Tensile mechanical properties of collagen type I and its enzymatic crosslinks.

Collagen type I crosslink type and prevalence can be influenced by age, tissue type, and health; however, the role that crosslink chemical structure plays in mechanical behavior is not clear. Molecular dynamics simulations of ~65-nm-long microfibril units were used to predict how difunctional (deH-HLNL and HLKNL) and trifunctional (HHL and PYD) crosslinks respond to mechanical deformation. Low- and high-strain stress-strain regions were observed, corresponding to crosslink alignment.

Fiber/collagen composites for ligament tissue engineering: influence of elastic moduli of sparse aligned fibers on mesenchymal stem cells.

Electrospun microfibers are attractive for the engineering of oriented tissues because they present instructive topographic and mechanical cues to cells. However, high-density microfiber networks are too cell-impermeable for most tissue applications. Alternatively, the distribution of sparse microfibers within a three-dimensional hydrogel could present instructive cues to guide cell organization while not inhibiting cell behavior.

Relationship between maximum isometric joint moment and functional task performance in patients with brachial plexus injury: A pilot study.

We evaluated whether subjects with brachial plexus injury (BPI) adapted their movements to reduce the mechanical demand on their impaired upper extremity. In 6 subjects with unilateral BPI with C5 and C6 involvement, we measured bilateral maximum isometric shoulder and elbow strength, and computed joint kinematics and net muscle-generated joint moments during 7 unimanual functional tasks. Compared to the unimpaired extremity, maximum strength in shoulder abduction, extension, and external rotation was 60% (p=0.

Multi-walled nanotubes for cellular reprogramming of cancer.

Unlabelled: Triple negative breast cancer is exceptionally difficult to treat due to the lack of distinguishing biomarkers for drug targeting. An alternative approach based on recent data indicates that these cells may be more susceptible to mechanical influences, such as alterations in the tumor stroma. Three dimensional collagen gels containing co-cultures of mesenchymal cells and MDA-MB-231 cancer cells were utilized to explore the effects of multi-walled nanotubes (MWNT) on cell contraction, invasion, viability, MMP-9 expression, and migration of breast cancer cells.

Bioengineered Human Pyloric Sphincters Using Autologous Smooth Muscle and Neural Progenitor Cells.

Gastroparesis leads to inadequate emptying of the stomach resulting in severe negative health impacts. Appropriate long-term treatments for these diseases may require pyloric sphincter tissue replacements that possess functional smooth muscle cell (SMC) and neural components. This study aims to bioengineer, for the first time, innervated human pylorus constructs utilizing autologous human pyloric sphincter SMCs and human neural progenitor cells (NPCs).

Is bioengineering a possibility in gastrointestinal disorders?

The gastrointestinal (GI) tract is responsible for conducting multiple functions including motility, digestion and absorption. In gastrointestinal disorders, some of those functions are weakened or lost. Excision of the diseased segment of the GI tract is a common treatment; however, patients suffer from complications and low quality of life.

Quantitative Analysis of Three-Dimensional Distribution and Clustering of Intramuscular Fat in Muscles of the Rotator Cuff.

The purpose of this study was to (1) develop and present a technique to quantitatively assess three-dimensional distribution and clustering of intramuscular fat and (2) use the technique to compare spatial characteristics of intramuscular fat in rotator cuff muscles of older adults with and without a supraspinatus tear. Moran's Index (I), an existing quantitative measure of clustering, was extended for use with MRI to allow comparisons across individuals with different size muscles. Sixteen older adults (>60 years) with (N = 6) and without (N = 10) a degenerative supraspinatus tear participated.

Development of Chitosan Scaffolds with Enhanced Mechanical Properties for Intestinal Tissue Engineering Applications.

Massive resections of segments of the gastrointestinal (GI) tract lead to intestinal discontinuity. Functional tubular replacements are needed. Different scaffolds were designed for intestinal tissue engineering application.

Bioengineering functional human sphincteric and non-sphincteric gastrointestinal smooth muscle constructs.

