Marília Trierveiler Martins

Cysteine Cathepsins in Human Dentin-Pulp Complex

INTRODUCTION Collagen-degrading matrix metalloproteinases (MMPs) are expressed by odontoblasts and present in dentin. We hypothesized that odontoblasts express other collagen-degrading enzymes such as cysteine cathepsins, and their activity would be present in dentin, because odontoblasts are known to express at least cathepsin D. Effect of transforming growth factor beta (TGF-beta) on cathepsin expression was also analyzed. METHODS Human odontoblasts and pulp tissue were cultured with and without TGF-beta, and cathepsin gene expression was analyzed with DNA microarrays. Dentin cathepsin and MMP activities were analyzed by degradation of respective specific fluorogenic substrates. RESULTS Both odontoblasts and pulp tissue demonstrated a wide range of cysteine cathepsin expression that gave minor responses to TGF-beta. Cathepsin and MMP activities were observed in all dentin samples, with significant negative correlations in their activities with tooth age. CONCLUSIONS These results demonstrate for the first time the presence of cysteine cathepsins in dentin and suggest their role, along with MMPs, in dentin modification with aging.

Carcinoma ex pleomorphic adenoma (CXPA): immunoprofile of the cells involved in carcinomatous progression

Aims : To characterize the cellular component in pleomorphic adenoma (PA) that undergoes malignant transformation in carcinoma ex pleomorphic adenoma (CXPA).

New Source of Muscle-Derived Stem Cells with Potential for Alveolar Bone Reconstruction in Cleft Lip and/or Palate Patients

Cleft lip and palate (CLP), one of the most frequent congenital malformations, affects the alveolar bone in the great majority of the cases, and the reconstruction of this defect still represents a challenge in the rehabilitation of these patients. One of the current most promising strategy to achieve this goal is the use of bone marrow stem cells (BMSC); however, isolation of BMSC or iliac bone, which is still the mostly used graft in the surgical repair of these patients, confers site morbidity to the donor. Therefore, in order to identify a new alternative source of stem cells with osteogenic potential without conferring morbidity to the donor, we have used orbicular oris muscle (OOM) fragments, which are regularly discarded during surgery repair (cheiloplasty) of CLP patients. We obtained cells from OOM fragments of four unrelated CLP patients (CLPMDSC) using previously described preplating technique. These cells, through flow cytometry analysis, were mainly positively marked for five mesenchymal stem cell antigens (CD29, CD90, CD105, SH3, and SH4), while negative for hematopoietic cell markers, CD14, CD34, CD45, and CD117, and for endothelial cell marker, CD31. After induction under appropriate cell culture conditions, these cells were capable to undergo chondrogenic, adipogenic, osteogenic, and skeletal muscle cell differentiation, as evidenced by immunohistochemistry. We also demonstrated that these cells together with a collagen membrane lead to bone tissue reconstruction in a critical-size cranial defects previously induced in nonimmunocompromised rats. The presence of human DNA in the new bone was confirmed by PCR with human-specific primers and immunohistochemistry with human nuclei antibodies. In conclusion, we showed that cells from OOM have phenotypic and behavior characteristics similar to other adult stem cells, both in vitro and in vivo. Our findings suggest that these cells represent a promising source of stem cells for alveolar bone grafting treatment, particularly in young CLP patients.

Extranodal follicular dendritic cell sarcoma of the palate

Follicular dendritic cell tumors are uncommon and usually occur in lymph nodes. We report the case of a follicular dendritic cell tumor that occurred in the palate of a 14-year-old boy and manifested itself as a nodular mass. Histologically, the neoplasm consisted of spindle-shaped or oval-shaped cells with eosinophilic cytoplasms and nuclei with delicate, dispersed chromatin. The lesional cells were principally arranged in diffuse, fascicular patterns with vaguely whorled or storiform areas. Focal multinucleate tumor giant cells and lymphocytes were observed throughout the neoplasm. Immunohistochemically, tumor cells were positive for the follicular dendritic cell markers CD21, CD35, and CD23 and for S-100 protein, CD68, and muscle-specific actin. Tumor cells were negative for LCA, CD20, EMA, CK (AE1/AE3), HMB45, and CD34. Lymphocytes were positive for LCA and CD45RO. Although follicular dendritic cell sarcoma is a very uncommon tumor, it should be included in the differential diagnosis of tumors in this location.

Biomarker analysis in carcinoma ex pleomorphic adenoma at an early phase of carcinomatous transformation.

