About

Laura Breda, PhD, is a Research Associate Professor of Pediatrics (Hematology) at the University of Pennsylvania and a Scientific Co-Director at the Comprehensive Center for the Cure of Sickle Cell Disease and Other RED Cell Disorders at Children's Hospital of Philadelphia. Her work is focused on developing genetic therapies aimed at curing hemoglobinopathies such as Sickle Cell Disease (SCD) and β-Thalassemia. She has engineered and tested gene therapy tools to restore hemoglobin production by using lentiviral vectors to carry and transfer the β-like globin gene into hematopoietic stem cells, demonstrating the potential for these cells to recover hemoglobin synthesis in patients with these conditions. Dr. Breda established procedures to measure hemoglobin synthesis increases in red blood cells with different genetic variants, leading to the identification of a leading gene therapy candidate. She co-authored a patent for a new lentiviral vector, ALS20, which received IND approval by the FDA in March 2023, and a clinical trial based on this product is underway at CHOP. Additionally, she has developed systems to deliver mRNA cargos to human hematopoietic stem cells in murine models, showing that it is possible to modify the fate of these cells with a single intravenous injection. Using Cas9-modified base editing technology, she has applied this to human sickle cells, correcting the genetic mutation responsible for sickle cell disease and preventing sickling of cells. Her research aims to expand access to gene therapy and reduce associated toxicities, contributing significantly to the advancement of curative treatments for hemoglobinopathies.

Research topics

• Cell biology
• Medicine
• Genetics
• Internal medicine
• Immunology
• Biology
• Cancer research

Selected publications

• CD47 peptide-cloaked lipid nanoparticles promote cell-specific mRNA delivery

  Molecular Therapy · 2025-03-13 · 26 citations

  articleOpen access

  mRNA-based therapeutics delivered via lipid nanoparticles (LNP-mRNA) hold great promise for treating diverse diseases. However, further improvements are needed to refine outcomes in non-vaccine, extrahepatic applications, such as minimizing the rapid clearance and off-target uptake in undesired tissues of the mononuclear phagocyte system (MPS). We propose modifying LNP surfaces with the phagocytic cell "don't eat me" signal, CD47, in combination with our previously established antibody-based targeted LNP (tLNP) to create a CD47/tLNP platform with reduced phagocytic clearance and off-target effects and improved efficiency for cell-specific delivery. We showed that CD47 modification decreased macrophage and hepatic uptake both in vitro and in vivo. Combining CD47 modification with antibodies targeting endothelial cells, T cells, or hematopoietic stem cells (HSCs) increased targeting efficiency up to 3-fold compared to tLNP alone. Enhanced targeting of CD47/tLNP to HSCs with reduced off-targeting enabled the delivery of pro-apoptotic mRNA for HSC depletion as a preconditioning strategy prior to bone marrow transplant. Additionally, CD47-modified LNPs showed diminished inflammatory effects on hepatic tissue and an altered protein corona. Our CD47/tLNP-mRNA platform, with its reduced phagocytic clearance, mitigated inflammatory effects, and enhanced targeted delivery, should further facilitate the development of in vivo mRNA therapeutics.

