Hyperbaric oxygen therapy in malignant otitis externa: a retrospective analysis.

PURPOSE: Malignant otitis externa (MOE) is a rare form of invasive osteomyelitis of the external ear canal. It is typically caused by Pseudomonas aeruginosa in immunocompromised patients. The diagnosis is clinical, and the initial treatment involves systemic antibiotics or antifungal therapy. Surgery is usually only considered when medical treatment has failed. Although hyperbaric oxygen therapy (HBOT) is recommended for refractory osteomyelitis, there are no specific guidelines for MOE. METHODS: This is a retrospective study that evaluates clinical data, treatment, and results obtained in patients diagnosed with MOE treated with HBOT at the Pedro Hispano Hospital between 2007 and 2022. RESULTS: During the study period, fifteen patients diagnosed with MOE were admitted for treatment with HBOT. All patients received antibiotic and/or antifungal therapy, and three required surgical intervention before starting HBOT. The pathology was successfully managed on all patients. CONCLUSIONS: HBOT may be an effective adjuvant treatment option in patients with MOE but it lacks robust scientific evidence. However, its therapeutic value should not be underestimated due to the good results and few adverse effects reported in recent retrospective studies and case reports.

Transforming the Niche: The Emerging Role of Extracellular Vesicles in Acute Myeloid Leukaemia Progression.

Acute myeloid leukaemia (AML) management remains a significant challenge in oncology due to its low survival rates and high post-treatment relapse rates, mainly attributed to treatment-resistant leukaemic stem cells (LSCs) residing in bone marrow (BM) niches. This review offers an in-depth analysis of AML progression, highlighting the pivotal role of extracellular vesicles (EVs) in the dynamic remodelling of BM niche intercellular communication. We explore recent advancements elucidating the mechanisms through which EVs facilitate complex crosstalk, effectively promoting AML hallmarks and drug resistance. Adopting a temporal view, we chart the evolving landscape of EV-mediated interactions within the AML niche, underscoring the transformative potential of these insights for therapeutic intervention. Furthermore, the review discusses the emerging understanding of endothelial cell subsets' impact across BM niches in shaping AML disease progression, adding another layer of complexity to the disease progression and treatment resistance. We highlight the potential of cutting-edge methodologies, such as organ-on-chip (OoC) and single-EV analysis technologies, to provide unprecedented insights into AML-niche interactions in a human setting. Leveraging accumulated insights into AML EV signalling to reconfigure BM niches and pioneer novel approaches to decipher the EV signalling networks that fuel AML within the human context could revolutionise the development of niche-targeted therapy for leukaemia eradication.

T-cell acute leukaemia exhibits dynamic interactions with bone marrow microenvironments.

It is widely accepted that complex interactions between cancer cells and their surrounding microenvironment contribute to disease development, chemo-resistance and disease relapse. In light of this observed interdependency, novel therapeutic interventions that target specific cancer stroma cell lineages and their interactions are being sought. Here we studied a mouse model of human T-cell acute lymphoblastic leukaemia (T-ALL) and used intravital microscopy to monitor the progression of disease within the bone marrow at both the tissue-wide and single-cell level over time, from bone marrow seeding to development/selection of chemo-resistance. We observed highly dynamic cellular interactions and promiscuous distribution of leukaemia cells that migrated across the bone marrow, without showing any preferential association with bone marrow sub-compartments. Unexpectedly, this behaviour was maintained throughout disease development, from the earliest bone marrow seeding to response and resistance to chemotherapy. Our results reveal that T-ALL cells do not depend on specific bone marrow microenvironments for propagation of disease, nor for the selection of chemo-resistant clones, suggesting that a stochastic mechanism underlies these processes. Yet, although T-ALL infiltration and progression are independent of the stroma, accumulated disease burden leads to rapid, selective remodelling of the endosteal space, resulting in a complete loss of mature osteoblastic cells while perivascular cells are maintained. This outcome leads to a shift in the balance of endogenous bone marrow stroma, towards a composition associated with less efficient haematopoietic stem cell function. This novel, dynamic analysis of T-ALL interactions with the bone marrow microenvironment in vivo, supported by evidence from human T-ALL samples, highlights that future therapeutic interventions should target the migration and promiscuous interactions of cancer cells with the surrounding microenvironment, rather than specific bone marrow stroma, to combat the invasion by and survival of chemo-resistant T-ALL cells.

