Tissue Engineering Restores Cornea

The Moscow scientists have conducted clinical trials of a new method for treatment of deep burns of cornea. Their effort has been supported by the Russian Foundation for Basic Research.

Specialists of the Koltsov Institute of Developmental Biology, Russian Academy of Sciences, and the Gelmgolts Scientific Research Institute of Eye Diseases suggest that deep burns of cornea should be treated by transplanting artificial equivalent of stroma (the tissue directly underlying the cornea) on the affected area. The researchers have developed technique for preparation and transplantation of live equivalent of stroma (LES) and tested it in the clinic on patients with heavy burns of eyes. They managed to help the overwhelming majority of patients.

The share of burns among all eye traumas makes about 38 percent, with considerable proportion of cases involving cornea damage. The cornea is supported by the stroma connective tissue, which also gets damaged in case of deep burns. If the stroma is missing or significantly destroyed, the remaining cornea cells are unable to recover injuries as they have no support. Therefore, the major task in treating cornea defects is stroma recovery. This task is convenient to solve via tissue transfer. Foreign researchers suggest that cell culture taken from a healthy eye should be transplanted on the burnt area. However, such operation poses a serious trauma by itself, which is not always justified.

The Moscow scientists chose another way. They created a live equivalent of stroma – a temporary framework, along which cornea cells could “crawl over” to the damaged area. The live equivalent of stroma represents human fibroblasts inclosed in collagen gel that can be kept for several days. Human fibroblasts were picked out of skin fragments remaining after cosmetic surgery or from the 3- to 5-week abortive material. The method has successfully passed first clinical trials.

The researchers treated 21 patients with severe and extremely severe eye burns. Previously, a lot of volunteers had already tried other treatment modes but without success. The ophthalmologists moved away mortified cells, laid a transplant on the wound and closed the transplant with a soft contact lens. In 3 to 5 days, the transplantation was repeated to reinforce medicinal effect. The live equivalent of stroma allowed not only to preserve traumatized patients’ eyes, but even to partially recover eyesight. Treatment efficiency depended on heaviness of stroma affection, condition of eyelids’ tissues adjacent to the cornea. If eyelids or conjunctiva had not been affected, and no corneal caligo had occurred, the wound closed within two weeks. Later on, the cornea retained transparency, which allowed to achieve maximum acuity of vision possible in case of such trauma (0.2-0.7). If at the point of treatment the cornea had been blurred, afterwards, acuity of vision did not exceed 0.06. However, with very young patients who started the treatment immediately after burning and cured it quickly, the cornea became more transparent in the course of time.

The researchers believe that the main advantage of the method is its multiple action. Transplanted fibroblasts protect tissues underlying the cornea from negative impact of external factors, create temporary matrix along which the cornea cells can move and close the burn, and excrete growth factors stimulating tissue recovery. As times goes by, the transplant is replaced by the patient’s own cells. The authors believe that another advantage of the method lies in the possibility to partially recover transparency of affected cornea.