Exosomes from SHED-MSC regulate polarization and stress oxidative indexes in THP-1 derived M1 macrophages.

OBJECTIVE: The inhibition of M1 macrophages may be interesting for targeted therapy with mesenchymal stem cell-derived Exosomes (MSC-EXOs). This study aimed to investigate the stem cells of human exfoliated deciduous teeth-derived EXOs (SHED-MSC-EXOs) effect on regulating the pro- and anti-oxidant indexes and inhibiting M1 macrophage polarization. Besides, an in-silico analysis of SHED-MSC-EXO miRNAs as the highest frequency of small RNAs in the exosomes was performed to discover the possible mechanism. METHODS: The flow cytometry analysis of CD80 and CD86 as M1-specific markers confirmed the polarization of macrophages derived from THP-1 cells. After exosome isolation, characterization, and internalization, THP-1-derived M1 macrophages were treated with SHED-MSC-EXOs. M1-specific markers and pro- and anti-oxidant indexes were evaluated. For in-silico analysis of SHED-MSC-EXOs miRNAs, initial miRNA array data of SHED-EXOs is collected from GEO, and the interaction of the miRNAs in M1 macrophage polarization (M1P), mitochondrial oxidative stress (MOS) and LPS-induced oxidative stress (LOS) were analyzed by miRWalk 3.0 server. Outcomes were filtered by 75th percentile signal intensity, score cut-off ≥0.95, minimum free energy (MEF)≤ -20 kcal/mol, and seed = 1. RESULTS: It shows a decrease in the expression of CD80 and CD81, a reduction in pro-oxidant indicators, and an increase in the anti-oxidant indexes (P < 0.05). Computational analysis showed that eight microRNAs of SHED-MSC-EXO miRNAs can bind to and interfere with the expression of candidate genes in the M1P, MOS, and LOS pathways simultaneously. CONCLUSION: SHED-MSCs-EXOs can be utilized to treat conditions related to M1 macrophage-induced diseases (M1IDs) due to their unique physical properties and ability to penetrate target cells easily.

Fluoxetine enhances the antitumor effect of olfactory ensheathing cell-thymidine kinase/ganciclovir gene therapy in human glioblastoma multiforme cells through upregulation of Connexin43 levels.

Glioblastoma multiforme (GBM) is the most invasive form of primary brain astrocytoma, resulting in poor clinical outcomes. Herpes simplex virus thymidine kinase/ganciclovir (HSV-TK/GCV) gene therapy is considered a promising strategy for GBM treatment. Since Connexin43 (Cx43) expression is reduced in GBM cells, increasing Cx43 levels could enhance the effectiveness of gene therapy. The present study aims to examine the impact of fluoxetine on HSV-TK/GCV gene therapy in human GBM cells using human olfactory ensheathing cells (OECs) as vectors. The effect of fluoxetine on Cx43 levels was assessed using the western blot technique. GBM-derived astrocytes and OECs-TK were Cocultured, and the effect of fluoxetine on the Antitumor effect of OEC-TK/GCV gene therapy was evaluated using MTT assay and flow cytometry. Our results showed that fluoxetine increased Cx43 levels in OECs and GBM cells and augmented the killing effect of OECs-TK on GBM cells. Western blot data revealed that fluoxetine enhanced the Bax/Bcl2 ratio and the levels of cleaved caspase-3 in the coculture of OECs-TK and GBM cells. Moreover, flow cytometry data indicated that fluoxetine increased the percentage of apoptotic cells in the coculture system. This study suggests that fluoxetine, by upregulating Cx43 levels, could strengthen the Antitumor effect of OEC-TK/GCV gene therapy on GBM cells.

Features of Pathobiology and Clinical Translation of Approved Treatments for Coronavirus Disease 2019.

BACKGROUND: Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is currently the most important etiological agent of acute respiratory distress syndrome (ARDS) with millions of infections and deaths in the last 2 years worldwide. Several reasons and parameters are responsible for the difficult management of coronavirus disease-2019 (COVID-19) patients; the first is virus behavioral factors such as high transmission rate, and the different molecular and cellular mechanisms of pathogenesis remain a matter of controversy, which is another factor. SUMMARY: In the present review, we attempted to explain about features of SARS-COV-2, particularly focusing on the various aspects of pathogenesis and treatment strategies. KEY MESSAGES: We note evidence for the understanding of the precise molecular and cellular mechanisms of SARS-CoV-2 pathogenesis, which can help design the appropriate drug or vaccine. Additionally, and importantly, we reported the updated issues associated with the history and development of treatment strategies such as, drugs, vaccines, and other medications that have been approved or under consideration in clinics and markets worldwide.