The interplay of leukemia cells and the bone marrow microenvironment.

The interplay of cancer cells and surrounding stroma is critical in disease progression. This is particularly evident in hematological malignancies that infiltrate the bone marrow and peripheral lymphoid organs. Despite clear evidence for the existence of these interactions, the precise repercussions on the growth of leukemic cells are poorly understood. Recent development of novel imaging technology and preclinical disease models has advanced our comprehension of leukemia-microenvironment crosstalk and has potential implications for development of novel treatment options.

Evaluation of post-tonsillectomy hemorrhage and assessment of risk factors.

PURPOSE: Tonsillectomy is one of the most common surgical procedures in otorhinolaryngology. Hemorrhage in the postoperative period has an incidence of up to 20% and is a potentially fatal complication. We aim to assess the incidence of hemorrhage after tonsillectomy in our institution, and to evaluate and identify the possible associated risk factors. METHODS: This retrospective study included 897 patients who underwent tonsillectomy between January 2015 and December 2018, 50.7% women and 49.3% men, aged between 2 and 83 years. No coagulopathies were identified. Comparison of age, gender, surgical indication, coagulation profile, concomitant adenoidectomy, surgical technique, surgeon's experience and hemostasis method between groups with and without post-operative bleeding was made. RESULTS: Our incidence of post-tonsillectomy hemorrhage was 6%. Most patients (83.3%) had secondary bleeding (> 24 h after surgery). In 22.2% of the bleeding cases, it was necessary to revise the hemostasis in the operating room. Adulthood (age ≥ 18 years) (p < 0.001), INR values ≥ 1.2 (p = 0.014), aPTT values ≥ 35 s (p = 0.001), as well as concomitant adenoidectomy (p < 0.001) were the predictors of post-tonsillectomy bleeding. CONCLUSION: Recognition of adult age, INR ≥ 1.2, aPTT ≥ 35 s and concomitant adenoidectomy as risk factors can be useful in identifying the patients at higher risk for bleeding complications.

Defining the in vivo characteristics of acute myeloid leukemia cells behavior by intravital imaging.

The majority of acute myeloid leukemia (AML) patients have a poor response to conventional chemotherapy. The survival of chemoresistant cells is thought to depend on leukemia-bone marrow (BM) microenvironment interactions, which are not well understood. The CXCL12/CXCR4 axis has been proposed to support AML growth but was not studied at the single AML cell level. We recently showed that T-cell acute lymphoblastic leukemia (T-ALL) cells are highly motile in the BM; however, the characteristics of AML cell migration within the BM remain undefined. Here, we characterize the in vivo migratory behavior of AML cells and their response to chemotherapy and CXCR4 antagonism, using high-resolution 2-photon and confocal intravital microscopy of mouse calvarium BM and the well-established MLL-AF9-driven AML mouse model. We used the Notch1-driven T-ALL model as a benchmark comparison and AMD3100 for CXCR4 antagonism experiments. We show that AML cells are migratory, and in contrast with T-ALL, chemoresistant AML cells become less motile. Moreover, and in contrast with T-ALL, the in vivo exploratory behavior of expanding and chemoresistant AML cells is unaffected by AMD3100. These results expand our understanding of AML cells-BM microenvironment interactions, highlighting unique traits of leukemia of different lineages.

Maxillary sinus actinomycosis: a diagnostic and therapeutic challenge.

The authors present a case of maxillary sinus actinomycosis in a young adult woman.This is a rare condition whose unspecific clinical presentation makes its diagnosis challenging. In this case, the diagnosis was given by the identification of Actinomyces colonies in samples of infected tissue.Treatment consisted of a combined medical and surgical approach. Endoscopic sinus surgery was performed to remove diseased mucosa and to aerate the involved sinuses, followed by long-term antibiotic therapy. No recurrence of the disease was observed during follow-up.

Heme (dys)homeostasis and liver disease.

Heme is essential for a variety of proteins involved in vital physiological functions in the body, such as oxygen transport, drug metabolism, biosynthesis of steroids, signal transduction, antioxidant defense and mitochondrial respiration. However, free heme is potentially cytotoxic due to the capacity of heme iron to promote the oxidation of cellular molecules. The liver plays a central role in heme metabolism by significantly contributing to heme synthesis, heme detoxification, and recycling of heme iron. Conversely, enzymatic defects in the heme biosynthetic pathway originate multisystemic diseases (porphyrias) that are highly associated with liver damage. In addition, there is growing evidence that heme contributes to the outcomes of inflammatory, metabolic and malignant liver diseases. In this review, we summarize the contribution of the liver to heme metabolism and the association of heme dyshomeostasis with liver disease.

