Articular cartilage lining joints, such as in the knee, functions to reduce friction and absorb shock. Collagen type II is the largest constituent in the extracellular matrix of articular cartilage and its restoration is of the highest interest to tissue engineers. Cartilage has little ability to naturally regenerate due to the absence of vascularity and the inability of the chondrocytes to proliferate at a high rate. It would be ideal to create a mimicking extracellular matrix/scaffold from type II collagen that could possibly be used to replace damaged articular cartilage that has the same function and morphology. Three different groups of cartilage chips were utilized to extract type II collagen. The yield of the three groups was compared. The extracted type II collagen from the three groups was electrospun at the concentrations of 0.06, 0.08, 0.10 and 0.12 g/mL. Both the pore size and fiber diameter were analyzed. A SDS-Page was performed on the material to assure it was pure type II collagen and that no collagen type I contamination was present.

Chronic respiratory diseases affects many people worldwide with little known about the mechanisms diving the pathology, making it difficult to find a cure. Improving the understanding of smooth muscle and extracellular matrix (ECM) interaction is key to developing a remedy to this leading cause of death. With currently no relevant or controllable in vivo or in vitro model to investigate diseased and normal interactions of small airway components, the development of a physiologically relevant in vitro model with comparable cell attachment, signaling, and organization is necessary to develop new treatments for airway disease. The goal of this study is to create a mechanically, biologically and structurally relevant in vitro model of small airway smooth muscle tissue. Synthetic Poly-L-Lactic Acid (PLLA) and decellularized pig lung ECM (DPLECM) were electrospun to form nanofibrous mats that can closely mimic natural bronchial tissue. The addition of DPLECM significantly changed the PLLA scaffold mechanically, biologically, and physically to bring it closer to the characteristics of the human lung. DPLECM scaffolds exhibited a significant decrease in the elastic modulus compared with PLLA alone. Histological staining and SDS-PAGE showed that after scaffold fabrication, essential proteins or protein fragments in natural ECM are still present after processing. Human bronchial smooth muscle cells (HBSMCs) seeded onto PLECM scaffolds formed multiple layers of cells compared to scaffolds composed solely of PLLA. Phenotype of smooth muscle is better maintained when DPLECM is incorporated into the scaffold shown by enhanced contractile protein expression and increased collagen production for normal smooth muscle remodeling of the scaffold. In summary, this research demonstrates that a PLLA/DPLECM composite electrospun mat is a promising tool to produce an in vitro model with the potential to uncover unknown characteristics of bronchiole smooth muscle behavior in diseased or normal states.

Aneurismas e dissecções da aorta ascendente são caracterizados por degradação das fibras elásticas e de colágeno e diminuição de células musculares lisas, predominantemente em áreas mucóides, as quais são relacionadas ao acúmulo de glicosaminoglicanos ou proteoglicanos. Tendo em vistas tais alterações, estudamos a topologia das metaloproteases nestas doenças. Cortes de 5?m de aortas, fixadas em fomol e embebidas em parafina, foram submetidos a reações imuno-histoquímicas para MMP-3 (estromelisina), MMP-7 (matrilisina) e plasminogênio/plasmina na camada média. Em paralelo, cortes de aortas foram submetidos a coloração pela hematoxilina e eosina e azul de Alcian (para material mucóide). Aortas de 8 pacientes com aneurisma de aorta torácica e 10 com dissecções agudas foram analisadas. Adicionalmente, 9 aortas normais foram estudadas como controle. Em todos os casos, MMP-3 e, mais expressivamente, MMP-7 apresentaram marcação dentro dos acúmulos mucóides. Em contrapartida, a marcação para plasmina/plasminogênio situou-se ao redor deles. Fora dessas áreas, a MMP-3 mostrou distribuição intra e extracelular, a MMP-7 apresentou marcação intra e extracelular predominante na segunda metade da túnica média, e plasmina/plasminogênio teve co-localização com células musculares lisas. Considerando que matrilisina e estromelisina atuam sobre os proteoglicanos e sobre outros componentes da matriz extracelular, estas enzimas poderiam estar envolvidas diretamente na gênese dos aneurismas e dissecções da aorta ascendente, com possível modulação por plasminogênio/plasmina / In dissections and non-inflammatory aneurysms of the ascending aorta there is an increase in mucoid (proteoglycan) deposition. We analyzed by immunoperoxidase the distribution of stromelysin (MMP-7), matrilysin (MMP-3) and plasminogen/plasmin, enzymes that act on proteoglycans, in sections of human aortas with these diseases and in controls. In cases with any of these diseases MMP-7 and MMP-3 were accumulated in the areas of mucoid degeneration, and plasmin around them. Such enzymes could thus be involved in these diseases. We also evaluated by morphometry the amount of collagen in the two halves of the aortic media.