Bioactivity and Antibacterial Behaviors of Nanostructured Lithium-Doped Hydroxyapatite for Bone Scaffold Application.

The material for bone scaffold replacement should be biocompatible and antibacterial to prevent scaffold-associated infection. We biofunctionalized the hydroxyapatite (HA) properties by doping it with lithium (Li). The HA and 4 Li-doped HA (0.5, 1.0, 2.0, 4.0 wt.%) samples were investigated to find the most suitable Li content for both aspects. The synthesized nanoparticles, by the mechanical alloying method, were cold-pressed uniaxially and then sintered for 2 h at 1250 °C. Characterization using field-emission scanning electron microscopy (FE-SEM) revealed particle sizes in the range of 60 to 120 nm. The XRD analysis proved the formation of HA and Li-doped HA nanoparticles with crystal sizes ranging from 59 to 89 nm. The bioactivity of samples was investigated in simulated body fluid (SBF), and the growth of apatite formed on surfaces was evaluated using SEM and EDS. Cellular behavior was estimated by MG63 osteoblast-like cells. The results of apatite growth and cell analysis showed that 1.0 wt.% Li doping was optimal to maximize the bioactivity of HA. Antibacterial characteristics against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were performed by colony-forming unit (CFU) tests. The results showed that Li in the structure of HA increases its antibacterial properties. HA biofunctionalized by Li doping can be considered a suitable option for the fabrication of bone scaffolds due to its antibacterial and unique bioactivity properties.

Elbow angle generation during activities of daily living using a submovement prediction model.

The present study aimed to develop a realistic model for the generation of human activities of daily living (ADL) movements. The angular profiles of the elbow joint during functional ADL tasks such as eating and drinking were generated by a submovement-based closed-loop model. First, the ADL movements recorded from three human participants were broken down into logical phases, and each phase was decomposed into submovement components. Three separate artificial neural networks were trained to learn the submovement parameters and were then incorporated into a closed-loop model with error correction ability. The model was able to predict angular trajectories of human ADL movements with target access rate = 100%, VAF = 98.9%, and NRMSE = 4.7% relative to the actual trajectories. In addition, the model can be used to provide the desired target for practical trajectory planning in rehabilitation systems such as functional electrical stimulation, robot therapy, brain-computer interface, and prosthetic devices.

Association of the human aryl hydrocarbon receptor repressor (AhRR)-c.565C>G transversion with male infertility: A case-control study from Iran.

Dioxins (eg, 2,3,7,8-tetrachlorodibenzo-p-dioxin/TCDD), as environmental endocrine disruptors and toxic carcinogens, can affect male reproductive health. The influence of dioxins is mediated via the aryl hydrocarbon receptor (AhR) pathway and its repressor (AhRR). In this study, we investigated the association of AhRR-c.565C>G transversion polymorphism with male infertility. In a hospital-based case-control study, 221 semen samples (111 infertile and 110 healthy controls) based on World Health Organization guidelines were collected from in vitro fertilization centers of Babol, Iran. The AhRR-c.565C>G (rs2292596) polymorphism was genotyped using a polymerase chain reaction-restriction fragment length polymorphism analysis. The difference in the allele frequency of AhRR-c.565C>G transversion polymorphism did not reach a significant level. The genotype frequency was statistically significantly different between fertile and infertile men. We found that polymorphism rs2292596 (Pro185Ala) was statistically significantly associated with the risk of male infertility. In addition, the statistical difference became more significant when the frequency was compared between the Pro/Pro genotype and the Pro/Ala plus Ala/Ala genotype. The 185 Pro wild-type alleles of AhRR may be associated with the risk of male infertility. The proallele also may diminish inhibition of AhR-mediated signaling of exposure to environmental pollutants.

Suppression of dsRNA response genes and innate immunity following Oct4, Stella, and Nanos2 overexpression in mouse embryonic fibroblasts.

