A critical review of therapeutic interventions in sickle cell disease: Progress and challenges.

Sickle cell disease (SCD) is an autosomal recessive genetic disorder that occurs due to the point mutation in the ß-globin gene, which results in the formation of sickle hemoglobin (HbS) in the red blood cells (RBCs). When HbS is exposed to an oxygen-depleted environment, it polymerizes, resulting in hemolysis, vaso-occlusion pain, and impaired blood flow. Still, there is no affordable cure for this inherited disease. Approved medications held promise but were met with challenges due to limited patient tolerance and undesired side effects, thereby inhibiting their ability to enhance the quality of life across various individuals with SCD. Progress has been made in understanding the pathophysiology of SCD during the past few decades, leading to the discovery of novel targets and therapies. However, there is a compelling need for research to discover medications with improved efficacy and reduced side effects. Also, more clinical investigations on various drug combinations with different mechanisms of action are needed. This review comprehensively presents therapeutic approaches for SCD, including those currently available or under investigation. It covers fundamental aspects of the disease, such as epidemiology and pathophysiology, and provides detailed discussions on various disease-modifying agents. Additionally, expert insights are offered on the future development of pharmacotherapy for SCD.

Lipopolymeric Nanocarrier Enables Effective Delivery of CRISPR/Cas9 Expressing Plasmid.

CRISPR/Cas9 has proven its accuracy and precision for gene editing by making a double-strand break at the predetermined site. Despite being a mainstream gene editing tool, CRISPR/Cas9 has limitations for its in vivo delivery due to the physico-chemical properties such as high molecular weight, supranegative charge, degradation in the presence of nucleases, etc. Hereby, a cationic lipopolymer is explored for its efficiency in delivering CRISPR/Cas9 plasmid (pCas9) in vitro and in vivo. The lipopolymer is utilized to form blank cationic nanoplexes having a zeta potential of +15.8 ± 0.7 mV. Being cationic, the blank nanoplexes are able to condense the pCas9 plasmid at a ratio of 1:20 with a complexation efficiency of ≈98% and show a size and zeta potential of ≈141 ± 16 nm and 4.2 mV ± 0.7, respectively. The pCas9-loaded nanoplexes show a transfection efficiency of ≈69% in ARPE-19 cells and show ≈22% of indel frequency, indicating the successful translation of Cas9 protein and guide RNA in the cytosol. Further, they are found to be stable under in vivo environment when given intravenously in Swiss albino mice. These lipopolymeric nanoplexes can be a potential carrier for CRISPR plasmids for genome editing applications.

IndiGenomes: a comprehensive resource of genetic variants from over 1000 Indian genomes.

With the advent of next-generation sequencing, large-scale initiatives for mining whole genomes and exomes have been employed to better understand global or population-level genetic architecture. India encompasses more than 17% of the world population with extensive genetic diversity, but is under-represented in the global sequencing datasets. This gave us the impetus to perform and analyze the whole genome sequencing of 1029 healthy Indian individuals under the pilot phase of the 'IndiGen' program. We generated a compendium of 55,898,122 single allelic genetic variants from geographically distinct Indian genomes and calculated the allele frequency, allele count, allele number, along with the number of heterozygous or homozygous individuals. In the present study, these variants were systematically annotated using publicly available population databases and can be accessed through a browsable online database named as 'IndiGenomes' http://clingen.igib.res.in/indigen/. The IndiGenomes database will help clinicians and researchers in exploring the genetic component underlying medical conditions. Till date, this is the most comprehensive genetic variant resource for the Indian population and is made freely available for academic utility. The resource has also been accessed extensively by the worldwide community since it's launch.

Development of an efficient single-cell cloning and expansion strategy for genome edited induced pluripotent stem cells.