  PublisherDOI

• Expansion of human hematopoietic stem cells by inhibiting translation

  Blood · 2025-11-03

  articleOpen access

  Abstract Hematopoietic stem cell (HSC) transplantation using umbilical cord blood (UCB) is a potentially life-saving treatment for leukemia and bone marrow failure but is limited by the low number of HSCs in UCB. The loss of HSCs after ex vivo manipulation is also a major obstacle to gene editing for inherited blood disorders. HSCs require a low rate of translation to maintain their capacity for self-renewal, but hematopoietic cytokines used to expand HSCs stimulate protein synthesis and impair long-term self-renewal. We previously described cytokine-free conditions that maintain human and mouse HSCs ex vivo using inhibitors of GSK-3 (CHIR) and mTOR (Rapamycin), referred to hereafter as “CR”. Here we performed a high throughput screen of 2,240 FDA approved and/or bioactive compounds and found that the translation inhibitor 4E1RCat allows ex vivo expansion of human HSCs from UCB in CR medium with minimal cytokine exposure. Single cell transcriptomic analysis demonstrates maintenance of HSCs expressing mediators of the unfolded protein stress response, further supporting the potential importance of regulated proteostasis in HSC maintenance and expansion. We confirmed that these culture conditions promote the expansion of long-term HSCs by limiting dilution analysis (LDA) and secondary transplantation. The LDA shows a ~5-fold expansion of functional HSCs from UCB after one week of culture in CR with low cytokines and 4E1RCat. Secondary transplantation assays confirm expansion of long-term HSCs with multilineage potential. CRISPR/Cas9 editing of the BCL11A+58 enhancer is now an FDA approved therapy for sickle cell disease and transfusion-dependent β-thalassemia. However, loss of functional HSCs after ex vivo manipulation and culture remains a major obstacle to therapeutic gene editing. Our culture conditions maintain and expand human adult HSCs after gene editing by both electroporation and lipid nanoparticles (LNPs) delivery methods. After 7 days of culture in CR with low cytokines and 4E1RCat, phenotypic HSCs expanded ~35-78-fold compared to day 0 for HSCs undergoing electroporation or exposure to LNPs. Fetal hemoglobin (HbF) expression increased substantially after BCL11A editing in erythroid cells derived from day 7 expansion after electroporation or LNP delivery. Transplant of BCL11A-edited HSCs cultured in CR and low cytokines with 4E1RCat showed high engraftment comparable to freshly isolated HSCs, indicating maintenance of HSCs after culture in these conditions. Culturing edited HSCs under these conditions may therefore overcome a major obstacle to ex vivo gene correction for human hemoglobinopathies by maintaining functional HSCs.

  PublisherOA PDFDOI

• Real-world comparative effects of curative and disease-modifying therapies on ineffective erythropoiesis in beta-thalassemia

  Blood · 2025-11-03

  articleOpen access

  Abstract Introduction In beta-thalassemia (BT), reduced or absent production of beta globin leads to the accumulation of excess alpha globin, which drives ineffective erythropoiesis (IE). In turn, IE leads to anemia and, indirectly, iron overload (IO). Parameters associated with IE and IO are elevated erythropoietin (EPO; renal hormone that stimulates erythropoiesis), high growth differentiation factor 15 (GDF-15; marker of cellular stress), low hepcidin (HAMP; hepatic hormone controlling iron absorption), and high erythroferrone (ERFE; erythroid hormone that suppresses hepcidin). Treatment options include regular transfusions with iron chelation; luspatercept, an erythroid maturation agent; and curative therapy with allogeneic hematopoietic stem cell transplant (allo-HSCT) or novel gene-modified autologous HSCT (auto-HSCT). The aim of this study was to explore the real-world impact of various treatment options in reducing IE in BT and provide parameters to compare current and future treatments for BT. Methods Patients with BT or HbE BT were enrolled from the Children's Hospital of Philadelphia and the Hospital of the University of Pennsylvania Thalassemia Centers. Patients were categorized into four treatment groups: allo-HSCT, luspatercept (all but one also received regular transfusions), auto-HSCT (all received beti-cel), and regular transfusions. Blood samples were obtained at a median of 36.3 (range 5.8-72) months (mo) after receiving allo-HSCT, 17 (6-109) mo after auto-HSCT, and 47 (5.7-56.5) mo after initiation of luspatercept. HAMP, ERFE, EPO and GDF-15 were measured by ELISA and hemoglobin (Hb) was obtained from routine clinical lab results obtained within 3 days of the research sample. Statistical comparisons among treatment groups were carried out with the Kruskal–Wallis test, followed by Dunn's post hoc correction for multiple comparisons. Results The study included 58 subjects with a mean age of 20.2 ± 14.1 (range 1-65) years, 39.7% male. Patients who underwent allo-HSCT (N=5) had Hb 11.6 ± 1.7 g/dL, with lower EPO (11.6 ± 5.9 mIU/mL), ERFE (1.3 ± 0.8 ng/mL), and GDF-15 (668.2 ± 632.3 pg/mL), and higher HAMP (86.7 ± 48.6 ng/mL) consistent with normalization of erythropoiesis and iron metabolism. Compared to allo-HSCT, patients who underwent auto-HSCT (N=17) achieved similar Hb (11.1 ± 1.0 g/dL) with slightly elevated but not statistically significant differences in EPO (27.5 ± 12.4) and GDF-15 (1574.8 ± 1094.2) and similar ERFE (1.6 ± 1.7) and HAMP (80.7 ± 28.8) levels. Taken together, these data suggest that control of IE following gene-modified auto-HSCT approaches that with allo-HSCT. The transfusion group (N=30) had lower Hb (10.0 ± 1.0 g/dL) with evidence of IE, including intermediate EPO (72.4 ± 77.8), ERFE (4.3 ± 3.7), GDF-15 (4594.0 ± 2717.0), and HAMP (68.0 ± 43.2) levels. GDF-15 was higher compared with both allo- (p<0.0049) and auto-HSCT (p=0.0071). Within the transfusion group, patients were stratified by Hb into 3 groups: high (>10.5 g/dL, N = 10), intermediate (9.5–10.5 g/dL, N = 8), and low (<9.5 g/dL, N = 12). Patients with lower Hb exhibited progressively higher EPO, ERFE, and GDF-15 levels and lower HAMP (all p<0.001), consistent with increased IE. The patients receiving luspatercept (N=6, Hb 10.1 ± 1.3 g/dL) had higher EPO (187.0 ± 140.0, p<0.001), ERFE (16.3 ± 7.5, p<0.001), and GDF-15 (7721.8 ± 1853.7, p<0.001) compared with both allo and auto-HSCT, with significantly lower HAMP (19.4 ± 17.5, p<0.01) compared with auto-HSCT. Compared to patients receiving transfusions, patients receiving luspatercept had comparable Hb but higher ERFE (p<0.05) and lower HAMP (p=0.093), consistent with significantly elevated markers of IE. Conclusions Our analysis of markers of IE and IO demonstrates that erythroid and iron homeostasis were fully restored in the group of BT patients who underwent allo-HSCT. Some markers of IE (EPO and GDF-15) remain mildly elevated in those who received gene-modified auto-HSCT; further study with larger numbers of patients is needed to determine if differences in these markers are clinically meaningful. These data also provide evidence to support a higher pre-transfusion Hb goal among regularly transfused individuals to better control IE. Finally, although luspatercept may reduce transfusion requirements, our data show that its use is associated with elevated markers of IE, suggesting that patients treated with luspatercept may benefit from close monitoring for sequelae of active IE.

