Abstract
Purpose: :
To elucidate the optimization of tissue transglutaminase (TG2) based surgical adhesive formulation, its method of delivery, properties and biocompatibility in different target tissues especially the cornea.
Methods: :
Human corneal tissue was tested for the presence of TG2 substrate sites using histochemical enzyme activity assay. The ability of the enzyme delivery system to precisely deliver the active enzyme without tissue damage was tested by contact transfer of the concentrated enzyme to human corneal cryosections, followed by the assay of the enzyme activity. The ability of the enzyme to achieve adhesion in corneal tissue was studied by incising cadaveric human corneal tissue to produce flap wounds, incubation, and then mechanical testing after contact-transferring concentrated enzyme to the tissue interface. The degradation of the enzyme activity with time at room temperature was studied by assaying the enzyme activity of the contact transfer spots at increasing time points after the delivery of the concentrated enzyme on human corneal cryosections.
Results: :
Human cornea showed abundant substrate sites for human TG2. Precise delivery of the concentrated active enzyme was demonstrated on human cornea. In initial mechanical testing, the breaking stress of the corneal flap wounds closed after the delivery of the active enzyme was many folds greater than that of the control without the active enzyme. The activity of the delivered enzyme spots on corneal tissue was observed to last more than 4 hour after the delivery.
Conclusions: :
Human cornea is proved to have abundant TG2 substrate sites and hence a good target for testing a TG2 based adhesive. The new enzyme delivery method is efficient in precisely delivering the active enzyme to the tissue interface where the adhesion is needed, with its activity maintained for an appropriate duration. The enzyme adhesive may serve as effective biological glue for the use in corneal surgeries; further studies are in order to demonstrate test performance with respect to currently available ophthalmic glues.
Keywords: wound healing • cornea: stroma and keratocytes