Subacute Neurotoxicity as an Adverse Reaction to Ceftazidime: A Case Report.

Neurotoxicity associated with cephalosporins is an increasingly recognized complication, although among cephalosporins, ceftazidime is rarely reported for such an adverse reaction. Moreover, subacute, rather than acute, presentation of neurotoxicity associated with cephalosporins is rare. A 77-year-old female patient with stage 4 chronic renal disease was admitted due to cellulitis in her right lower limb, multiorgan dysfunction complicated by oliguric acute kidney injury, and a need for hemodialysis via a central venous catheter. On the 13th day after admission, she became febrile, and bacteremia associated with a central venous catheter was identified, which prompted the initiation of empirical antibiotic therapy with vancomycin and ceftazidime. After 13 days of antibiotic therapy with vancomycin and ceftazidime, the patient became confused, with temporal-spatial disorientation and myoclonus, especially in the upper limbs, with worsening renal function. Ceftazidime was discontinued, and the patient's condition improved with complete remission of symptoms on the 8th day after symptom onset. Neurotoxicity associated with ceftazidime is a rare but probably underdiagnosed adverse reaction. It is more frequent in elderly patients with previous neurological dysfunction and end-stage kidney disease and/or acute kidney injury, and it usually manifests soon after starting treatment. Early identification and monitoring of risk factors and symptoms should lead the physician to a rapid withdrawal of the offending drug.

Nanoparticle-encapsulated retinoic acid for the modulation of bone marrow hematopoietic stem cell niche.

More effective approaches are needed in the treatment of blood cancers, in particular acute myeloid leukemia (AML), that are able to eliminate resistant leukemia stem cells (LSCs) at the bone marrow (BM), after a chemotherapy session, and then enhance hematopoietic stem cell (HSC) engraftment for the re-establishment of the HSC compartment. Here, we investigate whether light-activatable nanoparticles (NPs) encapsulating all-trans-retinoic acid (RA+NPs) could solve both problems. Our in vitro results show that mouse AML cells transfected with RA+NPs differentiate towards antitumoral M1 macrophages through RIG.1 and OASL gene expression. Our in vivo results further show that mouse AML cells transfected with RA+NPs home at the BM after transplantation in an AML mouse model. The photo-disassembly of the NPs within the grafted cells by a blue laser enables their differentiation towards a macrophage lineage. This macrophage activation seems to have systemic anti-leukemic effect within the BM, with a significant reduction of leukemic cells in all BM compartments, of animals treated with RA+NPs, when compared with animals treated with empty NPs. In a separate group of experiments, we show for the first time that normal HSCs transfected with RA+NPs show superior engraftment at the BM niche than cells without treatment or treated with empty NPs. This is the first time that the activity of RA is tested in terms of long-term hematopoietic reconstitution after transplant using an in situ activation approach without any exogenous priming or genetic conditioning of the transplanted cells. Overall, the approach documented here has the potential to improve consolidation therapy in AML since it allows a dual intervention in the BM niche: to tackle resistant leukemia and improve HSC engraftment at the same time.

Antibody blockade of the PSGL-1 immune checkpoint enhances T-cell responses to B-cell lymphoma.

Despite advancements in cancer immunotherapy, most lymphomas remain unresponsive to checkpoint inhibitors. P-selectin glycoprotein ligand-1 (PSGL-1), recently identified as a promoter of T-cell exhaustion in murine melanoma models, has emerged as a novel immune checkpoint protein and promising immunotherapeutic target. In this study, we investigated the potential of PSGL-1 antibody targeting in B-cell lymphoma. Using allogeneic co-culture systems, we demonstrated that targeted antibody interventions against human PSGL-1 enhanced T-cell activation and effector cytokine production in response to lymphoma cells. Moreover, in vitro treatment of primary lymphoma cell suspensions with PSGL-1 antibody resulted in increased activation of autologous lymphoma-infiltrating T cells. Using the A20 syngeneic B-cell lymphoma mouse model, we found that PSGL-1 antibody treatment significantly slowed tumor development and reduced the endpoint tumor burden. This antitumoral effect was accompanied by augmented tumor infiltration of CD4+ and CD8+ T cells and reduced infiltration of regulatory T cells. Finally, anti-PSGL-1 administration enhanced the expansion of CAR T cells previously transferred to mice bearing the aggressive Eµ-Myc lymphoma cells and improved disease control. These results demonstrate that PSGL-1 antibody blockade bolsters T-cell activity against B-cell lymphoma, suggesting a potential novel immunotherapeutic approach for treating these malignancies.