  PublisherOA PDFDOI

• Effective gene therapy for metachromatic leukodystrophy achieved with minimal lentiviral genomic integrations

  Molecular Therapy — Nucleic Acids · 2025-01-25

  articleOpen access

  -KO bone marrow (BM) cells transduced with 0.6 VCN of EA1 demonstrated behavior and CNS histology matching wild-type (WT) mice. Our novel vector boosts efficacy while improving safety as a robust approach for treating MLD patients.

  PublisherDOI

• An erythroid-specific lentiviral vector improves anemia and iron metabolism in a new model of XLSA

  Blood · 2024-12-10 · 3 citations

  articleOpen access

  ABSTRACT: X-linked sideroblastic anemia (XLSA) is a congenital anemia caused by mutations in ALAS2, a gene responsible for heme synthesis. Treatments are limited to pyridoxine supplements and blood transfusions, offering no definitive cure except for allogeneic hematopoietic stem cell transplantation, only accessible to a subset of patients. The absence of a suitable animal model has hindered the development of gene therapy research for this disease. We engineered a conditional Alas2-knockout (KO) mouse model using tamoxifen administration or treatment with lipid nanoparticles carrying Cre-mRNA and conjugated to an anti-CD117 antibody. Alas2-KOBM animals displayed a severe anemic phenotype characterized by ineffective erythropoiesis (IE), leading to low numbers of red blood cells, hemoglobin, and hematocrit. In particular, erythropoiesis in these animals showed expansion of polychromatic erythroid cells, characterized by reduced oxidative phosphorylation, mitochondria's function, and activity of key tricarboxylic acid cycle enzymes. In contrast, glycolysis was increased in the unsuccessful attempt to extend cell survival despite mitochondrial dysfunction. The IE was associated with marked splenomegaly and low hepcidin levels, leading to iron accumulation in the liver, spleen, and bone marrow and the formation of ring sideroblasts. To investigate the potential of a gene therapy approach for XLSA, we developed a lentiviral vector (X-ALAS2-LV) to direct ALAS2 expression in erythroid cells. Infusion of bone marrow (BM) cells with 0.6 to 1.4 copies of the X-ALAS2-LV in Alas2-KOBM mice improved complete blood cell levels, tissue iron accumulation, and survival rates. These findings suggest our vector could be curative in patients with XLSA.

