Ruesing Samuel, Stealey Samuel, Gan Qi, Winter Linda, Montaño Adriana M, Zustiak Silviya P
Department of Biomedical Engineering, Saint Louis University, 3507 Lindell Blvd, St. Louis, MO, 63103, USA.
Department of Pediatrics, School of Medicine, Saint Louis University, 1100 South Grand Blvd, St. Louis, MO, 63104, USA.
Appl Biochem Biotechnol. 2025 May 24. doi: 10.1007/s12010-025-05266-5.
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.
莫尔基奥A综合征是一种罕见的遗传性疾病，N - 乙酰半乳糖胺 - 6 - 硫酸酯酶（GALNS）缺乏会阻止糖胺聚糖（GAGs）的分解。重组人GALNS（rhGALNS）目前通过静脉输注给药，但这种治疗成本高、耗时且疗效有限。一种可注射的rhGALNS持续释放装置可以消除每周数小时的输注，从而改善患者的生活质量。聚乙二醇（PEG）水凝胶可以用作一种亲水、可调、无毒且可生物降解的药物递送系统，用于rhGALNS的持续释放，正如我们之前所探索的那样。在这里，我们研究了rhGALNS在各种模拟酶在PEG水凝胶内外会遇到的体内环境的缓冲液中的稳定性。在代表组织液和血浆的磷酸盐缓冲盐水（PBS）中，rhGALNS活性因可逆抑制而降低了85%。将缓冲液换成代表溶酶体的酸性缓冲液可恢复这种损失。然而，在PBS中孵育3天导致85%的不可逆损失。rhGALNS活性丧失后其流体动力学半径没有显著变化，表明结构完整。如果没有额外的稳定措施，如限制在水凝胶内，这种活性丧失会使持续递送变得不切实际。rhGALNS封装后活性得以保留，并且从水凝胶中释放的rhGALNS的平均比活性在7天内仅降低了20%。这些结果表明，rhGALNS在水凝胶中的活性比单独在缓冲液中保留得更好，这可能使我们的水凝胶递送装置能够实现rhGALNS或其他在生理条件下不稳定的酶的持续释放。
