Integrating Fused Deposition Modeling and Melt Electrowriting for Engineering Branched Vasculature.

We demonstrate for the first time the combination of two additive manufacturing technologies used in tandem, fused deposition modelling (FDM) and melt electrowriting (MEW), to increase the range of possible MEW structures, with a focus on creating branched, hollow scaffolds for vascularization. First, computer-aided design (CAD) was used to design branched mold halves which were then used to FDM print conductive polylactic acid (cPLA) molds. Next, MEW was performed over the top of these FDM cPLA molds using polycaprolactone (PCL), an FDA-approved biomaterial.

Lipids Reduce Cytokine-Induced Pro-Inflammatory Signalling and Barrier Dysfunction in Human Keratinocyte Models.

Atopic dermatitis is a chronic condition where epidermal barrier dysfunction and cytokine production by infiltrating immune cells exacerbate skin inflammation and damage. A total lipid extract from , a brown seaweed, was previously reported to suppress inflammatory responses in monocytes. Here, treatment of human HaCaT keratinocytes with lipids inhibited tumour necrosis factor (TNF)-α induced TNF receptor-associated factor 2 and monocyte chemoattractant protein (MCP)-1 protein production.

Development and optimisation of hydroxyapatite-polyethylene glycol diacrylate hydrogel inks for 3D printing of bone tissue engineered scaffolds.

In the event of excessive damage to bone tissue, the self-healing process alone is not sufficient to restore bone integrity. Three-dimensional (3D) printing, as an advanced additive manufacturing technology, can create implantable bone scaffolds with accurate geometry and internal architecture, facilitating bone regeneration. This study aims to develop and optimise hydroxyapatite-polyethylene glycol diacrylate (HA-PEGDA) hydrogel inks for extrusion 3D printing of bone tissue scaffolds.

3D printing of chitooligosaccharide-polyethylene glycol diacrylate hydrogel inks for bone tissue regeneration.

To date, lack of functional hydrogel inks has limited 3D printing applications in tissue engineering. This study developed a series of photocurable hydrogel inks based on chitooligosaccharide (COS)-polyethylene glycol diacrylate (PEGDA) for extrusion-based 3D printing of bone tissue scaffolds. The scaffolds were prepared by aza-Michael addition of COS and PEGDA followed by photopolymerisation of unreacted PEGDA.

Intervertebral Disc Tissue Engineering Using Additive Manufacturing.

Intervertebral disc (IVD) degeneration is one of the major causes of lower back pain, a common health condition that greatly affects the quality of life. With an increasing elderly population and changes in lifestyle, there exists a high demand for novel treatment strategies for damaged IVDs. Researchers have investigated IVD tissue engineering (TE) as a way to restore biological and mechanical functions by regenerating or replacing damaged discs using scaffolds with suitable cells.

3D Living Dressing Improves Healing and Modulates Immune Response in a Thermal Injury Model.

Thermal injury trauma can induce a state of immunosuppression, causing wounds to become chronic in nature. Stem cell-based therapies represent a promising new approach to treat such wounds due to their capacity to self-renew and their multi-lineage potential. Mesenchymal stem cells (MSCs) are known to secrete endogenous factors that stimulate wound healing by promoting angiogenesis, extracellular matrix remodeling, skin regeneration, and by dampening down inflammation.

Three-Dimensional Melt-Electrowritten Polycaprolactone/Chitosan Scaffolds Enhance Mesenchymal Stem Cell Behavior.

Melt electrowriting (MEW) is an emerging technique that precisely fabricates microfibrous scaffolds, ideal for tissue engineering, where biomimetic microarchitectural detail is required. Polycaprolactone (PCL), a synthetic polymer, was selected as the scaffold material due to its biocompatibility, biodegradability, mechanical strength, and melt processability. To increase PCL bioactivity, a natural polymer, chitosan, was added to construct MEW fibrous composite scaffolds.

A comparison between β-tricalcium phosphate and chitosan poly-caprolactone-based 3D melt extruded composite scaffolds.

