Patient-derived xenografts of a case of ameloblastic fibrodentinoma.

OBJECTIVES: The establishment of animal models of xenotransplantation can contribute to the elucidation of the molecular pathogenesis of ameloblastic fibrodentinomas (AFD) and it also provides an opportunity for drug tests. We aimed to evaluate the possibility of AFD tumour growth in a patient-derived xenograft (PDX) model. In addition, we characterized the human tumour and the PDXs. MATERIALS AND METHODS: A sample of a recurrent AFD was obtained and two fragments were contralaterally implanted subcutaneously in an 8-week old female NUDE mouse. After 250 days, the PDXs were removed and submitted to histopathological and molecular analysis. Immunohistochemical reactions for Ki67 and the phosphorylated form of ERK1/2 were carried out in both, PDXs and human tumour, and the presence of BRAFV600E was assessed. RESULTS: From day 135 onwards, the PDXs presented a growth peak and remained stable until day 250. Histopathologically, the PDXs presented the same features of the patient's tumour. Tumour cells exhibited Ki67 and pERK1/2 immunoexpression in the patient's tumour and PDX. The AFD was wild-type for BRAFV600E. CONCLUSION: The PDX model recapitulated well the human tumour after a long implantation time, representing a possible model to study the AFD and other odontogenic tumours pathobiology.

Diabetes alters inflammation, angiogenesis, and fibrogenesis in intraperitoneal implants in rats.

The increased prevalence of diabetes worldwide is associated with increasing numbers of diabetic individuals receiving synthetic matrices and biomedical implants to repair and/or replace biological tissues. This therapeutic procedure invariably leads to adverse tissue healing (foreign body reaction), thus impairing the biomedical device function of subcutaneous implants. However, the influence of diabetes on abnormal tissue healing in intraperitoneal implants is unclear. We investigated key components of foreign body reactions in diabetic rats. Polyether-polyurethane sponge discs were placed intraperitoneally in rats previously injected with streptozotocin for induction of diabetes and in non-diabetic rats. Implants removed 10 days after implantation were assessed by determining the components of the fibrovascular tissue (angiogenesis, inflammation, and fibrogenesis). In implants from diabetic rats, fibrous capsule thickness and fibrovascular tissue infiltration (hematoxylin & eosin and picrosirius staining) were reduced in comparison with implants from non-diabetic rats. Hemoglobin (Hb) content (vascular index) and VEGF levels (pro-angiogenic cytokine) were increased after diabetes. However, the number of vessels (H&E and CD31-immunostaining) in the fibrovascular tissue from diabetic rats was decreased when compared with vessel numbers in implants from non-diabetic animals. Overall, all inflammatory parameters (macrophage accumulation-NAG activity; TNF-α and MCP-1 levels) increased in intraperitoneal implants after diabetes induction. The pro-fibrogenic cytokine (TGFß-1) increased after diabetes, but collagen deposition remained unaltered in the implants from diabetic rats. These important diabetes-related changes (increased levels of pro-inflammatory and angiogenic and fibrogenic cytokines) in peritoneal implant healing provide an insight into the mechanisms of the foreign body response in the diabetic environment in rats.

Molecular and immunohistochemical analyses of uveal melanoma patient cohort.

Uveal melanoma is a rare form of melanoma and the most frequent primary eye malignancy in adults. The major molecular alterations underlying uveal melanoma pathogenesis affect mainly the GNAQ, GNA11, SF3B1, and BAP1 genes. In this study, we somatically genotyped 31 Brazilian uveal melanomas for BRAF, GNA11, GNAQ, SF3B1, and BAP1 gene mutations and assessed BRCA2 and p53 protein expression. GNAQ and GNA11 mutations were detected in 60%, and SF3B1 mutation rate was 30%. p53 Immunostaining was markedly positive in 5/31, and 3/31 samples showed negative BRCA2 expression. This study supports the importance of these key genes in uveal melanoma tumorigenesis; p53 and BRCA pathways seem to play a role in a subset of patients, possibly heralding unfavorable prognosis.

Familial STAG2 germline mutation defines a new human cohesinopathy.

We characterize a novel human cohesinopathy originated from a familial germline mutation of the gene encoding the cohesin subunit STAG2, which we propose to call STAG2-related X-linked Intellectual Deficiency. Five individuals carry a STAG2 p.Ser327Asn (c.980 G > A) variant that perfectly cosegregates with a phenotype of syndromic mental retardation in a characteristic X-linked recessive pattern. Although patient-derived cells did not show overt sister-chromatid cohesion defects, they exhibited altered cell cycle profiles and gene expression patterns that were consistent with cohesin deficiency. The protein level of STAG2 in patient cells was normal. Interestingly, STAG2 S327 is located at a conserved site crucial for binding to SCC1 and cohesin regulators. When expressed in human cells, the STAG2 p.Ser327Asn mutant is defective in binding to SCC1 and other cohesin subunits and regulators. Thus, decreased amount of intact cohesin likely underlies the phenotypes of STAG2-SXLID. Intriguingly, recombinant STAG2 p.Ser327Asn binds normally to SCC1, WAPL, and SGO1 in vitro, suggesting the existence of unknown in vivo mechanisms that regulate the interaction between STAG2 and SCC1.