The self-renewal capacity of germline derived stem cells (GSCs) makes them an ideal source for research and use in clinics. Despite the presence of active gene network similarities between embryonic stem cells (ESCs) and GSCs, there are unanswered questions regarding the roles of evolutionary conserved genes in GSCs. To determine the reprogramming potential of germ cell- specific genes, we designed a polycistronic gene cassette expressing Stella, Oct4 and Nanos2 in a lentiviral-based vector. Deep transcriptome analysis showed the activation of a set of pluripotency and germ-cell-specific markers and the downregulation of innate immune system. The global shut down of antiviral genes included MHC class I, interferon response genes and dsRNA 2'-5'-oligoadenylate synthetase are critical pathways that has been affected . Individual expression of each factor highlighted suppressive effect of Nanos2 on genes such as Isg15 and Oasl2. Collectively, to our knowledge this is the first report showing that Nanos2 could be considered as an immunosuppressive factor. Furthermore, our results demonstrate suppression of endogenous retrotransposons that harbor immune response but further analysis require to uncover the correlation between transposon suppression and immune response in germ cell development.

Lentiviral-mediated BCL2 gene knockdown using comparative microRNA adaptive shRNAs.

B-cell lymphoma 2 (BCL2) family proteins play a critical role in tuning cell death processes. Almost in half of all human cancers, a dysregulation in BCL2 family gene expression has been shown which made it an impressive target for human gene therapy as a novel approach in cancers. In this study we will optimize lentiviral-mediated RNA interference (RNAi), recombinant lentiviruses accommodating anti-BCL2 micro adaptive short hairpin RNAs (shRNAs), to downregulate BCL2 in human embryonic kidney 293T (HEK293T) cells to produce stable cell lines. We tested 4 different Dharmacon™ GIPZ™ shRNAmir lentiviral vectors targeting BCL2 in different positions and a pGIPZ non-silencing shRNAmir lentiviral vector (as a negative control). Lentivirus packaging was performed by the calcium phosphate precipitation method. HEK293T cells were transduced by each type of recombinant lentiviruses individually and selected by puromycin within 10 days. The relative mRNA level and protein expression were assayed by using real-time polymerase chain reaction (PCR) technic and western blotting, respectively. Lentivirus (LV) packaging was performed in high efficiency (transfection rate was > 90%). Recombinant viruses of 4 expression vector addition to a control vector were produced then transduced to HEK293T cells successfully. All the 4 cell groups showed a significant down regulation of BCL2 gene (~90-95%) at mRNA level compared to the control group (p<0.01) but differences between silenced groups were not significant (P > 0.05). We showed that the lentivirus-mediated RNAi technique is an efficient method to establish HEK293 cell lines with stable down-regulation of BCL2 gene.

A lentiviral vaccine expressing KMP11-HASPB fusion protein increases immune response to Leishmania major in BALB/C.

Hydrophilic acylated surface protein B (HASPB) is an immunogenic Leishmania-specific protein that antibodies are produced against it in the sera of Leishmania-infected individuals. Kinetoplastid membrane protein 11 (KMP11) is another Leishmania antigen and considered as the suitable candidate for vaccine development Leishmaniasis. It is a highly conserved surface protein expressed in both promastigotes and amastigotes. In this study, KMP11 and HASPB coding sequences were cloned into a pCDH-cGFP lentiviral vector as a fusion protein to be used as a DNA vaccine against L. major. The KMP11-HASPB fusion protein was successfully expressed as evidenced by RT-PCR and Western blot assays. The effect of the vaccine was determined by evaluating the level of IFN-γ, IL-10, IgG1, and IgG2a performed using ELISA as well as determining the parasite load after challenge with L. major in vaccinated mice. The results revealed that IFN-γ, IL-10, IgG1, and IgG2a significantly increased after vaccination using KMP11-HASPB-expressing lentiviruses in BALB/c mice. It is noteworthy that the level of IFN-γ and IgG2a was higher than that of IL-10 and IgG1, respectively, which indicates the activation Th1 cells, macrophages, and cellular immunity. Moreover, the parasite load in the spleen and lymph node of vaccinated mice after challenge was significantly lower than that of controls.