A matriz extracelular do endométrio (ECM) é constituída por moléculas secretadas que compõem o microambiente celular e são ativadas ou suprimidas principalmente pelos hormônios esteróides ovarianos, estradiol (E2) e progesterona (P4) durante o ciclo estral. A identificação de genes envolvidos no remodelamento e receptividade pode levar à descoberta de importantes processos biológicos ligados ao sucesso gestacional. Os objetivos foram: 1. identificar a relação de diferentes tamanhos de folículos pré-ovulatórios (FPO) e corpo lúteo (CL) e de seus respectivos hormônios E2 e P4 com a expressão endometrial de genes associados com o remodelamento da ECM durante o período de pré-implantação; e 2. analisar a relação entre a expressão gênica de determinados componentes da ECM avaliada no dia 6 após inseminação artificial (IA) com sucesso gestacional. Para tal, dois experimentos foram realizados. No experimento 1, estudo 1 e estudo 2, 42 e 74 vacas Nelore (Bos indicus) adultas, respectivamente foram sincronizadas obtendo-se ao final dois grupos com distintos tamanhos FPO e CL consequentemente, distintas concentrações de E2 no proestro e P4 no diestro. Os grupos foram: Folículo Grande-CL Grande (FG-CLG; estudo 1, n=20; estudo 2, n=35) e Folículo Pequeno-CL Pequeno (FP-CLP; estudo 1, n=22; estudo 2, n=39). Amostras de tecido endometrial foram coletadas por biópsia no D0 (estro) e pós-mortem no D4 (estudo 1) e D7 (estudo 2). Concentrações de E2 e P4 foram mensuradas por radioimunoensaio (RIA) obtendo- se menores concentrações no grupo FP-CLP. No experimento 2, vacas adultas, Nelore (Bos indicus; n=33) foram sincronizadas utilizando um protocolo a base de prostaglandina F 2α (PGF2α) e observação de estro. As vacas foram inseminadas artificialmente (IA) e seis dias após, uma biópsia endometrial coletada. O diagnóstico de gestação foi realizado após 30 dias por meio de ultrasonografia (US) e então as vacas foram divididas em grupo Prenhe e Não- Prenhe (P e NP) para análise retrospectiva. Abundância de transcritos foi avaliada por sequenciamento (RNAseq) assim como qPCR em amostras de ambos experimentos. Realizaram-se também exames histológicos em amostras do D4 e D7 (estudo 2) para avaliação de colágeno total assim como espessura de fibras colágenas. Resultados determinaram uma maior abundância de transcritos relacionados ao remodelamento de MEC, em destaque TGFβ, MMPs, TIMPs e colágenos em vacas pertencentes aos grupos NP e FP-CLP. O mesmo foi observado para abundância de colágeno. No entanto, não observou-se diferença na relação entre fibras grossas e finas entre os tratamentos. Análises de correlação e regressão indicaram que folículos pré-ovulatórios de maior tamanho geram CL maiores e assim maiores concentrações de P4, a qual está negativamente associada à abundância de colágenos. Assim, de acordo com resultados aqui descritos, assume-se que a alteração da homeostase da MEC devido ao incremento na abundância de colágeno pode ser prejudicial à gestação em bovinos. / The endometrial extracellular matrix (ECM) é build up of secretory molecules that make up