Mouse cortical organoids reveal key functions of p73 isoforms: TAp73 governs the establishment of the archetypical ventricular-like zones while DNp73 is central in the regulation of neural cell fate.

Introduction: Neurogenesis is tightly regulated in space and time, ensuring the correct development and organization of the central nervous system. Critical regulators of brain development and morphogenesis in mice include two members of the p53 family: p53 and p73. However, dissecting the in vivo functions of these factors and their various isoforms in brain development is challenging due to their pleiotropic effects. Understanding their role, particularly in neurogenesis and brain morphogenesis, requires innovative experimental approaches. Methods: To address these challenges, we developed an efficient and highly reproducible protocol to generate mouse brain organoids from pluripotent stem cells. These organoids contain neural progenitors and neurons that self-organize into rosette-like structures resembling the ventricular zone of the embryonic forebrain. Using this model, we generated organoids from p73-deficient mouse cells to investigate the roles of p73 and its isoforms (TA and DNp73) during brain development. Results and Discussion: Organoids derived from p73-deficient cells exhibited increased neuronal apoptosis and reduced neural progenitor proliferation, linked to compensatory activation of p53. This closely mirrors previous in vivo observations, confirming that p73 plays a pivotal role in brain development. Further dissection of p73 isoforms function revealed a dual role of p73 in regulating brain morphogenesis, whereby TAp73 controls transcriptional programs essential for the establishment of the neurogenic niche structure, while DNp73 is responsible for the precise and timely regulation of neural cell fate. These findings highlight the distinct roles of p73 isoforms in maintaining the balance of neural progenitor cell biology, providing a new understanding of how p73 regulates brain morphogenesis.

Mesenchymal stromal cell therapy for COVID-19 acute respiratory distress syndrome: a double-blind randomised controlled trial.

Mesenchymal stromal cells (MSC) have immunomodulatory and tissue-regenerative properties and have shown promising results in acute respiratory distress syndrome (ARDS) of multiple causes, including COVID-19. We conducted a randomised (1:1), placebo-controlled, double-blind clinical trial to assess the efficacy and safety of one bone marrow-derived MSC infusion in twenty patients with moderate to severe ARDS caused by COVID-19. The primary endpoint (increase in PaO2/FiO2 ratio from baseline to day 7, MSC 83.3 versus placebo 57.6) was not statistically significant, although a clinical improvement at day 7 in the WHO scale was observed in MSC patients (5, 50% vs 0, 0%, p = 0.033). Median time to discontinuation of supplemental oxygen was also shorter in the experimental arm (14 versus 23 days, p = 0.007), resulting in a shorter hospital stay (17.5 versus 28 days, p = 0.042). No significant differences were observed for other efficacy or safety secondary endpoints. No infusion or treatment-related serious adverse events occurred during the one-year follow-up. This study did not meet the primary endpoint of PaO2/FiO2 increase by day 7, although it suggests that MSC are safe in COVID-19 ARDS and may accelerate patients' clinical recovery and hospital discharge. Larger studies are warranted to elucidate their role in ARDS and other inflammatory lung disorders.Trial Registration: EudraCT Number: 2020-002193-27, registered on July 14th, 2020, https://www.clinicaltrialsregister.eu/ctr-search/trial/2020-002193-27/ES . NCT number: NCT04615429, registered on November 4th, 2020, https://clinicaltrials.gov/ct2/show/NCT04615429 .

An ERK5-KLF2 signalling module regulates early embryonic gene expression and telomere rejuvenation in stem cells.