Evaluation of AD-MSC (adipose-derived mesenchymal stem cells) as a vehicle for IFN-ß delivery in experimental autoimmune encephalomyelitis.

Interferon-ß (IFN-ß) is commonly used as a disease modifying drug for the treatment of relapse-remitting multiple sclerosis (RR-MS). However, the underlying mechanism by which IFN-ß mediate this immunosuppressive effect is still unknown. In this study, we analyzed the effects of genetically modified adipose-derived mesenchymal stem cells (AD-MSCs) expressing murine interferon beta (MSCs-VP/IFN-ß) on the animal model of MS, experimental autoimmune encephalomyelitis (EAE). Lymph node mononuclear cells and serum were examined by using RT-PCR and ELISA methods to measure the production of IL-10 and IL-17 gene and protein expression, respectively. Our results indicated that in the MSCs-VP/IFN-ß treated group induction of Tregs and IL-10 and reduction of IL-17 were significant. Taken together, we showed that using AD-MSCs expressing IFN-ß as an anti-inflammatory agent, offer evidence supporting that the stem cell therapies in EAE conceivably will improve the valuable effects of IFN-ß in this autoimmune disease.

Bypassing the need for pre-sensitization of cancer cells for anticancer TRAIL therapy with secretion of novel cell penetrable form of Smac from hA-MSCs as cellular delivery vehicle.

TNF-related apoptosis inducing ligand (TRAIL) is a novel anticancer agent with selective apoptosis-inducing activity on cancer cells. However, many malignant tumors still remain unresponsive. Although cells can bypass apoptosis by different functions, the defect in the blocking role of second mitochondria-derived activator of caspase (Smac) on X-linked inhibitor of apoptosis protein (XIAP) is known to be an important hub for immortal characteristic of malignant cells. Actually, XIAP is known as an apoptosis inhibitor. To date, the sensitization of cancerous cells to TRAIL was successfully performed with different protocols, mainly through blocking XIAP with Smac administration. However, all these sensitization methodologies need to be performed prior to TRAIL administration on cancerous cells which in turn limit their practical application in clinics. Therefore, we hypothesized that concurrent expression of Smac and TRAIL on human adipose-derived mesenchymal stem cells (hA-MSC-ST) could both sensitize and destroy cancerous cells. To this aim, we generated hA-MSC-ST, secreting a novel cell penetrable form of Smac and a trimeric form of TRAIL. Indeed, the cell penetrable form of Smac obviates the need for any pretreatment of cancerous cells. Our data depicted that individual overexpression of TRAIL or Smac in different breast cancer cell types induced limited or no apoptosis, respectively. Conversely, their concomitant overexpression markedly increased cell death even for a resistant type of breast cancer cells, MCF-7. Notably, we observed no cytotoxicity of our methodology on normal cells. In summary, this is the first demonstration that a dual approach using simultaneous overexpression of a cell penetrable form of Smac and TRAIL sensitize and promote apoptotic process even in resistant breast cancer cells.

Microscopic prediction of speech intelligibility in spatially distributed speech-shaped noise for normal-hearing listeners.

A binaural and psychoacoustically motivated intelligibility model, based on a well-known monaural microscopic model is proposed. This model simulates a phoneme recognition task in the presence of spatially distributed speech-shaped noise in anechoic scenarios. In the proposed model, binaural advantage effects are considered by generating a feature vector for a dynamic-time-warping speech recognizer. This vector consists of three subvectors incorporating two monaural subvectors to model the better-ear hearing, and a binaural subvector to simulate the binaural unmasking effect. The binaural unit of the model is based on equalization-cancellation theory. This model operates blindly, which means separate recordings of speech and noise are not required for the predictions. Speech intelligibility tests were conducted with 12 normal hearing listeners by collecting speech reception thresholds (SRTs) in the presence of single and multiple sources of speech-shaped noise. The comparison of the model predictions with the measured binaural SRTs, and with the predictions of a macroscopic binaural model called extended equalization-cancellation, shows that this approach predicts the intelligibility in anechoic scenarios with good precision. The square of the correlation coefficient (r(2)) and the mean-absolute error between the model predictions and the measurements are 0.98 and 0.62 dB, respectively.