the cellular microenvironment and suffer activation or suppression mainly by the ovarian steroid hormones, estradiol (E2) and progesterone (P4) during the estrous cycle. The identification of genes involved in endometrial remodeling and receptivity may reveal important biological processes linked to gestational success. The objectives were: 1. identify the relationship among preovulatory follicle (POF) size and corpus luteum (CL) and its respective hormones, E2 and P4 on the endometrial expression of genes related to extracellular matrix remodeling during the pre-implantation period; and 2. analyze the relationship between endometrial ECM gene expression evaluated on day 6 post artificial insemination (AI) with pregnancy outcome. For such, two experiments were carried on. On experiment 1, study 1 and study 2, 42 and 74, respectively, adult Nelore (Bos indicus) cows were synchronized aiming to manipulate the peri-ovulatory endocrine environment, obtaining at the end of the protocol, two groups with distinct pre-ovulatory follicle (POF) and corpus luteum (CL) sizes, leading to groups with distinct E2 and P4 concentrations. The groups were: Large Follicle/CL (LF/CL; study 1, n=20, study 2, n=35) and Small Follicle/Cl (SF/CL; study 1, n=22; study 2, n=39). Endometrial samples were collected by biopsy on D0 (Estrus) and post-mortem on D4 and on study 2 post-mortem on D7. P4 and E2 concentrations were measured by RIA with a significative difference between the groups, being lower hormonal concentrations in the SF- SCL group and higher concentrations in the LF-LCL group . In experiment 2, adult Nelore (Bos indicus) cows (n=33) were synchronized using a prostaglandin 2α (PGF2α) and heat detection based protocol. The cows were AI and six days after an endometrial biopsy was collected. Pregnancy diagnosis was performed on day 30 by ultrasound (US) examination and cows were divided into pregnant and non-pregnant (P vs. NP) groups for a retrospective analysis. Histology was performed on D4 and D7 samples for total collagen abundance as well as fiber thickness. Correlation and regression analysis indicate that larger preovulatory follicles as well as higher P4 concentrations have a negative effect on collagen content. RNA- Seq analysis and confirmation by qPRC was performed on selected samples from experiment 1, study 2 and experiment 2. Comparison of mRNA levels of ECM components samples revealed higher levels of transcripts envolved in ECM remodeling, highlighting TGFβ MMPs, TIMPs and collagens in NP cows when compared with P cows as well as in the SF- SCL compared to the LF-LCL group. The same was observed for collagen abundance. However, there was no difference between thin and thick collagen fibers between treatments. Correlation and regression analysis indicate that larger POF lead to larger CL and hence, higher P4 concentrations, which has a negative effects on collagen abundance. Therefore, according to the results presented here, we can imply that an alteration in ECM homeostasis due to increased collagen abundance may be harmful to pregnancy in cows.

The tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors of the matrix metalloproteinases (MMPs). Since unregulated MMP activities are linked to arthritis, cancer, and atherosclerosis, TIMP variants that are selective inhibitors of disease-related MMPs have potential therapeutic value. The structures of TIMP/MMP complexes reveal that most interactions with the MMP involve the N-terminal region of TIMP and the C-D B-strand connector which occupy the primed (right side of the active site) and unprimed (left side) regions of the active site. Substitutions for Thr2 of N-TIMP- 1 strongly influence MMP selectivity. In this study we found that Arg and Gly, which generally reduce MMP affinity, have less effect on binding to MMP-9. When the Arg mutation is added to the NTIMP-1 mutant with AB loop of TIMP-2, it produced a gelatinase-specific inhibitor with Ki values of 2.8 and 0.4 nM for MMP-2 and MMP-9, respectively. The Gly mutant has a Ki of 2.1 nM for MMP-9 and > 40 uM for MMP-2, indicating that engineered TIMPs can discriminate between MMPs in the same subfamily. In collaboration with Dr. Yingnan Zhang at Genentech, we have developed a protocol for the phage display of full-length human TIMP-2 to identify high-affinity selective inhibitors of human MMP-1, a protease that plays a role in cleaving extracellular matrix (ECM) components, connective tissue remodeling during development, angiogenesis, and apoptosis. We have generated a library containing 2x1010 variants of TIMP-2 randomized at residues 2-6 (L1), at residues 34-40 (L2) and 67-70 (L3). / The L1 library yielded a positive signal for MMP-1 binding. Clones from the L1 library, designated TM1, TM8, TM13, and TM14, were isolated after 5 rounds of selection on immobilized MMP-1 and MMP-3 and found to show a greater selectivity for MMP-1 relative to MMP-3. TM8, which has Ser2 to Asp and Ser4 to Ala substitutions, showed the greatest apparent selectivity of 10-fold toward MMP-1 compared to MMP-3. The various mutations identified by phage display were introduced into recombinant Nterminal TIMP-2 and the variants characterized as inhibitors of an array of MMP catalytic domains. The TM8-based mutant showed pronounced selectivity (> 1000-fold for MMP-1 vs. MMP-3) and may be a step towards the generation of MMP-1-specific inhibitors. Molecular modeling was used to rationalize the structural basis of MMP selectivity in the mutants. / by Harinathachari Bahudhanapati. / Thesis (Ph.D.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

The 23 matrix metalloproteinases (MMPs) in humans catalyze the turnover of all protein components of the extracellular matrix (ECM) and have important roles in tissue remodeling, wound healing, embryo implantation, cell migration and shedding of cell surface proteins. Excess MMP activities are associated with many diseases including arthritis, heart disease and cancer. The activities of MMPs are regulated by a family of four protein inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), that are endogenous inhibitors of matrix metalloproteinases (MMPs), ADAMs (A Disintegrin And Metalloproteinase) and ADAMTS (disintegrin-metalloproteinase with thrombospmdin motifs) .... The balance between TIMPs and active metzinicins is very important and imbalances are linked to human diseases such as arthritis, cancer, and atherosclerosis. The engineering of TIMPs to produce specific inhibitors of individual MPs could provide new therapeutic principles for disease treatment, but this requires a detailed understanding of the biophysical and structural basis of the interactions of TIMPs and MMPs and ADAMs. / by Wu Ying. / Thesis (Ph.D.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

Matrix metalloproteinases (MMPs) constitute the major class of enzymes capable of degrading all protein components of extracellular matrix (ECM) and have important roles in normal physiologic processes of maintaining tissue integrity and remodeling. However, excess MMP activities are associated with many diseases including rheumatoid arthritis and osteoarthritis, cardiomyopathy, and macular degeneration. The activity of MMPs is regulated by their endogenous protein inhibitors, the tissue inhibitors of metalloproteinases (TIMPs) which are avid broad-spectrum inhibitors of numerous human matrixins (MMPs and ADAMs). Uncontrolled matrix degradation occurs when the balance between TIMPs and MMPs is disrupted, resulting in serious diseases such as cancer, arthritis and chronic tissue ulcers. Thus, the engineering of TIMPs to produce highly selective and efficacious inhibitors of individual MMPs may be utilized for future treatment of diseases. Such engineering requires detailed analysis for the structural and biophysical information of MMP-TIMP interaction. Changes in the dynamics