O câncer de mama é o tumor mais incidente entre as mulheres no mundo. Assim como em outros tumores, a tumorigênese nas mamas é um processo complexo resultante da combinação de fatores genéticos e ambientais que dirigem a transformação das células normais em células malignas. O gene PAWR, conhecido como PAR-4 (Prostatic apoptosis response-4) foi primeiramente identificado em células de câncer de próstata de rato induzidas a apoptose e codifica uma proteína de 342 aminoácidos que é efetiva na indução de apoptose nas células tumorais e causa regressão dos tumores ativando Fas/FasL e inibindo a atividade de NF-B. O aumento de Par-4 é suficiente para causar apoptose seletiva em células tumorais, mas não em células normais ou imortalizadas. Recentemente, um estudo de nosso grupo demonstrou que a expressão reduzida de Par-4 está associada a um pior prognóstico em câncer de mama e que esta proteína pode ter um papel importante na morfogênese da glândula mamária. O estudo funcional do gene Par-4 em diferentes linhagens de mama é importante para o melhor entendimento do papel deste gene no processo tumorigênico da glândula mamária. Portanto, a proposta do presente estudo foi investigar os efeitos do aumento de expressão ou supressão de Par-4 na proliferação celular e sobrevivência das células normais e tumorais de mama. As células MCF10A e MCF-7 foram transfectadas com os vetores de expressão para Par-4 (pCMV6-PAR-4) ou com oligos siRNA para supressão transiente de Par-4. A caracterização dos clones foi feita por Real Time PCR e Western Blot. Os ensaios de proliferação foram feitos por MTT e os ensaios de apoptose por dupla marcação com Laranja de Acridina/ Hoechst 33342 e por citometria de fluxo. O aumento da expressão de Par-4 diminuiu a proliferação de ambas às células comparadas às células-controle (p<0,01). Por outro lado, a diminuição de expressão de Par-4 por siRNA levou ao aumento da proliferação das células tumorais MCF-7 (p<0,01). A quantificação das células em apoptose mostrou um aumento significativo de apoptose nas células MCF-7 com aumento de Par-4 em relação às células controle MCF-7 pcNEO tratadas com ambas as concentrações de docetaxel (5 nM 13,24% versus 3,89%; p=0.001; 100 nM 24,81% versus 6,07%; p=0,0001) por 24 horas. Embora preliminares, os resultados de citometria também mostraram que as células MCF-7 com aumento de Par-4 apresentam maior porcentagem de células em apoptose na ausência de tratamento e após tratamento com 100 nM de docetaxel por 24 horas. Embora novos estudos sejam necessários, nossos dados sugerem que o aumento de expressão de Par-4 sensibilizou as células MCF-7 ao quimioterápico docetaxel. Pela primeira vez, mostramos o efeito inibitório de Par-4 no crescimento e sobrevivência das células epiteliais mamárias / Breast cancer is the most common tumor among women in the world. As for other malignancies the tumorigenic process of the breast involves genetic alterations that drive the progressive transformation of normal cells into malignant cells with and aggressive phenotype. Alterations in cells that upregulate proliferation or downregulate apoptosis are one of essential mechanisms that dictate tumor growth. The PAWR gene, also known as PAR-4 (Prostatic apoptosis response-4), was first identified in prostate cancer cells undergoing apoptosis and encodes a 332 aminoacid protein that is effective in inducing cancer cell apoptosis and cause regression of tumors by activating Fas/FasL and inhibiting NF-B activity. Interestingly, Par-4 overexpression is sufficient to cause apoptosis in cancer cells, but not in normal or immortalized cells. Recently, we demonstrated that reduced expression of PAR-4 is associated with breast cancer poor prognosis and this protein may have a role in the process of the mammary gland morphogenesis. The functional study of Par-4 gene in different cell lines of breast is important to better understand its role in the tumorigenic process of the breast. Therefore, the