The ERK5 MAP kinase signalling pathway drives transcription of naïve pluripotency genes in mouse Embryonic Stem Cells (mESCs). However, how ERK5 impacts on other aspects of mESC biology has not been investigated. Here, we employ quantitative proteomic profiling to identify proteins whose expression is regulated by the ERK5 pathway in mESCs. This reveals a function for ERK5 signalling in regulating dynamically expressed early embryonic 2-cell stage (2C) genes including the mESC rejuvenation factor ZSCAN4. ERK5 signalling and ZSCAN4 induction in mESCs increases telomere length, a key rejuvenative process required for prolonged culture. Mechanistically, ERK5 promotes ZSCAN4 and 2C gene expression via transcription of the KLF2 pluripotency transcription factor. Surprisingly, ERK5 also directly phosphorylates KLF2 to drive ubiquitin-dependent degradation, encoding negative feedback regulation of 2C gene expression. In summary, our data identify a regulatory module whereby ERK5 kinase and transcriptional activities bi-directionally control KLF2 levels to pattern 2C gene transcription and a key mESC rejuvenation process.

Double-blind, randomized, controlled, trial to assess the efficacy of allogenic mesenchymal stromal cells in patients with acute respiratory distress syndrome due to COVID-19 (COVID-AT): A structured summary of a study protocol for a randomised controlled trial.

OBJECTIVES: 1. To assess the efficacy of Mesenchymal Stromal Cells (MSC) versus a control arm as described in the primary endpoint. 2. To evaluate the effects of MSC on the secondary efficacy endpoints. 3. To evaluate the safety and tolerability profiles of MSC. 4. To study soluble and cellular biomarkers that might be involved in the course of the disease and the response to the investigational product. TRIAL DESIGN: A double-blind, randomized, controlled, trial to evaluate the efficacy and safety of MSC intravenous administration in patients with COVID-induced Acute Respiratory Distress Syndrome (ARDS) compared to a control arm. PARTICIPANTS: The trial is being conducted at a third level hospital, Hospital Universitario Puerta de Hierro, in Majadahonda, Madrid (Spain). Inclusion criteria 1. Informed consent prior to performing study procedures (witnessed oral consent with written consent by representatives will be accepted to avoid paper handling). Written consent by patient or representatives will be obtained whenever possible. 2. Adult patients ≥18 years of age at the time of enrolment. 3. Laboratory-confirmed SARS-CoV-2 infection as determined by Polymerase Chain Reaction (PCR), in oropharyngeal swabs or any other relevant specimen obtained during the course of the disease. Alternative tests (e.g., rapid antigen tests) are also acceptable as laboratory confirmation if their specificity has been accepted by the Sponsor. 4. Moderate to severe ARDS (PaO2/FiO2 ratio equal or less than 200 mmHg) for less than 96 hours at the time of randomization. 5. Patients requiring invasive ventilation are eligible within 72 hours from intubation. 6. Eligible for ICU admission, according to the clinical team. Exclusion criteria 1. Imminent and unavoidable progression to death within 24 hours, irrespective of the provision of treatments (in the opinion of the clinical team). 2. "Do Not Attempt Resuscitation" order in place. 3. Any end-stage organ disease or condition, which in the investigator's opinion, makes the patient an unsuitable candidate for treatment. 4. History of a moderate/severe lung disorder requiring home-based oxygen therapy. 5. Patient requiring Extracorporeal Membrane Oxygenation (ECMO), haemodialysis or hemofiltration at the time of treatment administration. 6. Current diagnosis of pulmonary embolism. 7. Active neoplasm, except carcinoma in situ or basalioma. 8. Known allergy to the products involved in the allogeneic MSC production process. 9. Current pregnancy or lactation (women with childbearing potential should have a negative pregnancy test result at the time of study enrolment). 