A Combined Computational and Experimental Analysis of PLA and PCL Hybrid Nanocomposites 3D Printed Scaffolds for Bone Regeneration.

A combined computational and experimental study of 3D-printed scaffolds made from hybrid nanocomposite materials for potential applications in bone tissue engineering is presented. Polycaprolactone (PCL) and polylactic acid (PLA), enhanced with chitosan (CS) and multiwalled carbon nanotubes (MWCNTs), were investigated in respect of their mechanical characteristics and responses in fluidic environments. A novel scaffold geometry was designed, considering the requirements of cellular proliferation and mechanical properties.

Adhesion strength and anti-tumor agents regulate vinculin of breast cancer cells.

The onset and progression of cancer are strongly associated with the dissipation of adhesion forces between cancer cells, thus facilitating their incessant attachment and detachment from the extracellular matrix (ECM) to move toward metastasis. During this process, cancer cells undergo mechanical stresses and respond to these stresses with membrane deformation while inducing protrusions to invade the surrounding tissues. Cellular response to mechanical forces is inherently related to the reorganization of the cytoskeleton, the dissipation of cell-cell junctions, and the adhesion to the surrounding ECM.

The Role of Substrate Topography and Stiffness on MSC Cells Functions: Key Material Properties for Biomimetic Bone Tissue Engineering.

The hypothesis of the present research is that by altering the substrate topography and/or stiffness to make it biomimetic, we can modulate cells behavior. Substrates with similar surface chemistry and varying stiffnesses and topographies were prepared. Bulk PCL and CNTs-reinforced PCL composites were manufactured by solvent casting method and electrospinning and further processed to obtain tunable moduli of elasticity in the range of few MPa.

Engineering Breast Cancer Cells and hUMSCs Microenvironment in 2D and 3D Scaffolds: A Mechanical Study Approach of Stem Cells in Anticancer Therapy.

Cell biomechanics plays a major role as a promising biomarker for early cancer diagnosis and prognosis. In the present study, alterations in modulus of elasticity, cell membrane roughness, and migratory potential of MCF-7 (ER+) and SKBR-3 (HER2+) cancer cells were elucidated prior to and post treatment with conditioned medium from human umbilical mesenchymal stem cells (hUMSCs-CM) during static and dynamic cell culture. Moreover, the therapeutic potency of hUMSCs-CM on cancer cell's viability, migratory potential, and F-actin quantified intensity was addressed in 2D surfaces and 3D scaffolds.

Recent Advancements in 3D Printing and Bioprinting Methods for Cardiovascular Tissue Engineering.

Recent decades have seen a plethora of regenerating new tissues in order to treat a multitude of cardiovascular diseases. Autografts, xenografts and bioengineered extracellular matrices have been employed in this endeavor. However, current limitations of xenografts and exogenous scaffolds to acquire sustainable cell viability, anti-inflammatory and non-cytotoxic effects with anti-thrombogenic properties underline the requirement for alternative bioengineered scaffolds.

Gradient 3D Printed PLA Scaffolds on Biomedical Titanium: Mechanical Evaluation and Biocompatibility.

The goal of the present investigation was to find a solution to crucial engineering aspects related to the elaboration of multi-layered tissue-biomimicking composites. 3D printing technology was used to manufacture single-layered and gradient multi-layered 3D porous scaffolds made of poly-lactic acid (PLA). The scaffolds manufacturing process was optimized after adjusting key printing parameters.

Combined Optimized Effect of a Highly Self-Organized Nanosubstrate and an Electric Field on Osteoblast Bone Cells Activity.

The effect of an electric field within specific intensity limits on the activity of human cells has been previously investigated. However, there are a considerable number of factors that influence the in vitro development of cell populations. In biocompatibility studies, the nature of the substrate and its topography are decisive in osteoblasts bone cells development.

Apolipoprotein A-1 regulates osteoblast and lipoblast precursor cells in mice.

Imbalances in lipid metabolism affect bone homeostasis, altering bone mass and quality. A link between bone mass and high-density lipoprotein (HDL) has been proposed. Indeed, it has been recently shown that absence of the HDL receptor scavenger receptor class B type I (SR-B1) causes dense bone mediated by increased adrenocorticotropic hormone (ACTH).

