Treatment of Genetic Disease

Treatment of Genetic Disease Conventional Approaches to Treatment of Genetic Disease    Protein/Enzyme Replacement Drug Treatment Tissue Transplantation * * Drug Treatment  Statins can help to lower cholesterol levels in familial hypercholesterolemia    Sulfonylureas   Inhibiting (HMG-CoA) reductase upregulation of the LDL receptor bind to the ATP-sensitive potassium (KATP) channels of the beta cell to depolarize the membrane and allow insulin release. Rapamycin (sirolimus)   inhibit cellular proliferation and cell cycle progression via the PI3K/AKT/mTOR pathway. treat congenital hyperinsulinism as an alternative to sub-total pancreatectomy *  premature termination codon (PTC) therapy (ataluren) for patients with nonsense mutations causing CF or Duchenne muscular dystrophy.   Ataluren interacts with the ribosome to enable read-through of premature stop codons to produce full-length functional protein. An alternative approach for treating Duchenne muscular dystrophy is to upregulate the dystrophin homolog, utrophin.  SMT022357 leads to increased utrophin expression in skeletal, respiratory and cardiac muscles in the mdx mouse *  breakthrough in the treatment of CF  Ivacaftor, is a CFTR potentiator that improves the transport of chloride ions through the ion channel by increasing the open probability of the channel.   Lumacaftor, was developed to treat patients with the most common CFTR mutation, p.Phe508del.   It was approved originally for the 4% of CF patients who have the p.Gly551Asp (G551D) mutation, but is now also available for patients with nine other mutations that reduce channel activity. Lumacaftor is designed to improve the folding of the protein in order that more protein reaches the cell surface. In 2015, combination therapy of ivacaftor with lumacaftor was shown to improve lung function for patients who are homozygous for the p.Phe508del CFTR mutation. Tissue Transplantation  Islet transplantation for treating type 1 diabetes mellitus was transformed in 2000 with development of the ‘Edmonton’ protocol.  Islet cells are prepared from donated pancreases (usually two per patient) and injected into the liver of the recipient:  at 3 years post-transplant more than 80% of patients are still producing their own insulin Therapeutic Applications of Recombinant DNA Technology Gene Therapy  Regulatory Requirements    Technical Aspects   Germline gene therapy, Somatic cell gene therapy Insertional mutagenesis Gene Transfer  Target Organs   Viral Agents   (Liver, Central Nervous System, Muscle, Bone Marrow, Eye) (Lentiviruses, Adenoviruses, Adeno-Associated Viruses) Non-Viral Methods  (Liposomes ) Gene Transfer: Target Organs  Target Organs  Liver:    Central Nervous System    direct injection of foreign DNA into muscle Alipogenetiparvovec: human LPL gene packaged with a tissue-specific promoter in a non-replicating adeno-associated virus vector. Bone Marrow    Lentiviral vectors are particularly suitable: Parkinson and Alzheimer diseases Muscle   Liver cells are susceptible to transfection by retroviruses in vitro Hypercholesterolemia (SCID) caused by ADA deficiency lentiviral vector containing the HBB gene Eye  Leber congenital amaurosis   (AAV) vector containing the RPE65 gene injected into the retinal pigment cells choroidemia  Injection of an AAV vector carrying the CHM gene into the retina * Gene Transfer: Methods  Viral Agents  Lentiviruses    Adenoviruses    They are stable, can infect non-dividing cells and carry up to 36 kb of DNA. do not integrate into the host genome Adeno-Associated Viruses     they can be integrated into non-dividing cells. They may, therefore, be useful in the treatment of neurological conditions. are non-pathogenic parvoviruses in humans that require co-infection with helper adenoviruses or certain members of the herpes virus family to achieve infection. integrates into the long arm of chromosome 19 (19q13.3-qter). they can take inserts of foreign DNA of only up to 5 kb in size Non-Viral Methods  Liposomes  much larger DNA sequence can be introduced into the target cells or tissues than with viral vector systems. *RNA Modification  Antisense Oligonucleotides       typically 18 to 30 bases in length inhibition of gene expression at the protein level. exon skipping and convert out-of-frame deletions that cause DMD to in-frame deletions: Exondys-51 the non-expressed SMN2 gene could be converted to generate functional SMN1 protein in virtually all patients. in the treatment of patients with Huntington disease by silencing of the expanded repeat allele. RNA Interference   ALN-TTR02 (also known as patisiran), which targets TTR amyloid deposits. These are the cause of familial amyloidotic polyneuropathy in patients with TTR mutations. *Targeted Gene Correction  The latest strategy uses engineered zinc-finger nucleases (ZFNs) to stimulate homologous recombination.    stimulating homology directed DNA repair between the locus of interest and an extrachromosomal molecule. sickle cell disease. In the future, the new CRISPR/Cas9 technology  correct the genetic defect ex vivo before returning the cells to the patient’s bone marrow. *Stem Cell Therapy   Embryonic stem cells are pluripotent, which means they can give rise to derivatives of all three germ layers (i.e., all cell types that are found in the adult organism) Nowadays the term induced pluripotent stem cell (iPS) is used rather than somatic or adult stem cell.       Embryonic Stem Cell Therapy Embryonic Stem Cells for Transplantation Gene Therapy Using Embryonic Stem Cells Induced Pluripotent Stem Cell Therapy Mesenchymal Stem Cells Limbal Stem Cells