Crohn's disease is a chronic inflammatory bowel disease that can lead to fibrostenotic complications. These strictures result from an imbalance between inflammation and excessive healing, leading to an abnormal accumulation of extracellular matrix and a progressive thickening of the intestinal wall. To date, no specific treatment is available to prevent or reverse intestinal fibrosis. The management of strictures primarily focuses on controlling inflammation and addressing obstructive complications through endoscopic balloon dilation, stricturoplasty, or intestinal resection. Current medical therapies, such as anti-TNF agents, can help reduce inflammation but have no direct impact on fibrosis. New therapeutic strategies are emerging, including TL1A inhibitors (duvakitug, tulisokibart), an ALK5 inhibitor (AGMB-129), and targeted AGR2 therapies (TH-009). Additionally, mesenchymal stem cells are being investigated in our hospital center in combination with endoscopic balloon dilation, aiming to assess their therapeutic potential. The development of effective anti-fibrotic therapies remains a critical medical need to improve the management of intestinal strictures and reduce the need for invasive procedures in Crohn's disease.

Highlighted by the COVID-19 pandemic, the study of respiratory infections is a global health priority. To this end, many preclinical in vitro study models have been developed to reproduce nasal, bronchial or alveolar respiratory epithelium. These models can be established from immortalised cell lines, primary culture or induced pluripotent stem cells (iPSC). They can also be constructed in various three-dimensional structures that are more or less physiological and easy to use. This synthetic review puts into perspective the advantages and limitations of these models, while highlighting their relevance for the study of the mechanisms of SARS-CoV-2 infection.

Beta-haemoglobinopathies are severe genetic anemias caused by mutations that affect adult haemoglobin production. Many therapeutic approaches aim to reactivate the expression of the fetal hemoglobin genes. To this end, the CRISPR/Cas9 system has recently been used to genetically modify patients' hematopoietic stem/progenitor cells ex vivo and reactivate fetal hemoglobin expression in their erythroid progeny. More than 70 patients with severe β-thalassemia and sickle cell disease have been treated with the Casgevy® therapy. Most have achieved a significant improvement of clinical phenotype, with high editing efficiency in hematopoietic cells associated with normal or near normal hemoglobin levels. While the long-term safety and efficacy of this powerful approach still need to be evaluated, new strategies are being developed to further improve therapeutic outcomes, reduce potential genotoxicity and lower the costs of therapy.

The advent of high-throughput omics data and the generation of new algorithms provide the biologists with the opportunity to explore living processes in the context of systems biology aiming at revealing the gene interactions, the networks underlying complex cellular functions. In this article, we discuss two methods for gene network reconstruction, WGCNA (Weighted Gene Correlation Network Analysis) developed by Steve Horvath and collaborators in 2008, and MIIC (Multivariate Information-based Inductive Causation) developed by Hervé Isambert and his team in 2017 and 2024. These two methods are complementary, WGCNA generating undirected networks in which most gene-to-gene interactions are indirect, while MIIC reveals direct interactions and some causal links. We illustrate these aspects according to our own work aiming at identifying the gene interactions underlying the hematopoietic stem cell supportive activity of mesenchymal stromal cells at an early developmental stage.

This workshop presents the recommendations of the Société francophone de greffe de moelle et de thérapie cellulaire (SFGM-TC) for simulation-based training on bone marrow harvesting from healthy donors. Due to the decline in bone marrow harvests in favor of peripheral stem cells, a loss of expertise has been observed among younger hematologists. The training consists of an online theoretical component and a hands-on workshop using a mannequin at the PRESAGE simulation center at the Lille University School of Medicine. The goal is to acquire the necessary skills to safely perform bone marrow harvesting according to best practices, avoiding technical errors. Both theoretical and practical evaluations are conducted, and participants receive a training certificate upon completion.

Through their myogenic activity, adult muscle stem cells (MuSCs) are crucial for the regeneration of striated skeletal muscle. Once activated, they proliferate, differentiate and then fuse to repair or form new muscle fibers (myofibers). Their progression through myogenesis requires a complex regulation involving multiple players such as metabolism, in particular via AMPK. This protein kinase regulates the self-renewal and myonuclear accretion of MuSCs after acute skeletal muscle injury or skeletal muscle contraction. However, in a context of dystrophy such as Duchenne muscular dystrophy (DMD), the regenerative capacity of MuSCs is reduced, presumably due to an increase of the proliferation that is detrimental to differentiation. We are interested here in the potential of metabolism to regulate the myogenic activity of MuSCs in DMD via AMPK.