of proteins and solvent that accompany their associations with different binding partners, influence the specificity of binding through entropic effects. From the current studies it appears that the interactions of the inhibitory domains of TIMPs-1 and -2 (N-TIMPs) with MT1-MMP are driven by entropy increases that are partitioned between solvent and conformational entropy (ΔSsolv and ΔSconf), and a large conformational entropy penalty is responsible for the weak inhibition of MT1-MMP by NT1.We investigated how mutations that modify N-TIMP selectivity affect the thermodynamics of interactions with MMP1, MMP3 and MT1-MMP. The weak inhibition of MT1-MMP by N-TIMP-1 is enhanced by mutation of threonine 98, on the edge of the binding ridge, to leucine. This mutation increases the large ΔSconf cost for binding to MT1-MMP but this is offset by a greater increase in ΔSsolv. In contrast, this mutation enhances binding to MMP3 by increasing ΔSconf for the interaction. ΔSsolv and ΔSconf show mutual compensation for all interactions, with characteristic ranges for each MMP. Distinct electrostatic and dynamic features of MMPs are key factors in their selective inhibition. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

While the genetic control of ureteric bud (UB) morphogenesis has been extensively studied, the cellular basis of this process remains unclear. The renal organoid system is a novel technique in which embryonic kidneys are dissociated into single cells and then reaggregated, where they reassociate to form organotypic structures. This system may be very beneficial for investigating the cellular basis of ureteric bud development. Here, we first used a fluorescent UB marker, Hoxb7:myrVenus, and time-lapse microscopy to characterize the cellular and tissue-level events during self-organization and UB morphogenesis of E12.5 or E14.5 renal organoids. Briefly, we found that UB structures self-assembled by aggregation of individual cells that sent out long cell processes. The cellular aggregates grew and elongated into epithelial tubes that displayed characteristic ampullae, bifurcated, and appropriately expressed UB tip markers analogous to their in vivo counterparts. We also found that cap mesenchymal cells are attracted to newly formed epithelial structures early in renal organoid development, and were later found in cell clusters surrounding new branches. RET is a trans-membrane tyrosine kinase receptor (RTK), expressed in ureteric bud cells, whose expression is gradually restricted to the tips of the growing ureteric tree. We demonstrate that the renal organoid system can be used, as an alternative to the generation of in vivo chimeric embryos, to study Ret-dependent cell rearrangements previously shown to establish and maintain the UB tip progenitor domain. Chimeric renal organoids that juxtaposed wild-type cells with Sprouty1–/– mutant cells (higher Ret-signaling) or with Ret51/cre (lower Ret-signaling) mutant cells recapitulated the cell sorting pattern observed in similar in vivo chimeras. The cells with higher Ret-signaling preferentially sorted to, and were maintained in, the forming and growing tips of these mosaic ureteric bud structures, out-competing cells with lower Ret-signaling. We then used the mosaic organoid system to ask if fibroblast growth factor receptor 2 (Fgfr2), another RTK expressed in the ureteric bud and important for its development, also mediates individual cell rearrangements that generate and maintain the UB tips. UB cells null for Fgfr2 were largely unable to compete with wild-type cells for occupancy of the UB tips in chimeric renal organoids. Using the innovative MASTR (Mosaic Mutant Analysis with Spatial and Temporal Control of Recombination) technique in vivo, mosaic homozygous deletion of Fgfr2 in newly formed ureteric buds also revealed that mutant cells were slightly deficient in their ability to contribute to Fgfr2 heterozygous UB tips. This demonstrates a novel, cell-autonomous role of Fgfr2 in ureteric bud development. Matrix metalloproteinase 14 (MMP14) is a membrane-bound protein known to participate in a wide variety of cell functions including degradation of the extracellular matrix (ECM), cell signaling, and cell-autonomous cell migration. It is expressed in the UB and was discovered to act downstream of Ret-signaling. Although needed in the ureteric epithelium for ECM degradation and proper UB morphogenesis, its specific function in the UB has not been thoroughly investigated. In generating in vivo chimeras, we discovered that Mmp14 null cells could contribute to wild-type ureteric bud tips at E12.5 and E14.5, demonstrating that, despite its documented role in UB branching, Mmp14 does not have a cell-autonomous role in the cell rearrangements observed during UB morphogenesis.

