Embryonic stem cell-derived microvesicles reprogram hematopoietic progenitors: evidence for horizontal transfer of mRNA and protein delivery

Membrane-derived vesicles (MV) are released from the surface of activated eucaryotic cells and exert pleiotropic effects on surrounding cells. Since the maintenance of pluripotency and undifferentiated propagation of embryonic stem (ES) cells in vitro requires tight cell to cell contacts and effective intercellular signaling, we hypothesize that MV derived from ES cells (ES-MV) express stem cell-specific molecules that may also support self-renewal and expansion of adult stem cells. To address this hypothesis, we employed expansion of hematopoietic progenitor cells (HPC) as a model. We found that ES-MV (10 microg/ml) isolated from murine ES cells (ES-D3) in serum-free cultures significantly (i) enhanced survival and improved expansion of murine HPC, (ii) upregulated the expression of early pluripotent (Oct-4, Nanog and Rex-1) and early hematopoietic stem cells (Scl, HoxB4 and GATA 2) markers in these cells, and (iii) induced phosphorylation of MAPK p42/44 and serine-threonine kinase AKT. Furthermore, molecular analysis revealed that ES-MV express Wnt-3 protein and are selectively highly enriched in mRNA for several pluripotent transcription factors as compared to parental ES cells. More important, this mRNA could be delivered by ES-MV to target cells and translated into the corresponding proteins. The biological effects of ES-MV were inhibited after heat inactivation or pretreatment with RNAse, indicating a major involvement of protein and mRNA components of ES-MV in the observed phenomena. We postulate that ES-MV may efficiently expand HPC by stimulating them with ES-MV expressed ligands (e.g., Wnt-3) as well as increase their pluripotency after horizontal transfer of ES-derived mRNA.

Exacerbation of substrate toxicity by IPTG in Escherichia coli BL21(DE3) carrying a synthetic metabolic pathway

BACKGROUND

Heterologous expression systems based on promoters inducible with isopropyl-β-D-1-thiogalactopyranoside (IPTG), e.g., Escherichia coli BL21(DE3) and cognate LacI(Q)/P(lacUV5)-T7 vectors, are commonly used for production of recombinant proteins and metabolic pathways. The applicability of such cell factories is limited by the complex physiological burden imposed by overexpression of the exogenous genes during a bioprocess. This burden originates from a combination of stresses that may include competition for the expression machinery, side-reactions due to the activity of the recombinant proteins, or the toxicity of their substrates, products and intermediates. However, the physiological impact of IPTG-induced conditional expression on the recombinant host under such harsh conditions is often overlooked.

RESULTS

The physiological responses to IPTG of the E. coli BL21(DE3) strain and three different recombinants carrying a synthetic metabolic pathway for biodegradation of the toxic anthropogenic pollutant 1,2,3-trichloropropane (TCP) were investigated using plating, flow cytometry, and electron microscopy. Collected data revealed unexpected negative synergistic effect of inducer of the expression system and toxic substrate resulting in pronounced physiological stress. Replacing IPTG with the natural sugar effector lactose greatly reduced such stress, demonstrating that the effect was due to the original inducer's chemical properties.

CONCLUSIONS

IPTG is not an innocuous inducer; instead, it exacerbates the toxicity of haloalkane substrate and causes appreciable damage to the E. coli BL21(DE3) host, which is already bearing a metabolic burden due to its content of plasmids carrying the genes of the synthetic metabolic pathway. The concentration of IPTG can be effectively tuned to mitigate this negative effect. Importantly, we show that induction with lactose, the natural inducer of P lac , dramatically lightens the burden without reducing the efficiency of the synthetic TCP degradation pathway. This suggests that lactose may be a better inducer than IPTG for the expression of heterologous pathways in E. coli BL21(DE3).

