An overview of the production of tissue extracellular matrix and decellularization process

Thousands of patients need an organ transplant yearly, while only a tiny percentage have this chance to receive a tissue/organ transplant. Nowadays, decellularized animal tissue is one of the most widely used methods to produce engineered scaffolds for transplantation. Decellularization is defined as physically or chemically removing cellular components from tissues while retaining structural and functional extracellular matrix (ECM) components and creating an ECM-derived scaffold. Then, decellularized scaffolds could be reseeded with different cells to fabricate an autologous graft. Effective decellularization methods preserve ECM structure and bioactivity through the application of the agents and techniques used throughout the process. The most valuable agents for the decellularization process depend on biological properties, cellular density, and the thickness of the desired tissue. ECM-derived scaffolds from various mammalian tissues have been recently used in research and preclinical applications in tissue engineering. Many studies have shown that decellularized ECM-derived scaffolds could be obtained from tissues and organs such as the liver, cartilage, bone, kidney, lung, and skin. This review addresses the significance of ECM in organisms and various decellularization agents utilized to prepare the ECM. Also, we describe the current knowledge of the decellularization of different tissues and their applications.

Biology of Tenascin C and its role in physiology and pathology

Tenascin-C (TNC) is a multimodular extracellular matrix (ECM) protein hexameric with several molecular forms (180-250 kDa) produced by alternative splicing at the pre-mRNA level and protein modifications. The molecular phylogeny indicates that the amino acid sequence of TNC is a well-conserved protein among vertebrates. TNC has binding partners, including fibronectin, collagen, fibrillin-2, periostin, proteoglycans, and pathogens. Various transcription factors and intracellular regulators tightly regulate TNC expression. TNC plays an essential role in cell proliferation and migration. Unlike embryonic tissues, TNC protein is distributed over a few tissues in adults. However, higher TNC expression is observed in inflammation, wound healing, cancer, and other pathological conditions. It is widely expressed in a variety of human malignancies and is recognized as a pivotal factor in cancer progression and metastasis. Moreover, TNC increases both pro-and anti-inflammatory signaling pathways. It has been identified as an essential factor in tissue injuries such as damaged skeletal muscle, heart disease, and kidney fibrosis. This multimodular hexameric glycoprotein modulates both innate and adaptive immune responses regulating the expression of numerous cytokines. Moreover, TNC is an important regulatory molecule that affects the onset and progression of neuronal disorders through many signaling pathways. We provide a comprehensive overview of the structural and expression properties of TNC and its potential functions in physiological and pathological conditions.

The in vitro analysis of migration and polarity of blastema cells in the extracellular matrix derived from bovine mesenteric in the presence of fibronectin

Cell migration is an essential process in embryonic development, wound healing, and pathological conditions. Our knowledge of cell migration is often based on the two dimentional evaluation of cell movement, which usually differs from what occurred in vivo. In this study, we investigated cellular migration from blastema tissue toward bovine decellularized mesentery tissue. In this regard, fibronectin (FN) was assessed to confirm cell migration. Therefore, we established a cell migration model using blastema cells migration toward the extracellular matrix derived from bovine mesenteric tissue. A physiochemical decellularization method was utilized based on freeze-thaw cycles and agitation in sodium dodecyl sulfate and Triton X-100 to remove cells from the extracellular matrix (ECM) of bovine mesenteric tissue. These types of matrices were assembled by the rings of blastema tissues originated from the of New Zealand rabbits pinna and cultured in a medium containing FN in different days in vitro, and then they are histologically evaluated, and the expression of the Tenascin C gene is analyzed. By means of tissue staining and after confirmation of the cell removal from mesenteric tissue, polarity, and migration of blastema cells was observed in the interaction site with this matrix. Also, the expression of the Tenascin C gene was assessed on days 15 and 21 following the cell culture process. The results showed that the three dimentional model of cellular migration of blastema cells along with the ECM could be a suitable model for investigating cell behaviors, such as polarity and cell migration in vitro.