Digestion and motility of luminal content through the gastrointestinal (GI) tract are achieved by cooperation between distinct cell types. Much of the 3 dimensional (3D) in vitro modeling used to study the GI physiology and disease focus solely on epithelial cells and not smooth muscle cells (SMCs). SMCs of the gut function either to propel and mix luminal contents (phasic; non-sphincteric) or to act as barriers to prevent the movement of luminal materials (tonic; sphincteric).

Ethical considerations in tissue engineering research: Case studies in translation.

Tissue engineering research is a complex process that requires investigators to focus on the relationship between their research and anticipated gains in both knowledge and treatment improvements. The ethical considerations arising from tissue engineering research are similarly complex when addressing the translational progression from bench to bedside, and investigators in the field of tissue engineering act as moral agents at each step of their research along the translational pathway, from early benchwork and preclinical studies to clinical research. This review highlights the ethical considerations and challenges at each stage of research, by comparing issues surrounding two translational tissue engineering technologies: the bioartificial pancreas and a tissue engineered skeletal muscle construct.

Biomechanical Basis of Shoulder Osseous Deformity and Contracture in a Rat Model of Brachial Plexus Birth Palsy.

Background: The purpose of this study was to investigate the relative contributions of two proposed mechanisms, strength imbalance and impaired longitudinal muscle growth, to osseous and postural deformity in a rat model of brachial plexus birth palsy (BPBP).

Methods: Thirty-two Sprague-Dawley rat pups were divided into four groups on the basis of surgical interventions to induce a strength imbalance, impaired growth, both a strength imbalance and impaired growth (a combined mechanism), and a sham condition in the left forelimb. Maximum passive external shoulder rotation angle (ERmax) was measured bilaterally at four and eight weeks postoperatively.

Successful implantation of an engineered tubular neuromuscular tissue composed of human cells and chitosan scaffold.

Background: There is an urgent need for gut lengthening secondary to massive resections of the gastrointestinal tract. In this study, we propose to evaluate the remodeling, vascularization, and functionality of a chitosan-based, tubular neuromuscular tissue on subcutaneous implantation in the back of athymic rats.

Methods: Aligned innervated smooth muscle sheets were bioengineered with the use of human smooth muscle and neural progenitor cells.

Age-related structural changes in upper extremity muscle tissue in a nonhuman primate model.

Background: Longitudinal studies of upper extremity aging in humans include logistical concerns that animal models can overcome. The vervet is a promising species with which to study aging-related processes. However, age-related changes in upper extremity muscle structure have not been quantified in this species.

Design strategies of biodegradable scaffolds for tissue regeneration.

There are numerous available biodegradable materials that can be used as scaffolds in regenerative medicine. Currently, there is a huge emphasis on the designing phase of the scaffolds. Materials can be designed to have different properties in order to match the specific application.

Damage to dorsolateral prefrontal cortex affects tradeoffs between honesty and self-interest.

Substantial correlational evidence suggests that prefrontal regions are critical to honest and dishonest behavior, but causal evidence specifying the nature of this involvement remains absent. We found that lesions of the human dorsolateral prefrontal cortex (DLPFC) decreased the effect of honesty concerns on behavior in economic games that pit honesty motives against self-interest, but did not affect decisions when honesty concerns were absent. These results point to a causal role for DLPFC in honest behavior.

The influence of extracellular matrix composition on the differentiation of neuronal subtypes in tissue engineered innervated intestinal smooth muscle sheets.

Differentiation of enteric neural stem cells into several appropriate neural phenotypes is crucial while considering transplantation as a cellular therapy to treat enteric neuropathies. We describe the formation of tissue engineered innervated sheets, where intestinal smooth muscle and enteric neuronal progenitor cells are brought into close association in extracellular matrix (ECM) based microenvironments. Uniaxial alignment of constituent smooth muscle cells was achieved by substrate microtopography.

Selective detection and quantification of modified DNA with solid-state nanopores.

We demonstrate a solid-state nanopore assay for the unambiguous discrimination and quantification of modified DNA. Individual streptavidin proteins are employed as high-affinity tags for DNA containing a single biotin moiety. We establish that the rate of translocation events corresponds directly to relative concentration of protein-DNA complexes and use the selectivity of our approach to quantify modified oligonucleotides from among a background of unmodified DNA in solution.