Mechanisms of hippocampal astrocytes mediation of spatial memory and theta rhythm by gliotransmitters and growth factors.

Our knowledge about encoding and maintenance of spatial memory emphasizes the integrated functional role of the grid cells and the place cells of the hippocampus in the generation of theta rhythm in spatial memory formation. However, the role of astrocytes in these processes is often underestimated in their contribution to the required structural and functional characteristics of hippocampal neural network operative in spatial memory. We show that hippocampal astrocytes, by the secretion of gliotransmitters, such as glutamate, d-serine, and ATP and growth factors such as BDNF and by the expression of receptors and channels such as those of TNFα and aquaporin, have several diverse fuctions in spatial memory. We specifically focus on the role of astrocytes on five phases of spatial memory: (1) theta rhythm generation, (2) theta phase precession, (3) formation of spatial memory by mapping data of entorhinal grid cells into the place cells, (4) storage of spatial information, and (5) maintenance of spatial memory. Finally, by reviewing the literature, we propose specific mechanisms mentioned in the form of a hypothesis suggesting that astrocytes are important in spatial memory formation.

Decoding temporal muscle synergy patterns based on brain activity for upper extremity in ADL movements.

Muscle synergies have been hypothesized as specific predefined motor primitives that the central nervous system can reduce the complexity of motor control by using them, but how these are expressed in brain activity is ambiguous yet. The main purpose of this paper is to develop synergy-based neural decoding of motor primitives, so for the first time, brain activity and muscle synergy map of the upper extremity was investigated in the activity of daily living movements. To find the relationship between brain activities and muscle synergies, electroencephalogram (EEG) and electromyogram (EMG) signals were acquired simultaneously during activities of daily living. To extract the maximum correlation of neural commands with muscle synergies, application of a combined partial least squares and canonical correlation analysis (PLS-CCA) method was proposed. The Elman neural network was used to decode the relationship between extracted motor commands and muscle synergies. The performance of proposed method was evaluated with tenfold cross-validation and muscle synergy estimation of brain activity with R, VAF, and MSE of 84 ± 2.6%, 70 ± 4.7%, and 0.00011 ± 0.00002 were quantified respectively. Furthermore, the similarity between actual and reconstructed muscle activations was achieved more than 92% for correlation coefficient. To compare with the existing methods, our results showed significantly more accuracy of the model performance. Our results confirm that use of the expression of muscle synergies in brain activity can estimate the neural decoding performance for motor control that can be used to develop neurorehabilitation tools such as neuroprosthesis.

In Vitro Evaluation of Pore Size Graded Bone Scaffolds with Different Material Composition.

The demand for biomimetic and biocompatible scaffolds in equivalence of structure and material composition for the regeneration of bone tissue is relevantly high. This article is investigating a novel three-dimensional (3D) printed porous structure called bone bricks with a gradient pore size mimicking the structure of the bone tissue. Poly-ɛ-caprolactone (PCL) combined with ceramics such as hydroxyapatite (HA), ß-tricalcium phosphate (TCP), and bioglass 45S5 were successfully mixed using a melt blending method and fabricated with the use of screw-assisted extrusion-based additive manufacturing system. Bone bricks containing the same material concentration (20 wt%) were biologically characterized through proliferation and differentiation tests. Scanning electron microscopy (SEM) was used to investigate the morphology of cells on the surface of bone bricks, whereas energy dispersive X-ray (EDX) spectroscopy was used to investigate the element composition on the surface of the bone bricks. Confocal imaging was used to investigate the number of differentiated cells on the surface of bone bricks. Proliferation results showed that bone bricks containing PCL/HA content are presenting higher proliferation properties, whereas differentiation results showed that bone bricks containing PCL/Bioglass 45S5 are presenting higher differentiation properties. Confocal imaging results showed that bone bricks containing PCL/Bioglass 45S5 are presenting a higher number of differentiated cells on their surface compared with the other material contents.

Evidence for crossing the blood barrier of adult rat brain by human adipose-derived mesenchymal stromal cells during a 6-month period of post-transplantation.