PAX3 plays a crucial role in embryonic myogenesis, controlling the specification, migration, proliferation, and differentiation of muscle progenitor cells to ensure normal skeletal muscle development in the embryo. However, PAX3 potential role in a context of muscle homeostasis and regeneration remains poorly investigated. The adult muscle stem cells, known as satellite cells (SCs) exhibit heterogeneity in Pax3 expression in various muscles throughout the body and display a bimodal response to environmental stress exposure. To explore the role of PAX3 in the context of tissue damage, we performed regeneration studies, which unveiled a functional heterogeneity of the SCs populations depending on Pax3 expression. Together, this project aims to decipher cell-type specific dysregulations linked to tissue damage and identify PAX3 downstream gene regulatory networks that can lead to specific SC behavior, thus potentially providing novel strategies for muscle disease preventive therapies.

Rare genetic diseases with neurodevelopmental disorders (NDDs) encompass several heterogeneous conditions (autism spectrum disorder (ASD), intellectual disability (ID), attention deficit hyperactivity disorder (ADHD), specific learning disorder (SLD), among others). Currently, few treatments are available for these patients. The difficulty in accessing human brain samples and the discrepancies between human and animal models highlight the need for new research approaches. One promising approach is the use of the cerebral organoids. These 3D, self-organized structures, generated from induced pluripotent stem cells (iPSCs), enable the reproduction of the stages of human brain development, from the proliferation of neural stem cells to their differentiation into neurons, oligodentrocytes, and astrocytes. Cerebral organoids hold great promise in understanding brain development and in the search for treatments.

Management of acquired aplastic anemia (AA) in emerging countries depends on the means of prognostic stratification, treatment and logistics available. During the 13th annual harmonization workshop of the francophone Society of bone marrow transplantation and cellular therapy (SFGM-TC), a designated working group reviewed the literature in order to elaborate unified guidelines for allogeneic hematopoietic cell transplantation (Allo-HCT) in this disease. In terms of practice, the conclusions are as follows; The use of anti-tymocyte globuline (ATG) is mainly from rabbit and very little from horse. Access to bone marrow graft, total body irradiation, and the international unrelated donor registries is limited, which justifies the use of peripheral blood stem cells, chemotherapy-based conditioning, and related alternative donor. The workshop recommends matched sibling allo-HCT in all patients aged less than 40 years with acquired severe or very severe AA. For patients aged over than 40 years, or who lack an HLA-identical donor, treatment with the combination of cyclosporin, horse ATG, eltrombopag or cyclosporine, eltrombopag is recommended. If horse ATG and eltrombopag are not available, matched sibling allo-HCT may be indicated as first-line therapy in patients aged between 40-60 years, and good performance status. Although, in patients who have failed immunosuppressive treatments and thrombopoietin agonists, and in the absence of HLA-matched donor, a haplo-identical allo-HCT with modified Baltimore conditioning is recommended.

Allogeneic transplantation of haematopoietic stem cells is still the only curative treatment for certain haematological malignancies. This treatment can be responsible for a number of side-effects, leading to multiple and interdependent physical and psychological deficiencies that affect patients' quality of life and social participation, and can be experienced as a handicap, sometimes for several years after the transplant. For several years now, the integration of post-transplant rehabilitation pathways has been becoming more widespread, and initiatives to provide multidisciplinary care at an increasingly early stage are being studied. The aim of this early management is to improve the patient's overall functional state before, during and after the transplant, in order to limit the impact of the treatment and ensure the quickest possible return to a life that is as satisfying as possible. The international literature and the experiments carried out throughout the French-speaking world describe heterogeneous practices. Based on this literature and experience, the aim of this study is to issue homogenous recommendations for good clinical practice and to identify areas for further research into pre-transplant, per-transplant and post-transplant rehabilitation of haematopoietic stem cells.