Multiwalled carbon nanotubes enhance human bone marrow mesenchymal stem cells' spreading but delay their proliferation in the direction of differentiation acceleration.

Investigating the ability of films of pristine (purified, without any functionalization) multiwalled carbon nanotubes (MWCNTs) to influence human bone marrow mesenchymal stem cells' (hBMSCs) proliferation, morphology, and differentiation into osteoblasts, we concluded to the following: A. MWCNTs delay the proliferation of hBMSCs but increase their differentiation. The enhancement of the differentiation markers could be a result of decreased proliferation and maturation of the extracellular matrix B.

MWCNTs enhance hBMSCs spreading but delay their proliferation in the direction of differentiation acceleration.

Investigating the ability of films of pristine multiwalled nanotubes (MWCNTs) to influence human mesenchymal stem cells' proliferation, morphology, and differentiation into osteoblasts, we concluded to the following: A. MWCNTs delay the proliferation of hBMS cells but increase their differentiation. The enhancement of the differentiation markers could be a result of decreased proliferation and maturation of the extracellular matrix B.

Cellular function and adhesion mechanisms of human bone marrow mesenchymal stem cells on multi-walled carbon nanotubes.

Multiwalled carbon nanotubes (MWCNTs) are considered to be excellent reinforcements for biorelated applications, but, before being incorporated into biomedical devices, their biocompatibility need to be investigated thoroughly. We investigated the ability of films of pristine MWCNTs to influence human mesenchymal stem cells' proliferation, morphology, and differentiation into osteoblasts. Moreover, the selective integrin subunit expression and the adhesion mechanism to the substrate were evaluated on the basis of adherent cell number and adhesion strength, following the treatment of cells with blocking antibodies to a series of integrin subunits.

On the biocompatibility between TiO2 nanotubes layer and human osteoblasts.

Titanium and its alloys are the most popular biomaterials replacing hard tissues in implant surgeries. Clinicians are generally pleased by titanium mechanical properties and non-toxicity performances; on the other hand, there have been reported several cases of titanium implantation failure, phenomenon explained sometimes as "non adherence of human tissue to the metallic surface." Yet, researchers reported that titanium surfaces are favorable for osteoblasts adhesion.

Detachment strength of human osteoblasts cultured on hydroxyapatite with various surface roughness. Contribution of integrin subunits.

Hydroxyapatite (HA) has been widely used as a bone substitute in dental, maxillofacial and orthopaedic surgery and as osteoconductive bone substitute or precoating of pedicle screws and cages in spine surgery. The aim of the present study was to investigate the osteoblastic adhesion strength on HA substrata with different surface topography and biochemistry (pre-adsorption of fibronectin) after blocking of specific integrin subunits with monoclonal antibodies. Stoichiometric HA was prepared by precipitation followed by ageing and characterized by SEM, EDX, powder XRD, Raman spectroscopy, TGA, and specific surface area analysis.

Biomechanical and structural changes following the decellularization of bovine pericardial tissues for use as a tissue engineering scaffold.

To achieve natural scaffolds for tissue engineering applications we decellularized bovine pericardial (BP) tissues according to two different protocols: a novel treatment based on Triton(®) X-100 (12 h, 4 °C) (BP1) and a trypsin/EDTA treatment (37 °C, 48 h) (BP2). Results were compared with commercially available acellular xenogeneic biomaterials, Veritas(®) and Collamed(®). Biomechanical characteristics, high (E(h)) and low (E(l)) modulus of elasticity, of the fresh untreated tissue varied with the anatomical direction (apex to base (T) to transverse (L)) (mean ± SDEV): (41.

Estimation of hydrodynamic shear stresses developed on human osteoblasts cultured on Ti-6Al-4V and strained by four point bending. Effects of mechanical loading to specific gene expression.

The aim of the present investigation was to study the effects of mechanical strain on the orthopedic biomaterial Ti-6Al-4V-osteoblast interface, using an in vitro model. Homogeneous strain was applied to Human Bone Marrow derived Osteoblasts (HBMDOs) cultured on Ti-6Al-4V, at levels which are considered physiological, by a four-point bending mechanostimulatory system. A simple model for the estimation of maximum hydrodynamic shear stresses developed on cell culture layer and induced by nutrient medium flow during mechanical loading, as a function of the geometry of the culture plate and the load characteristics, is proposed.

