Rat Adipose Tissue-Derived Stem Cells Transplantation Attenuates Cardiac Dysfunction Post Infarction and Biopolymers Enhance Cell Retention

Background: Cardiac cell transplantation is compromised by low cell retention and poor graft viability. Here, the effects of co-injecting adipose tissue-derived stem cells (ASCs) with biopolymers on cell cardiac retention, ventricular morphometry and performance were evaluated in a rat model of myocardial infarction (MI). Methodology/Principal Findings: (99m)Tc-labeled ASCs (1 x 10(6) cells) isolated from isogenic Lewis rats were injected 24 hours post-MI using fibrin a, collagen (ASC/C), or culture medium (ASC/M) as vehicle, and cell body distribution was assessed 24 hours later by gamma-emission counting of harvested organs. ASC/F and ASC/C groups retained significantly more cells in the myocardium than ASC/M (13.8+/-2.0 and 26.8+/-2.4% vs. 4.8+/-0.7%, respectively). Then, morphometric and direct cardiac functional parameters were evaluated 4 weeks post-MI cell injection. Left ventricle (LV) perimeter and percentage of interstitial collagen in the spare myocardium were significantly attenuated in all ASC-treated groups compared to the non-treated (NT) and control groups (culture medium, fibrin, or collagen alone). Direct hemodynamic assessment under pharmacological stress showed that stroke volume (SV) and left ventricle end-diastolic pressure were preserved in ASC-treated groups regardless of the vehicle used to deliver ASCs. Stroke work (SW), a global index of cardiac function, improved in ASC/M while it normalized when biopolymers were co-injected with ASCs. A positive correlation was observed between cardiac ASCs retention and preservation of SV and improvement in SW post-MI under hemodynamic stress. Conclusions: We provided direct evidence that intramyocardial injection of ASCs mitigates the negative cardiac remodeling and preserves ventricular function post-MI in rats and these beneficial effects can be further enhanced by administrating co-injection of ASCs with biopolymers.

A collagen-poly(lactic acid-co-ɛ-caprolactone) hybrid scaffold for bladder tissue regeneration.

Scaffold materials should favor cell attachment and proliferation, and provide designable 3D structures with appropriate mechanical strength. Collagen matrices have proven to be beneficial scaffolds for tissue regeneration. However, apart from small intestinal submucosa, they offer a limited mechanical strength even if crosslinking can enhance their mechanical properties. A more cell-friendly way to increase material strength is to combine synthetic polymer meshes with plastic compressed collagen gels. This work describes the potential of plastic compressed collagen-poly(lactic acid-co-ɛ-caprolactone) (PLAC) hybrids as scaffolds for bladder tissue regeneration. Human bladder smooth muscle and urothelial cells were cultured on and inside collagen-PLAC hybrids in vitro. Scaffolds were analyzed by electron microscopy, histology, immunohistochemistry, and AlamarBlue assay. Both cell types proliferated in and on the hybrid, forming dense cell layers on top after two weeks. Furthermore, hybrids were implanted subcutaneously in the backs of nude mice. Host cell infiltration, scaffold degradation, and the presence of the seeded bladder cells were analyzed. Hybrids showed a lower inflammatory reaction in vivo than PLAC meshes alone, and first signs of polymer degradation were visible at six months. Collagen-PLAC hybrids have potential for bladder tissue regeneration, as they show efficient cell seeding, proliferation, and good mechanical properties.

Tumor cell budding and laminin-5 expression in colorectal carcinoma can be modulated by the tissue micro-environment.

Expression of laminin-5 alpha3, beta3 and gamma2 protein subunits was investigated in colorectal adenocarcinomas using immunostaining and confocal microscopy. The laminin-5 heterotrimer was found in basement membranes and as extracellular deposits in tumor stroma. In contrast to the alpha3 subunit, which was under-expressed, the gamma2 and beta3 subunits were detected in the cytoplasm of carcinoma cells dissociating (budding) from neoplastic tubules, suggestive of focal alterations in laminin-5 assembly and secretion. Laminin-5 gamma2 or beta3 subunit-reactive budding carcinoma cells expressed cytokeratins but not vimentin; they did not proliferate and were not apoptotic. Furthermore, expression of laminin-5 gamma2 and beta3 subunits in budding cells was associated with focal under-expression of the E-cadherin-beta-catenin complex. Results from xenograft experiments showed that budding activity in colorectal adenocarcinomas could be suppressed when these tumors grew at ectopic s.c. sites in nude mice. In vitro, cultured colon carcinoma cells, but not adenoma-derived tumor cells, shared the laminin-5 phenotype expressed by carcinoma cells in vivo. Using colon carcinoma cell lines implanted orthotopically and invading the cecum of nude mice, the laminin-5-associated budding was restored, indicating that this phenotype is not only determined by tumor cell properties but also dependent on the tissue micro-environment. Our results indicate that both laminin-5 alpha3 subunit expression and cell-cell cohesiveness are altered in budding carcinoma cells, which we consider to be actively invading. We propose that the local tissue micro-environment contributes to these events.

