A scaffold containing zinc oxide for Schwann cell-mediated axon growth.

Schwann cells (SCs) transplanted in damaged nervous tissue promote axon growth, which may support the recovery of function lost after injury. However, SC transplant-mediated axon growth is often limited and lacks direction.We have developed a zinc oxide (ZnO) containing fibrous scaffold consisting of aligned fibers of polycaprolactone (PCL) with embedded ZnO nanoparticles as a biodegradable, bifunctional scaffold for promoting and guiding axon growth.

Scaffolds containing GAG-mimetic cellulose sulfate promote TGF-β interaction and MSC Chondrogenesis over native GAGs.

Cartilage tissue engineering strategies seek to repair damaged tissue using approaches that include scaffolds containing components of the native extracellular matrix (ECM). Articular cartilage consists of glycosaminoglycans (GAGs) which are known to sequester growth factors. In order to more closely mimic the native ECM, this study evaluated the chondrogenic differentiation of mesenchymal stem cells (MSCs), a promising cell source for cartilage regeneration, on fibrous scaffolds that contained the GAG-mimetic cellulose sulfate.

Biomaterials and tissue engineering approaches using glycosaminoglycans for tissue repair: Lessons learned from the native extracellular matrix.

Glycosaminoglycans (GAGs) are an important component of the extracellular matrix as they influence cell behavior and have been sought for tissue regeneration, biomaterials, and drug delivery applications. GAGs are known to interact with growth factors and other bioactive molecules and impact tissue mechanics. This review provides an overview of native GAGs, their structure, and properties, specifically their interaction with proteins, their effect on cell behavior, and their mechanical role in the ECM.

Plant cell adhesion and growth on artificial fibrous scaffolds as an in vitro model for plant development.

Mechanistic studies of plant development would benefit from an in vitro model that mimics the endogenous physical interactions between cells and their microenvironment. Here, we present artificial scaffolds to which both solid- and liquid-cultured tobacco BY-2 cells adhere without perturbing cell morphology, division, and cortical microtubule organization. Scaffolds consisting of polyvinylidene tri-fluoroethylene (PVDF-TrFE) were prepared to mimic the cell wall’s fibrillar structure and its relative hydrophobicity and piezoelectric property.

The Effect of Physical Cues of Biomaterial Scaffolds on Stem Cell Behavior.

Stem cells have been sought as a promising cell source in the tissue engineering field due to their proliferative capacity as well as differentiation potential. Biomaterials have been utilized to facilitate the delivery of stem cells in order to improve their engraftment and long-term viability upon implantation. Biomaterials also have been developed as scaffolds to promote stem cell induced tissue regeneration.

Biodegradable zinc oxide composite scaffolds promote osteochondral differentiation of mesenchymal stem cells.

Osteoarthritis (OA) involves the degeneration of articular cartilage and subchondral bone. The capacity of articular cartilage to repair and regenerate is limited. A biodegradable, fibrous scaffold containing zinc oxide (ZnO) was fabricated and evaluated for osteochondral tissue engineering applications.

Aligned fibrous PVDF-TrFE scaffolds with Schwann cells support neurite extension and myelination in vitro.

Objective: Polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE), which is a piezoelectric, biocompatible polymer, holds promise as a scaffold in combination with Schwann cells (SCs) for spinal cord repair. Piezoelectric materials can generate electrical activity in response to mechanical deformation, which could potentially stimulate spinal cord axon regeneration. Our goal in this study was to investigate PVDF-TrFE scaffolds consisting of aligned fibers in supporting SC growth and SC-supported neurite extension and myelination in vitro.

Transplantation of Schwann Cells Inside PVDF-TrFE Conduits to Bridge Transected Rat Spinal Cord Stumps to Promote Axon Regeneration Across the Gap.

Among various models for spinal cord injury in rats, the contusion model is the most often used because it is the most common type of human spinal cord injury. The complete transection model, although not as clinically relevant as the contusion model, is the most rigorous method to evaluate axon regeneration. In the contusion model, it is difficult to distinguish regenerated from sprouted or spared axons due to the presence of remaining tissue post injury.

Three-dimensional piezoelectric fibrous scaffolds selectively promote mesenchymal stem cell differentiation.