Pathways and mechanisms for product release in the engineered haloalkane dehalogenases explored using classical and random acceleration molecular dynamics simulations

Eight mutants of the DhaA haloalkane dehalogenase carrying mutations at the residues lining two tunnels, previously observed by protein X-ray crystallography, were constructed and biochemically characterized. The mutants showed distinct catalytic efficiencies with the halogenated substrate 1,2,3-trichloropropane. Release pathways for the two dehalogenation products, 2,3-dichloropropane-1-ol and the chloride ion, and exchange pathways for water molecules, were studied using classical and random acceleration molecular dynamics simulations. Five different pathways, denoted p1, p2a, p2b, p2c, and p3, were identified. The individual pathways showed differing selectivity for the products: the chloride ion releases solely through p1, whereas the alcohol releases through all five pathways. Water molecules play a crucial role for release of both products by breakage of their hydrogen-bonding interactions with the active-site residues and shielding the charged chloride ion during its passage through a hydrophobic tunnel. Exchange of the chloride ions, the alcohol product, and the waters between the buried active site and the bulk solvent can be realized by three different mechanisms: (i) passage through a permanent tunnel, (ii) passage through a transient tunnel, and (iii) migration through a protein matrix. We demonstrate that the accessibility of the pathways and the mechanisms of ligand exchange were modified by mutations. Insertion of bulky aromatic residues in the tunnel corresponding to pathway p1 leads to reduced accessibility to the ligands and a change in mechanism of opening from permanent to transient. We propose that engineering the accessibility of tunnels and the mechanisms of ligand exchange is a powerful strategy for modification of the functional properties of enzymes with buried active sites.

High molecular weight FGF2: the biology of a nuclear growth factor

Fibroblast growth factor 2 (FGF2) is one of the most studied growth factors to date. Most attention has been dedicated to the smallest, 18 kDa FGF2 variant that is released by cells and acts through activation of cell-surface FGF-receptor tyrosine kinases. There are, however, several higher molecular weight (HMW) variants of FGF2 that rarely leave their producing cells, are retained in the nucleus and act independently of FGF-receptors (FGFR). Despite significant evidence documenting the expression and intracellular trafficking of HMW FGF2, many important questions remain about the physiological roles and mechanisms of action of HMW FGF2. In this review, we summarize the current knowledge about the biology of HMW FGF2, its role in disease and areas for future investigation.

Computer-assisted engineering of hyperstable fibroblast growth factor 2

Fibroblast growth factors (FGFs) serve numerous regulatory functions in complex organisms, and their corresponding therapeutic potential is of growing interest to academics and industrial researchers alike. However, applications of these proteins are limited due to their low stability. Here we tackle this problem using a generalizable computer-assisted protein engineering strategy to create a unique modified FGF2 with nine mutations displaying unprecedented stability and uncompromised biological function. The data from the characterization of stabilized FGF2 showed a remarkable prediction potential of in silico methods and provided insight into the unfolding mechanism of the protein. The molecule holds a considerable promise for stem cell research and medical or pharmaceutical applications.

Energy and dose rate dependence of BANG-2 polymer-gel dosimeter

The purpose of this study was to evaluate dependence of BANG-2 polymer-gel dosimeter sensitivity on different photon and electron energies as well as on different mean dose rates expressed as repetition rates for a standard clinically used linear accelerator. The sensitivity of the dosimeter was represented by the slope of calibration curve in the linear region measured for each modality. A calibration curve (in the linear region) based on five dosimeters (four irradiated and one background) was obtained for each photon and electron energy and different repetition rates. Dosimeter sensitivity dependence on energy was studied for 4, 6, and 18 MV x-ray photons and for nominal electron energies 9, 12, 16, and 20 MeV. Dosimeter sensitivity dependence on mean dose rate was separately studied for electron and photon beams with the use of repetition rates 80, 160, 240, 320, and 400 MU min(-1). Evaluation of dosimeters was performed on Siemens MAGNETOM EXPERT 1T scanner in the head coil. A multiecho sequence with 16 equidistant echoes was used for the evaluation of irradiated polymer-gel dosimeters. The parameters of the sequence were as follows: TR 2000 ms, TE 22.5-360.0 ms, slice thickness 5 mm, FOV 255 mm, one acquisition. There was observed a trend in polymer-gel dosimeter sensitivity dependence on the quality index of high energy x-ray beams used and on mean electron energy absorbed in the center of the dosimeter. Polymer-gel dosimeter sensitivity was decreasing with increasing photon or electron energy. There was observed no trend in polymer-gel dosimeter sensitivity dependence on mean dose rate expressed as a repetition rate for both photon and electron beams.

