Ocular diseases and wounds affect 15 million people each year worldwide according to World Health Organization (WHO), of which 10 million are related to the mechanical, thermal or chemical injuries of the cornea, the second most common cause of blindness. Cornea is the outermost transparent part of the eyeball covering the iris and pupil. It plays an important role as a physical barrier against pathogens, refracts the light entering the eye and absorbs harmful UV light. It is quite resistant to minor injuries but the most serious ones require treatment, including transplantation of the cornea from the donor. However, the availability of the donor corneas is very limited. One of the methods to approach this problem is the reconstruction of the corneal surface by transplantation of autologous limbal or oral mucosa epithelial cells. These cells have to be cultured ex vivo on a proper support which is then implanted onto the eye with the confluent sheet of expanded epithelial cells. The clinical standard material used as a corneal cell culture support is human amniotic membrane, which, however, is costly, may be contageous and is difficult to handle (has to be stored at -80^oC). Therefore alternative supports are strongly desired

Goals of the research

The research was focused on the development of polymeric membranes which could serve as biodegradable culture supports for the corneal epithelial cells. The supports have to meet several contradictory requirements. On one hand, they should be strong enough not to lose their mechanical strength when immersed in the culture medium and have to be suturable onto the eye. On the other hand, they should not be too much durable and undergo biodegradation during the time period long enough to allow growth of the implanted cells. 

Results of the research

We have developed a series of membranes based on crosslinked chitosan, a biodegradable polysaccharide obtained from chitin. Crosslinking was performed using genipin, a nontoxic natural compound extracted from the fruit of Gardenia jasminoides. The membranes with enhanced mechanical properties were also prepared from blends of chitosan with other biopolymers  (i.e., hydroxypropylcellulose, collagen, elastin, and keratin) and with a silicone surfactant. The chitosan membrane containing collagen was found to be the very promising. The physicochemical and biomechanical properties of this material were comparable to those of amniotic membrane. The corneal epithelial cells formed stratified structure on the support composed of up to nine layers compared to five layers of typical human epithelium. The membranes composed of chitosan, collagen and keratin also showed proper mechanical properties, regular stratified epithelial growth and antibacterial properties which can protect the recipient patients from the postoperative infections against Escherichia coli.

 

Collaboration

Prof. Edward Wylęgała

• Chair and Department of Ophthalmology, II School of Medicine with the Division of Dentistry in Zabrze, Poland
• Medical University of Silesia and District Railway Hospital, Panewnicka 65, 40-760 Katowice, Poland

 

Prof. Dariusz Dobrowolski

• Chair and Department of Ophthalmology, II School of Medicine with the Division of Dentistry in Zabrze, Poland
• Medical University of Silesia and District Railway Hospital, Panewnicka 65, 40-760 Katowice, Poland