purpose of the present study was to investigate the effects of overexpression and suppression of PAR-4 in cell proliferation and survival in mammary epithelial cells. MCF10A and MCF-7 cells were transfected with expression vectors for PAR-4 overexpression (pCMV6-PAR-4) or with small interfering RNAs duplexed oligonucleotides. Clone characterization was performed using real time PCR and western blot. Proliferation assays were carried out using MTT and apoptotic assays were performed by doublefluorescence staining technique (Acridine Orange/Hoechst 33342) or using flow cytometry. PAR-4 overexpression decreased the proliferation rates in both MCF10A and MCF-7 cells compared to the parental or control cells (p<0,01). On the other hand, PAR-4 knockdown leads to increased proliferation in MCF7 cells (p<0,01). We observed a significant increase in apoptosis of MCF-7 cells with increased expression of Par-4 compared to control cells (MCF-7 pcNEO) in both concentrations of docetaxel (5 nM 13,24% versus 3,89%, p = 0,001; 100 nM 24,81% versus 6,07%, p < 0,0001). Cytometry analysis, although preliminary, showed that MCF-7 pcPar-4 have a higher percentage of apoptotic cells in the absence of treatment and after treatment of 100 nM of docetaxel. Although more studies are needed, our data suggest that increased expression of Par-4 sensitizes breast cancer cells to treatment with docetaxel. This is the first report showing that PAR-4 has inhibitory effects on mammary epithelial cells proliferation and survival

O leite materno constitui uma rica fonte de nutrientes e peptídeos. O desmame precoce (DP) induz o aumento da proliferação e da diferenciação celular, e pode ser uma condição estressante capaz de elevar a corticosterona (CORT). Neste estudo, investigamos a interação entre padrão alimentar, CORT, TGF<font face=\"Symbol\">a e TGF<font face=\"Symbol\">b na regulação da proliferação celular na mucosa gástrica de ratos em desenvolvimento pós-natal. Utilizamos ratos Wistar em DP a partir do 15ºd, e observamos o aumento de CORT aos 16, 17 e 18d (p<0,05). No 17ºd, encontramos nível alto de TGF<font face=\"Symbol\">a e baixo de TGF<font face=\"Symbol\">b1 na mucosa gástrica (p<0,05). Para avaliarmos a ação da CORT, usamos o RU486, que ao reduzir a ação hormonal, estimulou a proliferação celular nos animais amamentados e DP (p<0,05), sem alterar os níveis de TGF<font face=\"Symbol\">a e TGF<font face=\"Symbol\">b. A sinalização para esses fatores foi estudada, e RU486 reduziu a ativação de ERK1/2 (p<0,05) no DP. Concluímos que a corticosterona circulante possui efeito antiproliferativo sobre a mucosa gástrica de ratos, e sua ação parece direta sem depender da regulação dos níveis de TGF<font face=\"Symbol\">a e TGF<font face=\"Symbol\">b. / Milk is a source of nutrients and active peptides. Early weaning (EW) leads to the increase of cell proliferation and differentiation, and can characterize a stressful condition to induce corticosterone (CORT). In the current study we investigated the interaction among dietary pattern, CORT, TGF<font face=\"Symbol\">a and TGF<font face=\"Symbol\">b on the regulation of cell proliferation in gastric mucosa of developing rats. We used Wistar rats submitted to EW on the 15thd, and we observed higher CORT levels throughout EW (p<0.05). At 17d, we also found higher TGF<font face=\"Symbol\">a and lower TGF<font face=\"Symbol\">b1 in the gastric mucosa (p<0.05). To evaluate CORT action, we used RU486 which antagonized the hormone and increased cell proliferation in both suckling and EW pups (p<0.05), without changing TGF<font face=\"Symbol\">a and TGF<font face=\"Symbol\">b1 levels. The signaling pathways triggered by these factors were studied and RU486 reduced ERK1/2 phosphorylation (p<0.05) in EW. We conclude that CORT is repressive for cell proliferation in the rat gastric mucosa, and its action seems to be direct, i.e. independent of TGF<font face=\"Symbol\">a and TGF<font face=\"Symbol\">b regulation.