Computer-assisted engineering of the synthetic pathway for biodegradation of a toxic persistent pollutant

Anthropogenic halogenated compounds were unknown to nature until the industrial revolution, and microorganisms have not had sufficient time to evolve enzymes for their degradation. The lack of efficient enzymes and natural pathways can be addressed through a combination of protein and metabolic engineering. We have assembled a synthetic route for conversion of the highly toxic and recalcitrant 1,2,3-trichloropropane to glycerol in Escherichia coli, and used it for a systematic study of pathway bottlenecks. Optimal ratios of enzymes for the maximal production of glycerol, and minimal toxicity of metabolites were predicted using a mathematical model. The strains containing the expected optimal ratios of enzymes were constructed and characterized for their viability and degradation efficiency. Excellent agreement between predicted and experimental data was observed. The validated model was used to quantitatively describe the kinetic limitations of currently available enzyme variants and predict improvements required for further pathway optimization. This highlights the potential of forward engineering of microorganisms for the degradation of toxic anthropogenic compounds.

Association of ABC gene profiles with time to progression and resistance in ovarian cancer revealed by bioinformatics analyses

Introduction

Ovarian cancer (OC) represents a serious disease with high mortality and lack of efficient predictive and prognostic biomarkers. ATP‐binding cassette (ABC) proteins constitute a large family dedicated to active transmembrane transport including transport of xenobiotics.

Materials and methods

mRNA level was measured by quantitative RT‐PCR in tumor tissues from OC patients. Bioinformatics analyses were applied to two gene expression datasets (60 primary tumors and 29 peritoneal metastases). Two different approaches of expression data normalization were applied in parallel, and their results were compared. Data from publically available cancer datasets were checked to further validate our conclusions.

Results

The results showed significant connections between ABC gene expression profiles and time to progression (TTP), chemotherapy resistance, and metastatic progression in OC. Two consensus ABC gene profiles with clinical meaning were documented. (a) Downregulation of ABCC4, ABCC10, ABCD3, ABCE1, ABCF1, ABCF2, and ABCF3 was connected with the best sensitivity to chemotherapy and TTP. (b) Oppositely, downregulation of ABCB11 and upregulation of ABCB1 and ABCG2 were connected with the worst sensitivity to chemotherapy and TTP. Results from publicly available online databases supported our conclusions.

Conclusion

This study stressed the connection between two well‐documented ABC genes and clinicopathological features—ABCB1 and ABCG2. Moreover, we showed a comparable connection also for several other ABC genes—ABCB11, ABCC4, ABCC10, ABCD3,ABCE1, ABCF1, ABCF2, and ABCF3. Our results add new clinically relevant information to this oncology field and can stimulate further exploration.

Immobilized synthetic pathway for biodegradation of toxic recalcitrant pollutant 1,2,3-trichloropropane

The anthropogenic compound 1,2,3-trichloropropane (TCP) has recently drawn attention as an emerging groundwater contaminant. No living organism, natural or engineered, is capable of the efficient aerobic utilization of this toxic industrial waste product. We describe a novel biotechnology for transforming TCP based on an immobilized synthetic pathway. The pathway is composed of three enzymes from two different microorganisms: engineered haloalkane dehalogenase from Rhodococcus rhodochrous NCIMB 13064, and haloalcohol dehalogenase and epoxide hydrolase from Agrobacterium radiobacter AD1. Together, they catalyze consecutive reactions converting toxic TCP to harmless glycerol. The pathway was immobilized in the form of purified enzymes or cell-free extracts, and its performance was tested in batch and continuous systems. Using a packed bed reactor filled with the immobilized biocatalysts, 52.6 mmol of TCP was continuously converted into glycerol within 2.5 months of operation. The efficiency of the TCP conversion to the intermediates was 97%, and the efficiency of conversion to the final product glycerol was 78% during the operational period. Immobilized biocatalysts are suitable for removing TCP from contaminated water up to a 10 mM solubility limit, which is an order of magnitude higher than the concentration tolerated by living microorganisms.

