Abstract
With the prevalence of eye diseases, such as cataracts, retinal degenerative diseases, and glaucoma, different treatments including lens replacement, vitrectomy, and stem cell transplantation have been developed; however, they are not without their respective shortcomings. For example, current methods to seal corneal incisions induced by cataract surgery, such as suturing and stromal hydration, are less than ideal due to the potential for surgically induced astigmatism or wound leakage. Vitrectomy performed on patients with diabetic retinopathy requires an artificial vitreous substitute, with current offerings having many shortcomings such as retinal toxicity. The use of stem cells has also been investigated in retinal degenerative diseases; however, an optimal delivery system is required for successful transplantation. The incorporation of hydrogels into ocular therapy has been a critical focus in overcoming the limitations of current treatments. Previous reviews have extensively documented the use of hydrogels in drug delivery; thus, the goal of this review is to discuss recent advances in hydrogel technology in surgical applications, including dendrimer and gelatin-based hydrogels for ocular adhesives and a variety of different polymers for vitreous substitutes, as well as recent advances in hydrogel-based retinal pigment epithelium (RPE) and retinal progenitor cell (RPC) delivery to the retina.
Highlights
According to the World Health Organization (WHO), at least 2.2 billion people suffer from some form of vision impairment, with 1 billion people suffering from moderate or severe impairments
In vivo results showed that there were more eyes with surviving cells in the gel-cell mixture cohort, relative to the saline-delivered control. They concluded that this hydrogel may increase the chances of cell survival upon transplantation, and that it is promising as a vehicle for retinal stem cell delivery; future work should study the effects of incorporating growth factors into the hydrogel and should continue to investigate more gelatin-based cross-linking hydrogels to help advance in situ retinal tissue engineering
They found that gelatin-hyaluronic acid (gel-HA)-PDA hydrogel improved neuronal differentiation and cell migration and adhesion, which could be attributed to the strong adhesive property of these hydrogels. They found that the gel-HA hydrogel promoted cell proliferation, demonstrating its potential for retinal progenitor cell (RPC) proliferation in transplantation therapy. These results provide a deeper understanding of the development and usage of biomaterials for RPC-based transplantation therapy
Summary
According to the World Health Organization (WHO), at least 2.2 billion people suffer from some form of vision impairment, with 1 billion people suffering from moderate or severe impairments. In terms of drug delivery, common treatments include eye drops and ointments for the anterior segment of the eye and intravitreal injections to target the posterior segment of the eye [5]. Surgical treatment of retinal detachment and diabetic retinopathy involve of the vitreous humor and replacement with gas (air, SF6, C2F6, C3F8) or liquids (silicone removal of the vitreous humor and replacement with gas (air, SF6 , C2 F6 , C3 F8 ) or liquids oils, perfluorocarbons) as a short-term tamponading agent [23,24,25]. In terms of ocular adhesives, hydrogels have the advantage of being biodegradable and bioabsorbable while having the relevant mechanical properties to serve as an effective ocular wound sealant [35] They show great promise as vitreous substitutes owing to their high water content, tunability, optical clarity, and similar refractive indices to the natural vitreous [36]. Hydrogels can dually serve as a delivery system and scaffold for retinal cell and stem cell delivery, as they can encapsulate cells, are permeable to nutrients, and are less invasive than solid scaffolds to install [37,38]
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