Mechanical Stimulation of Adipose-Derived Stromal/Stem Cells for Functional Tissue Engineering of the Musculoskeletal System via Cyclic Hydrostatic Pressure, Simulated Microgravity, and Cyclic Tensile Strain.

It is critical that human adipose-derived stromal/stem cell (hASC) tissue engineering therapies possess appropriate mechanical properties in order to restore the function of the load-bearing tissues of the musculoskeletal system. In an effort to elucidate hASC response to mechanical stimulation and develop mechanically robust tissue-engineered constructs, recent research has utilized a variety of mechanical loading paradigms, including cyclic tensile strain, cyclic hydrostatic pressure, and mechanical unloading in simulated microgravity. This chapter will describe the methods for applying these mechanical stimuli to hASC to direct differentiation for functional tissue engineering of the musculoskeletal system.

A biomechanical assessment of tissue-engineered polymer neo-uteri after orthotopic implantation.

Objective: To assess the in vivo biomechanical maturation of tissue-engineered neo-uteri that have previously supported live births in a rabbit model.

Design: Nonclinical animal study.

Setting: University-based research laboratory.

The evaluation of a multiphasic 3D-bioplotted scaffold seeded with adipose derived stem cells to repair osteochondral defects in a porcine model.

There is a need for the development of effective treatments for focal articular cartilage injuries. We previously developed a multiphasic 3D-bioplotted osteochondral scaffold design that can drive site-specific tissue formation when seeded with adipose-derived stem cells (ASC). The objective of this study was to evaluate this scaffold in a large animal model.

Developing Implantable Scaffolds to Enhance Neural Stem Cell Therapy for Post-Operative Glioblastoma.

Pre-clinical and clinical studies have shown that engineered tumoricidal neural stem cells (tNSCs) are a promising treatment strategy for the aggressive brain cancer glioblastoma (GBM). Yet, stabilizing human tNSCs within the surgical cavity following GBM resection is a significant challenge. As a critical step toward advancing engineered human NSC therapy for GBM, we used a preclinical variant of the clinically utilized NSC line HB1.

Investigation of multiphasic 3D-bioplotted scaffolds for site-specific chondrogenic and osteogenic differentiation of human adipose-derived stem cells for osteochondral tissue engineering applications.

Osteoarthritis is a degenerative joint disease that limits mobility of the affected joint due to the degradation of articular cartilage and subchondral bone. The limited regenerative capacity of cartilage presents significant challenges when attempting to repair or reverse the effects of cartilage degradation. Tissue engineered medical products are a promising alternative to treat osteochondral degeneration due to their potential to integrate into the patient's existing tissue.

LRP receptors in chondrocytes are modulated by simulated microgravity and cyclic hydrostatic pressure.

Mechanical loading is essential for the maintenance of musculoskeletal homeostasis. Cartilage has been demonstrated to be highly mechanoresponsive, but the mechanisms by which chondrocytes respond to mechanical stimuli are not clearly understood. The goal of the study was to determine how LRP4, LRP5, and LRP6 within canonical Wnt-signaling are regulated in simulated microgravity and cyclic hydrostatic pressure, and to investigate the potential role of LRP 4/5/6 in cartilage degeneration.

Primary Cilia Exhibit Mechanosensitivity to Cyclic Tensile Strain and Lineage-Dependent Expression in Adipose-Derived Stem Cells.

Non-motile primary cilia are dynamic cellular sensory structures and are expressed in adipose-derived stem cells (ASCs). We have previously shown that primary cilia are involved in chemically-induced osteogenic differentiation of human ASC (hASCs) in vitro. Further, we have reported that 10% cyclic tensile strain (1 Hz, 4 hours/day) enhances hASC osteogenesis.

Corin is a key regulator of endochondral ossification and bone development via modulation of vascular endothelial growth factor A expression.

Corin has been studied extensively within the vascular system and is known to regulate blood pressure. We have shown that corin is one of the most highly upregulated genes during osteogenic differentiation of human adipose-derived stem cells (hASCs). This study tested the hypothesis that, through modulation of angiogenic signalling pathways, corin is a critical regulator of osteogenic differentiation and endochondral ossification.

Industrial-scale fabrication of an osteogenic and antibacterial PLA/silver-loaded calcium phosphate composite with significantly reduced cytotoxicity.

In this study, we report an industrial-scale fabrication method of a multifunctional polymer composite as a scaffold material for bone tissue engineering. This study successfully demonstrated the potential of applying industrial polymer processing technologies to produce specially functionalized tissue engineering scaffolds. With the inclusion of a newly synthesized multifunctional additive, silver-doped-calcium phosphate (silver-CaP), the composite material exhibited excellent osteogenic inducibility of human adipose-derived stem cells (hASC) and satisfactory antibacterial efficacy against Escherichia coli and Staphylococcus aureus.

