Ferritin-H and a Phytotherapeutic, Alone or Combined, Reprogram RBC Precursor Cells From SCD Patients to Produce Levels of Fetal Hemoglobin That Constitute a Phenotypic Cure for Sickle Cell As Well As Providing Resistance to Malaria and a Probable Treatment for Beta-Thalassemia
Authors: Broyles Robert H. , Belegu Visar , Roth Austin C. , Curry Emily J. , Floyd Robert A. , Levi Sonia , Arosio Paolo , Santambrogio Paolo , Trudel Marie , Joshi Sunil K. 
Published: October 2019

Abstract 903

OBJECTIVE:

To test the phenotypic cure we have discovered for SCD and malaria in vivo in mice and in vitro in human red blood cell precursors from SCD patients in two-phase cultures.

BACKGROUND:

Gene regulation of developmental hemoglobin switching provides phenotypic cures for beta thalassemias, sickle cell disease, and malaria since it is known that reactivation of fetal globin expression alleviates all these disorders. We discovered a protein that regulates this developmental switch. Ferritin heavy chain (FtH) represses adult β-globin and activates γ(fetal)-globin gene expression in embryonic/K562 erythroid cells (Broyles et al., PNAS98: 9145, 2001; US Patents #7,517,669, #7,718,669, & #2009/0232783 A1; EU Patent # EP1354032B1; Australia patent #2002217964), leading us to propose FtH as a therapeutic agent.

METHODS:

Normal C57BL/6 mice, transgenics carrying the complete human beta-globin gene cluster (Beta-YAC Tg), and transgenic mice that express human FtH in definitive erythroid cells have been used under an IACUC-approved protocol to show the safety and efficacy of human FtH and our phytotherapeutic in vivo. Erythroid precursor cells from pediatric SCD patients obtained under an IRB-approved protocol and cultured in a two-phase system allow direct testing of an FtH expression plasmid, FtH protein, and our phytotherapeutic for manipulating Hb phenotypes. Hemoglobins were identified and quantified by HPLC; fetal Hb was confirmed by immunofluorescence.

RESULTS AND DISCUSSION:

Human FtH transgenic mice, in which the FtH gene is driven by a truncated b-promoter lacking the FtH-binding motif, express human FtH in definitive erythroid cells which results in repression of bMajor-globin but not bMinor-globin. Thus, these TgFtH mice are born with a reduced ratio of bMajor/bMinor globins, resulting in α-globin chain excess and a mild b-thalassemia. In applying this therapy to humans, thalassemia would not be expected since FtH also activates g (fetal)-globin, preventing the chain imbalance. Recent results with normal mice and Beta-YacTg mice show that FtH protein and our phytotherapeutic are both well tolerated in vivo. We have used numbers of target cells (found in the FtH transgenics) as an initial screen for determining an effective dosing regimens. Initial results indicate that both therapeutics are altering the Hb phenotype as predicted.

With cultured erythroid precursor cells from the pediatric SCD patients, our results show a complete switch from HbS to HbF with each mode of delivery of FtH or the phytotherapeutic. These results were replicated 15 times using cells from 9 SCD donors, as well as in erythroid precursors from normal donors. Human erythroid precursor cells have surface receptors specific for FtH. Immunofluorescence showed that human FtH is taken into the precursor cells in culture; and confocal microscopy confirmed nuclear localization of exogenously applied FtH. These results suggest that the purified protein and/or the phytotherapeutic can be directly delivered without gene therapy. Therefore, these methods of generating a phenotypic cure for malaria, beta-thal, and SCD should be inexpensive to deliver in vivo. Supported in part by donations to The Sickle Cell Cure Foundation and by a Grand Challenges in Global Health grant from the Bill & Melinda Gates Foundation.

Disclosures:

No relevant conflicts of interest to declare.