Morquio A syndrome is a rare genetic disorder where deficiency in N-acetylgalactosamine-6-sulfate sulfatase (GALNS) enzyme prevents breakdown of glycosaminoglycans (GAGs). Recombinant human GALNS (rhGALNS) is currently administered by intravenous infusion, but the treatment is costly and time-consuming and provides limited efficacy. Patient quality of life could be improved by an injectable sustained rhGALNS release device that would eliminate weekly multi-hour infusions. Polyethylene glycol (PEG) hydrogels can be employed as a hydrophilic, tunable, non-toxic, and biodegradable drug delivery system for the sustained release of rhGALNS, as explored by us previously. Here, we investigated the stability of rhGALNS in various buffers mimicking the in vivo environment that would be encountered by the enzyme, inside of and outside the PEG hydrogels. rhGALNS activity was reduced 85% by reversible inhibition in phosphate-buffered saline (PBS), representing interstitial fluid and plasma. Buffer exchanging into acidic buffer representing the lysosome recovered this loss. However, incubation in PBS for 3 days resulted in an irreversible loss of 85%. There were no significant changes in rhGALNS hydrodynamic radius upon activity loss, suggesting structural integrity. Such activity loss makes sustained delivery impractical without additional stabilization, such as confinement within the hydrogel. rhGALNS activity was retained upon encapsulation, and the average specific activity of rhGALNS released from a hydrogel decreased only 20% over 7 days. These results show that the activity of rhGALNS was better retained within the hydrogel than in buffer alone, potentially enabling sustained release for rhGALNS or other enzymes unstable in physiological conditions with our hydrogel delivery device.

The myelin is responsible for providing stability to the axons of the nerve cells, but above all, to improve transmission speed of the nerve impulse in vertebrates. Over 70% of the myelin sheath is composed of lipids and the remaining portion by approximately 2,000 proteins. The myelin sheath has been constantly evolving, and it is known that unusually high concentrations of galactosylceramide (GalCer) and its sulfated form play a major role in the biophysical properties of the myelin. To gain insights of the evolutionary role of GalCer, we have studied two lysosomal enzymes involved in GalCer degradation, arylsulfatase A (ARSA) and galactocerebrosidase (GALC). Deficiency of ARSA or GALC causes demyelinating disorders. We conducted phylogenetic analyses of 105 ARSA and 110 GALC orthologs representing more than 600 million years ago of evolution. We examined i) low values of the ratio of nonsynonymous to synonymous nucleotide-substitution rates (dN/dS) indicating purifying selection and ii) negative selection of amino acids located in the active site preventing pathogenic mutations. Gene structure analyses showed evidence of rearrangement with gain and loss of exons while there were conserved regions mainly located around the active site. We also found a limited number of sites under positive selection pressure that do not cause alterations to the overall protein structure. Our results indicate that ARSA and GALC have been highly conserved during the evolutionary process to maintain the metabolism of GalCer, which is essential for the integrity of the white matter in vertebrate species.

This study assessed growth patterns in patients with mucopolysaccharidosis (MPS) VII before enzyme replacement therapy.

Morquio A disease is a genetic disorder resulting in N-acetylgalactosamine-6-sulfate sulfatase (GALNS) deficiency, and patients are currently treated with enzyme replacement therapy via weekly intravenous enzyme infusions. A means of sustained enzyme delivery could improve patient quality of life by reducing the administration time, frequency of hospital visits, and treatment cost. In this study, we investigated poly(ethylene-glycol) (PEG) hydrogels as a tunable, hydrolytically degradable drug delivery system for the encapsulation and sustained release of recombinant human GALNS (rhGALNS). We evaluated hydrogel formulations that optimized hydrogel gelation and degradation time while retaining rhGALNS activity and sustaining rhGALNS release. We observed the release of active rhGALNS for up to 28 days in vitro from the optimized formulation. rhGALNS activity was preserved in the hydrogel relative to buffer over the release window, and encapsulation was found to have no impact on the rhGALNS structure when measured by intrinsic fluorescence, circular dichroism, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In vivo, we monitored the retention of fluorescently labeled rhGALNS in C57BL/6 albino mice when administered via subcutaneous injection and observed rhGALNS present for up to 20 days when delivered in a hydrogel versus 7 days in the buffer control. These results indicate that PEG hydrogels are suitable for the encapsulation, preservation, and sustained release of recombinant enzymes and may present an alternative method of delivering enzyme replacement therapies that improve patient quality of life.

Morphologic features of the mandible are influenced by the genes of each individual. Mandible size is important to orthodontists because the mandible is the mechanism by which the lower face influences facial esthetics and dental function. To date, no biological marker has been identified that indicates eventual mandible size. This study aimed to correlate the expression of DLX5, DLX6, EDN1, HAND2, PRRX1, and MSX1 to mandible size.