Durante as últimas décadas, pesquisas em biologia do tumor com a utilização de novas técnicas de biologia molecular produziram informações em profusão, motivando e dando condições para que fossem criados novos modelos matemáticos dedicados à análise de vários aspectos de crescimento e proliferação da população celular. Alguns desses modelos têm sido dedicados à descrição e análise do regime estacionário do processo de desenvolvimento de uma população celular sob condições químicas que se consideram favorecer a aceleração ou desaceleração do crescimento da população de células tumorais. Todavia, a dinâmica temporal do crescimento de uma população de células tumorais ainda não foi analisada nesses trabalhos. Uma das dificuldades é o estabelecimento da interação entre células de múltiplos tipos que sirvam como descrição para essa dinâmica. Nosso trabalho vem preencher essa lacuna e a presente dissertação tem como objetivo a apresentação do modelo, desenvolvido por nós, de simulação da dinâmica do crescimento e proliferação celular do melanoma (câncer de baixa incidência, mas de letalidade extremamente alta) e também dos resultados obtidos através das simulações deste modelo computacional / During the last decades, tumor biology research with the use of new techniques in molecular biology resulted in a profusion of information that have given conditions and motivated the development of new mathematical models dedicated to analyzing various aspects of growth and proliferation of the cell population. Some of these models have been devoted to the description and analysis of the steady state of the development process of a cell population under chemical conditions that, in theory, promote the acceleration or deceleration of the growth of tumor cell population. However, these studies have not yet analyzed the temporal dynamics of growth of a tumor cell population. One of the difficulties is the establishment of the interaction between cells of multiple types that serve as the description for this dynamic. Our work fills this gap and this dissertation aims to present the model, developed by us, to simulate the growth dynamics and cellular proliferation of melanoma (cancer of low incidence but of extremely high lethality) and the results obtained through the simulations of this computational model

O carcinoma tiroidiano apresenta alterações na via MAPK, destacando-se o rearranjo RET/PTC. Alterações na expressão de microRNAs também são observadas. O aumento da expressão de miR-21 nos levou a analisar o papel deste na tumorigênese tiroidiana, bem como a influência da ativação oncogênica de RET/PTC3 durante este processo. A expressão de miR-21 foi analisada em 4 linhagens e a sua modulação foi realizada em células PCCL3 e KTC-2. RET/PTC3 foi ativado em células PTC3-5 e analisou-se a sua influência na expressão de miR-21 e na proliferação celular. Todas as linhagens expressam miR-21. A transfecção de anti-miR-21 em células KTC-2 inibiu em 80% a expressão deste miRNA, observando-se um aumento de SMAD7. A super-expressão de miR-21 em PCCL3 não alterou a proliferação. A indução de RET/PTC3 aumentou a expressão de miR-21 e diminui a proliferação, e quando ativado concomitante ao tratamento com TGFb-1, a diminuição na proliferação se acentuou, sugerindo que RET/PTC3 ative a via TGFb através da inibição de SMAD7 mediada por miR-21. / Alterations in MAPK signaling are common in thyroid cancer, including RET/PTC rearrangement. Additionally, several studies described the altered expression of microRNAs. The up-regulation of miR-21 on thyroid cancer led us to evaluate the role of this molecule on thyroid tumorigenesis, and also the influence of RET/PTC3 activation in this process. MiR-21 expression was analyzed in four thyroid cell lines, and the modulation of this miRNA was performed in KTC-2 and PCCL3 cells. PTC3-5 cells were used to analyze the influence of RET/PTC3 on miR-21 expression and cell proliferation. miR-21 expression was found in both cell lines. Anti-miR-21 transfection in KTC-2 cells decreased miR-21 levels in 80% and also increased SMAD7 expression. The up-regularion of RET/PTC3 increased miR-21 expression and decreased cell growth. The activation of RET/PTC3 combined to TGFb-1 treatment accentuated decrease in proliferation, suggesting that RET/PTC3 positively regulates TGFb pathway through miR-21-dependent SMAD7 inhibition.

Endometriosis is a gynecological disease in which endometrial glands and stroma are present outside the uterus. Pelvic pain, infertility and decreased quality of life are the main problems caused by this disease carrying epidemiological and social impact. Peritoneal endometriosis which is characterized by the presence of red, black and white pelvic endometriotic lesions is clearly a multifactorial pathology associated with a local inflammatory response in the pelvic cavity. In vitro studies suggest that the transcription factor nuclear factor-kappaB (NF-êB) is implicated in the transduction of proinflammatory signals in endometriosis. The aim of this study was to investigate the involvement and role of the NF-êB pathway in endometriosis in vivo. Firstly, NF-êB activation and intercellular adhesion molecule (ICAM)-1 expression were investigated in thirty-six peritoneal endometriotic lesions from women. Constitutive NF-êB activation, involving p65- and p50-containing dimers, was demonstrated in peritoneal endometriotic lesions by electrophoretic mobility shift assays and supershift analyses, as well as NF-êB (p65) DNA-binding activity immunodetection assays. NF-êB activation and ICAM-1 expression were significantly higher in red lesions than black lesions, while IêBá (NF-êB inhibitory protein) expression was constant, as shown by Western blot analyses. Secondly, endometriosis was induced in nude mice by intraperitoneal injection of fluorescent labeled menstrual endometrium. Two NF-êB inhibitors (BAY 11-7085 and SN-50) were injected intraperitoneally and endometriotic lesions were recovered on day 5. Both NF-êB inhibitors induced a significant reduction in lesion development compared to control mice. NF-êB activation and ICAM-1 expression of endometriotic lesions were significantly reduced in treated mice, and cell proliferation in BAY 11-7085-treated mice. Both inhibitors produced a significant increase in apoptosis of endometriotic lesions, as assessed by active caspase-3 immunostaining and the TUNEL method. In conclusion, this is the first study to show constitutive NF-êB activation in peritoneal endometriotic lesions collected from women and during the initial development of endometriotic lesions in an animal model. Differential levels of NF-êB activation have been established between red and black lesions, providing more evidence on the distinct inflammatory status of these two types of peritoneal endometriotic lesions. In addition, this study offers further insight into the pathways implicated in NF-êB activation in endometriotic lesions, showing the involvement of p50/p65 dimers and suggesting participation of the canonical pathway of NF-êB activation. This study also demonstrates, for the first time, that NF-êB inhibition reduces the initial development of endometriotic lesions by inhibiting the inflammatory response and cell proliferation, and inducing apoptosis of endometriotic lesions. The NF-êB pathway therefore looks to be a promising therapeutic target for endometriosis prevention and treatment.

