Using iPS Cells To Investigate Treatment For Sickle Cell Disease

Main Category: Blood / Hematology
Also Included In: Genetics
Article Date: 27 Jul 2011 - 0:00 PDT


Researchers from the Boston University School of Medicine (BUSM) were recently awarded a five-year $9 million grant from the National Heart, Lung, and Blood Institute (NHLBI) to mass-produce sickle cell anemia-specific induced Pluripotent Stem (iPS) cells. Under the direction of principal investigators Martin H. Steinberg, MD and George Murphy, PhD, the researchers propose making iPS cells from the blood of patients with sickle cell disease to better understand how certain genes are involved in the disease.

This initiative, which is being done in collaboration with Boston Medical Center (BMC), brings together two of the most dynamic entities at the Boston University Medical Campus: the Center of Excellence in Sickle Cell Disease, directed by Steinberg, and the Center for Regenerative Medicine (CReM), which is co-directed by Murphy, Gustavo Mostoslavsky, MD, PhD, and Darrell Kotton, MD.

iPS cells are derived by reprogramming adult cells into a primitive stem cell state. This process results in the creation of cells that are similar to embryonic stem (ES) cells in terms of their capability to differentiate into different types of cells. It is now widely accepted that iPS cells share many of the characteristics ES cells, including gene expression profiles, epigenetic signatures and pluripotency. iPS cells can be generated from mature somatic cells, such as skin or blood cells, allowing for the development of patient-specific cells and tissues that should not elicit inappropriate immune responses, making them a powerful tool for biological research and a resource for regenerative medicine.

Sickle cell anemia, an orphan disease of African Americans, is noted for its extensive morbidity and high mortality. Only one Food and Drug Administration (FDA) approved drug is available for its pathophysiologically based treatment. This agent, hydroxyurea, works through its ability to induce fetal hemoglobin (HbF) expression, which thwarts sickle hemoglobin polymerization. Not all patients respond to this treatment, so additional HbF inducing drugs are needed.

"This funding will allow us to create the largest library of sickle cell disease-specific iPS cell lines in the world," said Murphy, assistant professor of Medicine and Hematology-Oncology at BUSM. "It enables the creation of an in vitro system for the study of sickle cell anemia in the exact genetic context of the patients."

Using a novel excisable reprogramming vector, they will generate 'clinical grade' human iPS cells free of any residual reprogramming transgenes. These directly differentiated sickle iPS cells will be used to produce an unlimited supply of erythroid-lineage cells to better understand HbF genetic regulation and perform pre-clinical small molecule drug screens.

"These studies will illuminate how specific genes behave in different tissues and should clarify the mechanisms by which a gene associated with a disease affects the biology of different tissues," said Susan B. Shurin, MD, acting director of the National Institutes of Health's (NIH) NHLBI, which is funding most of the studies. "Understanding the cellular and tissue biology will allow us to develop and test new therapies and prevention methods. These approaches using iPS cells on a large scale could improve the predictive value of preclinical testing, benefit regenerative medicine and reduce the need for animal models of disease."

"We have an opportunity here to study tissue-specific cells on a large scale, including how gene variants are expressed and alter a tissue's behavior," said Cashell Jaquish, PhD, a program officer in the NHLBI's Division of Cardiovascular Sciences. "That is something we haven't been able to get near before" because the technology was not available. The opportunities are great because genome-wide association studies have identified multiple potentially important genetic variants, she added.

"Ultimately, we hope to translate these findings into clinically efficacious treatments," said Steinberg, also a professor of Medicine, Pediatrics, Pathology and Laboratory Medicine at BUSM.

Other BUSM faculty members involved with this research project are Gustavo Mostoslavsky, MD, PhD, Gastroenterology, Darrell Kotton, MD, Pulmonary, David Chui, MD, Hematology and Oncology, Paola Sebastiani, PhD, Biostatistics, Clinton Baldwin, PhD, Genetics, and Susan Perrine, MD, Hematology and Oncology.

The NIH has funded nine new studies that will develop induced pluripotent stem cells, or iPS cells, from patients with genetic variations that have been associated with coronary artery disease, pulmonary hypertension, clotting disorders, diabetes, and other conditions. Building upon previous genome-wide association study (GWAS) findings, these studies will seek to illuminate how gene variants lead to the physical manifestations of disease. The nine cooperative agreements total $85 million over five years. The NHLBI is contributing $76 million and the NIH's National Human Genome Research Institute (NHGRI) is contributing $9 million of the total.

Source:
Jenny Eriksen Leary
Boston University Medical Center

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