An overview of progress from empirical to rational design in modern vaccine development, with an emphasis on computational tools and immunoinformatics approaches

Vaccination remains the most effective strategy for preventing and controlling infectious diseases. Numerous conventional vaccines, especially live attenuated, inactivated (killed) microorganisms and subunit vaccines, lead to an effective induction of protective immune responses, mainly antibody-mediated responses against pathogens. However, it has become known that a wide range of highly dangerous pathogens are uncontrollable via conventional vaccination strategies. Recent advances in molecular biology, immunology, genetics, biochemistry, and bioinformatics have provided new prospects for vaccine development. As a result of these advances, several new strategies for vaccine design, development, and production have appeared. These strategies show advantages over conventional vaccines. In this review, we discuss some of the major novel approaches, including recombinant protein vaccines, live recombinant viral and bacterial vectors, DNA and RNA vaccines, reverse vaccinology and reverse genetics approaches. Moreover, we have described the recent progresses on computational tools and immunoinformatics approaches for identifying, designing, and developing new candidate vaccines.

Design, development, and evaluation of the efficacy of a nucleic acid-free version of a bacterial ghost candidate vaccine against avian pathogenic E. coli (APEC) O78:K80 serotype

One of the major bacterial infectious diseases in the poultry industry is avian pathogenic Escherichia coli (APEC), which causes colibacillosis in chickens. To develop a novel nucleic acid-free bacterial ghost (BG) vaccine against the O78:K80 serotype of APEC, in this study we constructed a plasmid that harbored E-lysis and S nuclease (SNUC). Following the expression, the O78:K80 bacteria lost all of their cytoplasmic content and nucleic acids by enzymatic digestion. The functionality of these two proteins in the production procedure of bacterial ghosts was confirmed by monitoring the number of colonies, scanning electron microscopy imaging, gel electrophoresis of genomic DNA, and qPCR on the plasmid content of bacterial ghosts. The protective efficacy of the ghost vaccine generated from O78:K80 serotype of APEC was tested in chickens by injection and inhalation routes and compared with that in chickens that received the injection of a killed vaccine. The O78:K80 BG vaccine candidate, used as injection and inhalation, in comparison with the killed vaccine, triggered higher proinflammatory cytokine expression including IL-6, IL-1β, and TNFSF15; a higher level of antibody-dependent humoral (IgY and IgA) and cellular immune responses (IFNγ and lymphocyte proliferation); and lower lesion scores. According to the results of this study, we suggest that the bacterial ghost technology has the potential to be applied for the development of novel vaccines against avian colibacillosis. This technology provides an effective and reliable approach to make multivalent vaccines for more prevalent APEC strains involved in the establishment of this infectious disease in the poultry industry.

Reverse Genetics Assembly of Newcastle Disease Virus Genome Template Using Asis-Sal-Pac BioBrick Strategy

Background

The BioBrick construction as an approach in synthetic biology provides the ability to assemble various gene fragments. To date, different BioBrick strategies have been exploited for assembly and cloning of a variety of gene fragments. We present a new BioBrick strategy, here referred as Asis-Sal-Pac BioBrick, which we used for the assembly of NDV as a candidate for single-stranded non-segmented, negative-sense RNA genome viruses.

Results

In the present study, we isolated three NDVs from clinical samples which were classified into the VIId genotype based on their pathogenicity and phylogenetic analyses. Then, SalI, AsisI, and PacI enzymes were used to design and develop a novel BioBrick strategy, which enabled us to assemble the NDV genome, adopting the “rule of six”. In this method, in each assembly step, the restriction sites in the newly formed destination plasmid are reproduced, which will be used for the next insertion. In this study using two overlapping PCRs, the cleavage site of the F gene was also modified from ¹¹²RRQKRF¹¹⁷to ¹¹²GRQGRL¹¹⁷ in order to generate the attenuated recombinant NDV. Finally, in order to construct the recombinant NDV viruses, the plasmids harboring the assembled full-length genome of the NDV and the helper plasmids were co-transfected into T7-BHK cells. The rescue of the recombinant NDVwas confirmed by RT-PCR and HA tests.

