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ABSTRACT: In utero hematopoietic cell transplantation is an experimental nonmyeloablative therapy with potential applications in hematologic disorders, including sickle cell disease (SCD). Its clinical utility has been limited due to the early acquisition of T-cell immunity beginning at ∼14 weeks gestation, posing significant technical challenges and excluding treatment fetuses evaluated after the first trimester. Using murine neonatal transplantation at 20 days postcoitum (DPC) as a model for late-gestation transplantation (LGT) in humans, we investigated whether immune modulation with anti-CD3 monoclonal antibody (mAb) could achieve donor-specific tolerance and sustained allogeneic engraftment comparable with that of the early-gestation fetal recipient at 14 DPC. In allogeneic wild-type strain combinations, administration of anti-CD3 mAb with transplantation resulted in transient T-cell depletion followed by central tolerance induction confirmed by donor-specific clonal deletion and skin graft tolerance. Normal immune responses to third-party major histocompatibility complex and viral pathogens were preserved, and graft-versus-host disease did not occur. We further demonstrated the successful application of this approach in the Townes mouse model of SCD. These findings confirm the developing fetal T-cell response as a barrier to LGT and support transient T-cell depletion as a safe and effective immunomodulatory strategy to overcome it.

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Sickle cell disease (SCD) is the most common genetic disorder, affecting millions of people worldwide. Aromatic aldehydes, which increase the oxygen affinity of human hemoglobin to prevent polymerization of sickle hemoglobin and inhibit red blood cell (RBC) sickling, have been the subject of keen interest for the development of effective treatment against SCD. However, the aldehyde functional group metabolic instability has severly hampered their development, except for voxelotor, which was approved in 2019 for SCD treatment. To improve the metabolic stability of aromatic aldehydes, we designed and synthesized novel molecules by incorporating Michael acceptor reactive centers into the previously clinically studied aromatic aldehyde, 5-hydroxymethylfurfural (5-HMF). Eight such derivatives, referred to as MMA compounds were synthesized and studied for their functional and biological activities. Unlike 5-HMF, which forms Schiff-base interaction with αVal1 nitrogen of hemoglobin, the MMA compounds covalently interacted with ßCys93, as evidenced by reverse-phase HPLC and disulfide exchange reaction, explaining their RBC sickling inhibitory activities, which at 2 mM and 5 mM, range from 0% to 21% and 9% to 64%, respectively. Additionally, the MMA compounds showed a second mechanism of sickling inhibition (12%-41% and 13%-62% at 2 mM and 5 mM, respectively) by directly destabilizing the sickle hemoglobin polymer. In vitro studies demonstrated sustained pharmacologic activities of the compounds compared to 5-HMF. These findings hold promise for advancing SCD therapeutics.

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Medicinal plants have been used traditionally in Africa, especially Nigeria, in the management of sickle cell disorder (SCD) whose treatment has been mainly palliative. The antisickling properties of ethanol extract of Telfairia occidentalis Hook, F. (TO) (Family Cucurbitaceae) leaf was tested in vitro at concentrations 1, 2, 4, 8 and 16 mg/mL using inhibitory and reversal models. Nitrogen gas was used to induce hypoxia for 1 h. The effect of TO on red cell density and cell membrane were also determined. The methanol sub fraction of TO extract was subjected to GC/MS to identify some of the active compounds. The TO gave antisickling activities of 78.84 ± 1.34% inhibition and 95.4 ± 0.81% reversal, which are significantly (p < 0.05) higher than that of Ciklavit®. The TO extract gave a change in density of 17.83 ± 0.77% and a dose dependent activity on RBC membrane. Methyl 9-cis 11- trans-octadecadienoate; 1, 4- benzenedicarboxylic acid; 9, 12-octadecadienoic acid (Linoleic acid); and hexadecanoic acid methyl ester (palmitic acid); were identified from TO ethanol leaf extract for the first time using GC/MS. This study authenticated the ethnomedicinal claims of the use of T. occidentalis in the management of sickle cell disorder.

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Terminalia avicennioides Guill. & Perr. (Combretaceae) is used traditionally to treat malaria in Nigeria. To establish its efficacy, methanolic extract of T. avicennioides bark was investigated for antimalarial activity against Plasmodium berghei (NK-65) in mice. Twenty-five mice in five groups were used for this study. Group 1 was uninfected normal control. Twenty mice infected with P. berghei were grouped as untreated negative control (group 2), 5 mg/kg b.w. p.o. artesunate-treated positive control (group 3), and 100 and 200 mg/kg b.w. p.o. T. avicennioides-treated infected mice (groups 4 and 5, respectively). Four-day suppressive effects on P. berghei and hematological and oxidative statuses of the mice were assessed. Suppression of parasitemia by artesunate and methanolic extract of T. avicennioides (at 100 and 200 mg/kg b.w.) after 1 day of treatment was 10, 18, and 11% respectively; at day 5, the level of suppression was 77, 82, and 84% respectively. P. berghei infection decreased hemoglobin, red blood cell, and lymphocyte counts and increased neutrophil count; artesunate and medicinal plant treatment restored these parameters to normal control levels. Also, artesunate and medicinal plant treatment of infected mice significantly (p < 0.05) increased serum and liver superoxide dismutase activities and significantly (p < 0.05) reduced serum malondialdehyde concentration compared to untreated infected mice. The antimalarial effect of T. avicennioides is comparable to that of artesunate. The restoration of oxidative and hematological statuses, to normal values by T. avicennioides, may provide better protection against the malaria severity and complications.

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