Activities of the DEAD box (Asp-Glu-Ala-Asp) family of proteins- including RNA-dependent ATPase and RNA helicase- function in all organisms to sculpt RNA-RNA duplex and RNA-protein complexes, ensuring that necessary rearrangements are rapidly and properly resolved during genetic information processing. Identified as a prototypic member of the DEAD box family and documented as an ATPase and RNA helicase, p68 plays essential and diverse functions in the control of gene expression ranging from pre-mRNA/rRNA processing and mRNA decay/stability to transcriptional activation and initiation. Despite the early implied roles in organ maturation and tumor progression, the functional contributions of p68 to growth/differentiation regulation and cancer development remain undefined. Here, we show c-Abl-dependent phosphorylation of p68 markedly associates with abnormal cell growth and cancer development. Importantly, we characterize an unanticipated signaling module through which p68 functionally contributes to Epithelial-Mesenchymal Transition (EMT) and cell proliferation. p68, which appears to be phosphorylated by c-Abl at tyrosine 593, consequently promotes an EMT through its ability to recruit â-catenin into cell nucleus via a canonic Wnt/â-catenin axis independent way; accordingly, phosphor-p68 (phosphorylated at tyrosine 593 residue) also stimulates tumor cell growth, which requires the ATPase activity of the protein. These findings define a potential mechanism whereby phosphor-p68 recruits â-catenin into cell nucleus in ATP hydrolysis driven fashion and cooperatively regulates transcriptional programs that control an EMT. The dissertation thus demonstrates a tight coordination between DEAD box RNA helicase and cancer development.

The transcription factor NFAT5/TonEBP belongs to the Rel family, which also comprises NF ÛB and NFATc proteins. NFAT5 only shares structural and functional homology with other Rel family members at the level of the DNA binding domain, and differs from them considerably in other regions. NFAT5 enables mammalian cells to adapt to and withstand hypertonicity by orchestrating an osmoprotective gene expression program whose products include chaperones as well as ransporters and enzymes that increase the intracellular concentration of compatible osmolytes. NFAT5-null mice suffer severe embryonic and perinatal lethality, and surviving adults manifest growth defects, pronounced renal atrophy and lymphocyte dysfunction associated with ineffective responses to hypertonicity. To circumvent the lethality of these mice and study the function of NFAT5 in specific cell types without the possible side effects of generalized defects in the organism, we have produced conditional knockout mice that allow the deletion of NFAT5 in specific cell types. Here we have investigated the hypertonic stress response in wild-type and NFAT5-/- lymphocytes. Proliferating lymphocytes exposed to hypertonic conditions exhibited an early, NFAT5- independent, genotoxic stress-like response with induction of p53, p21 and GADD45, downregulation of cyclins E1, A2 and B1 mRNA, and arrest in S and G2/M. This was followed by an NFAT5-dependent adaptive phase in wild-type cells, which induced osmoprotective gene products, downregulated stress markers, and resumed cyclin expression and cell cycle progression. NFAT5-/- cells, however, failed to induce osmoprotective genes and though they downregulated genotoxic stress markers, they displayed defective cell cycle progression associated with reduced expression of cyclins E1, A2, B1, and aurora B kinase. Finally, T cell receptor-induced expression of cyclins, aurora B kinase, and cell cycle progression were inhibited in NFAT5-/- lymphocytes exposed to hypertonicity levels in the range reported in plasma in patients and animal models of osmoregulatory disorders. Our results support the conclusion that the activation of an osmoprotective gene expression program by NFAT5 enables cells to proliferate under hypertonic stress conditions by maintaining the expression of S and G2/M cyclins and cell cycle progression.