10. Current participation in a clinical trial with an experimental treatment for COVID-19 (the use of any off-label medicine according to local treatment protocols is not an exclusion criteria). 11. Any circumstances that in the investigator's opinion compromises the patient's ability to participate in the clinical trial. INTERVENTION AND COMPARATOR: - Experimental treatment arm: Allogeneic MSC (approximately 1 x 106 cells/kg). - Control arm: placebo solution (same composition as the experimental treatment, without the MSC). One single intravenous dose of the assigned treatment will be administered on Day 0 of the study. All trial participants will receive standard of care (SOC). In the context of the current worldwide pandemic, SOC can include medicines that are being used in clinical practice (e.g. lopinavir/ritonavir; hydroxy/chloroquine, tocilizumab, etc.), as well as those authorised for COVID (e.g., remdesivir). MAIN OUTCOMES: Primary endpoint: Change in the PaO2/FiO2 ratio from baseline to day 7 of treatment administration, or to the last available PaO2/FiO2 ratio if death occurs before day 7. Secondary endpoints: - All-cause mortality on days 7, 14, and 28 after treatment. - PaO2/FiO2 ratio at baseline and days 2, 4, 7, 14 and 28 after treatment. - Oxygen saturation (by standardized measurement) at baseline, daily until day 14, and on day 28 after treatment. - Time to PaO2/FiO2 ratio greater than 200 mmHg. - Subjects' clinical status on the WHO 7-point ordinal scale at baseline, daily until day 14, and on day 28 after treatment. - Time to an improvement of one category from admission on the WHO 7-point ordinal scale. - Percentage of patients that worsen at least one category on the WHO 7-point ordinal scale. - Percentage of patients that improve at least one category (maintained 48h) on the WHO 7-point ordinal scale. - Sequential Organ Failure Assessment (SOFA) scale at baseline and days 2, 4, 7, 14 and 28 after treatment. - Duration of hospitalization (days). - Duration of ICU stay (days). - Oxygen therapy-free days in the first 28 days after treatment. - Duration of supplemental oxygen. - Incidence of and duration of non-invasive and invasive mechanical ventilation in the first 28 days after treatment. - Mechanical ventilation-free days in the first 28 days after treatment. - Ventilation parameters. - Incidence of new onset pulmonary fibrosis at 3 and 12 months after treatment, based on CT scan and pulmonary function tests. - Survival at 3 and 12 months. - Cumulative incidence of Serious Adverse events (SAEs) and Grade 3 and 4 Adverse Events (AEs). - Cumulative incidence of Adverse Drug Reactions (ADR) in the experimental treatment arm. - Cumulative incidence of AEs of special interest. - Levels of analytical markers (C-Reactive Protein, lymphocyte and neutrophil counts, lymphocyte subpopulations, LDH, ferritin, D-dimer, coagulation tests and cytokines...) at baseline and days 2, 4, 7, 14 and 28 after treatment. - Other soluble and cellular biomarkers that might be involved in the course of the disease and the response to MSC. RANDOMISATION: The assignment to treatment will be carried out randomly and blinded, with a 1:1 allocation. Randomization will be done through a centralized system embedded in the electronic Case Report Form (CRF). BLINDING (MASKING): To ensure blinding, treatments will be prepared for administration at the Cell Production Unit and the administration of the treatment will be masked, not allowing the identification of the Investigational Medicinal Product (IMP). NUMBERS TO BE RANDOMISED (SAMPLE SIZE): A total of 20 participants are planned to be randomized, 10 to each treatment group. TRIAL STATUS: Protocol version: 1.2, dated October 14th, 2020 Start of recruitment: 01/10/2020 End of recruitment (estimated): December 2020. TRIAL REGISTRATION: EudraCT Number: 2020-002193-27 , registered on July 14th, 2020. NCT number: NCT04615429 , registered on November 4th, 2020. FULL PROTOCOL: The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol.