BACKGROUND: Disease-specific human induced pluripotent stem cells (hiPSCs) can be generated directly from individuals with known disease characteristics or alternatively be modified using genome editing approaches to introduce disease causing genetic mutations to study the biological response of those mutations. The genome editing procedure in hiPSCs is still inefficient, particularly when it comes to homology directed repair (HDR) of genetic mutations or targeted transgene insertion in the genome and single cell cloning of edited cells. In addition, genome editing processes also involve additional cellular stresses such as poor cell viability and genetic stability of hiPSCs. Therefore, efficient workflows are desired to increase genome editing application to hiPSC disease models and therapeutic applications. METHODS AND RESULTS: To this end, we demonstrate an efficient workflow for feeder-free single cell clone generation and expansion in both CRISPR-mediated knock-out (KO) and knock-in (KI) hiPSC lines. Using StemFlex medium and CloneR supplement in conjunction with Matrigel cell culture matrix, we show that cell viability and expansion during single-cell cloning in edited and unedited cells is significantly enhanced. Keeping all factors into account, we have successfully achieved hiPSC single-cell survival and cloning in both edited and unedited cells with rates as maximum as 70% in less than 2 weeks. CONCLUSION: This simplified and efficient workflow will allow for a new level of sophistication in generating hiPSC-based disease models to promote rapid advancement in basic research and also the development of novel cellular therapeutics.

cRGD-modified hybrid lipopolymeric nanoplexes for gene editing in the posterior segment of the eye.

Eye-related diseases, specifically retinal dystrophy (RD) conditions, are the leading cause of blindness worldwide. Gene addition, regulation, or editing could potentially treat such diseases through gene expression regulation. CRISPR/Cas9 gene editing is one of the most prominent and precise gene editing tools which could be employed to edit genes related to the dystrophic condition. However, CRISPR/Cas9 faces in vivo delivery challenges due to its high molecular weight, negative charge, prone to degradation in the presence of nucleases and proteases, poor cellular degradation, etc., which makes it challenging to adopt for therapeutic applications. We developed cRGD-modified lipopolymeric nanoplexes loaded with Cas9 RNPs with a particle size and zeta potential of 175 ±â€¯20 nm and 2.15 ±â€¯0.9 mV, respectively. The cRGD-modified lipopolymeric nanoplexes were stable for 194 h and able to transfect >70 % ARPE-19 and NIH3T3 cells with an Indel frequency of ~40 % for the VEGF-A gene. The cRGD-modified lipopolymeric nanoplexes found good vitreous mobility and could transfection retinal cells in vivo after 48 h of intravitreal injection in Wistar Rats. Moreover, in vivo VEGFA gene editing was ~10 % with minimal toxicities. Collectively, the cRGD-modified lipopolymeric nanoplexes were found to have extreme potential in delivering CRISPR/Cas9 RNPs payload to the retinal tissues for therapeutic applications.

Development of pathophysiologically relevant models of sickle cell disease and ß-thalassemia for therapeutic studies.

Ex vivo cellular system that accurately replicates sickle cell disease and ß-thalassemia characteristics is a highly sought-after goal in the field of erythroid biology. In this study, we present the generation of erythroid progenitor lines with sickle cell disease and ß-thalassemia mutation using CRISPR/Cas9. The disease cellular models exhibit similar differentiation profiles, globin expression and proteome dynamics as patient-derived hematopoietic stem/progenitor cells. Additionally, these cellular models recapitulate pathological conditions associated with both the diseases. Hydroxyurea and pomalidomide treatment enhanced fetal hemoglobin levels. Notably, we introduce a therapeutic strategy for the above diseases by recapitulating the HPFH3 genotype, which reactivates fetal hemoglobin levels and rescues the disease phenotypes, thus making these lines a valuable platform for studying and developing new therapeutic strategies. Altogether, we demonstrate our disease cellular systems are physiologically relevant and could prove to be indispensable tools for disease modeling, drug screenings and cell and gene therapy-based applications.

Scalable noninvasive amplicon-based precision sequencing (SNAPseq) for genetic diagnosis and screening of ß-thalassemia and sickle cell disease using a next-generation sequencing platform.

ß-hemoglobinopathies such as ß-thalassemia (BT) and Sickle cell disease (SCD) are inherited monogenic blood disorders with significant global burden. Hence, early and affordable diagnosis can alleviate morbidity and reduce mortality given the lack of effective cure. Currently, Sanger sequencing is considered to be the gold standard genetic test for BT and SCD, but it has a very low throughput requiring multiple amplicons and more sequencing reactions to cover the entire HBB gene. To address this, we have demonstrated an extraction-free single amplicon-based approach for screening the entire ß-globin gene with clinical samples using Scalable noninvasive amplicon-based precision sequencing (SNAPseq) assay catalyzing with next-generation sequencing (NGS). We optimized the assay using noninvasive buccal swab samples and simple finger prick blood for direct amplification with crude lysates. SNAPseq demonstrates high sensitivity and specificity, having a 100% agreement with Sanger sequencing. Furthermore, to facilitate seamless reporting, we have created a much simpler automated pipeline with comprehensive resources for pathogenic mutations in BT and SCD through data integration after systematic classification of variants according to ACMG and AMP guidelines. To the best of our knowledge, this is the first report of the NGS-based high throughput SNAPseq approach for the detection of both BT and SCD in a single assay with high sensitivity in an automated pipeline.