Enterolignans (enterodiol and enterolactone) exhibit structural similarity to estradiol and have therefore been hypothesized to modulate hormone related cancers such as breast cancer. The bioactivation of the plant lignan secoisolariciresinol diglucoside (SDG) requires the transformation by intestinal bacteria including the deglycosylation of SDG to secoisolariciresinol (SECO) followed by demethylation and dehydroxylation of SECO to enterodiol (ED). Finally, ED is dehydrogenated to enterolactone (EL). It is unclear whether the bacterial activation of SDG to ED and EL is crucial for the cancer preventing effects of dietary lignans. The possible protective effect of bacterial lignan transformation on a 7,12 dimethylbenz(a)anthracene (DMBA)-induced breast cancer in gnotobiotic rats was investigated. Germ-free rats were associated with a defined lignan-converting consortium (Clostridium saccharogumia, Blautia producta, Eggerthella lenta, and Lactonifactor longoviformis). The rats colonized with lignan-converting bacteria consortium (LCC) were fed a lignan-rich flaxseed diet and breast cancer was chemical induced. Identically treated germ-free rats served as control. All bacteria of the consortium successfully colonized the intestine of the LCC rats. The plant lignan SDG was converted into the enterolignans ED and EL in the LCC rats but not in the germ-free rats. This transformation did not influence cancer incidence but significantly decreased tumor numbers per tumor-bearing rat, and tumor size. Cell proliferation was significantly inhibited and apoptosis was significantly induced in LCC rats. No differences between LCC and control rats were observed in the expression of the genes encoding the estrogen receptors (ERα and ERβ) and G-coupled protein receptor 30 (GPR30). Similar findings were observed for both insulin-like growth factor 1 (IGF-1) and epidermal growth factor receptor (EGFR) genes involved in tumor growth. Proteome analysis revealed that 24 proteins were differentially expressed in tumor tissue from LCC and germ-free. RanBP-type and C3HC4-type zinc finger-containing protein 1 (RBCK1) and poly(rC)-binding protein 1 (PBCP1) were down-regulated by 3.2- and 2.0-fold, respectively. These proteins are associated with cell proliferation. The activity of selected enzymes involved in the degradation of oxidants in plasma and liver was significantly increased in the LCC rats. However, plasma and liver concentrations of reduced glutathione (non-enzymatic antioxidant) and malondialdehyde (oxidative stress marker) did not differ between the groups. In conclusion, the bacterial conversion of plant lignan to enterolignans beneficially influences their anti-cancer effect. However, the mechanisms involved in these effects remain elusive. / Enterolignanen (Enterodiol ED und Enterolacton EL) wird aufgrund ihrer strukturellen Ähnlichkeit zu Estradiol ein modulierender Einfluss auf hormonell bedingte Krebserkrankungen wie Brustkrebs nachgesagt. Das pflanzliche Lignan Secoisolariciresinoldiglucosid (SDG) wird durch Darmbakterien zum Enterolignan aktiviert. Dies erfolgt über dessen Deglykosylierung zu Secoisolariciresinol (SECO) gefolgt durch die Demethylierung und die Dehydroxylierung zu Enterodiol (ED). Schließlich wird ED zu Enterolacton (EL) dehydrogeniert. Es ist allerdings noch nicht bewiesen, dass die bakterielle Aktivierung von SDG zu ED und EL für die antikanzerogenen Wirkungen verantwortlich ist, die für dieses in der menschlichen Ernährung vorkommende Lignan beschrieben wurden. Um dies zu klären, wurde der Einfluss der bakteriellen Lignan-Transformation auf die Protektion gegenüber einem durch 7,12-Dimethylbenz(a)anthracen (DMBA)-induzierten Brustkrebs im gnotobiotischen Rattenmodell untersucht. Keimfreie Ratten wurden hierfür mit einem Konsortium aus vier Bakterienstämmen (Clostridium saccharogumia, Blautia producta, Eggerthella lenta, und Lactonifactor longoviformis) besiedelt, das die Umsetzung von SDG zu ED und EL katalysiert (LCC-Ratten). Ratten, die über den gesamten Versuchszeitraum keimfrei blieben, dienten als Kontrolle. Die Tiere wurden über 16 Wochen mit einer Leinsamen-Diät gefüttert, die reich an pflanzlichen Lignanen war. Während der Fütterung