Conclusions

These findings suggest that the combination of reverse genetic technology and BioBrick assembly have the potential to be applied for the development of novel vaccine candidates. This promising strategy provides an effective and reliable approach to make genotype-matched vaccines against specific NDV strains or any other virus.

Evaluation of testis hormonal and histopathological alterations in type I and type II diabetic rats

BACKGROUND

Diabetes is a devastating metabolic disease that causes long-term damage to various organs. An important leading complication of diabetes is a degenerative effect on the reproductive system including infertility and gonadal dysfunction. This study aimed to evaluate the effects of experimental type I and II diabetes on the levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone.

METHODS

Male Wistar rats were randomly divided into four separate groups: (1) type I diabetes (T1DM), (2) type II diabetes (T2DM), (3) cetrorelix acetate-treated nondiabetic control group, and (4) normal untreated group (n = 6). T1DM was experimentally induced by a single injection of alloxan (135 mg/kg) while T2DM was induced by feeding the animals with drinking water enriched with fructose (10%). Cetrorelix acetate (100 mg/kg, intraperitoneal for 1 week) treatment group was used as a positive control. All rats were killed and blood and testes were collected after 8 weeks of the study. The effects of induced diabetes on the levels of blood glucose and insulin were assessed. The levels of sex hormones and insulin were determined by radioimmunoassay. Histological staining was used to check abnormal patterns of testicular morphology, the diameter of seminiferous tubules, testicular diameter, and germinal layer thickness.

RESULTS

A significant reduction in the testosterone, FSH, and LH levels were observed in T1DM, T2DM, and also in cetrorelix acetate-treated groups. Analysis of testicular histology sections revealed significantly reduced thickness of cell layer in T1DM and cetrorelix acetate-treated groups compared with the T2DM group. In T2DM, the cell numbers, the thickness of cell layer, the diameter of seminiferous tubules, and weight of testicles were slightly increased. In contrast, total tubules of empty seminiferous increased significantly in T1D and cetrorelix treated groups compared with the control group.

CONCLUSION

Overall, diabetes can induce hypothalamus-pituitary-gonad axis dysfunction, affects hormonal secretion, and causes histological damage to testes, collectively leading to deleterious effects on male fertility.

Triggering apoptosis in cancer cells with an analogue of cribrostatin 6 that elevates intracellular ROS

Elevation of reactive oxygen species (ROS) is both a consequence and driver of the upregulated metabolism and proliferation of transformed cells. The resulting increase in oxidative stress is postulated to saturate the cellular antioxidant machinery, leaving cancer cells susceptible to agents that further elevate their intracellular oxidative stress. Several small molecules, including the marine natural product cribrostatin 6, have been demonstrated to trigger apoptosis in cancer cells by increasing intracellular ROS. Here, we report the modular synthesis of a series of cribrostatin 6 derivatives, and assessment of their activity in a number of cell lines. We establish that placing a phenyl ring on carbon 8 of cribrostatin 6 leads to increased potency, and observe a window of selectivity towards cancer cells. The mechanism of activity of this more potent analogue is assessed and demonstrated to induce apoptosis in cancer cells by increasing ROS. Our results demonstrate the potential for targeting tumors with molecules that enhance intracellular oxidative stress.

The half Heusler system Ti1+xFe1.33−xSb–TiCoSb with Sb/Sn substitution: phase relations, crystal structures and thermoelectric properties

Phase equilibria for Heusler Phase Ti_1+xFe_1.33−xSb at 800 °C and calculated isosurfaces (ϒ = 0.42) of the electron localization function in TiFe_1.25Sb.

