Biocompatibility in vitro of titanium dental implants. Immunocytochemical expression of fibronectin and extracellular matrix receptors.
BACKGROUND
Cell-substratum interactions play a peculiar role in cell proliferation, differentiation and migration. They are regulated by various glycoproteins, among which fibronectin, and by receptors connecting cells to the extracellular matrix, i.e. integrins. Therefore, the aim of this study was to correlate the proliferation rates of the human fibroblast line WI-38 cultured in presence of titanium dental implants to cell adhesion capability to substrata.


METHODS
WI-38 fibroblasts were cultured in presence of four dental implants in titanium (one hydroxyapatite coated) for 48, 72 and 96 hours. Cell proliferation was evaluated by detecting 5-bromodeoxyuridine incorporation. Fibronectin organization and alpha5beta1 integrin expression were evidenced by indirect immunofluorescence.


RESULTS
A correlation between fibronectin organization and cell proliferation rates was demonstrated: cultures showing fibronectin mainly organized in fibrils presented the highest cell proliferation degrees. After 96 hours, the observed decrease of the number of proliferating cells corresponded to a different fibronectin organization. In presence of the hydroxyapatite coated implant, colocalization of fibronectin and alpha5beta1 integrin was represented in focal contacts in cultures exhibiting the highest proliferation rate, while cells with the lowest proliferation one expressed alpha5beta1 integrin in point contacts.


CONCLUSIONS
Evidences obtained in this work showed that both the organization of fibronectin and the expression of alpha5beta1 integrin are strictly correlated to cell proliferation rates. Therefore, these parameters could be useful for evaluating the biocompatibility of dental materials in vitro.
Grill
V
V
Dipartimento di Morfologia Umana Normale, Università degli Studi, Trieste. grill@univ.trieste.it
Sandrucci
M A
MA
Rizzo
R
R
Narducci
P
P
Bareggi
R
R
Dorigo
E
E
D000497:Alloys; D001672:Biocompatible Materials / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line / Q000187:drug effects / Q000378:metabolism; D020099:Coated Materials, Biocompatible / Q000494:pharmacology; D015921:Dental Implants; D017886:Durapatite / Q000494:pharmacology; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D005353:Fibronectins / Q000096:biosynthesis* / Q000235:genetics; D022001:Focal Adhesions / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D066298:In Vitro Techniques; D039081:Integrin alpha5beta1 / Q000096:biosynthesis* / Q000235:genetics; D008422:Materials Testing; D020894:Microfibrils / Q000187:drug effects / Q000648:ultrastructure; D014025:Titanium / Q000494:pharmacology*
D000497:Alloys; D001672:Biocompatible Materials; D020099:Coated Materials, Biocompatible; D015921:Dental Implants; D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D039081:Integrin alpha5beta1; C031462:titanium alloy (TiAl6V4); D017886:Durapatite; D014025:Titanium