Effects of physiological mechanical strains on the release of growth factors and the expression of differentiation marker genes in human osteoblasts growing on Ti-6Al-4V.

Mechanical loading factors at the bone-implant interface are critical for the osseointegration and clinical success of the implant. The aim of the present investigation was to study the effects of mechanical strain on the orthopedic biomaterial Ti-6Al-4V/osteoblast interface, using an in vitro model. Homogeneous strain was applied to human bone marrow derived osteoblasts (HBMDOs) cultured on Ti-6Al-4V, at physiological levels (strain magnitudes 500 microstrain (microepsilon) and 1000 microepsilon, at frequencies of load application 0.

Biomechanical comparison of callus over a locked intramedullary nail in various segmental bone defects in a sheep model.

Background: Little has been written about the size of a bone defect that can be restored with one-stage lengthening over a reamed intramedullary nail.

Material/methods: Sixteen adult female sheep were divided into four main groups: a simple osteotomy group (group I) and three segmental defect groups (1-, 2-, and 3-cm gaps, groups II-IV). One intact left tibia from each group was also used as the non-osteotomized intact control group (group V).

Biomechanical evaluation of conventional internal contemporary spinal fixation techniques used for stabilization of complete sacroiliac joint separation: a 3-dimensional unilaterally isolated experimental stiffness study.

Study Design: Comparative 3-dimensional biomechanical testing.

Objective: To compare 5 fixation techniques, 3 using screws or screw and plates and 2 spinal, used for stabilization of complete unilateral sacroiliac dislocation in composite models.

Summary Of Background Data: Harrington compression rods have been used for posterior iliosacral stabilization.

Experimental usage of hydroxyapatite preadsorption with fibronectin to increase permanent stability and longevity of spinal implants.

Unlabelled: Hydroxyapatite has been used in orthopaedic and particularly in spinal surgery by precoating implants to indirectly increase osteoblasts' adhesion and subsequently their stability and longevity. Fibronectin preadsorption synergistically with appropriately constructed hydroxyapatite's surface texture to enhance osteoblasts' adhesion has not been, to the authors' knowledge, previously investigated. In osteoporotic spines, methods to increase implant stability (pedicle screws and cages) are of major value.

Fibronectin preadsorbed on hydroxyapatite together with rough surface structure increases osteoblasts' adhesion "in vitro": the theoretical usefulness of fibronectin preadsorption on hydroxyapatite to increase permanent stability and longevity in spine implants.

Objective: The aim of this study was to investigate the contribution of fibronectin (FN) preadsorption to enhance osteoblast adhesion and strength on hydroxyapatite (HA) used either as osteoconductive bone substitute or precoating of pedicle screws and cages in spine surgery.

Methods: HA substrata with two different surface roughness values (rough HA180 and smooth HA1200) were produced, and human osteoblasts were seeded after culturing on them. Prior to osteoblast seeding, the HA substrata were immersed in FN solution.

Role of surface roughness of titanium versus hydroxyapatite on human bone marrow cells response.

This study was designed to assess human bone marrow cell response and particularly cell adhesion, proliferation, and differentiation, when cultured in vitro on titanium alloy and hydroxyapatite with different values of surface roughness. A further aim was to compare the cell response on the two materials, currently used in spinal surgery. Cell adhesion was determined after 0.

Comparative strength measurements of five different fixation systems applied on an in vitro model of femoral midshaft osteotomy.

Oblique midshaft fractures of long bones can be stabilized using either plates and screws, lag screws, wires, cerclages, or a combination of these methods. Fractures at the distal tip of a well-fixed femoral prosthesis are difficult to stabilize with plates and screws because of the underlying intramedullary stem, polymethylmetacrylate (PMMA) cement, and thin periprosthetic femoral cortex. In this study we compared in vitro the mechanical performance of five different osteosynthesis techniques applied on an oak femoral model obliquely oscillated to mimic a short oblique fracture: (a) Double stainless steel wiring; (b) two 4.