Diagnostic criteria for intracapsular carcinoma ex pleomorphic adenoma (CXPA) are subjective and vary among authors. Biomarker analysis, which could provide more objective evaluation of these tumors, has rarely been studied in intracapsular CXPA. Immunohistochemical evaluation of c-erbB-2, p53 protein, bcl-2, and Ki-67 was performed in 8 cases of CXPA at an early phase of malignant transformation (4 intracapsular and 4 minimally invasive) and in 17 pleomorphic adenomas (PA). In all cases of CXPA, p53 and Ki-67 were demonstrated predominantly in luminal cells of benign and malignant areas, significantly more in the latter. Few benign myoepithelial cells were p53 positive. c-erbB-2 reactivity was strongly associated with atypical luminal cells. Bcl-2 expression was weak and focal in malignant areas from 2 cases. In conclusion, both p53 and c-erbB-2 proteins appear to be involved at an early stage of malignization of PA. In PA with atypical cells, evaluation of the expression of these 2 markers provides more objective criteria for the diagnosis of intracapsular CXPA.

Maspin expression in carcinoma ex pleomorphic adenoma

Aims: To investigate the presence and distribution of the protein maspin in carcinoma ex pleomorphic adenoma (CXPA). Methods: Maspin expression was studied by means of immunohistochemistry in 16 cases of CXPA, using the labelled polymer method. Results: According to the extent of invasion, the tumours were subdivided into: intracapsular (five cases), minimally invasive (four cases), and invasive (seven cases). Twelve patients had carcinoma with only epithelial differentiation, whereas four had a malignant myoepithelial component. Non-luminal cells in the duct-like structures of the remnant pleomorphic adenoma were strongly positive for maspin, whereas only a few luminal cells were immunopositive. A few positive cells were seen in the frequent hypocellular and hyalinised areas. Maspin was abundantly expressed, mainly in non-luminal cells, in transitional areas of CXPA with only epithelial differentiation. In frankly carcinomatous areas there was a gradual decrease in maspin expression. Almost all cells were maspin positive in CXPA with a myoepithelial component. When present, luminal cells were in general negative for maspin. Conclusions: When only epithelial cells undergo malignant transformation, maspin expression is gradually lost. In cases with a myoepithelial component, maspin expression is high, and this might be related to the tumour suppressor activity attributed to this cell.

Immunohistochemical Mdm2 expression in minor salivary gland tumours and its relationship to p53 gene status

Mdm2 protein is a cellular regulator of p53 protein activity. Minor salivary gland tumours were investigated for immunohistochemical expression of Mdm2 protein and for p53 gene status. Formalin-fixed sections were submitted to monoclonal antibody anti-Mdm2 through use of the streptavidin-biotin method. Nuclear immunoreactivity was scored 1 (0-25% nuclei positive), 2 (26-50%), 3 (51-75%) and 4 (> 75%). The scores found were: PLGA = 1-4; ACC = 3 and 4; ACA = 2 and 4; PA = 3. Genomic DNA of p53 gene exons 5-8 was examined by polymerase chain reaction and no alterations were detected. The strong immunohistochemical Mdm2 expression may represent an alternative mechanism to the development of salivary gland tumours.

The severity of epithelial dysplasia is associated with loss of maspin expression in actinic cheilitis

Background:  Prolonged exposure of the lip to sunlight may cause actinic cheilitis (AC) and squamous cell carcinoma (SCC). Maspin is a serpin with tumor suppressor functions. This work analyzed the presence and distribution of maspin in AC and lip SCC.

An experimental model for the study of craniofacial deformities

PURPOSE To develop an experimental surgical model in rats for the study of craniofacial abnormalities. METHODS Full thickness calvarial defects with 10x10-mm and 5x8-mm dimensions were created in 40 male NIS Wistar rats, body weight ranging from 320 to 420 g. The animals were equally divided into two groups. The periosteum was removed and dura mater was left intact. Animals were killed at 8 and 16 weeks postoperatively and cranial tissue samples were taken from the defects for histological analysis. RESULTS Cranial defects remained open even after 16 weeks postoperatively. CONCLUSION The experimental model with 5x8-mm defects in the parietal region with the removal of the periosteum and maintenance of the integrity of the dura mater are critical and might be used for the study of cranial bone defects in craniofacial abnormalities.

Compound odontoma in three dogs.

Three young, female dogs were operated for compound odontoma. All tumors were considered stage III with treatment consisting of partial mandibulectomy or maxillectomy. Microscopic examination of the resected tissue confirmed the diagnosis. Relatively aggressive, resective surgery resulted in prolonged tumor-free intervals.