Phosphoproteomics identifies a bimodal EPHA2 receptor switch that promotes embryonic stem cell differentiation.

Embryonic Stem Cell (ESC) differentiation requires complex cell signalling network dynamics, although the key molecular events remain poorly understood. Here, we use phosphoproteomics to identify an FGF4-mediated phosphorylation switch centred upon the key Ephrin receptor EPHA2 in differentiating ESCs. We show that EPHA2 maintains pluripotency and restrains commitment by antagonising ERK1/2 signalling. Upon ESC differentiation, FGF4 utilises a bimodal strategy to disable EPHA2, which is accompanied by transcriptional induction of EFN ligands. Mechanistically, FGF4-ERK1/2-RSK signalling inhibits EPHA2 via Ser/Thr phosphorylation, whilst FGF4-ERK1/2 disrupts a core pluripotency transcriptional circuit required for Epha2 gene expression. This system also operates in mouse and human embryos, where EPHA receptors are enriched in pluripotent cells whilst surrounding lineage-specified trophectoderm expresses EFNA ligands. Our data provide insight into function and regulation of EPH-EFN signalling in ESCs, and suggest that segregated EPH-EFN expression coordinates cell fate with compartmentalisation during early embryonic development.

Potential Survival Benefit for Patients Receiving Allogeneic Hematopoietic Stem Cell Transplantation after Nivolumab Therapy for Relapse/Refractory Hodgkin Lymphoma: Real-Life Experience in Spain.

Clinical trials have shown that nivolumab has remarkable activity against relapsed/refractory classical Hodgkin lymphoma (cHL). However, the role of allogeneic hematopoietic stem cell transplantation (allo-HSCT) as consolidation therapy in these patients remains controversial. We performed a retrospective analysis of data from 74 patients treated with nivolumab. The overall response rate was 58% (including 30.6% with complete responses). Treatment-related adverse events were reported in 56.8% of patients (grade ≥3 in 9.4%). The main reasons for nivolumab discontinuation were referral for transplantation (41.7% patients) and disease progression (37.5%). The 2-year overall survival (OS) rate was 52% for the entire series. Ultimately, 39 patients underwent allo-HSCT. The cumulative incidence of grade II-IV acute graft-versus-host disease was 33.3% (grade III-IV in 2 patients). The cumulative incidence of nonrelapse mortality was 13.2%. Among the patients who responded to nivolumab, the 2-year OS and progression-free survival (PFS) were higher in patients who underwent consolidation with allo-HSCT (77.5% versus 42.6% [P = .126] and 73.9% versus 27.2% [P = .025], respectively). Thus, the efficacy and safety of nivolumab were comparable to values reported in previous clinical trials. The percentage of patients who bridged to transplantation was high, indicating a preference for Spanish physicians. These results suggest that consolidation allo-HSCT increases OS and PFS.

A paired trial comparing mononuclear cell collection in two machines for further inactivation through an inline or offline extracorporeal photopheresis procedure.

BACKGROUND: Extracorporeal photopheresis (ECP) is an effective treatment. However, protocols differ widely, and some questions, such as the number of cells to be collected or the number of ECP treatment days per treatment cycle, are still unsolved. The aim of this study was to compare a multistep (offline) (Spectra Optia and Macogenic G2) against an integrated (inline) ECP system (Therakos Cellex system) with respect to mononuclear cell (MNC) collection. STUDY DESIGN AND METHODS: The number and quality parameters of the MNC products collected were evaluated together with some machine parameters, such as collection time. Comparisons were made through paired sample analysis with the t test. RESULTS: Fourteen patients underwent 15 double-paired procedures using both ECP protocols. The average MNC collected in the multistep procedure was 77.4 × 108 , four times more than in the integrated procedure (18.5 × 108 ). MNC purity (84.4% vs. 63.8%) and enrichment (27.9 vs. 5.9) in the product collected were also higher in the multistep procedure. The whole ECP time was higher in the multistep than in the integrated procedure (272 vs. 106 min), but the calculated time to collect 25 × 108 MNCs in the multistep was shorter compared with the one-step procedure (77.8 vs. 172 min). All these differences between the two protocols were statistically significant. CONCLUSIONS: These two ECP protocols are different with respect to MNC collection and length of procedure. Some unresolved questions, such as the better MNC dose to inactivate or the number of consecutive days that ECP should be performed for optimal clinical efficacy, require further review.

Brd4-Brd2 isoform switching coordinates pluripotent exit and Smad2-dependent lineage specification.