Cationic lipopolymeric nanoplexes containing the CRISPR/Cas9 ribonucleoprotein for genome surgery.

sgRNA/Cas9 ribonucleoproteins (RNPs) provide a site-specific robust gene-editing approach avoiding the mutagenesis and unwanted off-target effects. However, the high molecular weight (∼165 kDa), hydrophilicity and net supranegative charge (∼-20 mV) hinder the intracellular delivery of these RNPs. In the present study, we have prepared cationic RNPs lipopolymeric nanoplexes that showed a size of 117.3 ± 7.64 nm with +6.17 ± 1.04 mV zeta potential and >90% entrapment efficiency of RNPs. Further, these RNPs lipopolymeric nanoplexes showed good complexation efficiency and were found to be stable for 12 h with fetal bovine serum. These RNPs lipopolymeric nanoplexes did not induce any significant cytotoxicity in HEK293T cells, and were efficiently uptaken via a clathrin-mediated pathway with optimal transfection efficiency and nuclear localization after 48 h. Further, HEK293T cells having the mGFP insert were used as a cell line model for gene editing, wherein the loss of the mGFP signal was observed as a function of gene editing after transfection with mGFP targeting RNPs lipopolymeric nanoplexes. Further, the T7 endonuclease and TIDE assay data showed a decent gene editing efficiency. Additionally, the lipopolymeric nanoplexes were able to transfect muscle cells in vivo, when injected intra-muscularly. Collectively, this study explored the potential of cationic lipopolymeric nanoplexes for delivering gene-editing endonucleases.

Dynamic Palmitoylation of Red Cell Membrane Proteins Governs Susceptibility to Invasion by the Malaria Parasite, Plasmodium falciparum.

Phosphorylation and other post-translational modifications of red blood cell (RBC) proteins govern membrane function and have a role in the invasion of RBCs by the malaria parasite, Plasmodium falciparum. Furthermore, a percentage of RBC proteins are palmitoylated, although the functional consequences are unknown. We establish dynamic palmitoylation of 118 RBC membrane proteins using click chemistry and acyl biotin exchange (ABE)-coupled LC-MS/MS and characterize their involvement in controlling membrane organization and parasite invasion. RBCs were treated with a generic palmitoylation inhibitor, 2-bromopalmitate (2-BMP), and then analyzed using ABE-coupled LC-MS/MS. Only 42 of the 118 palmitoylated proteins detected were palmitoylated in the 2-BMP-treated sample, indicating that palmitoylation is dynamically regulated. Interestingly, membrane receptors such as semaphorin 7A, CR1, and ABCB6, which are known to be involved in merozoite interaction with RBCs and parasite invasion, were found to be dynamically palmitoylated, including the blood group antigen, Kell, whose antigenic abundance was significantly reduced following 2-BMP treatment. To investigate the involvement of Kell in merozoite invasion of RBCs, a specific antibody to its extracellular domain was used. The antibody targeting Kell inhibited merozoite invasion of RBCs by 50%, implying a role of Kell, a dynamically palmitoylated potent host-derived receptor, in parasite invasion. Furthermore, a significant reduction in merozoite contact with the RBC membrane and a consequent decrease in parasite invasion following 2-BMP treatment demonstrated that palmitoylation does indeed regulate RBC susceptibility to parasite invasion. Taken together, our findings revealed the dynamic palmitoylome of RBC membrane proteins and its role in P. falciparum invasion.

A Simple, Cost-Effective, and Extraction-Free Molecular Diagnostic Test for Sickle Cell Disease Using a Noninvasive Buccal Swab Specimen for a Limited-Resource Setting.