Iron overload induces dysplastic erythropoiesis and features of myelodysplasia in Nrf2-deficient mice.

Iron overload (IOL) is hypothesized to contribute to dysplastic erythropoiesis. Several conditions, including myelodysplastic syndrome, thalassemia and sickle cell anemia, are characterized by ineffective erythropoiesis and IOL. Iron is pro-oxidant and may participate in the pathophysiology of these conditions by increasing genomic instability and altering the microenvironment. There is, however, lack of in vivo evidence demonstrating a role of IOL and oxidative damage in dysplastic erythropoiesis. NRF2 transcription factor is the master regulator of antioxidant defenses, playing a crucial role in the cellular response to IOL in the liver. Here, we crossed Nrf2-/- with hemochromatosis (Hfe-/-) or hepcidin-null (Hamp1-/-) mice. Double-knockout mice developed features of ineffective erythropoiesis and myelodysplasia including macrocytic anemia, splenomegaly, and accumulation of immature dysplastic bone marrow (BM) cells. BM cells from Nrf2/Hamp1-/- mice showed increased in vitro clonogenic potential and, upon serial transplantation, recipients disclosed cytopenias, despite normal engraftment, suggesting defective differentiation. Unstimulated karyotype analysis showed increased chromosome instability and aneuploidy in Nrf2/Hamp1-/- BM cells. In HFE-related hemochromatosis patients, NRF2 promoter SNP rs35652124 genotype TT (predicted to decrease NRF2 expression) associated with increased MCV, consistent with erythroid dysplasia. Our results suggest that IOL induces ineffective erythropoiesis and dysplastic hematologic features through oxidative damage in Nrf2-deficient cells.

Xanthohumol modulates inflammation, oxidative stress, and angiogenesis in type 1 diabetic rat skin wound healing.

Type 1 diabetes mellitus is responsible for metabolic dysfunction, accompanied by chronic inflammation, oxidative stress, and endothelium dysfunction, and is often associated with impaired wound healing. Phenol-rich food improves vascular function, contributing to diabetes prevention. This study has evaluated the effect of phenol-rich beverage consumption in diabetic rats on wound healing, through angiogenesis, inflammation, and oxidative stress modulation. A wound-healing assay was performed in streptozotocin-induced diabetic Wistar rats drinking water, 5% ethanol, and stout beer with and without 10 mg/L xanthohumol (1), for a five-week period. Wounded skin microvessel density was reduced to normal values upon consumption of 1 in diabetic rats, being accompanied by decreased serum VEGF-A and inflammatory markers (IL-1ß, NO, N-acetylglucosaminidase). Systemic glutathione and kidney and liver H2O2, 3-nitrotyrosine, and protein carbonylation also decreased to healthy levels after treatment with 1, implying an improvement in oxidative stress status. These findings suggest that consumption of xanthohumol (1) by diabetic animals consistently decreases inflammation and oxidative stress, allowing neovascularization control and improving diabetic wound healing.

When a Hypersomnolent Hemodialyzed Patient Actually Has a Rare Stroke: A Case of Artery of Percheron Infarction With Paradoxical Embolism.