BACKGROUND AIMS: Therapeutic promises of adult stem cells have been overshadowed by an elicited immune response, low maintenance of implanted cells or concerns regarding their migration to non-target sites. These problems might be lessened by the use of immune privilege cells and tissues for implantation. METHODS: In this study, human adipose-derived mesenchymal stromal cells (hADMSCs) were stably transfected with a vector containing Turbo green fluorescent protein (GFP) and JRed, which allows tracing the cells after transplantation. Labeled hADMSCs were transplanted into the adult rat brain followed by assessment of their survival and migration during 6 months after transplantation. RESULTS: Results indicate that there were no postsurgical complications, and the animals thrived after transplantation. The lesions of the surgical process were remarkable at the first weeks, and a high number of transplanted cells were accumulated around them. Cell populations declined over time as they partly migrated away from the injection sites; nonetheless, they were detectable at each examination time point. Although the cells could survive and remain at the injection site for up to 6 months, some of them drifted to spleen, which is an indication of their ability to cross the blood-brain barrier. CONCLUSIONS: Despite the high survival rate of hADMSCs in the xenogenic condition, which is an ideal criterion in cell therapy, irregular migration tendency must be handled with caution.

Brain Connectivity Estimation Pitfall in Multiple Trials of Electroencephalography Data.

Introduction: The electroencephalography signal is well suited to calculate brain connectivity due to its high temporal resolution. When the purpose is to compute connectivity from multi-trial electroencephalography (EEG) data, confusion arises about how these trials involved in calculating the connectivity. The purpose of this paper is to study this confusing issue using simulated and experimental data. Methods: To this end, Granger causality-based connectivity measures were considered. Using simulations, two signals were generated with known AR (auto-regressive) coefficients and then simple multivariate autoregressive (MVAR) models based on different numbers of trials were extracted. For accurate estimation of the MVAR model, the data samples should be sufficient. Two Granger causality-based connectivity, granger causality (GC) and Partial directed coherence (PDC) were estimated. Results: Estimating connectivity corresponding to small trial numbers (5 and 10 trials) resulted in an average value of connectivity that is significantly higher and also more variable over different estimates. By increasing the number of trials, the MVAR model has fitted more appropriately to the data and the connectivity values were converged. This procedure was implemented on real EEG data. The obtained results agreed well with the findings of simulated data. Conclusion: The results showed that the brain connectivity should calculate for each trial, and then average the connectivity values on all trials. Also, the larger the trial numbers, the MVAR model has fitted more appropriately to the data, and connectivity estimations are more reliable. Highlights: The average of connectivity values on trials is considered brain connectivity.Connectivity estimations are more reliable for larger trial numbers.Estimations of connectivity for small trial numbers are not valid. Plain Language Summary: Several different techniques can be utilized to evaluate brain connectivity such as functional magnetic resonance imaging (fMRI), magnetoencephalography (MEG), electroencephalography (EEG) and etc. Connectivity estimation methods are associated with computing the correspondence of neural signals over time, therefore modalities such as EEG due to their fine temporal resolution are well suited to calculate such connectivity. When the purpose is to compute connectivity from multi-trial data, confusion arises about how these trials and how many trials are involved in calculating the connectivity. During calculating brain connectivity from data with many observation epochs, the question arises whether brain connectivity is calculated for each trial and then average or for the averaged trials. The target of this paper is to study the abovementioned issue using simulated data and realistic EEG data. Our analysis indicated that the brain connectivity should calculate for each trial, and then average the connectivity values on all trials. It was also found that estimating connectivity corresponding to small trial numbers resulted in an average value of connectivity that is significantly higher and also more variable over different estimates and is not valid. These findings can help us in the correct estimation of brain connectivity.

Design and 3D Printing of Personalized Hybrid and Gradient Structures for Critical Size Bone Defects.