Sickle cell disease (SCD) is the most prevalent life-threatening blood monogenic disorder. Currently, there is no cure available, apart from bone marrow transplantation. Early and efficient diagnosis of SCD is key to disease management, which would make considerable strides in alleviating morbidity and reducing mortality. However, the cost and complexity of diagnostic procedures, such as the Sanger sequencing method, impede the early detection of SCD in a resource-limited setting. To address this, the current study demonstrates a simple and efficient proof-of-concept assay for the detection of patients and carriers using extraction-free non-invasive buccal swab samples by isothermal DNA Amplification coupled Restrictase-mediated cleavage (iDAR). This study is a first of its kind reporting the use of buccal swab specimens for iDA in molecular diagnosis of a genetic disease, all the while being cost effective and time saving, with the total assay time of around 150 min at a cost of USD 5. Further, iDAR demonstrates 91.5% sensitivity and 100% specificity for detecting all three alleles: SS, AS, and AA, having a 100% concordance with Sanger sequencing. The applicability of the iDAR assay is further demonstrated with its adaptation to a one-pot reaction format, which simplifies the assay system. Overall, iDAR is a simple, cost-effective, precise, and non-invasive assay for SCD screening, with the potential for use in a limited resource setting.

Pharmacogenomic landscape of COVID-19 therapies from Indian population genomes.

Aim: Numerous drugs are being widely prescribed for COVID-19 treatment without any direct evidence for the drug safety/efficacy in patients across diverse ethnic populations. Materials & methods: We analyzed whole genomes of 1029 Indian individuals (IndiGen) to understand the extent of drug-gene (pharmacogenetic), drug-drug and drug-drug-gene interactions associated with COVID-19 therapy in the Indian population. Results: We identified 30 clinically significant pharmacogenetic variants and 73 predicted deleterious pharmacogenetic variants. COVID-19-associated pharmacogenes were substantially overlapped with those of metabolic disorder therapeutics. CYP3A4, ABCB1 and ALB are the most shared pharmacogenes. Fifteen COVID-19 therapeutics were predicted as likely drug-drug interaction candidates when used with four CYP inhibitor drugs. Conclusion: Our findings provide actionable insights for future validation studies and improved clinical decisions for COVID-19 therapy in Indians.

Genetic epidemiology of autoinflammatory disease variants in Indian population from 1029 whole genomes.

BACKGROUND: Autoinflammatory disorders are the group of inherited inflammatory disorders caused due to the genetic defect in the genes that regulates innate immune systems. These have been clinically characterized based on the duration and occurrence of unprovoked fever, skin rash, and patient's ancestry. There are several autoinflammatory disorders that are found to be prevalent in a specific population and whose disease genetic epidemiology within the population has been well understood. However, India has a limited number of genetic studies reported for autoinflammatory disorders till date. The whole genome sequencing and analysis of 1029 Indian individuals performed under the IndiGen project persuaded us to perform the genetic epidemiology of the autoinflammatory disorders in India. RESULTS: We have systematically annotated the genetic variants of 56 genes implicated in autoinflammatory disorder. These genetic variants were reclassified into five categories (i.e., pathogenic, likely pathogenic, benign, likely benign, and variant of uncertain significance (VUS)) according to the American College of Medical Genetics and Association of Molecular pathology (ACMG-AMP) guidelines. Our analysis revealed 20 pathogenic and likely pathogenic variants with significant differences in the allele frequency compared with the global population. We also found six causal founder variants in the IndiGen dataset belonging to different ancestry. We have performed haplotype prediction analysis for founder mutations haplotype that reveals the admixture of the South Asian population with other populations. The cumulative carrier frequency of the autoinflammatory disorder in India was found to be 3.5% which is much higher than reported. CONCLUSION: With such frequency in the Indian population, there is a great need for awareness among clinicians as well as the general public regarding the autoinflammatory disorder. To the best of our knowledge, this is the first and most comprehensive population scale genetic epidemiological study being reported from India.

Generation and characterization of induced pluripotent stem cell line (IGIBi001-A) from a sickle cell anemia patient with homozygous ß-globin mutation.

Sickle cell disease (SCD) is an autosomal recessive disorder caused by a mutation in ß-globin (HBB) gene. We have generated an induced pluripotent stem cell (iPSC) line, IGIBi001-A from an Indian sickle cell patient with a homozygous HBB gene mutation using Sendai virus reprogramming system. Characterization of IGIBi001-A showed that these iPSCs are transgene-free and expressed pluripotent stem cell markers. They had a normal karyotype and were able to differentiate into all three germ layers. This new SCD-iPSC line will contribute to better understanding of the disease biology of sickle cell anemia and for screening of small molecule drugs.