Impact of IMRT and leaf width on stereotactic body radiotherapy of liver and lung lesions

PURPOSE

The present study explored the impact of intensity-modulated radiotherapy (IMRT) on stereotactic body RT (SBRT) of liver and lung lesions. Additionally, because target dose conformity can be affected by the leaf width of a multileaf collimator (MLC), especially for small targets and stereotactic applications, the use of a micro-MLC on "uniform intensity" conformal and intensity-modulated SBRT was evaluated.

METHODS AND MATERIALS

The present study included 10 patients treated previously with SBRT in our institution (seven lung and three liver lesions). All patients were treated with 3 x 12 Gy prescribed to the 65% isodose level. The actual MLC-based conformal treatment plan served as the standard for additional comparison. In total, seven alternative treatment plans were made for each patient: a standard (actual) plan and an IMRT plan, both calculated with Helax TMS (Nucletron) using a pencil beam model; and a recalculated standard and a recalculated IMRT plan on Helax TMS using a point dose kernel approach. These four treatment plans were based on a standard MLC with 1-cm leaf width. Additionally, the following micro-MLC (central leaf width 3 mm)-based treatment plans were calculated with the BrainSCAN (BrainLAB) system: standard, IMRT, and dynamic arc treatments. For each treatment plan, various target parameters (conformity, coverage, mean, maximal, and minimal target dose, equivalent uniform doses, and dose-volume histogram), as well as organs at risk parameters (3 Gy and 6 Gy volume, mean dose, dose-volume histogram) were evaluated. Finally, treatment efficiency was estimated from monitor units and the number of segments for IMRT solutions.

RESULTS

For both treatment planning systems, no significant difference could be observed in terms of target conformity between the standard and IMRT dose distributions. All dose distributions obtained with the micro-MLC showed significantly better conformity values compared with the standard and IMRT plans using a regular MLC. Dynamic arc plans were characterized by the steepest dose gradient and thus the smallest V(6 Gy) values, which were on average 7% smaller than the standard plans and 20% lower than the IMRT plans. Although the Helax TMS IMRT plans show about 18% more monitor units than the standard plan, BrainSCAN IMRT plans require approximately twice the number of monitor units relative to the standard plan. All treatment plans optimized with a pencil beam model but recalculated with a superposition method showed significant qualitative, as well as quantitative, differences, especially with respect to conformity and the dose to organs at risk.

CONCLUSION

Standard conformal treatment techniques for SBRT could not be improved with inversely planned IMRT approaches. Dose calculation algorithms applied in optimization modules for IMRT applications in the thoracic region need to be based on the most accurate dose calculation algorithms, especially when using higher energy photon beams.

ABC gene expression profiles have clinical importance and possibly form a new hallmark of cancer

Adenosine triphosphate-binding cassette proteins constitute a large family of active transporters through extracellular and intracellular membranes. Increased drug efflux based on adenosine triphosphate-binding cassette protein activity is related to the development of cancer cell chemoresistance. Several articles have focused on adenosine triphosphate-binding cassette gene expression profiles (signatures), based on the expression of all 49 human adenosine triphosphate-binding cassette genes, in individual tumor types and reported connections to established clinicopathological features. The aim of this study was to test our theory about the existence of adenosine triphosphate-binding cassette gene expression profiles common to multiple types of tumors, which may modify tumor progression and provide clinically relevant information. Such general adenosine triphosphate-binding cassette profiles could constitute a new attribute of carcinogenesis. Our combined cohort consisted of tissues from 151 cancer patients-breast, colorectal, and pancreatic carcinomas. Standard protocols for RNA isolation and quantitative real-time polymerase chain reaction were followed. Gene expression data from individual tumor types as well as a merged tumor dataset were analyzed by bioinformatics tools. Several general adenosine triphosphate-binding cassette profiles, with differences in gene functions, were established and shown to have significant relations to clinicopathological features such as tumor size, histological grade, or clinical stage. Genes ABCC7, A3, A8, A12, and C8 prevailed among the most upregulated or downregulated ones. In conclusion, the results supported our theory about general adenosine triphosphate-binding cassette gene expression profiles and their importance for cancer on clinical as well as research levels. The presence of ABCC7 (official symbol CFTR) among the genes with key roles in the profiles supports the emerging evidence about its crucial role in various cancers. Graphical abstract.