Post-translational control of protein function with light using a LOV-intein fusion protein

Methods for the post-translational control of protein function with light hold much value as tools in cell biology. To this end, we report a fusion protein that consists of DnaE split-inteins, flanking the light sensitive LOV2 domain of Avena sativa. The resulting chimera combines the activities of these two unrelated proteins to enable controlled formation of a functional protein via upregulation of intein splicing with blue light in bacterial and human cells.

Mesenchymal stem cells can survive on the extracellular matrix-derived decellularized bovine articular cartilage scaffold

OBJECTIVE S

The scarcity of articular cartilage defect to repair due to absence of blood vessels and tissue engineering is one of the promising approaches for cartilage regeneration. The objective of this study was to prepare an extracellular matrix derived decellularized bovine articular cartilage scaffold and investigate its interactions with seeded rat bone marrow mesenchymal stem cells (BM-MSCs).

MATERIALS AND METHODS

Bovine articular cartilage that was cut into pieces with 2 mm thickness, were decellularized by combination of physical and chemical methods including snap freeze-thaw and treatment with sodium dodecyl sulfate (SDS). The scaffolds were then seeded with 1, 1'-dioctadecyl-3, 3, 3', 3'-tetramethylindocarbocyanine perchlorate (DiI) labeled BM-MSCs and cultured for up to two weeks.

RESULTS

Histological studies of decellularized bovine articular cartilage showed that using 5 cycles of snap freeze-thaw in liquid nitrogen and treatment with 2.5% SDS for 4 hr led to the best decellularization, while preserving the articular cartilage structure. Adherence and penetration of seeded BM-MSCs on to the scaffold were displayed by histological and florescence examinations and also confirmed by electron microscopy.

CONCLUSION

ECM-derived decellularized articular cartilage scaffold provides a suitable environment to support adhesion and maintenance of cultured BM-MSCs and could be applied to investigate cellular behaviors in this system and may also be useful for studies of cartilage tissue engineering.

Probing the epigenetic regulation of HIF-1α transcription in developing tissue

HIF-1-mediated hypoxia signalling in embryonic tissue is probed by assessing the methylation status of the HIF-1α and EPO HRE promoters using bisulfite sequencing.

HIF-1 promotes the expression of its α-subunit via an epigenetically regulated transactivation loop

A HIF-1 protein–protein interaction inhibitor is used to establish the presence of a HIF-1α transactivation loop in hypoxia.

Scaffolds derived from cancellous bovine bone support mesenchymal stem cells' maintenance and growth

Since bone defects can lead to various disabilities, in recent years, many increasing attempts have been made in bone tissue engineering. In this regard, scaffolds have attracted a lot of attention as three dimensional substrates for cell attachment which improve successful tissue engineering. The aim of the present study was to provide an interconnected porous scaffold to facilitate cell infiltration. To do so, cancellous bone from bovine femur was dissected in fragments and decellularized by physicochemical methods, including snap freeze/thaw, rinsing in hot water and treatment with different solutions of sodium dodecyl sulfate (SDS). Histological analysis and 4',6-diamidino-2-phenylindole staining revealed that the best results were obtained after treatment with 2.5%, 5%, and 8% SDS for 8, 3, or 1 h respectively, which significantly removed bone cells with intact trabeculae geometry. Further characterization of decellularized scaffolds by the compression tests also revealed no significant difference between elastic modulus values of the three different SDS treatments. Moreover, studying the ratio of bone trabeculae to bone surfaces (BT/BS) as assessed by Clemex vision software 3.5 showed that treatment with 2.5% SDS for 8 h resulted in a BT/BS score in the range of native bone and therefore this treatment was used for further experiments. Histological studies and scanning electron microscopy revealed rat mesenchymal stem cells integration, adhesion, and maintenance during the 2 and 7 d of culture in vitro. In conclusion, the present results support the effective role of SDS in cancellous bovine bone decellularization and also propensity of treated samples in providing a suitable three-dimentional environment to support the maintenance and growth of mesenchymal stem cells.

