Biomimetic hydrogel with tunable mechanical properties for vitreous substitutes

Abstract

The vitreous humor of the eye is a biological hydrogel principally composed of collagen fibers interspersed with hyaluronic acid. Certain pathological conditions necessitate its removal and replacement. Current substitutes, like silicone oils and perfluorocarbons, are not biomimetic and have known complications. In this study, we have developed an in situ forming two-component biomimetic hydrogel with tunable mechanical and osmotic properties. The components are gellan, an analogue of collagen, and poly(methacrylamide-co-methacrylate), an analogue of hyaluronic acid; both endowed with thiol side groups. We used response surface methodology to consider seventeen possible hydrogels to determine how each component affects the optical, mechanical, sol-gel transition temperature and swelling properties. The optical and physical properties of the hydrogels were similar to vitreous. The shear storage moduli ranged from 3 to 358 Pa at 1Hz and sol-gel transition temperatures from 35.5 to 43 °C. The hydrogel had the ability to remain swollen without degradation for four weeks in vitro. Three hydrogels were tested for biocompatibility on primary porcine retinal pigment epithelial cells, human retinal pigment epithelial cells, and fibroblast (3T3/NIH) cells, by electric cell-substrate impedance sensing system. The two-component hydrogels allowed for the tuning and optimizing of mechanical, swelling, and transition temperature to obtain three biocompatible hydrogels with properties similar to vitreous. Future studies include testing of the optimized hydrogels in animal models for use as a long-term substitute, whose preliminary results are mentioned.

Antifouling Super Water Absorbent Supramolecular Polymer Hydrogel as an Artificial Vitreous Body

“…EWCs of the PNAGA and PNAGA‐PCBAA hydrogels were measured at room temperature by using a gravimetric method reported earlier 41. The refractive indexes of PNAGA and PNAGA‐PCBAA hydrogels were determined on an Abbe refractometer (WYA‐2W, Lumsail Industrial Inc., Shanghai, China).…”

Insight into halloysite nanotubes-loaded gellan gum hydrogels for soft tissue engineering applications

“…Furthermore, thanks to its versatility, gellan gum is attracting increasing interest in the biomedical field and is being proposed for tissue engineering and regenerative medicine applications (Coutinho et al, 2010;Santhanam et al, 2016). A pioneering study by Shoichet et al exploited a gellan gum matrix to support the adhesion and proliferation of neural stem cells, showing that the peptide-modified gellan gum, together with the olfactory ensheathing glia, enhanced neural stem/progenitor cell survival (Silva et al, 2012).…”

Recent Strategies in Fabrication of Gradient Hydrogels for Tissue Engineering Applications

“…Hydrogels are 3D structures comprising crosslinked polymers and water, and have been utilized in a variety of tissue engineering applications 20–22. Since hydrogels resemble natural ECM structurally and compositionally, they provide a microenvironment to cells for effective adhesion, proliferation, and invasion 23–26. Several hydrogels have been used as an effective scaffold for the delivery of cells and/or signals for tissue regeneration and tissue model 27,28.…”

“…[20][21][22] Since hydrogels resemble natural ECM structurally and compositionally, they provide a microenvironment to cells for effective adhesion, proliferation, and invasion. [23][24][25][26] Several hydrogels have been used as an effective scaffold for the delivery of cells and/or signals for tissue regeneration and tissue model. [27,28] For example, Kim et al demonstrated that bone morphogenetic protein-2 (BMP-2) incorporated thiolated gelatin and poly(ethylene glycol) diacrylate (PEGDA) composite hydrogel scaffold could exhibit effective regeneration of calvarial bone in a rat model.…”