  PublisherOA PDFDOI

• An Erythroid-Specific Lentiviral Vector Improves Anemia and Iron Metabolism in a New Model of Xlsa

  Blood · 2024-11-05

  article

  X-linked sideroblastic anemia (XLSA) is caused by germline mutations in the erythroid-specific 5-aminolevulinate synthase (Alas2) gene, encoding the enzyme ALAS2. Typically, XLSA affects hemizygous males with hypochromic microcytic anemia, systemic iron overload, and ring sideroblasts. Treatments are limited to pyridoxine supplements and blood transfusions, with allogeneic hematopoietic stem cell (HSC) transplantation as the only definitive cure, accessible to very few patients. The absence of a suitable animal model has hindered preclinical studies. We have engineered a Cre recombinase LoxP XLSA mouse model by inducing Alas2 knock-out using either tamoxifen or ex-vivo HSC recombination via lipid nanoparticles (LNP) carrying Cre-mRNA conjugated to an anti-CD117 antibody. The resulting Alas2-KO HSCs are transplanted into lethally irradiated recipient mice, generating - chimeras that are Alas2 deficient only in the bone marrow compartment (Alas2-KOBM). Alas2 -KOBM animals display a severe anemic phenotype characterized by ineffective erythropoiesis (IE), with low numbers of red blood cells (RBC) (3.0±0.3), hemoglobin (Hb) (3.4±0.4), and hematocrit (HCT) (16.3±1.6).In these animals, IE is reflected by an expansion of polychromatic erythroid (PolyE) cells and concomitant reduction of orthochromatic/reticulocyte and RBC populations. Alas2-KOBM animals show splenomegaly with extramedullary hematopoiesis, lymphoid hyperplasia, and erythroid hyperplasia in the BM. Notably, the iron staining of BM tissues and smears confirms the presence of ring sideroblasts. Electron microscopy (EM) analysis of the isolated PolyE population revealed iron accumulation in the mitochondria, corroborating the presence of iron overload and the inability of this population to differentiate due to the lack of Alas2. To confirm the dysregulation of iron homeostasis, we evaluated erythroferrone (ERFE) and hepatic hepcidin (HAMP) serum levels. Diseases characterized by IE are generally associated with high levels of erythropoietin (EPO) and ERFE and low levels of HAMP, leading to iron overload. Alas2-KOBManimals showed increased ERFE and decreased HAMP levels, consistent with increased EPO, serum iron levels, and organ iron overload. We also observed increased ferritin levels and transferrin saturation. Metabolic analysis of PolyE cells showed reduced oxidative phosphorylation, mitochondria's function, and key Tricarboxylic Acid (TCA) cycle enzyme activity. In contrast, glycolysis was increased in the unsuccessful attempt to extend cell survival despite mitochondrial dysfunction. To alleviate the Alas2-KOBM phenotype, we developed a lentiviral vector (X-ALAS2-LV) to promote human Alas2 expression in erythroid cells. The infusion of BM cells with 0.6-1.4 copies of the X-ALAS2-LV in Alas2-KOBM mice rescued the phenotype and significantly improved CBC levels, tissue iron accumulation, and survival rates. Treated animals showed remarkable improvements in Hb (10.3±0.5), RBC (6.5±0.3), and HCT (33.6±1.0) levels. The splenomegaly observed in Alas2-KOBM mice was also markedly reduced. Iron levels in the liver, spleen, and BM were normalized, and the formation of ring sideroblasts was prevented. Additionally, no iron accumulation was detected in the mitochondria. Treated animals exhibited improved mitochondrial and glycolytic functions, with the expression of glycolytic enzymes and electron transport chain components trending toward normal levels . Most importantly, there was a significant reduction in pro-apoptotic and inflammatory gene expression, indicating anti-apoptotic and anti-inflammatory effects conferred by reintroducing functional Alas2. Secondary BM transplants confirmed the integration stability and efficacy of treatment with X-ALAS2-LV. Secondary recipients showed vector copy numbers and effective erythropoiesis comparable to primary chimeras . Our study established a robust anemic phenotype in mice through Alas2 gene deletion, including the first case of ring sideroblasts formation. Notably, animals rescued by X-ALAS2-LV showed VCN in the range of 0.6-1.4, suggesting that HSCs carrying relatively low VCN could be curative in XLSA patients with hypomorphic or residual Alas2 expression. This potential for a curative treatment provides a solid foundation for further clinical development and instills confidence in the vector's potential.