The discovery of electric fields in biological tissues has led to efforts in developing technologies utilizing electrical stimulation for therapeutic applications. Native tissues, such as cartilage and bone, exhibit piezoelectric behavior, wherein electrical activity can be generated due to mechanical deformation. Yet, the use of piezoelectric materials have largely been unexplored as a potential strategy in tissue engineering, wherein a piezoelectric biomaterial acts as a scaffold to promote cell behavior and the formation of large tissues.

Controlled Release of Vanadium from a Composite Scaffold Stimulates Mesenchymal Stem Cell Osteochondrogenesis.

Large bone defects often require the use of autograft, allograft, or synthetic bone graft augmentation; however, these treatments can result in delayed osseous integration. A tissue engineering strategy would be the use of a scaffold that could promote the normal fracture healing process of endochondral ossification, where an intermediate cartilage phase is later transformed to bone. This study investigated vanadyl acetylacetonate (VAC), an insulin mimetic, combined with a fibrous composite scaffold, consisting of polycaprolactone with nanoparticles of hydroxyapatite and beta-tricalcium phosphate, as a potential bone tissue engineering scaffold.

Gelatin Scaffolds Containing Partially Sulfated Cellulose Promote Mesenchymal Stem Cell Chondrogenesis.

Articular cartilage has a limited capacity to heal after damage from injury or degenerative disease. Tissue engineering constructs that more closely mimic the native cartilage microenvironment can be utilized to promote repair. Glycosaminoglycans (GAGs), a major component of the cartilage extracellular matrix, have the ability to sequester growth factors due to their level and spatial distribution of sulfate groups.

The Biology of Bone and Ligament Healing.

This review describes the normal healing process for bone, ligaments, and tendons, including primary and secondary healing as well as bone-to-bone fusion. It depicts the important mediators and cell types involved in the inflammatory, reparative, and remodeling stages of each healing process. It also describes the main challenges for clinicians when trying to repair bone, ligaments, and tendons with a specific emphasis on Charcot neuropathy, fifth metatarsal fractures, arthrodesis, and tendon sheath and adhesions.

Investigating cellulose derived glycosaminoglycan mimetic scaffolds for cartilage tissue engineering applications.

Articular cartilage has a limited capacity to heal and, currently, no treatment exists that can restore normal hyaline cartilage. Creating tissue engineering scaffolds that more closely mimic the native extracellular matrix may be an attractive approach. Glycosaminoglycans, which are present in native cartilage tissue, provide signalling and structural cues to cells.

Enhanced noradrenergic axon regeneration into schwann cell-filled PVDF-TrFE conduits after complete spinal cord transection.

Schwann cell (SC) transplantation has been utilized for spinal cord repair and demonstrated to be a promising therapeutic strategy. In this study, we investigated the feasibility of combining SC transplantation with novel conduits to bridge the completely transected adult rat spinal cord. This is the first and initial study to evaluate the potential of using a fibrous piezoelectric polyvinylidene fluoride trifluoroethylene (PVDF-TrFE) conduit with SCs for spinal cord repair.

Piezoelectric materials for tissue regeneration: A review.

Unlabelled: The discovery of piezoelectricity, endogenous electric fields and transmembrane potentials in biological tissues raised the question whether or not electric fields play an important role in cell function. It has kindled research and the development of technologies in emulating biological electricity for tissue regeneration. Promising effects of electrical stimulation on cell growth and differentiation and tissue growth has led to interest in using piezoelectric scaffolds for tissue repair.

Evaluating protein incorporation and release in electrospun composite scaffolds for bone tissue engineering applications.

Electrospun polymer/ceramic composites have gained interest for use as scaffolds for bone tissue engineering applications. In this study, we investigated methods to incorporate Platelet Derived Growth Factor-BB (PDGF-BB) in electrospun polycaprolactone (PCL) or PCL prepared with polyethylene oxide (PEO), where both contained varying levels (up to 30 wt %) of ceramic composed of biphasic calcium phosphates, hydroxyapatite (HA)/β-tricalcium phosphate (TCP). Using a model protein, lysozyme, we compared two methods of protein incorporation, adsorption and emulsion electrospinning.

An investigation of common crosslinking agents on the stability of electrospun collagen scaffolds.