Evidence for Aryl hydrocarbon Receptor-Mediated Inhibition of Osteoblast Differentiation in Human Mesenchymal Stem Cells.

Multipotent mesenchymal stem cells (MSCs) maintain the ability to differentiate into adipogenic, chondrogenic, or osteogenic cell lineages. There is increasing concern that exposure to environmental agents such as aryl hydrocarbon receptor (AhR) ligands, may perturb the osteogenic pathways responsible for normal bone formation. The objective of the current study was to evaluate the potential of the prototypic AhR ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to disrupt osteogenic differentiation of human bone-derived MSCs (hBMSCs) in vitro.

Mechanical Stimulation of Adipose-Derived Stem Cells for Functional Tissue Engineering of the Musculoskeletal System via Cyclic Hydrostatic Pressure, Simulated Microgravity, and Cyclic Tensile Strain.

It is critical that human adipose stem cell (hASC) tissue-engineering therapies possess appropriate mechanical properties in order to restore function of the load bearing tissues of the musculoskeletal system. In an effort to elucidate the hASC response to mechanical stimulation and develop mechanically robust tissue engineered constructs, recent research has utilized a variety of mechanical loading paradigms including cyclic tensile strain, cyclic hydrostatic pressure, and mechanical unloading in simulated microgravity. This chapter describes methods for applying these mechanical stimuli to hASC to direct differentiation for functional tissue engineering of the musculoskeletal system.

Key developments that impacted the field of mechanobiology and mechanotransduction.

Advances in mechanobiology have evolved through insights from multiple disciplines including structural engineering, biomechanics, vascular biology, and orthopaedics. In this paper, we reviewed the impact of key reports related to the study of applied loads on tissues and cells and the resulting signal transduction pathways. We addressed how technology has helped advance the burgeoning field of mechanobiology (over 33,600 publications from 1970 to 2016).

Creation and Evaluation of New Porcine Model for Investigation of Treatments of Surgical Site Infection.

Surgical site infection (SSI) is the most common cause of surgical failure, increasing the risks of postoperative mortality and morbidity. Recently, it has been reported that the use of antimicrobial dressings at the incision site help with prevention of SSI. Despite the increased body of research on the development of different types of antimicrobial dressings for this application, to our knowledge, nobody has reported a reliable large animal model to evaluate the efficacy of developed materials in a preclinical SSI model.

High-Throughput Fabrication Method for Producing a Silver-Nanoparticles-Doped Nanoclay Polymer Composite with Novel Synergistic Antibacterial Effects at the Material Interface.

In this study, we report a high-throughput fabrication method at industrial pilot scale to produce a silver-nanoparticles-doped nanoclay-polylactic acid composite with a novel synergistic antibacterial effect. The obtained nanocomposite has a significantly lower affinity for bacterial adhesion, allowing the loading amount of silver nanoparticles to be tremendously reduced while maintaining satisfactory antibacterial efficacy at the material interface. This is a great advantage for many antibacterial applications in which cost is a consideration.

Fabrication and Evaluation of Electrospun, 3D-Bioplotted, and Combination of Electrospun/3D-Bioplotted Scaffolds for Tissue Engineering Applications.

Electrospun scaffolds provide a dense framework of nanofibers with pore sizes and fiber diameters that closely resemble the architecture of native extracellular matrix. However, it generates limited three-dimensional structures of relevant physiological thicknesses. 3D printing allows digitally controlled fabrication of three-dimensional single/multimaterial constructs with precisely ordered fiber and pore architecture in a single build.

Comparison of Simulated Microgravity and Hydrostatic Pressure for Chondrogenesis of hASC.

Background: Cartilage tissue engineering is a growing field due to the lack of regenerative capacity of native tissue. The use of bioreactors for cartilage tissue engineering is common, but the results are controversial. Some studies suggest that microgravity bioreactors are ideal for chondrogenesis, while others show that mimicking hydrostatic pressure is crucial for cartilage formation.

Electrical Cell-Substrate Impedance Spectroscopy Can Monitor Age-Grouped Human Adipose Stem Cell Variability During Osteogenic Differentiation.

Human adipose stem cells (hASCs) are an attractive cell source for bone tissue engineering applications. However, a critical issue to be addressed before widespread hASC clinical translation is the dramatic variability in proliferative capacity and osteogenic potential among hASCs isolated from different donors. The goal of this study was to test our hypothesis that electrical cell-substrate impedance spectroscopy (ECIS) could track complex bioimpedance patterns of hASCs throughout proliferation and osteogenic differentiation to better understand and predict variability among hASC populations.

