Tissue Engineering and Regenerative Medicine Therapies for Cell Senescence in Bone and Cartilage.

The bone repair and substitute have been developed for decades with the bone defect repair applied successfully in clinical. However, implant complications may occur in more challenging situations, bone cell senescence and osteoporosis (OP). Due to certain microenvironment conditions, including hormonal, nutritional, and aging factors, the bone cell responses are regulated to alteration and end into cell senescence and OP.

Calcium-Infiltrated Biphasic Hydroxyapatite Scaffolds for Human Hematopoietic Stem Cell Culture.

Long-term in vitro expansion of hematopoietic stem cells (HSCs), while maintaining their functionality and multilineage differentiation potential, is still challenging. In this study, three-dimensional (3D) high-porosity hydroxyapatite (HA) foams have been designed to closely mimic the chemistry and physical structure of cancellous bone. Furthermore, calcium oxide was distributed in the HA ceramics to provide surface calcium ion release, hypothesizing that a local surface calcium gradient supports HSC localization and maintenance.

Effect of Calcium-Infiltrated Hydroxyapatite Scaffolds on the Hematopoietic Fate of Human Umbilical Vein Endothelial Cells.

Foamed hydroxyapatite offers a three-dimensional scaffold for the development of bone constructs, mimicking perfectly the in vivo bone structure. In vivo, calcium release at the surface is assumed to provide a locally increased gradient supporting the maintenance of the hematopoietic stem cells niche. We fabricated hydroxyapatite scaffolds with high surface calcium concentration by infiltration, and used human umbilical vein endothelial cells (HUVECs) as a model to study the effects on hematopoietic lineage direction.

A microstructural study of the degradation and calcium release from hydroxyapatite-calcium oxide ceramics made by infiltration.

Hydroxyapatite pellets, partially densified in a low-temperature heat treatment, were infiltrated with calcium nitrate solution followed by in-situ precipitation of Ca(OH) and CaCO. The infiltrated bodies were then densified to high relative density and the calcium carbonate transformed to calcium oxide during sintering and resulted in biphasic hydroxyapatite-CaO ceramics. This work investigated the influence of the infiltration on surface morphology, weight change, and microstructural-level degradation caused by exposure to saline at pH=7.

Open-Porous Hydroxyapatite Scaffolds for Three-Dimensional Culture of Human Adult Liver Cells.

Liver cell culture within three-dimensional structures provides an improved culture system for various applications in basic research, pharmacological screening, and implantable or extracorporeal liver support. Biodegradable calcium-based scaffolds in such systems could enhance liver cell functionality by providing endothelial and hepatic cell support through locally elevated calcium levels, increased surface area for cell attachment, and allowing three-dimensional tissue restructuring. Open-porous hydroxyapatite scaffolds were fabricated and seeded with primary adult human liver cells, which were embedded within or without gels of extracellular matrix protein collagen-1 or hyaluronan.

A method for rapid quantitative assessment of biofilms with biomolecular staining and image analysis.

The accumulation of bacteria in surface-attached biofilms can be detrimental to human health, dental hygiene, and many industrial processes. Natural biofilms are soft and often transparent, and they have heterogeneous biological composition and structure over micro- and macroscales. As a result, it is challenging to quantify the spatial distribution and overall intensity of biofilms.

Induction of Hepatic and Endothelial Differentiation by Perfusion in a Three-Dimensional Cell Culture Model of Human Fetal Liver.

The development of functional engineered tissue constructs depends on high cell densities and appropriate vascularization. In this study we implemented a four-compartment three-dimensional perfusion bioreactor culture model for studying the effects of medium perfusion on endothelial, hepatic, and hematopoietic cell populations of primary human fetal liver in an in vivo-like environment. Human fetal liver cells were cultured in bioreactors configured to provide either perfusion or diffusion conditions.

Long-term three-dimensional perfusion culture of human adult bone marrow mononuclear cells in bioreactors.

The construction and long-term maintenance of three-dimensional in vitro bone marrow models is of great interest but still quite challenging. Here we describe the use of a multi-compartment hollow-fiber membrane based three-dimensional perfusion bioreactor for long-term culture of whole human bone marrow mononuclear cells. We also investigated bioreactors with incorporated open-porous foamed hydroxyapatite scaffolds, mimicking the in vivo bone matrix.

Mutation of environmental mycobacteria to resist silver nanoparticles also confers resistance to a common antibiotic.

Non-tuberculous mycobacteria are a threat to human health, gaining entry to the body through contaminated water systems, where they form persistent biofilms despite extensive attempts at disinfection. Silver is a natural antibacterial agent and in nanoparticle form activity is increased by a high surface area. Silver nanoparticles (AgNPs) have been used as alternative disinfectants in circulating water systems, washing machines and even clothing.

Antimycobacterial efficacy of silver nanoparticles as deposited on porous membrane filters.

Environmental mycobacteria pose a significant health burden. Non-tuberculous mycobacteria infections have been traced to water treatment networks, where mycobacterial biofilms are ubiquitous. Filters that remove potential pathogens have significant medical applications.