Conditioning regimen prior to hematopoietic stem cell transplantation have an impact on patient fertility through the use of gonadal irradiation and/or bifunctional alkylating agents. Their impact on fertility depends mainly on the dose used and, in women, on age at the time of treatment. All patients should benefit before treatment from a consultation informing them of the potential impact on fertility and of fertility preservation techniques. In the absence of contraindications, the major toxicity of myeloablative conditioning regimen justifies fertility preservation. There are few data concerning fertility after reduced-intensity conditioning. Despite lower theoretical gonadotoxicity, we also recommend fertility preservation, if possible before transplantation. The fertility preservation techniques used depend on the patient's age, pathology and conditioning. In the event of subsequent use of harvested gonadal tissue in the context of acute leukemia or aggressive lymphoma, it is advisable to assess the risk of reintroduction of tumor cells. Finally, it is recommended to assess gonadal function after transplant, especially after reduced conditioning. If there is persistent residual gonadal function, post-treatment fertility preservation should be discuss.

Treatment of complex perianal fistulas in Crohn's disease remains a challenge especially after the failure of Infliximab.

One of the greatest challenges in neuroscience is to understand how a complex structure, such as the brain, is built. Spatial and temporal patternings of neuronal progenitors are responsible for the generation of most of the neuronal diversity observed in the brain. This review focuses on the temporal patterning of neuronal progenitors, i.e. the sequential expression of transcription factors that changes the capacity of stem cells to generate different neuronal types, and which is conserved in animals. Recent papers have offered a near complete understanding of the mechanism of temporal patterning in the developing visual system of Drosophila, and of how this contributes to the specification of diverse neuronal identities, which are then maintained by the sustained expression of downstream transcription factors. The insect visual system provides a unique model to study the evolution of neuronal cell types, as well as the evolution of neurodevelopmental mechanisms that generate them.

Totipotency is the ability of a cell to generate a whole organism, a property that characterizes the first embryonic cells, such as the zygote and the blastomeres. This review provides a retrospective on the progress made in the last decade in the study of totipotency, especially with the discovery of mouse ES cells expressing markers of the 2-cell stage (2C-like cells). This model has greatly contributed to a better understanding of the molecular mechanisms involved in totipotency (pioneer factors, epigenetic regulation, splicing, nuclear maturation). 2C-like cells have also paved the way for the development of new cellular models of human totipotency.

Chronic Granulomatosis Disease (CGD) is an inherited immune deficiency due to a mutation in the genes coding for the subunits of the NADPH oxidase enzyme that affects the oxidative capacity of phagocytic cells. It is characterized by increased susceptibility to bacterial and fungal infections, particularly Aspergillus, as well as complications associated with hyperinflammation and granulomatous tissue infiltration. There exist two types of frequently encountered pulmonary manifestations: (1) due to their being initially pauci-symptomatic, possibly life-threatening infectious complications are often discovered at a late stage. Though their incidence has decreased through systematic anti-bacterial and anti-fungal prophylaxis, they remain a major cause of morbidity and mortality; (2) inflammatory complications consist in persistent granulomatous mass or interstitial pneumoniae, eventually requiring immunosuppressive treatment. Pulmonary complications recurring since infancy generate parenchymal and bronchial sequelae that impact functional prognosis. Hematopoietic stem cell allograft is a curative treatment; it is arguably life-sustaining and may limit the morbidity of the disease. As a result of improved pediatric management, life expectancy has increased dramatically. That said, new challenges have appeared with regard to adults: difficulties of compliance, increased inflammatory manifestations, acquired resistance to anti-infectious therapies. These different developments underscore the importance of the transition period and the need for multidisciplinary management.

Immunotherapy strategies have revolutionized the management of a significant number of patients in recent years, whether they are undergoing treatment for hematologic malignancies or solid tumors. This therapeutic class is extensive, ranging from antibodies targeting immune checkpoint molecules to adoptive cell therapy strategies, including bispecific antibodies and anticancer vaccines. All these strategies are currently in active development. Adoptive cell therapy involves the infusion of normal or genetically modified immune cells into a patient with the aim of restoring strong antitumor immunity, primarily associated with the cytotoxicity of T lymphocytes. Currently, there are three major adoptive cell therapy strategies: allogeneic hematopoietic stem cell transplantation, CAR-T cell therapy, and TCR-T cell therapy. The objective of this article is to describe the mechanisms of action of these three strategies as well as their current advantages, limitations and constraints.