Temperature dependence of polymer-gel dosimeter nuclear magnetic resonance response

The purpose of this study was to find a physical-mathematical description capable to correct a polymer-gel dosimeter relaxation rate R2-dose response for different temperatures. Four different modifications of polymer-gel dosimeters were used in this study. Samples with polymer-gel dosimeter in glass test vessels were homogeneously irradiated by 60Co gamma photons. A multi-echo sequence with 16 equidistant echoes was used for evaluation of irradiated polymer-gel dosimeters. The sequence parameters were as follows: TR 2000 ms, TE 22.5-360.0 ms, slice thickness 5 mm, FOV 255 mm, one acquisition. The proposed description recommends to subtract R2 response of the nonirradiated dosimeter from the total R2-dose response. The relaxation rate for the irradiated dosimeter can be expressed as a function of temperature and dose. The temperature dependence has an exponential behavior in the measured range. The proposed description allows to correct the measured NMR R2-dose responses for different temperatures.

Maximizing the efficiency of multienzyme process by stoichiometry optimization

Multienzyme processes represent an important area of biocatalysis. Their efficiency can be enhanced by optimization of the stoichiometry of the biocatalysts. Here we present a workflow for maximizing the efficiency of a three-enzyme system catalyzing a five-step chemical conversion. Kinetic models of pathways with wild-type or engineered enzymes were built, and the enzyme stoichiometry of each pathway was optimized. Mathematical modeling and one-pot multienzyme experiments provided detailed insights into pathway dynamics, enabled the selection of a suitable engineered enzyme, and afforded high efficiency while minimizing biocatalyst loadings. Optimizing the stoichiometry in a pathway with an engineered enzyme reduced the total biocatalyst load by an impressive 56 %. Our new workflow represents a broadly applicable strategy for optimizing multienzyme processes.

CERVANTES: an international randomized trial of radical surgery followed by adjuvant (chemo) radiation versus no further treatment in patients with early-stage, intermediate-risk cervical cancer (CEEGOG-CX-05; ENGOT-CX16)

BACKGROUND

The role of adjuvant treatment in the intermediate-risk group of patients with early-stage cervical cancer is controversial and is supported by a single randomized Gynecologic Oncology Group (GOG) 92 study performed more than 20 years ago. Recent retrospective studies have shown excellent local control in this group of patients after radical surgery with no additional adjuvant treatment.

PRIMARY OBJECTIVE

To evaluate if adjuvant (chemo)radiation is associated with a survival benefit after radical surgery in patients with intermediate-risk cervical cancer.

STUDY HYPOTHESIS

Radical surgery alone is non-inferior to the combined treatment of radical surgery followed by adjuvant (chemo)radiation in disease-free survival in patients with intermediate-risk cervical cancer.

TRIAL DESIGN

This is a phase III, international, multicenter, randomized, non-inferiority trial in which patients with intermediate-risk cervical cancer will be randomized 1:1 into arm A, with no additional treatment after radical surgery, and arm B, receiving adjuvant external beam radiotherapy±brachytherapy ± concomitant chemotherapy. Patient data will be collected over 3 years post-randomization of the last enrolled patient for primary endpoint analysis or for 6 years for the overall survival analysis.

MAJOR INCLUSION/EXCLUSION CRITERIA

Patients with intermediate-risk early-stage cervical cancer (IB1-IIA), defined as lymph node-negative patients with a combination of negative prognostic factors (tumor size >4 cm; tumor size >2 cm and lymphovascular space invasion; deep stromal invasion >2/3; or tumor-free distance <3 mm) with squamous cell carcinoma or human papillomavirus (HPV)-related adenocarcinoma, are eligible for the trial.