INTRODUCTION: Artery of Percheron (AOP) is an uncommon anatomic variant of the arterial supply of the medial thalami. Owing to variable clinical presentation, challenging imaging diagnosis, and its rarity, it is difficult to diagnose AOP infarctions. We present a clinical case of a unique presentation of AOP infarction associated with paradoxical embolism and highlight the atypical clinical manifestations and challenging diagnosis of this stroke syndrome. CASE REPORT: A 58-year-old White female with chronic renal insufficiency on hemodialysis was admitted to our center with a 10-hour course of hypersomnolence and right-sided ataxia. She had normal body temperature, blood pressure, peripheral oxygen saturation, and heart rate and scored 11 points in the Glasgow Coma Scale and 12 points in National Institutes of Health Stroke Scale. Initial brain computerized tomography scan, electrocardiogram, and thoracic radiography were normal; transcranial Doppler ultrasound showed >50% stenosis at the P2 segment of the right posterior cerebral artery, and transthoracic echocardiogram, a patent foramen ovale and thrombus adherent to the hemodialysis catheter. On day 3, she underwent brain magnetic resonance that showed acute ischemic lesions at the paramedian thalami and the superior cerebral peduncles. AOP infarction due to a paradoxical embolism from a patent foramen ovale with a right atrial thrombus was the final diagnosis. CONCLUSIONS: AOP infarctions are a rare type of stroke with elusive clinical presentations and frequently, initial imaging assessment is normal. Early recognition is crucial, and a high index of suspicion is needed to suspect this diagnosis.

Xanthohumol-supplemented beer modulates angiogenesis and inflammation in a skin wound healing model. Involvement of local adipocytes.

Angiogenesis and inflammation are two intermingled processes that play a role in wound healing. Nevertheless, whenever exacerbated, these processes result in nonhealing wounds. Xanthohumol (XN), a beer-derived polyphenol, inhibits these processes in many physiopathological situations. This study aimed at examining whether XN ingestion affects wound healing. Wistar rats drinking water, 5% ethanol, stout beer (SB) or stout beer supplemented with 10 mg/L XN (Suppl SB) for 4 weeks, were subjected to a 1.5 cm full skin-thickness longitudinal incision, and further maintained under the same beverage conditions for another week. No differences in beverage consumption or body weight were found throughout the study but food intake decreased in every group relative to controls. Consumption of Suppl SB resulted in decreased serum VEGF levels (18.42%), N-acetylglucosaminidase activity (27.77%), IL1ß concentration (9.07%), and NO released (77.06%), accompanied by a reduced redox state as observed by increased GSH/GSSG ratio (to 198.80%). Also, the number of blood vessels within the wound granulation tissue seems to reduce in animals drinking Suppl SB (23.08%). Interestingly, SB and primarily Suppl SB showed a tendency to increase adipocyte number (to 194.26% and 156.68%, respectively) and reduce adipocyte size (4.60% and 24.64%, respectively) within the granuloma. Liver function and metabolism did not change among the animal groups as analyzed by plasma biochemical parameters, indicating no beverage toxicity. This study shows that XN intake in its natural beer context reduced inflammation, oxidative stress, and angiogenesis, ameliorating the wound healing process, suggesting that this polyphenol may exert beneficial effect as a nutritional supplement.

Flow Cytometry Analysis of Murine Bone Marrow Hematopoietic Stem and Progenitor Cells and Stromal Niche Cells.

The bone marrow (BM) is the soft tissue found within bones where hematopoiesis, the process by which new blood cells are generated, primarily occurs. As such, it contains hematopoietic stem and progenitor cells (HSPCs), as well as supporting stromal cells that contribute to the maintenance and regulation of HSPCs. Hematological and other BM disorders disrupt hematopoiesis by affecting hematopoietic cells directly and/or through the alteration of the BM niche. Here, we describe a method to study hematopoiesis in health and malignancy through the phenotypic analysis of murine BM HSPCs and stromal niche populations by flow cytometry. Our method details the required steps to enrich BM cells in endosteal and central BM fractions, as well as the appropriate gating strategies to identify the two key niche cell types involved in HSPC regulation, endothelial cells and mesenchymal stem cells. The phenotypic analysis proposed here may be combined with mouse mutants, disease models, and functional assays to characterize the HSPC compartment and its niche.

Acute organ failure and risk of admission to intensive medical care in cancer patients: a single center prospective cohort study. / Falência aguda de órgão e risco de admissão em unidade de terapia intensiva nos pacientes oncológicos: estudo de coorte prospectivo unicêntrico.