Primary cilia are sensors of electrical field stimulation to induce osteogenesis of human adipose-derived stem cells.

In this study, we report for the first time that the primary cilium acts as a crucial sensor for electrical field stimulation (EFS)-enhanced osteogenic response in osteoprogenitor cells. In addition, primary cilia seem to functionally modulate effects of EFS-induced cellular calcium oscillations. Primary cilia are organelles that have recently been implicated to play a crucial sensor role for many mechanical and chemical stimuli on stem cells.

Enhanced cellular infiltration of human adipose-derived stem cells in allograft menisci using a needle-punch method.

Background: The meniscus plays a crucial role in knee joint stability, load transmission, and stress distribution. Meniscal tears are the most common reported knee injuries, and the current standard treatment for meniscal deficiency is meniscal allograft transplantation. A major limitation of this approach is that meniscal allografts do not have the capacity to remodel and maintain tissue homeostasis due to a lack of cellular infiltration.

Evaluation of Silver Ion-Releasing Scaffolds in a 3D Coculture System of MRSA and Human Adipose-Derived Stem Cells for Their Potential Use in Treatment or Prevention of Osteomyelitis.

Bone infection, also called osteomyelitis, can result when bacteria invade a bone. Treatment of osteomyelitis usually requires surgical debridement and prolonged antimicrobial therapy. The rising incidence of infection with multidrug-resistant bacteria, in particular methicillin-resistant staphylococcus aureus (MRSA), however, limits the antimicrobial treatment options available.

Mechanical and Vascular Cues Synergistically Enhance Osteogenesis in Human Mesenchymal Stem Cells.

Development and maintenance of a vascular network are critical for bone growth and homeostasis; strategies that promote vascular function are critical for clinical success of tissue-engineered bone constructs. Co-culture of endothelial cells (ECs) with mesenchymal stem cells (MSCs) and exposure to 10% cyclic tensile strain have both been shown to regulate osteogenesis in isolation, but potential synergistic effects have yet to be explored. The objective of this study was to expose an MSC-EC co-culture to 10% cyclic tensile strain to examine the role of this mechanical stimulus on MSC-EC behavior.

Electrospun nanofibrous scaffolds increase the efficacy of stem cell-mediated therapy of surgically resected glioblastoma.

Engineered stem cell (SC)-based therapy holds enormous promise for treating the incurable brain cancer glioblastoma (GBM). Retaining the cytotoxic SCs in the surgical cavity after GBM resection is one of the greatest challenges to this approach. Here, we describe a biocompatible electrospun nanofibrous scaffold (bENS) implant capable of delivering and retaining tumor-homing cytotoxic stem cells that suppress recurrence of post-surgical GBM.

Fabrication of novel high surface area mushroom gilled fibers and their effects on human adipose derived stem cells under pulsatile fluid flow for tissue engineering applications.

Unlabelled: The fabrication and characterization of novel high surface area hollow gilled fiber tissue engineering scaffolds via industrially relevant, scalable, repeatable, high speed, and economical nonwoven carding technology is described. Scaffolds were validated as tissue engineering scaffolds using human adipose derived stem cells (hASC) exposed to pulsatile fluid flow (PFF). The effects of fiber morphology on the proliferation and viability of hASC, as well as effects of varied magnitudes of shear stress applied via PFF on the expression of the early osteogenic gene marker runt related transcription factor 2 (RUNX2) were evaluated.

Concise Review: Primary Cilia: Control Centers for Stem Cell Lineage Specification and Potential Targets for Cell-Based Therapies.

Directing stem cell lineage commitment prevails as the holy grail of translational stem cell research, particularly to those interested in the application of mesenchymal stem cells and adipose-derived stem cells in tissue engineering. However, elucidating the mechanisms underlying their phenotypic specification persists as an active area of research. In recent studies, the primary cilium structure has been intimately associated with defining cell phenotype, maintaining stemness, as well as functioning in a chemo, electro, and mechanosensory capacity in progenitor and committed cell types.

Continuous-Wave Stimulated Emission Depletion Microscope for Imaging Actin Cytoskeleton in Fixed and Live Cells.

Stimulated emission depletion (STED) microscopy provides a new opportunity to study fine sub-cellular structures and highly dynamic cellular processes, which are challenging to observe using conventional optical microscopy. Using actin as an example, we explored the feasibility of using a continuous wave (CW)-STED microscope to study the fine structure and dynamics in fixed and live cells. Actin plays an important role in cellular processes, whose functioning involves dynamic formation and reorganization of fine structures of actin filaments.