Electrospun Nanofibers Application in Ocular Injuries
Injured or damaged corneal epithelium represents one ofthe frequent causes ofimpaired vision or even blindness. Ocular injuries require immediate management that may allow critical function restoration and minimize tissue loss. Such processes may be appropriate for ocular repair dressing, cleansing solutions, and antibiotics. Current treatment for ocular surface injuries includes the suturing of human amniotic membrane over the injury site. However, the membrane is costly and fragile, and the treatment is possible only with the most advanced surgical settings. Another option includes synthetic bandages that are usually available for more severe open globe injuries. However, synthetic bandages lack the flexibility and transparency required to restore the globe integrity in addition to monitoring the wound until permanent treatments can be available.
A biologically inspired ocular repair dressing, known as BIOcular, has been designed to fill the unmet need. BIOcular dressings are composed of biopolymeric hydrogel and NF. The hydrogel provides control release and NF provides the mechanical properties. The dressing is designed to treat corneal abrasions and ulcers on the surface of the eye. This dressing also provides resistance to bacterial penetration. It naturally resorbs over time. The dressing has a refractive index of 1.335 similar to cornea (1.38). It allows visible light transmission of 85% (http://lunainc.com/synthetic-bandages-ocular-injury- treatment/). BIOcular dressings are compatible with primary human corneal epithelial cells. Ifthe corneal damage is extensive, it may also involve the limbal region. Such defect can lead to limbal stem cell (LSC) deficiency. LSCs are essential for the regeneration of the corneal epithelium in normal and diseased states. Absence leads to corneal neovascularization, chronic inflammation, and persistent epithelial defects, all ofwhich may result in a visual disability or often lead to blindness. The effective way to treat LSC deficiency is the transplantation of the intact limbal tissue containing LSCs or the transfer of ex vivo expanded stem cells [76,77]. In recent years, promising scaffolds for the growth and transfer of various types of SCs have been possible due to NF. NFs enables production of the required porosity and a specified basic weight in addition to the large surface area. It can mimic the structure ofECM proteins, which provide support for stem cell growth. Biocompatibility of NFs can be obtained by natural polymers, such as chitosan, gelatin, or collagen, or synthetic polymers, such as PVA, polyamide, and poly (L-lactic acid). During seeding of NFs with SCs, the stability of nanofibrous architecture in aqueous solutions and optimal biocompatibility should be monitored. Various SC types grow on NFs or even better than on plastic surfaces. Under standard conditions, LSCs are cultured for 2—3 weeks on plastic dishes. The cells are then detached and transferred onto NF scaffolds for additional 24 or 48 h to allow cells to adhere. Then, cell-seeded scaffolds are transferred onto the ocular surface with the cell side facing down on the ocular surface and fixed by sutures. In addition to their ability to serve as a SC carrier, NFs can be loaded with various pharmacologically active substances. These agents can promote SC growth and/or attenuate the local inflammatory reaction occurring after stem cell transplantation [78].