Electrospinning is a widely used processing method to form fibrous tissue engineering scaffolds that mimic the structural features of the native extracellular matrix. Electrospun fibers made of collagen have been sought because it is a natural structural protein that supports cell attachment and growth. Yet, conventional solvents used to electrospin collagen can result in the loss of hydrolytic stability and fiber morphology of the scaffold.

Evaluating apatite formation and osteogenic activity of electrospun composites for bone tissue engineering.

Significant interest has been in examining calcium phosphate ceramics, specifically β-tricalcium phosphate (β-TCP) (Ca3 (PO4)2 ) and synthetic hydroxyapatite (HA) (Ca10 (PO4)6 (OH)2 ), in composites and more recently, in fibrous composites formed using the electrospinning technique for bone tissue engineering applications. Calcium phosphate ceramics are sought because they can be bone bioactive, which means an apatite forms on their surface that facilitates bonding to bone tissue, and are osteoconductive. However, studies examining the bioactivity of electrospun composites containing calcium phosphates and their corresponding osteogenic activity have been limited.

Structural changes in PVDF fibers due to electrospinning and its effect on biological function.

Polyvinylidine fluoride (PVDF) is being investigated as a potential scaffold for bone tissue engineering because of its proven biocompatibility and piezoelectric property, wherein it can generate electrical activity when mechanically deformed. In this study, PVDF scaffolds were prepared by electrospinning using different voltages (12-30 kV), evaluated for the presence of the piezoelectric β-crystal phase and its effect on biological function. Electrospun PVDF was compared with unprocessed/raw PVDF, films and melt-spun fibers for the presence of the piezoelectric β-phase using differential scanning calorimetry, Fourier transform infrared spectroscopy and x-ray diffraction.

Examining the formulation of emulsion electrospinning for improving the release of bioactive proteins from electrospun fibers.

Emulsion electrospinning has been sought as a method to prepare fibrous materials/scaffolds for growth factor delivery. Emulsion conditions, specifically sonication and the addition of a surfactant, were evaluated to determine their effect on the release and bioactivity of proteins from electrospun scaffolds. Polycaprolactone (PCL) and poly(ethylene oxide) (PEO/PCL) blends were evaluated where PEO, a hydrophilic polymer, was shown to enhance the incorporation of proteins.

The influence of piezoelectric scaffolds on neural differentiation of human neural stem/progenitor cells.

Human neural stem/progenitor cells (hNSCs/NPCs) are a promising cell source for neural tissue engineering because of their ability to differentiate into various neural lineages. In this study, hNSC/NPC differentiation was evaluated on piezoelectric, fibrous scaffolds. These smart materials have an intrinsic material property where transient electric potential can be generated in the material upon minute mechanical deformation.

Neurite extension of primary neurons on electrospun piezoelectric scaffolds.

Neural tissue engineering may be a promising option for neural repair treatment, for which a well-designed scaffold is essential. Smart materials that can stimulate neurite extension and outgrowth have been investigated as potential scaffolding materials. A piezoelectric polymer polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) was used to fabricate electrospun aligned and random scaffolds having nano- or micron-sized fiber dimensions.

Microscale versus nanoscale scaffold architecture for mesenchymal stem cell chondrogenesis.

Nanofiber scaffolds, produced by the electrospinning technique, have gained widespread attention in tissue engineering due to their morphological similarities to the native extracellular matrix. For cartilage repair, studies have examined their feasibility; however these studies have been limited, excluding the influence of other scaffold design features. This study evaluated the effect of scaffold design, specifically examining a range of nano to micron-sized fibers and resulting pore size and mechanical properties, on human mesenchymal stem cells (MSCs) derived from the adult bone marrow during chondrogenesis.

Mesenchymal stem cells accelerate bone allograft incorporation in the presence of diabetes mellitus.

Allograft (Allo) incorporation in the presence of a systemic disease like diabetes mellitus (DM) is becoming a major issue in the orthopedic community. Mesenchymal stem cells (MSC) are multipotent stem cells that may be derived from adult, whole bone marrow and have been shown to induce bone formation in segmental defects when combined with the appropriate carrier/scaffold. The objectives of this study were to analyze the effect of DM upon Allo incorporation in a segmental rat femoral defect and to also investigate MSC augmentation of Allo incorporation.