The effects of strength and power training on single-step balance recovery in older adults: a preliminary study.

Improving muscle strength and power may mitigate the effects of sarcopenia, but it is unknown if this improves an older adult's ability to recover from a large postural perturbation. Forward tripping is prevalent in older adults and lateral falls are important due to risk of hip fracture. We used a forward and a lateral single-step balance recovery task to examine the effects of strength training (ST) or power (PT) training on single-step balance recovery in older adults.

Tissue engineering in the gut: developments in neuromusculature.

The complexity of the gastrointestinal (GI) tract lies in its anatomy as well as in its physiology. Several different cell types populate the GI tract, adding to the complexity of cell sourcing for regenerative medicine. Each cell layer has a specialized function in mediating digestion, absorption, secretion, motility, and excretion.

In vivo skeletal muscle biocompatibility of composite, coaxial electrospun, and microfibrous scaffolds.

One weakness with currently researched skeletal muscle tissue replacement is the lack of contraction and relaxation during the regenerative process. A biocompatible scaffold that can act similar to the muscle would be a pivotal innovation. Coaxial electrospun scaffolds, capable of movement with electrical stimulation, were created using poly(ɛ-caprolactone) (PCL), multiwalled carbon nanotubes (MWCNT), and a (83/17 or 40/60) poly(acrylic acid)/poly(vinyl alcohol) (PAA/PVA) hydrogel.

Development, calibration, and validation of a head-neck complex of THOR mod kit finite element model.

Introduction/objective: In an effort to continually improve upon the design of the test device for human occupant restraint (THOR) dummy, a series of modifications have recently been applied. The first objective of this study was to update the THOR head-neck finite element (FE) model to the specifications of the latest dummy modifications. The second objective was to develop and apply a new optimization-based methodology to calibrate the FE head-neck model based on experimental test data.

Computational sensitivity analysis to identify muscles that can mechanically contribute to shoulder deformity following brachial plexus birth palsy.

Purpose: Two mechanisms, strength imbalance or impaired longitudinal muscle growth, potentially cause osseous and postural shoulder deformity in children with brachial plexus birth palsy. Our objective was to determine which muscles, via either deformity mechanism, were mechanically capable of producing forces that could promote shoulder deformity.

Methods: In an upper limb computational musculoskeletal model, we simulated strength imbalance by allowing each muscle crossing the shoulder to produce 30% of its maximum force.

Neo-innervation of a bioengineered intestinal smooth muscle construct around chitosan scaffold.

Neuromuscular disorders of the gut result in disturbances in gastrointestinal transit. The objective of this study was to evaluate the neo-innervation of smooth muscle in an attempt to restore lost innervation. We have previously shown the potential use of composite chitosan scaffolds as support for intestinal smooth muscle constructs.

Mechanical recruitment of N- and C-crosslinks in collagen type I.

Collagen type I is an extracellular matrix protein found in connective tissues such as tendon, ligament, bone, skin, and the cornea of the eyes, where it functions to provide tensile strength; it also serves as a scaffold for cells and other extracellular matrix components. A single collagen type I molecule is composed of three amino acid chains that form a triple helix for most of the molecule's length; non-triple-helical extensions called N- and C-telopeptides are located at the amino/N-terminal and carboxy/C-terminal ends of the molecule, respectively. In two of the three chains, the C-telopeptide has been reported to possess a hair-pin/hook conformation, while the three N-telopeptides display a more extended structure.

Quantitation of Complexed versus Free Polymers in Interpolyelectrolyte Polyplex Formulations.

The quantity of free polymer in a polymer/DNA complex (polyplex) formulation critically impacts its gene transfection efficiency, cellular uptake, and toxicity. In this study, the compositions of three interpolyelectrolyte polyplex formulations were quantified by a facile NMR method. Using careful integration of a 1D H NMR spectrum with a broad spectral width, the quantities of unbound polymer and polyplexes in solution were determined.