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Injectable Hyaluronan Microgel-embedded Gelatin Hydrogel and Gelatin Hydrogel Rod with Controlled Protein Delivery for Neovascular Retinal Therapy
- Author(s)
- 이시민
- Alternative Author(s)
- Simin Lee
- Advisor
- 박기동
- Department
- 일반대학원 분자과학기술학과
- Publisher
- The Graduate School, Ajou University
- Publication Year
- 2022-08
- Language
- eng
- Keyword
- Retinal neovascularization; biodegradability; extended intravitreal drug maintenance; formulation design of hydrogels; hydrogel rods; inhibited drug clearance; intravitreal controlled anti-VEGF delivery; microgels; minimally invasiveness
- Alternative Abstract
- Globally, the development of treatment strategies for the neovascularization in the posterior segment of eye is inevitable. There have been numerous studies for retinal neovascularization treatment including laser therapies and intraocular anti-vascular endothelial growth factor (anti-VEGF) delivery systems. However, the laser therapies temporarily stabilize the existing leaky blood vessels, not prevent the neovascularization which cause disease progression. While intravitreal drug delivery systems enhance the therapeutic efficacy to prevent the retinal neovascularization compared to conventional drug administration, they still have limitations in requirement of surgery, fast clearance, and non-biodegradability in the eyes, causing frequent administration, additional surgery, and adverse effects. Thus, the development of injectable drug delivery systems with long-term drug efficacy, and degradability is required. The objectives of this dissertation are to develop the hydrogel-based drug delivery carriers with minimally invasiveness, intravitreal controlled anti-VEGF delivery for long-term efficacy, and biodegradability for improved clinical performance and less adverse effects by reducing intravitreal injection frequency, especially in treatment of retinal neovascularization, through formulation design of hydrogels in particle and rod shapes. In chapter 2, injectable microgel/hydrogel composites were developed to achieve long-term and sustained ranibizumab delivery for the treatment of neovascular retinal diseases. Hyaluronic acid (HA) microgels were fabricated through thiol-ene reaction and emulsification, showing adjustable ranibizumab loading efficiency (43.3 ~ 97.6%) depending on size of microgels. The microgel/hydrogel composites were prepared by incorporating HA microgels into enzyme-mediated in situ crosslinkable gelatin-PEG-tyramine (GPT) hydrogels as a secondary barrier matrix, exhibiting reduced initial burst release and prolonged release of ranibizumab over 90 days compared to HA microgels. The released ranibizumab revealed biological activity by neutralizing VEGF in vitro. Then, in vivo pharmacokinetics (PK) were evaluated via rabbit intravitreal injection of bolus ranibizumab, ranibizumab-loaded microgel, and ranibizumab-loaded microgel/hydrogel composites, resulting in significantly reduced burst release and maintenance of ranibizumab concentration for 120 days in the gel-implant groups compared to bolus ranibizumab. Moreover, all eyes showed no inflammatory signs or abnormal apoptosis by microscopic and histologic analyses. These results indicated that both HA microgels and microgel/hydrogel composites are expected to serve as promising carriers independently to overcome current challenges of intravitreal anti-VEGF therapy by sustaining anti-VEGF release and extending the injection intervals. Chapter 3 described a novel intravitreally injectable pre-crosslinked hydrogel rod for controlling the bevacizumab release profiles and extend the intravitreal maintenance of bevacizumab concentration for several months to contribute the treatment of posterior segment eye disease. As prescribed, enzyme-mediated in situ cross-linkable gelatin-PEG-tyramine (GPT) hydrogels were utilized for fabricating the hydrogel rod to achieve a potentially sustainable and controllable protein delivery. The GPT hydrogel rod loaded with bevacizumab was prepared using easily removable thermo-responsible gelatin mold. The hydrogel rods were injectable through 21-gauge needle using precisely designed rod injector. By adjusting the crosslinking degree of hydrogel rods, precise control of initial release amount and long-term release of bevacizumab for several months were achieved. Moreover, the in vitro protein release profile of pre-crosslinked hydrogel rods was significantly controlled in comparison to in situ forming hydrogels at the same crosslinking degree. The therapeutic effects of anti-VEGF and cytocompatibility were proven via in vitro cellular assays using Human Umbilical Vein Endothelial Cells (HUVECs). Then, in vivo PK were evaluated via rabbit intravitreal injection of bolus bevacizumab, bevacizumab-loaded injectable hydrogels, and bevacizumab-loaded hydrogel rods, resulting in significantly inhibited bevacizumab clearance and prolonged maintenance of bevacizumab over effective concentration for 120 days in the hydrogel rod groups compared with bolus bevacizumab and injectable hydrogel groups. The structural stability, safety, and biodegradability of hydrogel rods were assessed by ultrasound images. Moreover, the non-inflammatory response of eyes was evaluated via enzyme-linked immunosorbent assay (ELISA) of rabbit TNF-α and rabbit VEGF. These results indicated that this novel hydrogel rods have a potential for drug delivery in a controlled manner, contributing to the clinical application to treat retinal neovascular diseases as well as various diseases that need potential sustained local drug delivery.
- Fulltext
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- Graduate School of Ajou University > Department of Molecular Science and Technology > 4. Theses(Ph.D)
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