The aim of this thesis is to evaluate the role of the extracellular environment in regulating breast cancer cell morphological and invasive characteristics. In vitro experiments of breast cancer cell lines in three dimensional matrices, which afford control over variables of interest while maintaining physiological relevance, were utilized for this purpose. We evaluated the sensitivity of cell morphology to the dimensionality, biochemistry, and mechanical properties of the extracellular environment as well as the reciprocal effects cells display when remodeling the extracellular environment during invasion. Chapter 1 introduces background material on breast cancer development, classification systems, and in vitro methods of research. Chapter 2 describes protocols for cell care and experiments used in these studies. In chapter 3, we explore the role of fibrillar collagen I environments in breast cancer cell invasion. This was motivated by previous research that has associated high breast tissue density with breast cancer risk and poor prognosis as well as tissue stiffness with cancer cell aggressiveness. Breast cancer cells were found to regain an invasive phenotype in sterically constrained environments when the extracellular matrix included a fibrillar component. In chapter 4, the relationship between cell morphology and invasive behavior in various dimensional contexts was assessed. Anecdotal evidence has shown stellate morphology may be associated with epithelial to mesenchymal transition and invasive capacity in cancer cells. Differences in the dimensionality and biochemistry of the environment resulted in changes to cell aggregate morphology. Although morphology did not predict invasive capacity as measured by spheroid invasion in collagen I, invasion was found to correlate with cancer-related gene expression profiling, suggesting the ability of cancer cells to utilize more than one mode of invasion. Chapter 5 explores to what degree the presence of invasive cells can give rise to invasive behavior from noninvasive cells. Segregation of cell subtypes during co-culture spheroid formation was found to be altered in the presence of BME. When implanted into collagen gels, invasive cell lines that generate structural changes to the extracellular matrix on their own were able to confer invasive behavior to otherwise noninvasive cell lines in some cases. Chapter 6 summarizes these findings and suggests further studies. Appendix 1 lists useful abbreviations. In Appendices 2 and 3, codes for ImageJ and Matlab-based analyses are recorded. Through this work, we see how cell morphology and invasive capacity are influenced by the extracellular environment. Cells that can interact with components of the extracellular matrix through matrix-specific integrins show a range of capacities for remodeling the extracellular environment, which in turn plays a role in invasive capacity. We anticipate that enhanced understanding of the role of the extracellular environment in regulating cell morphology and invasive behavior will lead to advances in the study of cell locomotion as well as in cancer research, diagnosis, and treatment.

A matriz extracelular do endométrio (ECM) é constituída por moléculas secretadas que compõem o microambiente celular e são ativadas ou suprimidas principalmente pelos hormônios esteróides ovarianos, estradiol (E2) e progesterona (P4) durante o ciclo estral. A identificação de genes envolvidos no remodelamento e receptividade pode levar à descoberta de importantes processos biológicos ligados ao sucesso gestacional. Os objetivos foram: 1. identificar a relação de diferentes tamanhos de folículos pré-ovulatórios (FPO) e corpo lúteo (CL) e de seus respectivos hormônios E2 e P4 com a expressão endometrial de genes associados com o remodelamento da ECM durante o período de pré-implantação; e 2. analisar a relação entre a expressão gênica de determinados componentes da ECM avaliada no dia 6 após inseminação artificial (IA) com sucesso gestacional. Para tal, dois experimentos foram realizados. No experimento 1, estudo 1 e estudo 2, 42 e 74 vacas Nelore (Bos indicus) adultas, respectivamente foram sincronizadas obtendo-se ao final dois grupos com distintos tamanhos FPO e CL consequentemente, distintas concentrações de E2 no proestro e P4 no diestro. Os grupos foram: Folículo Grande-CL Grande (FG-CLG; estudo 1, n=20; estudo 2, n=35) e Folículo Pequeno-CL Pequeno (FP-CLP; estudo 1, n=22; estudo 2, n=39). Amostras de tecido endometrial foram coletadas por biópsia no D0 (estro) e pós-mortem no D4 (estudo 1) e D7 (estudo 2). Concentrações de E2 e P4 foram mensuradas por radioimunoensaio (RIA) obtendo- se