Microarray analysis of gene involved in cell prolifration and development in inflamed human dental pulp

Department Of Medical, Oral And Biotecnological Sciences, “g. D’annunzio” University, Chieti, Italia (1) - Center Of Excellence On Aging (ce.s.i.), “g. D’annunzio” University, Chieti, Italia (2) - Base Sanitary District (d.s.b), Francavilla Al Mare, Base Sanitary District (d.s.b), Francavilla Al Mare, Chieti, Italia (3) - Department Of Medical, Oral And Biotecnological Sciences, Center Of Excellence On Aging (ce.s.i.), "g. D'annunzio" Foundation, Chieti, Italia (4) - Center Of Excellence On Aging (ce.s.i.), "g. D'annunzio" Foundation, Chieti, Italia (5) - 1department Of Medical, Oral And Biotecnological Sciences, Center Of Excellence On Aging (ce.s.i.), “g. D’annunzio” University, Chieti, Italia (6) Introduction: In this study, inflamed and healthy dental pulp samples were analyzed and compared in order to detect variation in expression of genes involved in cell proliferation and development, and to verify the persistence of osteogenic markers in inflamed dental pulp tissue. Methods: Human dental pulp were obtained from third molars. Four patients underwent tooth extraction because of pain or high sensitivity due to deep caries (Test Group); four patients (Control Group) underwent tooth extraction for orthodontic reasons. The age range for the two groups did not display significant differences (16-25 years). tRNA was isolated using SV Total RNA Isolation System. Results were analyzed by cluster, in order to identify homogeneous sets of genes. Data were analyzed by SAM and through Ingenuity Pathway Analysis (IPA), which allows to identify the genes according to their location, cellular components and functions. Among the gene profiling we selected two genes, with functions in the inflammatory response and cellular growth and proliferation, KITLG (also known as SCF – stem cell factors) and FLT3LG. Results: The tRNA microarray executed on the different tissue samples revealed 993 genes profiles, 834 genes up-regulated and 159 down-regulated. Both KITLG and FLT3LG were statistically over-expressed compared to control samples. In addition, no different expression was recorded for genes considered as markers for ostegenic differentiation, such as STRO-1, CD105 and RUNX-2. Conclusion: Our results confirmed that the gene expression pattern could significantly vary between inflamed and healthy dental pulp. Both KITLG and FLT3G were over-expressed in inflamed dental pulp, probably because of their specific funtions. KITLG is a pleiotropic ligand for the receptor tyrosine kinase C-kit, expressed in different cell types, and involved in promoting cell proliferation and differentiation. FLT3LG, has been showed to be able to stimulate stem cells growth in bone marrow. Moreover, genes considered as markers for ostegenic differentiation could be normally expressed in the inflamed pulp as well as in the healthy one, attesting inflammation seem not to affect the capability of dental pulp tissues to be induced, under appropriate condition, to differentiate towards an osteogenic pathway.