Engineering a lysosomal enzyme with a derivative of receptor-binding domain of apoE enables delivery across the blood–brain barrier

Abstract

To realize the potential of large molecular weight substances to treat neurological disorders, novel approaches are required to surmount the blood-brain barrier (BBB). We investigated whether fusion of a receptor-binding peptide from apolipoprotein E (apoE) with a potentially therapeutic protein can bind to LDL receptors on the BBB and be transcytosed into the CNS. A lysosomal enzyme, α-L-iduronidase (IDUA), was used for biological and therapeutic evaluation in a mouse model of mucopolysaccharidosis (MPS) type I, one of the most common lysosomal storage disorders with CNS deficits. We identified two fusion candidates, IDUAe1 and IDUAe2, by in vitro screening, that exhibited desirable receptor-mediated binding, endocytosis, and transendothelial transport as well as appropriate lysosomal enzyme trafficking and biological function. Robust peripheral IDUAe1 or IDUAe2 generated by transient hepatic expression led to elevated enzyme levels in capillary-depleted, enzyme-deficient brain tissues and protein delivery into nonendothelium perivascular cells, neurons, and astrocytes within 2 d of treatment. Moreover, 5 mo after long-term delivery of moderate levels of IDUAe1 derived from maturing red blood cells, 2% to 3% of normal brain IDUA activities were obtained in MPS I mice, and IDUAe1 protein was detected in neurons and astrocytes throughout the brain. The therapeutic potential was demonstrated by normalization of brain glycosaminoglycan and β-hexosaminidase in MPS I mice 5 mo after moderate yet sustained delivery of IDUAe1. These findings provide a noninvasive and BBB-targeted procedure for the delivery of largemolecule therapeutic agents to treat neurological lysosomal storage disorders and potentially other diseases that involve the brain.in vivo evaluation | LDL receptor-related protein 1 | lysosomal storage diseases | neurological disorders | CNS protein delivery

Setting-up an <em>In Vitro</em> Model of Rat Blood-brain Barrier (BBB): A Focus on BBB Impermeability and Receptor-mediated Transport

“…biOasis develops the Transcend technology using a protein melanotransferrin for the transport of biologics such as lysosomal enzymes and antibodies across the BBB 33 while VECT-HORUS develops peptide vectors that target the LDLR 34 . There is data suggesting that the LRP and LDLR can be used to transport different molecules such as lysosomal enzymes 35,36 or nanoparticle complexes across the BBB 37 .…”

Effective Intravenous Therapy for Neurodegenerative Disease With a Therapeutic Enzyme and a Peptide That Mediates Delivery to the Brain

“…Thus, there are strategies for IV delivery of proteins across the BBB 13,14 including permeabilization of the BBB, 15 use of molecular Trojan horses in which receptor-binding domains from apolipoproteins are used to construct chimeric enzymes, 16,17 and high-dose administration of unmodified or glycan-modified proteins. [18][19][20][21] For LSDs, promising progress is being made but to date, only fractional levels, ranging from ~1.5 to 12%, of normal activity, have been achieved in the brain of mouse models.…”

Platelets are efficient and protective depots for storage, distribution, and delivery of lysosomal enzyme in mice with Hurler Syndrome

“…The catalytic activity of IDUA was measured as previously reported (15,39). One unit of enzyme activity is defined as the release of 1 nmol of 4-methylumbelliferyl in a 1-h reaction at 37°C, and IDUA-specific activity was calculated as unit per milligram of protein or per milliliter of liquid.…”