menores concentrações no grupo FP-CLP. No experimento 2, vacas adultas, Nelore (Bos indicus; n=33) foram sincronizadas utilizando um protocolo a base de prostaglandina F 2α (PGF2α) e observação de estro. As vacas foram inseminadas artificialmente (IA) e seis dias após, uma biópsia endometrial coletada. O diagnóstico de gestação foi realizado após 30 dias por meio de ultrasonografia (US) e então as vacas foram divididas em grupo Prenhe e Não- Prenhe (P e NP) para análise retrospectiva. Abundância de transcritos foi avaliada por sequenciamento (RNAseq) assim como qPCR em amostras de ambos experimentos. Realizaram-se também exames histológicos em amostras do D4 e D7 (estudo 2) para avaliação de colágeno total assim como espessura de fibras colágenas. Resultados determinaram uma maior abundância de transcritos relacionados ao remodelamento de MEC, em destaque TGFβ, MMPs, TIMPs e colágenos em vacas pertencentes aos grupos NP e FP-CLP. O mesmo foi observado para abundância de colágeno. No entanto, não observou-se diferença na relação entre fibras grossas e finas entre os tratamentos. Análises de correlação e regressão indicaram que folículos pré-ovulatórios de maior tamanho geram CL maiores e assim maiores concentrações de P4, a qual está negativamente associada à abundância de colágenos. Assim, de acordo com resultados aqui descritos, assume-se que a alteração da homeostase da MEC devido ao incremento na abundância de colágeno pode ser prejudicial à gestação em bovinos. / The endometrial extracellular matrix (ECM) é build up of secretory molecules that make up the cellular microenvironment and suffer activation or suppression mainly by the ovarian steroid hormones, estradiol (E2) and progesterone (P4) during the estrous cycle. The identification of genes involved in endometrial remodeling and receptivity may reveal important biological processes linked to gestational success. The objectives were: 1. identify the relationship among preovulatory follicle (POF) size and corpus luteum (CL) and its respective hormones, E2 and P4 on the endometrial expression of genes related to extracellular matrix remodeling during the pre-implantation period; and 2. analyze the relationship between endometrial ECM gene expression evaluated on day 6 post artificial insemination (AI) with pregnancy outcome. For such, two experiments were carried on. On experiment 1, study 1 and study 2, 42 and 74, respectively, adult Nelore (Bos indicus) cows were synchronized aiming to manipulate the peri-ovulatory endocrine environment, obtaining at the end of the protocol, two groups with distinct pre-ovulatory follicle (POF) and corpus luteum (CL) sizes, leading to groups with distinct E2 and P4 concentrations. The groups were: Large Follicle/CL (LF/CL; study 1, n=20, study 2, n=35) and Small Follicle/Cl (SF/CL; study 1, n=22; study 2, n=39). Endometrial samples were collected by biopsy on D0 (Estrus) and post-mortem on D4 and on study 2 post-mortem on D7. P4 and E2 concentrations were measured by RIA with a significative difference between the groups, being lower hormonal concentrations in the SF- SCL group and higher concentrations in the LF-LCL group . In experiment 2, adult Nelore (Bos indicus) cows (n=33) were synchronized using a prostaglandin 2α (PGF2α) and heat detection based protocol. The cows were AI and six days after an endometrial biopsy was collected. Pregnancy diagnosis was performed on day 30 by ultrasound (US) examination and cows were divided into pregnant and non-pregnant (P vs. NP) groups for a retrospective analysis. Histology was performed on D4 and D7 samples for total collagen abundance as well as fiber thickness. Correlation and regression analysis indicate that larger preovulatory follicles as well as higher P4 concentrations have a negative effect on collagen content. RNA- Seq analysis and confirmation by qPRC was performed on selected samples from experiment 1, study 2 and experiment 2. Comparison of mRNA levels of ECM components samples revealed higher levels of transcripts envolved in ECM remodeling, highlighting TGFβ MMPs, TIMPs and collagens in NP cows when compared with P cows as well as in the SF- SCL compared to the LF-LCL group. The same was observed for collagen abundance. However, there was no difference between thin and thick collagen fibers between treatments. Correlation and regression analysis indicate that larger POF lead to larger CL and hence, higher P4 concentrations, which has a negative effects on collagen abundance. Therefore, according to the results presented here, we can imply that an alteration in ECM homeostasis due to increased collagen abundance may be harmful to pregnancy in cows.