Research Areas    |    Sickle Cell Disease    |    Cartilage Tissue Engineering

Sickle Cell Disease

Sickle Cell Adhesion

Sickle cell disease is a complex genetic blood disorder characterized by aberrant sickle hemoglobin resulting from a single amino acid substitution. The abnormal adhesion of sickle red blood cells to white blood cells and to the vessel wall is of central importance to the pathogenesis of vaso-occlusive events in patients with sickle cell disease.  We develop and employ in vitro microscopy-based flow chamber assays and microfluidics to characterize sickle cell adhesion mechanisms and the conditions under which they occur in order to better understand the molecular determinants of sickle cell adhesion and provide the basis for the development of anti-adhesion therapeutic agents.  We also employ computational and animal models to provide further understanding of sickle cell disease pathophysiology.

Exosomal release of reticulocyte-derived microRNA in sickle cell anemia

Since the 1980s, reticulocytes have been known to exocytose intracellular materials as they develop into mature red blood cells.  What is unknown is whether microRNAs, which were discovered later, are also packaged in these nanometer-sized exosomes.  In our disease model of sickle cell anemia, there is a net increase of reticulocytes in the plasma.  Reticulocytes have also been suggested to initiate the onset of occlusion in the microvasculature. We are investigating whether microRNA transfer from reticulocytes to bone marrow endothelial cells could promote reticulocyte exit from the bone marrow.  Elucidating a mechanism of reticulocyte exit from the bone marrow could uncover potential points of reticulocyte transmigration control that could delay the onset, or reduce the frequency, of vasoocclusion.  Such results could be therapeutically relevant to sickle cell anemia, or be generalized to other anemias that feature aberrant bone marrow activity.

Bone Phenotype in Sickle Cell Disease

Avascular necrosis is a well described pathology of sickle cell disease, however, the etiology is still not completely understood.  We are interested in studying the state of bone in mouse and human models of sickle cell disease.  To determine the effect of sickle cell disease on bone, we use microcomputed tomographic (microCT) analysis, real time PCR and immunohistochemistry to characterize the bone phenotype in the Townes mouse model of sickle cell disease.  We also aim to identify the genes that are differentially expressed in patients diagnosed with avascular necrosis using a high-throughput targeted gene expression approach. Our animal studies will be complemented with an in vitro engineered bone model mimicking conditions in the bone vasculature in sickle cell disease.

Novel Prognostic Microfluidic Systems for Cell Separation from Whole Blood

In sickle cell disease (SCD) RBCs lose their deformability due to polymerization of hemoglobin and assume a stiff, sickle or granular shape under physiologically deoxygenated conditions. To analyze different aspects of SCD in general and its severity and progression for an individual patient, it is imperative to be able to separate different types of blood cells from patient samples in a reasonably short time and with low expenses.  Existing techniques require a large amount of samples, stress the cells physically, and are time consuming and expensive. The objective of this project is to design a microfluidic-based device that will combine dual separation techniques (mechanical and affinity based) to separate different cells from a single whole blood sample. Successful implementation of this device will enable the assessment of disease progression and treatment monitoring within a short time and at reduced cost.

Development of a microfluidic model for the study of multiforme glioblastoma

Tumors of the brain are difficult to treat because of the presence of the blood brain and blood tumor barriers (BBB and BTB respectively). The BBB and BTB are characterized by tight junctions that restrict the permeability of the barriers, thereby reducing the efficacy of systemic chemotherapeutic treatment. Nitrous oxide (NO) plays a ubiquitous role in human physiology and has been demonstrated to affect permeability of the BBB. Our primary objective is to engineer physiologically relevant in vitro microfluidic models of both the BBB and the BTB in order to study the effects of targeted NO donors on chemotherapeutic delivery to brain tumors. Additionally, the model will be adapted to study the effects of NO on cell adhesion events in sickle cell disease.