Pluripotent stem cells (PSCs) hold great clinical potential, as they possess the capacity to differentiate into fully specialised tissues such as pancreas, liver, neurons and cardiac muscle. However, the molecular mechanisms that coordinate pluripotent exit with lineage specification remain poorly understood. To address this question, we perform a small molecule screen to systematically identify novel regulators of the Smad2 signalling network, a key determinant of PSC fate. We reveal an essential function for BET family bromodomain proteins in Smad2 activation, distinct from the role of Brd4 in pluripotency maintenance. Mechanistically, BET proteins specifically engage Nodal gene regulatory elements (NREs) to promote Nodal signalling and Smad2 developmental responses. In pluripotent cells, Brd2-Brd4 occupy NREs, but only Brd4 is required for pluripotency gene expression. Brd4 downregulation facilitates pluripotent exit and drives enhanced Brd2 NRE occupancy, thereby unveiling a specific function for Brd2 in differentiative Nodal-Smad2 signalling. Therefore, distinct BET functionalities and Brd4-Brd2 isoform switching at NREs coordinate pluripotent exit with lineage specification.

Protein Kinases in Pluripotency-Beyond the Usual Suspects.

Post-translational modification of proteins by phosphorylation plays a key role in regulating all aspects of eukaryotic biology. Embryonic stem cell (ESC) pluripotency, defined as the ability to differentiate into all cell types in the adult body, is no exception. Maintenance and dissolution of pluripotency are tightly controlled by phosphorylation. As a result, key signalling pathways that regulate pluripotency have been identified and their functions well characterised. Amongst the best studied are the fibroblast growth factor (FGF)-ERK1/2 pathway, PI3K-AKT, the leukemia inhibitory factor (LIF)-JAK-STAT3 axis, Wnt-GSK3 signalling, and the transforming growth factor (TGF)ß family. However, these kinase pathways constitute only a small proportion of the protein kinase complement of pluripotent cells, and there is accumulating evidence that diverse phosphorylation systems modulate ESC pluripotency. Here, we review recent progress in understanding the overarching role of phosphorylation in mediating communication from the cellular environment, metabolism, and cell cycle to the core pluripotency machinery.

Erk5 Is a Key Regulator of Naive-Primed Transition and Embryonic Stem Cell Identity.

Embryonic stem cells (ESCs) can self-renew or differentiate into any cell type, a phenomenon known as pluripotency. Distinct pluripotent states, termed naive and primed pluripotency, have been described. However, the mechanisms that control naive-primed pluripotent transition are poorly understood. Here, we perform a targeted screen for kinase inhibitors, which modulate the naive-primed pluripotent transition. We find that XMD compounds, which selectively inhibit Erk5 kinase and BET bromodomain family proteins, drive ESCs toward primed pluripotency. Using compound selectivity engineering and CRISPR/Cas9 genome editing, we reveal distinct functions for Erk5 and Brd4 in pluripotency regulation. We show that Erk5 signaling maintains ESCs in the naive state and suppresses progression toward primed pluripotency and neuroectoderm differentiation. Additionally, we identify a specialized role for Erk5 in defining ESC lineage selection, whereby Erk5 inhibits a cardiomyocyte-specific differentiation program. Our data therefore reveal multiple critical functions for Erk5 in controlling ESC identity.

p73 plays a role in erythroid differentiation through GATA1 induction.

The TP73 gene gives rise to transactivation domain-p73 isoforms (TAp73) as well as DeltaNp73 variants with a truncated N terminus. Although TAp73alpha and -beta proteins are capable of inducing cell cycle arrest, apoptosis, and differentiation, DeltaNp73 acts in many cell types as a dominant-negative repressor of p53 and TAp73. It has been proposed that p73 is involved in myeloid differentiation, and its altered expression is involved in leukemic degeneration. However, there is little evidence as to which p73 variants (TA or DeltaN) are expressed during differentiation and whether specific p73 isoforms have the capacity to induce, or hinder, this differentiation in leukemia cells. In this study we identify GATA1 as a direct transcriptional target of TAp73alpha. Furthermore, TAp73alpha induces GATA1 activity, and it is required for erythroid differentiation. Additionally, we describe a functional cooperation between TAp73 and DeltaNp73 in the context of erythroid differentiation in human myeloid cells, K562 and UT-7. Moreover, the impaired expression of GATA1 and other erythroid genes in the liver of p73KO embryos, together with the moderated anemia observed in p73KO young mice, suggests a physiological role for TP73 in erythropoiesis.