Treating critical-size bone defects with autografts, allografts, or standardized implants is challenging since the healing of the defect area necessitates patient-specific grafts with mechanically and physiologically relevant structures. Three-dimensional (3D) printing using computer-aided design (CAD) is a promising approach for bone tissue engineering applications by producing constructs with customized designs and biomechanical compositions. In this study, we propose 3D printing of personalized and implantable hybrid active scaffolds with a unique architecture and biomaterial composition for critical-size bone defects. The proposed 3D hybrid construct was designed to have a gradient cell-laden poly(ethylene glycol) (PEG) hydrogel, which was surrounded by a porous polycaprolactone (PCL) cage structure to recapitulate the anatomical structure of the defective area. The optimized PCL cage design not only provides improved mechanical properties but also allows the diffusion of nutrients and medium through the scaffold. Three different designs including zigzag, zigzag/spiral, and zigzag/spiral with shifting the zigzag layers were evaluated to find an optimal architecture from a mechanical point of view and permeability that can provide the necessary mechanical strength and oxygen/nutrient diffusion, respectively. Mechanical properties were investigated experimentally and analytically using finite element analysis (FEA), and computational fluid dynamics (CFD) simulation was used to determine the permeability of the structures. A hybrid scaffold was fabricated via 3D printing of the PCL cage structure and a PEG-based bioink comprising a varying number of human bone marrow mesenchymal stem cells (hBMSCs). The gradient bioink was deposited inside the PCL cage through a microcapillary extrusion to generate a mineralized gradient structure. The zigzag/spiral design for the PCL cage was found to be mechanically strong with sufficient and optimum nutrient/gas axial and radial diffusion while the PEG-based hydrogel provided a biocompatible environment for hBMSC viability, differentiation, and mineralization. This study promises the production of personalized constructs for critical-size bone defects by printing different biomaterials and gradient cells with a hybrid design depending on the need for a donor site for implantation.

Accelerated Degradation of Poly-ε-caprolactone Composite Scaffolds for Large Bone Defects.

This research investigates the accelerated hydrolytic degradation process of both anatomically designed bone scaffolds with a pore size gradient and a rectangular shape (biomimetically designed scaffolds or bone bricks). The effect of material composition is investigated considering poly-ε-caprolactone (PCL) as the main scaffold material, reinforced with ceramics such as hydroxyapatite (HA), ß-tricalcium phosphate (TCP) and bioglass at a concentration of 20 wt%. In the case of rectangular scaffolds, the effect of pore size (200 µm, 300 µm and 500 µm) is also investigated. The degradation process (accelerated degradation) was investigated during a period of 5 days in a sodium hydroxide (NaOH) medium. Degraded bone bricks and rectangular scaffolds were measured each day to evaluate the weight loss of the samples, which were also morphologically, thermally, chemically and mechanically assessed. The results show that the PCL/bioglass bone brick scaffolds exhibited faster degradation kinetics in comparison with the PCL, PCL/HA and PCL/TCP bone bricks. Furthermore, the degradation kinetics of rectangular scaffolds increased by increasing the pore size from 500 µm to 200 µm. The results also indicate that, for the same material composition, bone bricks degrade slower compared with rectangular scaffolds. The scanning electron microscopy (SEM) images show that the degradation process was faster on the external regions of the bone brick scaffolds (600 µm pore size) compared with the internal regions (200 µm pore size). The thermal gravimetric analysis (TGA) results show that the ceramic concentration remained constant throughout the degradation process, while differential scanning calorimetry (DSC) results show that all scaffolds exhibited a reduction in crystallinity (Xc), enthalpy (Δm) and melting temperature (Tm) throughout the degradation process, while the glass transition temperature (Tg) slightly increased. Finally, the compression results show that the mechanical properties decreased during the degradation process, with PCL/bioglass bone bricks and rectangular scaffolds presenting higher mechanical properties with the same design in comparison with the other materials.

Rhabdomyosarcoma: Current Therapy, Challenges, and Future Approaches to Treatment Strategies.

Rhabdomyosarcoma is a rare cancer arising in skeletal muscle that typically impacts children and young adults. It is a worldwide challenge in child health as treatment outcomes for metastatic and recurrent disease still pose a major concern for both basic and clinical scientists. The treatment strategies for rhabdomyosarcoma include multi-agent chemotherapies after surgical resection with or without ionization radiotherapy. In this comprehensive review, we first provide a detailed clinical understanding of rhabdomyosarcoma including its classification and subtypes, diagnosis, and treatment strategies. Later, we focus on chemotherapy strategies for this childhood sarcoma and discuss the impact of three mechanisms that are involved in the chemotherapy response including apoptosis, macro-autophagy, and the unfolded protein response. Finally, we discuss in vivo mouse and zebrafish models and in vitro three-dimensional bioengineering models of rhabdomyosarcoma to screen future therapeutic approaches and promote muscle regeneration.