  PublisherDOI

• Quand l’ubiquitination se mêle du mélanome cutané

  médecine/sciences · 2024-03-01

  articleOpen access
  PublisherOA PDFDOI

• POS0157 THE EUROFEVER FMF LONGITUDINAL COHORT: FIRST LONGITUDINAL DATA

  Annals of the Rheumatic Diseases · 2024-06-01

  article
  PublisherDOI

• POS0773 STRATIFICATION OF PEDIATRIC SAPHO SYNDROME BASED ON SKIN MANIFESTATIONS: RESULTS FROM AN ITALIAN MULTICENTRIC STUDY (SAPHOPED)

  Annals of the Rheumatic Diseases · 2024-06-01

  article
  PublisherDOI

• Use of HSC-targeted LNP to generate a mouse model of lethal α-thalassemia and treatment via lentiviral gene therapy

  Blood · 2024-07-01 · 6 citations

  articleOpen access

  ABSTRACT: α-Thalassemia (AT) is one of the most commonly occurring inherited hematological diseases. However, few treatments are available, and allogeneic bone marrow transplantation is the only available therapeutic option for patients with severe AT. Research into AT has remained limited because of a lack of adult mouse models, with severe AT typically resulting in in utero lethality. By using a lipid nanoparticle (LNP) targeting the receptor CD117 and delivering a Cre messenger RNA (mRNACreLNPCD117), we were able to delete floxed α-globin genes at high efficiency in hematopoietic stem cells (HSC) ex vivo. These cells were then engrafted in the absence or presence of a novel α-globin-expressing lentiviral vector (ALS20αI). Myeloablated mice infused with mRNACreLNPCD117-treated HSC showed a complete knock out (KO) of α-globin genes. They showed a phenotype characterized by the synthesis of hemoglobin H (HbH; also known as β-tetramers or β4), aberrant erythropoiesis, and abnormal organ morphology, culminating in lethality ∼8 weeks after engraftment. Mice infused with mRNACreLNPCD117-treated HSC with at least 1 copy of ALS20αI survived long term with normalization of erythropoiesis, decreased production of HbH, and amelioration of the abnormal organ morphology. Furthermore, we tested ALS20αI in erythroid progenitors derived from α-globin-KO CD34+ cells and cells isolated from patients with both deletional and nondeletional HbH disease, demonstrating improvement in α-globin/β-globin mRNA ratio and reduction in the formation of HbH by high-performance liquid chromatography. Our results demonstrate the broad applicability of LNP for disease modeling, characterization of a novel mouse model of severe AT, and the efficacy of ALS20αI for treating AT.

  PublisherOA PDFDOI

Frequent coauthors

• Stefano Rivella

  University of Pennsylvania

  152 shared

• Roberto Gambari

  University of Ferrara

  32 shared

• Patricia J. Giardina

  30 shared

• Pedro Luiz Ramos

  27 shared

• Nicoletta Bianchi

  University of Ferrara

  27 shared

• Francesco Chiarelli

  University of Chieti-Pescara

  24 shared

• Monica Borgatti

  22 shared

• Carla Casu

  Children's Hospital of Philadelphia

  21 shared

Labs

• Lab of Laura BredaPI

Education

• Master of Science, Pediatrics/Hem-Onc

  Joan and Sanford I Weill Medical College of Cornell University

  2012

• PhD

  Universita' degli Studi di Ferrara

  2004

Awards & honors

• Patent for lentiviral vector ALS20 (2023)
• IND approval by FDA for ALS20 (2023)