BIOLOGICAL EFFECTS AND CYTOTOXICITY OF TRICALCIUM PHOSPHATE AND FORMALDEHYDE CROSS-LINKED GELATIN COMPOSITE

The purpose of this study was to prepare and evaluate a composite, GTF , combining tricalcium phosphate (TCP) ceramic particles and formaldeh yde cross-linked gelatin, as bone substitute. The content of formaldeh yde in the developed material was used to control the physical and mec hanical properties of the gelatin structure, in terms of cross-linked gelatin molecules, solubility, and biodegradation of the reconstituted matrices. Formaldehyde, however, is known to be a potentially toxic s ubstance that would cause inflammation and severe tissue response. Thu s, it is necessary to know whether the substances released from the GT F composite will cause severe tissue response. Tn this study, the bioc ompatibility and cytotoxicity of the GTF composite were examined by th e in vitro method of human myoblast cell culture. Extracts were obtain ed by soaking the GTF composite in normal saline for 1, 2, 4, 6, and 8 days. The extract mixed with complete medium in a ratio of 1:1 was ad ded to cell culture wells each containing 1 x 10(5) myoblasts. After b eing cultured for 2 days, the cells were trypsinized and counted in a Neubauer counting-chamber under an optical microscope. The culture dis hes were washed with 0.185 M sodium cacodylate buffer (pH 7.2) and fix ed with 4% glutaraldehyde solution for 30 min. They were then dehydrat ed through a graded ethanol series and stained with hematoxylin/eosin for optical microscopic examination. The substances released from the GTF composite were analyzed by gas chromatography (GC), capillary elec trophoresis (CE), and inductive coupled plasma-atomic emission spectro metry (ICP-AES). The results showed that the GTF composite was well to lerated by the myoblast. The unchained or uncross-linked formaldehyde was completely released from the GTF composites after being soaked in the normal saline for 4 days. The extract was thought to inhibit the c ell growth for the initial 4 days of soaking time. After soaking for 4 -6 days, the GTF composite gradually began to release some nutritious elements which were beneficial to the myoblast growth and caused cell numbers to increase substantially. The released nutritious constituent s were analyzed by the above-mentioned instruments. The results were i n agreement with the above observations.