Biomedical subjects

Vivien A Sheehan

Publications and source records attributed to Vivien A Sheehan.

3 recordsLinked to original sources

PubMed2026

Nephropathies Associated with Sickle Cell Trait and How to Study Them.

Sickle cell trait (SCT), which carries a single point mutation in the hemoglobin-β (HBB) gene, has long been considered a benign condition. However, epidemiological evidence challenges this assumption, revealing that individuals with SCT face an elevated risk of renal dysfunction. However, this field of study remains ill-defined as it has focused on sickle cell disease (SCD), where renal complications are severe. As SCT is more prevalent than SCD, consequences of nephropathies in this group translate into a substantial and largely unaddressed public health burden. Clinical data, primarily observational, implicate age and sex in the development of SCT-associated nephropathies. These manifestations span glomerular hyperfiltration, tubular damage, hematuria, renal papillary necrosis, renal medullary carcinoma, and progression to chronic kidney disease, all complications that cluster disproportionately in older male individuals. Despite this, the mechanistic basis of SCT nephropathy, the thresholds at which renal injury becomes clinically significant, and the optimal strategies for early identification and prevention remain inadequately defined. In vitro studies have primarily focused on SCD blood cell biology, with SCT receiving comparatively little attention. Humanized murine models (i.e., Berkeley and Townes) have recapitulated some SCT-associated renal phenotypes but need to be more fully characterized. This review aims to provide an overview of the biology of sickle cell trait nephropathies, the gaps in our knowledge, and the model systems we can use to fill those gaps.

Journal Article↗

PubMed2026

Combinatorial base editing couples disease correction with lineage amplification in hematopoietic stem and progenitor cells.

First-generation genome editing therapies have largely focused on correcting or compensating for pathogenic variants. However, as these approaches enter the clinic, emerging biological constraints limit maximal therapeutic impact. Because globin genes are activated late during erythroid differentiation, genome-corrected hematopoietic stem and progenitor cells (HSPCs) gain little selective advantage in the bone marrow. Here, we establish a strategy that links therapeutic genome edits to an erythroid fitness-enhancing allele to amplify the output of clinically relevant cells. We develop a multiplex base editing strategy that couples fetal hemoglobin (HbF) reactivation with erythroid lineage expansion. Introduction of a naturally occurring erythropoietin receptor truncation (tEPOR) associated with benign erythrocytosis increased erythroid cell production without impairing viability or differentiation. Combinatorial editing of tEPOR together with the BCL11A erythroid enhancer and HBG1/2 promoters in healthy donor, sickle cell disease, and β-thalassemia HSPCs synergistically increased erythroid proliferation and HbF expression beyond single base-edited or Casgevy-treated controls. Multiplex base-edited HSPCs retained long-term lineage repopulation and engraftment capacity in vivo, establishing a modular strategy that pairs disease correction with lineage amplification to improve therapeutic potency.

Journal Article↗

PubMed2026

Gene expression profiling identifies potential biomarkers for vaso-occlusive episodes in sickle cell disease.

Vaso-occlusive episodes (VOEs) or acute pain events, involving complex interactions between sickle erythrocytes and other blood cells, are a hallmark of sickle cell disease (SCD). In this study, we analyzed changes in peripheral blood transcriptomes between steady state and VOEs in individuals with SCD. We followed a cohort of 174 individuals with SCD with or without chronic pain and collected peripheral blood at clinic visits (steady state) and during hospitalizations (VOEs). We performed RNA-Seq profiling of CD45+ leukocytes and CD71+ erythroid cells. Pathways linked to complement activation, coagulation, and IL-6/JAK/STAT3 signaling were enriched during VOEs in the CD45+ cells. Contrastingly, the CD71+ cells showed an enrichment of pathways related to the cell cycle, such as mTORC1 signaling and the G2M checkpoint during VOEs. We then analyzed the expression changes of genes in patients with longitudinal data to determine potential biomarkers for VOEs. Expression of 4 genes - FAM20A, IL1B, MS4A4A, and SERPINB2 - was elevated during VOEs compared with steady state in the majority of patients. Furthermore, our results indicate that patients experiencing chronic pain exhibited 44% increased enrichment of significant pathways during VOEs when compared with patients without chronic pain.

Humans↗