Foreign body response to subcutaneous implants in diabetic rats.

Implantation of synthetic matrices and biomedical devices in diabetic individuals has become a common procedure to repair and/or replace biological tissues. However, an adverse foreign body reaction that invariably occurs adjacent to implant devices impairing their function is poorly characterized in the diabetic environment. We investigated the influence of this condition on the abnormal tissue healing response in implants placed subcutaneously in normoglycemic and streptozotocin-induced diabetes in rats. In polyether-polyurethane sponge discs removed 10 days after implantation, the components of the fibrovascular tissue (angiogenesis, inflammation, fibrogenesis, and apoptosis) were assessed. Intra-implant levels of hemoglobin and vascular endothelial growth factor were not different after diabetes when compared with normoglycemic counterparts. However, there were a lower number of vessels in the fibrovascular tissue from diabetic rats when compared with vessel numbers in implants from non-diabetic animals. Overall, the inflammatory parameters (neutrophil accumulation--myeloperoxidase activity, tumor necrosis factor alpha, and monocyte chemotactic protein-1 levels and mast cell counting) increased in subcutaneous implants after diabetes induction. However, macrophage activation (N-acetyl-ß-D-glucosaminidase activity) was lower in implants from diabetic rats when compared with those from normoglycemic animals. All fibrogenic markers (transforming growth factor beta 1 levels, collagen deposition, fibrous capsule thickness, and foreign body giant cells) decreased after diabetes, whereas apoptosis (TUNEL) increased. Our results showing that hyperglycemia down regulates the main features of the foreign body reaction induced by subcutaneous implants in rats may be relevant in understanding biomaterial integration and performance in diabetes.

Apoptose na maturação placentária de vacas em diferentes estágios de gestação: evidenciação imuno-histoquímica e bioquímica / Apoptosis in placental maturation of cows in different stages of pregnancy: Immunohistochemical and biochemical evidences

Apoptose tem um papel importante na manutenção da homeostase placentária, e o desequilíbrio desse processo pode comprometer a gestação. O objetivo do presente estudo foi avaliar a ocorrencia de apoptose em amostras de placenta de vacas em diferentes fases de gestação. Amostras de placentomos de 15 vacas saudáveis com 4 (n=5), 6 (n=5) e 9 (n=5) meses de gestação foram colhidas e processadas rotineiramente para a histologia, imuno-histoquímica e isolamento de DNA. As lâminas obtidas foram coradas em HE, ou submetidas à análise imuno-histoquímica das proteínas pró-apoptóticas caspase-3 e Bax, e da proteína anti-apoptótica Bcl-2. O DNA isolado foi submetido à eletroforese em gel de agarose para detecção da fragmentação internucleossômica do genoma. Os resultados de histomorfometria revelaram que as células apoptóticas aumentaram progressivamente com o avanço da gestação. Confirmou-se a apoptose pela fragmentação característica do DNA genômico, visualizada pelo clássico "padrão em escada" na eletroforese em gel de agarose. Adcionalmente, a imunoexpressão de caspase-3, Bax e Bcl-2 foram observadas em todas as amostras. Entretanto, a proteína caspase-3 apresentou marcação mais intensa em todos os tempos gestacionais, quando comparada com a marcação das proteínas Bcl-2 e Bax. Esses resultados confirmam e reforçam a importância da apoptose na maturação placentária. Além disto, indica que caspase-3, Bax e Bcl-2 estão envolvidas nos mecanismos de ativação da apoptose pela via intrínseca mitocondrial ao longo da gestação, contribuindo para o equilíbrio fisiológico da celularidade e renovação celular na placenta bovina.

Apoptosis is important for placental homeostasis maintenance, and a misbalance in this process may compromise the success of pregnancy. The aim of this study is to evaluate apoptosis in bovine placental samples at different stages of pregnancy. Placentome samples from 15 healthy cows, at gestational ages of 4 (n=5), 6 (n=5) and 9 (n=5) months were collected and routinely processed for histological and immunohistochemical analysis, and for DNA isolation. Histopathology sections were stained with HE. Others were submitted to immunohistochemistry, using pro-apoptotic caspase-3 and Bax protein, and anti-apoptotic Bcl-2 specific antibodies. Isolated DNAs were processed for electrophoresis in agarose gel, for detection of internucleosomal fragmentation. Histomorphometry results demonstrated that apoptotic cells gradually increase with the advance of the gestation. Also, the DNA ladder pattern was observed in all groups. In addition, caspase-3, Bax and Bcl-2 were all expressed in the three different gestation periods. However, caspase-3 presented a higher expression in all groups, in comparison to Bcl-2 and Bax. These results confirm the importance of the apoptosis in the placental maturation. Also, these results indicated that caspase-3, Bcl-2 and Bax are involved in apoptotic activation mechanisms by mitochondrial intrinsic pathway during placental maturation, contributing for physiological cellularity and cellular turn over balance in bovine placenta.