INVESTIGATION INTO THE TENSILE PROPERTIES OF COLLAGEN CHONDROITIN-6-SULFATE GELS - THE EFFECT OF CROSS-LINKING AGENTS AND DIAMINES/

Artificial skin substitutes based on autologous keratinocytes are bein g developed for grafting onto burns patients. In order to be used succ essfully in the clinic, these skin substitutes need to have sufficient strength to allow ease of handling. This may be achieved by crosslink ing the collagen substratum on which the cells are cultured. The influ ence of potential crosslinking agents on the tensile properties of ace llular collagen gels has been investigated, including the glycosaminog lycan, chondroitin-6-sulphate (Ch6SO(4)), the water-soluble carbodiimi de crosslinking agents 1-ethyl-3-(3-diaminopropyl) carbodiimide (EDAC) , and 1,1-carbonyldiimidazole (CDI), and the polyamines, putrescine an d diaminohexane. Values for Young's modulus, maximum load, stress, dis placement and percentage strain at maximum load were generated by subj ecting the samples to a tear propagation test. Incorporation of 20% Ch 6SO(4) into collagen gels caused a significant increase in the Young's modulus, maximum load and stress at maximum load. Crosslinking treatm ent with EDAC, CDI or polyamines had little further benefit, and in ma ny cases resulted in a decrease in particular parameters. In terms of mechanical strength, the best crosslinking combination proved to be th e combination of CDI and diaminohexane, with results either improved o r maintained when compared with the control no treatment variants. How ever, previous experience suggests that the use of CDI as a crosslinki ng reagent may inhibit infiltration and proliferation of fibroblasts i n the substratum and it may be necessary to reach a compromise to obta in the best combination of biological and mechanical properties for ar tificial skin substitutes.