Bioengineered Corneal Graft Could Restore Sight
Scientists at the University of California at Davis have successfully created a corneal implant which could restore the sight of patients whose corneas have been irreparably damaged by disease or traumatic injury. The implant is a fibrin/fibronectin gel matrix, seeded with corneal stem cells and key clotting proteins isolated from the patient's own plasma.
The gel matrix used was the CryoSeal FS System originally developed by biotech company, ThermoGenesis Corp as a surgical sealant. However its soft, pliable and elastic properties allows it to conform to the contours of the eye. And because the implant uses only cells from the patient, the risk of transmitting pathogenic viruses, bacteria or prions is considerably reduced.
The biodegradable proteinaceous gel is designed to protect the embedded
corneal stem cells, and then naturally reabsorb after implantation,leaving the confluent monolayer of stem cells to further divide and differentiate into transparent corneal epithelial cells.
The UC Davis research team has previously demonstrated that corneal epithelial stem cells harvested from a patient's non-affected eye could be cultured on an amnionic membrane to make a bioengineered replacement tissue.
Explaining how this new system is a definite step forward, the investigators focused on the fact that the CryoSeal FS gel consists of
multiple, biologically active plasma proteins -- fibronectin, Factor VIII, Factor XIII as well as thrombin and fibrinogen -- which can be sourced from
a single unit of the patient's blood plasma. In contrast, conventional fibrin sealants include only fibrinogen and thrombin, and are manufactured from "pools" of thousands of units of plasma from blood banks.
It is estimated that approximately 35,000 adults and children in the U.S.
and Europe suffer from blindness or severely impaired vision resulting from
irreparable corneal injury, according to Dr. Ivan Schwab, Ophthalmologist at
UC Davis.
ThermoGenesis Corp. received FDA approval in December 2001 to initiate a pivotal US human clinical trial of the CryoSeal FS System. A Phase III study is currently in progress to evaluate the use of a fully autologous fibrin sealant prepared with the CryoSeal FS System for controlling bleeding during elective liver surgery. That trial is expected to be completed early in 2003.
In March, ThermoGenesis Corp. signed an agreement with Dideco SpA. to
distribute the newly CE marked CryoSeal FS System and associated disposables
in Europe, where it is licensed for the production of autologous or single-donor fibrin sealant products.
www.thermogenesis.com/
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