Bone Abstracts

Changes in the ability of self-renewal and differentiation of mesenchymal stem cells may be affected by osteoporosis. The aim of this investigation was to compare the transcriptional profile of mRNAs and miRNAs of osteoblastic cells from calvaria and bone marrow of female rats after ovariectomy. Following the approval by ethics committee, 18 wistar rats were divided into control (sham) and ovariectomized groups. After 150 days, both groups were sacrificed to collect the femurs and fragments of calvaria from which cells were isolated and cultivated until subconfluence. It was performed the extraction and quantification of total RNA, followed by RNA integrity evaluation. Identification of gene modulation by cDNA microarray and evaluation of microRNAs involved in gene inhibition was carried out by means of Agilent Feature Extraction Software, and the files generated in the program were analyzed in bioinformatics platform Agilent GeneSpring GX 12.6. Data obtained showed that 5.447 differentially expressed mRNAs were detected in cells from calvaria and 4.399 in cells from bone marrow. There were found 84 miRNAs differentially expressed in osteoblastic cells from calvaria and 55 miRNAs from bone marrow. Genes found in the group of calvaria were related to ossification, bone morphogenesis and development, whereas in bone marrow genes were related to differentiation and response to estrogen stimulation. Among the miRNAs, members of 30 family were up-regulated in both ovariectomized groups, which act as negative regulators of osteoblast differentiation. The miR-17 that is associated with up-regulation of osteogenesis was down-regulated in both osteoporotic groups. These data suggest a difference in the transcriptional profile of osteoblastic cells from calvaria and bone marrow, both affecting the proper formation of bone tissue in a situation of osteoporosis.