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Gene & Protein in Disease Oral-ERT in PD knockout mice with tobrhGAA

effectiveness of ERT and supplement currently available their therapeutic efficacy. 60,61,82-85 Protalix Biotherapeutics
therapies. Korlimarla et al. used standardized behavior and Shaaltiel et al. 85,86 produced glucocerebrosidase for
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checklists as a screening tool for the early identification ERT of Gaucher’s disease using a plant cell system and
and treatment of behavior, emotional, and social concerns an exploratory, open-label study to evaluate the safety of
in children with PD. Although alglucosidase alfa is an PRX-112 and the pharmacokinetics (PK) of oral prGCD
effective first-line treatment for individuals with PD, subtle in patients receiving 250 mL of resuspended carrot cells.
aspects must be addressed for successful treatment. 19,41,43-51 Administration of PRX-112 using carrot cells as a carrier
ERT has identified previously unrecognized clinical vehicle overcomes absorption, degradation, and uptake in
manifestations, including tracheobronchomalacia, the small intestine and can be found in the bloodstream in
vascular aneurysms, and gastrointestinal (GI) discomfort, an active form. 87-89
which impact smooth muscle. Persistent smooth muscle Previously, we expressed human GAA cDNA in the
pathology has a substantial impact on quality of life and chloroplasts, callus, and leaves of transgenic tomato and
can lead to life-threatening complications. In addition to tobacco plants, but this was not enzymatically active.
airway smooth muscle weakness, vascular deterioration, However, hGAA was expressed in tobacco seeds expressing
GI discomfort, and loss of genitourinary control have human GAA (tobrhGAA) by targeting the endoplasmic
been observed. Cerebral and aortic aneurysms may cause reticulum using the signal peptide sequence/promoter of
microhemorrhages that lead to symptoms ranging from soybean β-conglycinin. The tobrhGAA from transgenic
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headaches and numbness to coma and death. 52-55 Kenney- plant seeds was enzymatically active, taken up by PD
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Jung et al. found that the median age of the onset of fibroblasts and white blood cells to reverse the enzyme
seizures and encephalopathy was 11.9 years in six patients defect, and bound to the affinity matrix Sephadex G100,
with infantile-onset PD (IOPD) treated with ERT for 12 – which was eluted by maltose. A crude lysate of transgenic
15 years. All patients were noted to have extensive white seeds administered intraperitoneally to GAA KO mice
matter hyperintensities in the brain MRIs and very high increased GAA activity by 10% – 20% in the tissues, most
Fazekas scores, which preceded the onset of neurological notably in the heart, skeletal muscle, and diaphragm. 90-95
symptoms. Longitudinal IQ scores from four of these
patients suggested developmental plateauing. PD results This study is an extension of these pre-clinical studies
in the subsequent pathology in smooth muscle cells and in PD KO mice with ground tobrhGAA seeds that support
may lead to life-threatening complications if not treated the Oral-ERT proof-of-concept for future clinical trials. In
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properly. In GAA-knockout (GAAKO) mice, there is brief, Oral-ERT with various preparations of tobrhGAA
increased glycogen in the smooth muscle cells of the showed a significant reversal of forelimb and hindlimb
aorta, trachea, esophagus, stomach, and bladder as well as muscle weakness; increased motor coordination, balance,
increased lysosome membrane protein and autophagosome strength, and mobility; improved spontaneous learning;
membrane protein (LC3). Importantly, lifelong treatment increased GAA baseline activity in tissues; reduced
($250,000 – 600,000/year for an adult) can be prohibitively glycogen in tissues; and negligible GAA serum titers in
expensive, resulting in the reluctance of insurance GAA KO mice. PK analysis revealed the maximum serum
companies to reimburse costs for adult patients ; thus, GAA concentration at 8 – 10 h and peak urine excretion
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more affordable and novel delivery strategies are needed at 10 – 12 h. Similar to human placenta GAA and rhGAA,
for the treatment of PD. tobrhGAA was taken up in fibroblast and lymphoid cells
from infantile, juvenile, and adult-onset patients. Exposure
The technological platform involving the accumulation of tobrhGAA to a human PD myoblast cell line increased
of recombinant proteins in seeds warrants improved GAA to 24% – 35% of the normal level. Enzyme kinetics
availability of the products and allows for the long-term for tobrhGAA versus placental hGAA, alglucosidase alfa,
storage of biomass for processing. 59-61 Transgenic plants, or other rhGAAs for K , V , optimal pH, thermal heat
max
m
seeds, and cultured plant cells are potentially one of the stability, and IC for inhibitors revealed that tobrhGAA was
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most economical systems for the large-scale production of comparable to placental GAA and superior to alglucosidase
recombinant enzymes for pharmaceutical use. 61-69 Seeds are alfa and other rhGAAs. The tobrhGAA in seeds stored for
particularly attractive because of their high rates of protein 15 years at room temperature showed <15% loss in GAA
synthesis and their ability to remain viable in a mature-dry activity, thereby indicating extreme stability. Oral-ERT with
state as a stable repository. 61,68-79 More than one-third of tobrhGAA is an innovative approach that overcomes some
approved pharmaceutical proteins are glycoproteins, 73-82 and of the challenges of alglucosidase alfa-ERT and provides an
even minor differences in N-glycan structures can change the effective, safe, and affordable treatment option. Oral-ERT
distribution, activity, or longevity of recombinant proteins with tobrhGAA is an innovative approach that overcomes
compared with their native counterparts, thereby altering some of the challenges of alglucosidase alfa-ERT and

Volume 4 Issue 1 (2025) 3 doi: 10.36922/gpd.1760