OBJECTIVE: To ascertain the cumulative incidence of acute organ failure and intensive care unit admission in cancer patients. METHODS: This was a single-center prospective cohort study of adult cancer patients admitted for unscheduled inpatient care while on systemic cancer treatment. RESULTS: Between August 2018 and February 2019, 10,392 patients were on systemic treatment, 358 had unscheduled inpatient care and were eligible for inclusion, and 285 were included. The mean age was 60.9 years, 50.9% were male, and 17.9% of patients had hematologic cancers. The cumulative risk of acute organ failure was 39.6% (95%CI: 35 - 44), and that of intensive care unit admission among patients with acute organ failure was 15.0% (95%CI: 12 - 18). On admission, 62.1% of patients were considered not eligible for artificial organ replacement therapy. The median follow-up time was 9.5 months. Inpatient mortality was 17.5%, with an intensive care unit mortality rate of 58.8% and a median cohort survival of 134 days (95%CI: 106 - 162). In multivariate analysis, acute organ failure was associated with 6-month postdischarge mortality (HR 1.6; 95%CI: 1.2 - 2.2). CONCLUSION: The risk of acute organ failure in cancer patients admitted for unscheduled inpatient care while on systemic treatment was 39.6%, and the risk of intensive care unit admission was 15.0%. Acute organ failure in cancer patients was an independent poor prognostic factor for inpatient hospital mortality and 6-month survival.

OBJETIVO: Determinar a incidência cumulativa de falência aguda de órgão e internamento em unidade de terapia intensiva em pacientes oncológicos. MÉTODOS: Estudo de coorte prospectivo de pacientes oncológicos adultos em tratamento sistêmico antineoplásico, internados de forma não programada. RESULTADOS: Entre agosto de 2018 e fevereiro de 2019, 10.392 pacientes foram submetidos a tratamento sistêmico antineoplásico, sendo que 358 necessitaram de internamento hospitalar não programado e foram elegíveis para inclusão; por fim, 258 desses pacientes foram incluídos. A média de idade foi de 60,9 anos, e 50,9% eram do sexo masculino; 17,9% dos pacientes tinham câncer hematológico. O risco acumulado de falência de órgãos foi de 39,6% (IC95% 35 - 44) e o risco de internamento na unidade de terapia intensiva em pacientes com falência aguda de órgão foi de 15,0% (IC95% 12 - 18). À admissão em internamento, 62,1% dos pacientes foram considerados não elegíveis para terapia de substituição artificial de órgãos. O tempo mediano de seguimento foi de 9,5 meses. A mortalidade hospitalar foi de 17,5%, na unidade de terapia intensiva de 58,8%. A mediana de sobrevivência da coorte foi de 134 dias (IC95% 106 - 162). Na análise multivariada, a falência aguda de órgão se associou com a mortalidade aos 6 meses após a alta (hazard ratio: 1,6; IC95% 1,2 - 2,2). CONCLUSÃO: O risco de falência aguda de órgão em pacientes oncológicos admitidos para tratamento hospitalar não programado durante o tratamento sistémico foi de 39,6% e o risco de internamento em unidade de terapia intensiva foi de 15,0%. A falência aguda de órgão em pacientes oncológicos foi um fator de prognóstico independente para maior mortalidade intra-hospitalar e menor sobrevivência aos 6 meses após a alta.

Metalloproteinase inhibition reduces AML growth, prevents stem cell loss, and improves chemotherapy effectiveness.

Acute myeloid leukemia (AML) is a blood cancer of the myeloid lineage. Its prognosis remains poor, highlighting the need for new therapeutic and precision medicine approaches. AML symptoms often include cytopenias linked to loss of healthy hematopoietic stem and progenitor cells (HSPCs). The mechanisms behind HSPC decline are complex and still poorly understood. Here, intravital microscopy (IVM) of a well-established experimental model of AML allows direct observation of the interactions between healthy and malignant cells in the bone marrow (BM), suggesting that physical dislodgment of healthy cells by AML through damaged vasculature may play an important role. Multiple matrix metalloproteinases (MMPs), known to remodel extracellular matrix, are expressed by AML cells and the BM microenvironment. We reason MMPs could be involved in cell displacement and vascular leakiness; therefore, we evaluate the therapeutic potential of MMP pharmacological inhibition using the broad-spectrum inhibitor prinomastat. IVM analyses of prinomastat-treated mice reveal reduced vascular permeability and healthy cell clusters in circulation and lower AML infiltration, proliferation, and cell migration. Furthermore, treated mice have increased retention of healthy HSPCs in the BM and increased survival following chemotherapy. Analysis of a human AML transcriptomic database reveals widespread MMP deregulation, and human AML cells show susceptibility to MMP inhibition. Overall, our results suggest that MMP inhibition could be a promising complementary therapy to reduce AML growth and limit HSPC loss and BM vascular damage caused by MLL-AF9 and possibly other AML subtypes.