Macroporous Scaffolds for Bone Engineering. Studies on Cell Culture and Ectopic Bone Formation

Bone engineering is a rapidly developing area of reconstructive medicine where bone inducing factors and/or cells are combined with a scaffold material to regenerate the structure and function of the original tissue. The aim of this study was to compare the suitability of different macroporous scaffold types for bone engineering applications. The two scaffold categories studied were a) the mechanically strong and stable titanium fiber meshes and b) the elastic and biodegradable porous polymers. Furthermore, bioactive modifications were applied to these basic scaffold types, and their effect on the osteogenic responses was evaluated in cell culture and ectopic bone formation studies. The osteogenic phenotype of cultured cell-scaffold constructs was heightened with a sol-gel derived titania coating, but not with a mixed titania-silica coating. The latter coating also resulted in delayed ectopic bone formation in bone marrow stromal cell seeded scaffolds. However, the better bone contact in early implantation times and more even bone tissue distribution at later times indicated enhanced osteoconductivity of both the coated scaffold types. Overall, the most promising bone engineering results were obtained with titania coated fiber meshes. Elastic and biodegradable poly(ε-caprolactone/D,L-lactide) based scaffolds were also developed in this study. The degradation rates of the scaffolds in vitro were governed by the hydrophilicity of the polymer matrix, and the porous architecture was controlled by the amount and type of porogen used. A continuous phase macroporosity was obtained using a novel CaCl2 • 6H2O porogen. Dynamic culture conditions increased cell invasion, but decreased cell numbers and osteogenicity, within the scaffolds. Osteogenic differentiation in static cultures and ectopic bone formation in cell seeded scaffolds were enhanced in composites, with 30 wt-% of bioactive glass filler.

Application of x-ray computed tomography in the evaluation of soil porosity in soil management systems

The study aimed to evaluate a methodology to quantify the porosity of the soil using computed tomography in areas under no-tillage, conventional tillage and native forest. Three soil management systems were selected for the study: forest, conventional tillage and no-tillage. In each soil management system, undisturbed soil samples were collected in the surface layer (0.0 to 0.10 m). The tomographic images were obtained using a X-ray microtomography. After obtaining the images, they were processed, and a methodology was evaluated for image conversion into numerical values. The statistical method which provided the greatest accuracy was the percentile method. The methodology used to analyze the tomographic image allowed quantifying the porosity of the soil under different soil management. The method enabled the characterization of soil porosity in a non-evasive and non-destructive way.

Verification of computed tomographic estimates of cochlear implant array position: A micro-CT and histological analysis

We examine the efficacy two volume spatial registration of pre and postoperative clinical computed tomography (CT) imaging to verify post-operative electrode array placement in cochlear implant (CI) patients. To measure the degree of accuracy with which the composite image predicts in-vivo placement of the array, we replicate the CI surgical process in cadaver heads. Pre-operative, post-operative, micro CT imaging and histology are utilized for verification.

Periodontal effects of rapid maxillary expansion with tooth-tissue-borne and tooth-borne expanders: A computed tomography evaluation

Introduction: The force delivered during rapid maxillary expansion (RME) produces areas of compression on the periodontal ligament of the supporting teeth. The resulting alveolar bone resorption can lead to unwanted tooth movement in the same direction. The purpose of this study was to evaluate periodontal changes by means of computed tomography after RME with tooth-tissue-borne and tooth-borne expanders. Methods: The sample comprised 8 girls, 11 to 14 years old, with Class I or II malocclusions with unilateral or bilateral posterior crossbites Four girls were treated with tooth-tissue-borne Haas-type expanders, and 4 were treated with tooth-borne Hyrax expanders. The appliances were activated up to the full 7-mm capacity of the expansion screw. Spiral CT scans were taken before expansion and after the 3-month retention period when the expander was removed. One-millimeter thick axial sections were exposed parallel to the palatal plane, comprising the dentoalveolar area and the base of the maxilla up to the inferior third of the nasal cavity. Multiplanar reconstruction was used to measure buccal and lingual bone plate thickness and buccal alveolar bone crest level by means of the computerized method. Results and Conclusions: RME reduced the buccal bone plate thickness of supporting teeth 0.6 to 0.9 mm and increased the lingual bone plate thickness 0.8 to 1.3 mm. The increase in lingual bone plate thickness of the maxillary posterior teeth was greater in the tooth-borne expansion group than in the tooth-tissue-borne group. RME induced bone dehiscences on the anchorage teeth's buccal aspect (7.1 ± 4.6 mm at the first premolars and 3.8 ± 4.4 mm at the mesiobuccal area of the first molars), especially in subjects with thinner buccal bone plates. The tooth-borne expander produced greater reduction of first premolar buccal alveolar bone crest level than did the tooth-tissue-borne expander. © 2006 American Association of Orthodontists.