Eye movements selective for spatial frequency and orientation during active visual search

Visual search can simply be defined as the task of looking for objects of interest in cluttered visual environments. Typically, the human visual system succeeds at this by making a series of rapid eye movements called saccades, interleaved by discrete fixations. However, very little is known on how the brain programs saccades and selects fixation loci in such naturalistic tasks. In the current study, we use a technique developed in our laboratory based on reverse-correlation(1) and stimuli that emulate the natural visual environment to examine observers' strategies when seeking low-contrast targets of various spatial frequency and orientation characteristics. We present four major findings. First, we provide strong evidence of visual guidance in saccadic targeting characterized by saccadic selectivity for spatial frequencies and orientations close to that of the search target. Second, we show that observers exhibit inaccuracies and biases in their estimates of target features. Third, a complementarity effect is generally observed: the absence of certain frequency components in distracters affects whether they are fixated or mistakenly selected as the target. Finally, an unusual phenomenon is observed whereby distracters containing close-to-vertical structures are fixated in searches for nonvertically oriented targets. Our results provide evidence for the involvement of band-pass mechanisms along feature dimensions (spatial frequency and orientation) during visual search.

Flow-injection analysis of nitrate by reduction to nitrite and gas-phase molecular absorption spectrometry

Two flow-injection manifolds have been investigated for the determination of nitrate. These manifolds are based on the reduction of nitrate to nitrite and determination of nitrite by gas-phase molecular absorption spectrophotometry. Nitrate sample solution (300 microL) which is injected to the flow line, is reduced to nitrite by reaction with hydrazine or passage through the on-line copperized cadmium (Cd-Cu) reduction column. The nitrite produced reacts with a stream of hydrochloric acid and the evolved gases are purged into the stream of O2 carrier gas. The gaseous phase is separated from the liquid phase using a gas-liquid separator and then swept into a flow-through cell which has been positioned in the cell compartment of an UV-visible spectrophotometer. The absorbance of the gaseous phase is measured at 204.7 nm. A linear relationship was obtained between the intensity of absorption signals and concentration of nitrate when Cd-Cu reduction method was used, but a logarithmic relationship was obtained when the hydrazine reduction method was used. By use of the Cd-Cu reduction method, up to 330 microg of nitrate was determined. The limit of detection was 2.97 microg nitrate and the relative standard deviations for the determination of 12.0, 30.0 and 150 microg nitrate were 3.32, 3.87 and 3.6%, respectively. Maximum sampling rate was approximately 30 samples per hour. The Cd-Cu reduction method was applied to the determination of nitrate and the simultaneous determination of nitrate and nitrite in meat products, vegetables, urine, and a water sample.

Transplantation in utero of fetal human hematopoietic stem cells into mice results in hematopoietic chimerism

Allogeneic and xenogeneic hematolymphoid chimerism has been achieved in large and small animals using varied techniques to circumvent immune mediated graft rejection by the recipient. We show here the establishment of long-term chimerism in normal mice transplanted in utero with human fetal hematopoietic stem cells (HSC). HSCs from fetal (13-20 weeks' gestation) human livers were injected into fetal mouse peritoneal cavities on days 11-13 of gestation. Histologic examination demonstrated human chimerism in 29% of 38 live born mice using fluorescein conjugated antibodies to both the CD45 and CD14 antigens present on human peripheral blood (PB) cells. Further investigation using flow cytometric analysis of cells from 70 mice transplanted in utero revealed 28% of mice greater than 16 weeks of age contained human cells in at least one organ at the following frequencies: 14% PB, 8% bone marrow, 8% spleen and 12% thymus. These data indicate that human fetal HSC can be engrafted into mouse fetuses. Additionally, the identification of circulating human cells 18 months following transplantation supports the engraftment and proliferation of a primitive hematopoietic progenitor.