating a two-layer model. By applying gel mass loss into Darcy's law, experimental k values of the lamella, along with the thickness of lamella (c) and hydrated gel layer (b) were measured. An increase in either compression level or compression time resulted in a decrease in k, decrease in b, and an increase in c. In conclusion, controlled compression of collagen gels can be used to produce multi-layered biomimetic scaffolds with defined microstructures and k in order to attain optimal properties for tissue engineering applications