wurde bei allen Tieren Brustkrebs chemisch induziert. Das pflanzliche Lignan SDG wurde nur in den LCC Ratten zu den Enterolignanen ED und EL umgewandelt. Keimfreie Ratten zeigten keine Transformation von SDG. Die bakterielle Transformation von SDG hatte zwar keinen Einfluss auf die Inzidenz von Brustkrebs, jedoch verringerten sich durch die Besiedlung der Ratten mit SDG-transformierenden Bakterien die Anzahl von Tumoren pro tumortragender Ratte und die Tumorgröße deutlich. Zudem wurde die Zellproliferation in den LCC-Ratten deutlich gehemmt und die Apoptose induziert. Unterschiede in der Genexpression der Östrogenrezeptoren (ERα und ERß) und G-Protein-gekoppelte Rezeptoren (GPR30) wurden zwischen den LCC-Ratten und den Kontrolltieren nicht beobachtet. Ebenso verhielt es sich für die Gene des Insulinähnliche Wachstumsfaktoren 1 (IGF-1) und Epidermale Wachstumsfaktor rezeptoren (EGFR), welche in das Tumorwachstum involviert sind. Die Analyse des Proteoms des Tumorgewebes ergab 24 differentiell exprimierte Proteine zwischen keimfreien und LCC-Ratten. So wurden zum Beispiel die Proteine RanBP-type and C3HC4-type zinc finger-containing protein 1 (RBCK1) und poly(rC)-binding protein 1 (PBCP1), die mit der Zellproliferation assoziiert sind, in LCC-Ratten um das 3,2 bzw. 2,0-fache herunterreguliert. Die Aktivität ausgewählter antioxidativer Enzyme in Plasma und Leber war in den LCC-Ratten im Vergleich zu den keimfreien Tieren deutlich erhöht. Allerdings unterschieden sich die Konzentrationen von reduziertem Glutathion (nichtenzymatisches Antioxidans) und Malondialdehyd (oxidativer Stress-Marker) in Plasma und Leber nicht zwischen den beiden Besiedlungs-Gruppen. Zusammenfassend zeigen die Ergebnisse, dass die bakterielle Umwandlung von pflanzlichen Lignanen zu Enterolignanen deren antikanzerogene Wirkung entscheidend beeinflusst. Allerdings bleiben die zugrunde liegenden Mechanismen weiterhin ungeklärt.

The trend for designing of a titanium implant explored using different chemical compositions and crystallinity materials until people realized that the implant surface character was another important factor affecting the rate and extent of osseointegartion. Titanium received a macroporous titania surface layer by anodization, which contains open pores with average pore diameter around 5μm. An additional mesoporous titania top layer was created that followed the contour of the macropores and having 100–200 nm thickness and a pore diameter of 10 nm. Thus, a coherent laminar titania surface layer was obtained producing a hierarchical macro- and mesoporous surface. The interfacial bonding between the surface layers and the titanium matrix was characterized by a scratch test that confirmed a stable and strong bonding of the laminar titania surface layers upon titanium. The wettability to water and the effects on the osteosarcoma cell line (SaOS-2) proliferation and mineralization of the formed titania surface layers were studied systematically by cell culture and scanning electron microscopy (SEM). A synergistic role of the hierarchical macro- and mesoporosities was revealed in terms of enhancing cell adhesion, proliferation and mineralization, when compared with the titania surface with solo porosity scale topography. For the in vivo results of the evaluation of osseointegration, an argon ion beam polishing technique was applied to prepare the cross sections of implants feasible for the high resolution SEM investigation. The interfacial microstructure between newly formed bone and implants with four modified surfaces including the new hierarchical macro- and mesoporous implant surface retrieved after in vivo tests were characterized. By this approach it has become possible to directly observe early bone formation, the increase of bone density, and the evolution of bone structure. The two bone growth mechanisms, distant osteogenesis and contact osteogenesis, can also be distinguished. These direct observations give, at microscopic level, a better view of osseointegration and explain the functional mechanisms of various implant surfaces for osseointegration. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: In press. Paper 4: Manuscript.</p>

No description available.