Allogeneic hematopoietic stem cell transplantation (HCT) and CAR-T cells therapy are treatments with curative aim for certain hematological malignancies, refractory or relapse. Nevertheless, they carry the risk of morbidity and mortality and may have a significant psychosocial impact, particularly for HCT. It is therefore necessary to identify psychological difficulties and social problems, as well as the patient's resources, and those of his entourage, in order to improve his overall management. The objective of this evaluation is not to pose contraindications to treatments, but to adapt the personalized care project. This identification must be carried out early on in the pre-HCT assessment journey to enable the implementation of appropriate actions by the various care providers. Based on a review of the literature, we designed a psychosocial data collection grid that can be initiated in pre-transplant and updated by accompanying the patient at each stage of follow-up (discharge from hospital, day-hospital follow-up, D100 evaluation). This grid is divided into 3 axes: socio-family context, psychological and somatic aspects. This tool allows the traceability of the interventions of different professionals and is a support for multidisciplinary exchanges.

Relapse after allogeneic hematopoietic cell transplantation (allo-HCT) remains a major concern because it is associated with poor survival. A second allo-HCT is a valid option in this situation. During the 13th annual harmonization workshops of the francophone Society of bone marrow transplantation and cellular therapy (SFGM-TC), a designated working group reviewed the literature in order to update the second allo-HCT recommendations elaborated during the previous workshop (2016). The main indication for a second allo-HCT remains relapse of initial hematologic malignancy. Disease status; complete remission (CR), and relapse time after the first allo-HCT>6 months impact positively the overall survival of patients after the second allo-HCT. Donor change is a valid option, particularly if there is HLA loss on leukemic cells after a first haploidentical or following a mismatched allo-HCT is documented. Reduced intensity conditioning is recommended, while a sequential protocol is a reasonable option in patients with proliferative disease. A post-transplant maintenance strategy after hematological recovery is recommended as soon as day 60, even if the immunosuppressive treatment has not yet been stopped. Hypomethylating agents, and targeted therapies such as anti FLT3, anti BCL2, anti-IDH1/2, TKI, anti-TP53, anti-CD33, anti-CD19, anti-CD22, anti-CD30, check point inhibitors, and CAR-T cells can be used as a bridge to transplant or as an alternative treatment to the second allo-HCT.

Cystinosis is an autosomal recessive metabolic disease characterized by lysosomal accumulation of cystine in all the cells of the body. Infantile cystinosis begins in infancy by a renal Fanconi syndrome and eventually leads to multi-organ failure, including the kidney, eye, thyroid, muscle, and pancreas, eventually causing premature death in early adulthood. The current treatment is the drug cysteamine that only delays the progression of the disease. We identified the gene involved, CTNS, and showed that the encoded protein, cystinosin, is a proton-driven cystine transporter. We generated a mouse model of cystinosis, the Ctns-/- mice, that recapitulates the main disease complications. The goal was next to develop a gene therapy approach for cystinosis. We used bone marrow stem cells as a vehicle to bring the healthy CTNS gene to tissues, and we showed that wild-type hematopoietic stem and progenitor cell (HSPC) transplantation led to abundant tissue integration of bone marrow-derived cells, significant decrease of tissue cystine accumulation and long-term kidney, eye and thyroid preservation. We then developed an autologous transplantation approach of HSPCs modified ex vivo using a lentiviral vector to introduce a functional CTNS cDNA, and showed its efficacy in Ctns-/- mice. We conducted the pharmacology/toxicology studies, developed the manufacturing process using human CD34+ cells, and design the clinical trial. We received Food and Drug Administration (FDA)-clearance to start a phase 1/2 clinical trial for cystinosis in December 2018. Six patients have been treated so far. In this review, we describe the path to go from the gene to a gene therapy approach for cystinosis.

Elderly patients with acute myeloid leukemia, ineligible for intensive chemotherapy, have long had a very poor prognosis and have always represented one of the main patient populations included in early phase clinical research trials. In recent years, many molecules have shown very interesting efficacy, often targeted therapies whose indication is based on a specific mutation profile (gilteritinib, ivosidenib), or mutation-independent (venetoclax), but also drugs whose indication is based on a specific biomarker (tamibarotene) or on new generation immunotherapies targeting macrophages (magrolimab) or other immune effectors while targeting leukemic cells resulting in forced immunological synapse (flotetuzumab) or activation of lymphocyte effectors associated with inhibition of the AML cells' stem signature in their microenvironment (cusatuzumab sabatolimab). All of these new strategies are discussed in this review, as well as the challenges of this frail population, which has benefited in recent months from all the major advances in the field, questioning in a second phase the modification of practices in younger patients.