PRIMARY ENDPOINT

Disease-free survival defined as time from randomization to recurrence diagnosis.

SAMPLE SIZE

514 patients from up to 90 sites will be randomized.

ESTIMATED DATES FOR COMPLETING ACCRUAL AND PRESENTING RESULTS

It is estimated that the accrual will be completed by 2027 (with 3 additional years of follow-up) and primary endpoint results will be published by 2031. Estimated trial completion is by 2034.

TRIAL REGISTRATION

NCT04989647.

Stereotactic Arrhythmia Radioablation (STAR): Assessment of cardiac and respiratory heart motion in ventricular tachycardia patients - A STOPSTORM.eu consortium review

AIM

To identify the optimal STereotactic Arrhythmia Radioablation (STAR) strategy for individual patients, cardiorespiratory motion of the target volume in combination with different treatment methodologies needs to be evaluated. However, an authoritative overview of the amount of cardiorespiratory motion in ventricular tachycardia (VT) patients is missing.

METHODS

In this STOPSTORM consortium study, we performed a literature review to gain insight into cardiorespiratory motion of target volumes for STAR. Motion data and target volumes were extracted and summarized.

RESULTS

Out of the 232 studies screened, 56 provided data on cardiorespiratory motion, of which 8 provided motion amplitudes in VT patients (n = 94) and 10 described (cardiac/cardiorespiratory) internal target volumes (ITVs) obtained in VT patients (n = 59). Average cardiac motion of target volumes was < 5 mm in all directions, with maximum values of 8.0, 5.2 and 6.5 mm in Superior-Inferior (SI), Left-Right (LR), Anterior-Posterior (AP) direction, respectively. Cardiorespiratory motion of cardiac (sub)structures showed average motion between 5-8 mm in the SI direction, whereas, LR and AP motions were comparable to the cardiac motion of the target volumes. Cardiorespiratory ITVs were on average 120-284% of the gross target volume. Healthy subjects showed average cardiorespiratory motion of 10-17 mm in SI and 2.4-7 mm in the AP direction.

CONCLUSION

This review suggests that despite growing numbers of patients being treated, detailed data on cardiorespiratory motion for STAR is still limited. Moreover, data comparison between studies is difficult due to inconsistency in parameters reported. Cardiorespiratory motion is highly patient-specific even under motion-compensation techniques. Therefore, individual motion management strategies during imaging, planning, and treatment for STAR are highly recommended.

Increased expression of fibroblast growth factor receptor 3 in CD34+ BCR-ABL+ cells from patients with chronic myeloid leukemia

Previously, we showed that expression of myeloma-associated (proto)oncogene fibroblast growth factor receptor 3 (FGFR-3) is increased in white blood cells from patients with chronic myeloid leukemia (CML). The abnormal expression was returned back to the normal levels as soon as these patients reconstituted their hematopoiesis following transplantation of allogeneic peripheral blood stem cells. The aims of this study were: (1) to define population(s) of cells overexpressing FGFR-3, and (2) to determine the expression of FGFR-3 during the clinical course of the disease. We show that the vast majority of FGFR-3 transcripts as well as FGFR-3 protein arise from CD34+ BCR-ABL+ cells. Although increased levels of FGFR-3 were found in majority of late chronic phase patients treated with interferon alpha or hydroxyurea, the expression of FGFR-3 was always lowered following treatment with BCR-ABL tyrosine kinase inhibitor STI571. Compared to unstimulated cells, high levels of FGFR-3 were also identified in CD34+ cells from granulocyte colony-stimulating factor-mobilized blood stem cell harvests from healthy donors, suggesting a potential growth factor-dependent basis for elevated expression of FGFR-3 in CML. These findings have implications for the involvement of FGFR-3 in malignant hematopoiesis and depict FGFR-3 tyrosine kinase in CD34+ leukemic cells as a possible target for tyrosine kinase inhibitors.