Biocompatibility of a porous alumina ceramic scaffold coated with hydroxyapatite and bioglass

This study aimed to evaluate the osteointegration and genotoxic potential of a bioactive scaffold, composed of alumina and coated with hydroxyapatite and bioglass, after their implantation in tibias of rats. For this purpose, Wistar rats underwent surgery to induce a tibial bone defect, which was filled with the bioactive scaffolds. Histology analysis (descriptive and morphometry) of the bone tissue and the single-cell gel assay (comet) in multiple organs (blood, liver, and kidney) were used to reach this aim after a period of 30, 60, 90, and 180 days of material implantation. The main findings showed that the incorporation of hydroxyapatite and bioglass in the alumina scaffolds produced a suitable environment for bone ingrowth in the tibial defects and did not demonstrate any genotoxicity in the organs evaluated in all experimental periods. These results clearly indicate that the bioactive scaffolds used in this study present osteogenic potential and still exhibit local and systemic biocompatibility. These findings are promising once they convey important information about the behavior of this novel biomaterial in biological system and highlight its possible clinical application. © 2013 Wiley Periodicals, Inc.

Processamento, caracterização microestrutural e propriedades elásticas de metais celulares do sistema Ti-6Al-4V para fins de regeneração óssea

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Quantification of Biological Tissue and Construction of Patient Equivalent Phantom (Skull and Chest) for Infants (1-5 years old)

Our main purpose in this study was to quantify biological tissue in computed tomography (CT) examinations with the aim of developing a skull and a chest patient equivalent phantom (PEP), both specific to infants, aged between 1 and 5 years old. This type of phantom is widely used in the development of optimization procedures for radiographic techniques, especially in computed radiography (CR) systems. In order to classify and quantify the biological tissue, we used a computational algorithm developed in Matlab (R). The algorithm performed a histogram of each CT slice followed by a Gaussian fitting of each tissue type. The algorithm determined the mean thickness for the biological tissues (bone, soft, fat, and lung) and also converted them into the corresponding thicknesses of the simulator material (aluminum, PMMA, and air). We retrospectively analyzed 148 CT examinations of infant patients, 56 for skull exams and 92 were for chest. The results provided sufficient data to construct a phantom to simulate the infant chest and skull in the posterior anterior or anterior posterior (PA/AP) view. Both patient equivalent phantoms developed in this study can be used to assess physical variables such as noise power spectrum (NPS) and signal to noise ratio (SNR) or perform dosimetric control specific to pediatric protocols.

In vitro and in vivo biological behavior of CDHA/OCP/β-TCP scaffold

The biological behavior of a new bioactive material composed of calcium-deficient hydroxyapatite, octacalcium phosphate, and beta-tricalcium phosphate was investigated by in vitro indirect and direct cytotoxicity, cell adhesion and proliferation tests, and by in vivo subcutaneous and bone implantation in rats. The results of the in vitro studies showed that the material is biocompatible and no cytotoxic. Slightly poorer initial cell adhesion and lower cell proliferation than in control was observed, which were attributed to the reactivity and roughness of the material surface, In vivo results showed that the material is biodegradable and bioactive in bone tissue, but only biocompatible and partially biodegradable in soft tissue.

Study of Micro Rotary Ultrasonic Machining

Product miniaturization for applications in fields such as biotechnology, medical devices, aerospace, optics and communications has made the advancement of micromachining techniques essential. Machining of hard and brittle materials such as ceramics, glass and silicon is a formidable task. Rotary ultrasonic machining (RUM) is capable of machining these materials. RUM is a hybrid machining process which combines the mechanism of material removal of conventional grinding and ultrasonic machining. Downscaling of RUM for micro scale machining is essential to generate miniature features or parts from hard and brittle materials. The goal of this thesis is to conduct a feasibility study and to develop a knowledge base for micro rotary ultrasonic machining (MRUM). Positive outcome of the feasibility study led to a comprehensive investigation on the effect of process parameters. The effect of spindle speed, grit size, vibration amplitude, tool geometry, static load and coolant on the material removal rate (MRR) of MRUM was studied. In general, MRR was found to increase with increase in spindle speed, vibration amplitude and static load. MRR was also noted to depend upon the abrasive grit size and tool geometry. The behavior of the cutting forces was modeled using time series analysis. Being a vibration assisted machining process, heat generation in MRUM is low which is essential for bone machining. Capability of MRUM process for machining bone tissue was investigated. Finally, to estimate the MRR a predictive model was proposed. The experimental and the theoretical results exhibited a matching trend.