Melt extrusion 3D printing has become an attractive additive manufacturing technology to construct degradable scaffolds as tissue precursors in order to create clinically relevant medical devices. Towards this end, a commonly used synthetic polyester, poly-caprolactone (PCL), was used to make scaffolds composed of different biomaterial compositions to increase bioactivity using 3D melt pneumatic extrusion technology. Varying ratios of the natural biopolymer, chitosan, or the bioceramic, β-tricalcium phosphate (TCP) were blended with PCL to fabricate support scaffolds with three-dimensional (3D) architecture for human bone-marrow derived mesenchymal stem cell (hBMSC) growth for potential bone regeneration application.

Melt Electrowritten Sandwich Scaffold Technique Using Sulforhodamine B to Monitor Stem Cell Behavior.

Three-dimensional (3D) printing using melt electrowriting (MEW) technology is a recently developed technique to produce biocompatible micron-level mesh scaffolds layer-by-layer that can be seeded with cells for tissue engineering. Examining cell behavior, such as growth rate and migration, can be problematic in these opaque 3D scaffolds. A straightforward and quantitative method was developed to examine these cellular parameters on poly-ɛ-caprolactone (PCL) multilayered MEW scaffolds developed as components of the annulus fibrosus region of bioengineered intervertebral discs.

Peptide Chitosan/Dextran Core/Shell Vascularized 3D Constructs for Wound Healing.

Three-dimensional (3D) bioprinting has emerged to create novel cell-based therapies for regenerative medicine applications. Vascularized networks within engineered constructs are required, and toward this end, we report a promising strategy using core-shell (c/s) extrusion 3D-bioprinting technology that employs biomimetic biomaterials to construct regenerative, prevascularized scaffolds for wound care. A custom-designed cell-responsive bioink consisting of a 13% (w/v) cell-laden gelatin methacryloyl (GelMA) shell surrounding a peptide-functionalized, succinylated chitosan (C)/dextran aldehyde (D) cell-laden core was successfully bioprinted resulting in organized microdesigns exhibiting excellent cell viability and subsequent vessel formation.

Melt-electrowriting with novel milk protein/PCL biomaterials for skin regeneration.

Demand for skin replacements is rapidly increasing as burn and full-thickness wounds are difficult to repair due to the low regeneration capability of innate tissues, as well as the physical drawbacks associated with currently available substitutes. To address this need, an emerging 3D printing technique, melt-electrowriting (MEW) was used to create novel bioactive scaffolds to promote skin regeneration. Polycaprolactone (PCL), a bioresorbable and biocompatible, synthetic polymer with Food and Drug Administration approval for use in the human body was selected as scaffold material due to its mechanical stability, flexibility, and superior melt processing properties.

A chitosan/dextran-based hydrogel as a delivery vehicle of human bone-marrow derived mesenchymal stem cells.

A chitosan/dextran-based (CD) injectable, surgical hydrogel has been developed and shown to be an effective post-operative aid in prevention of scar tissue formation in vivo. The CD hydrogel's effectiveness in a surgical setting prompted an investigation into its capacity as a potential delivery vehicle for bone marrow derived mesenchymal stem cells (BM-MSCs) for regenerative wound healing applications. By housing BM-MSCs within a biocompatible, injectable, hydrogel matrix, viability and protection in cultivation, as well as direct delivery to the damaged site in the host tissue may be achieved.

Strong poly(ethylene oxide) based gel adhesives via oxime cross-linking.

Unlabelled: There is a demand for materials to replace or augment the use of sutures and staples in surgical procedures. Currently available commercial surgical adhesives provide either high bond strength with biological toxicity or polymer and protein-based products that are biologically acceptable (though with potential sensitizing potential) but have much reduced bond strength. It is desirable to provide novel biocompatible and biodegradable surgical adhesives/sealants capable of high strength with minimal immune or inflammatory response.

Reducing the Oxidation Level of Dextran Aldehyde in a Chitosan/Dextran-Based Surgical Hydrogel Increases Biocompatibility and Decreases Antimicrobial Efficacy.

A highly oxidized form of a chitosan/dextran-based hydrogel (CD-100) containing 80% oxidized dextran aldehyde (DA-100) was developed as a post-operative aid, and found to significantly prevent adhesion formation in endoscopic sinus surgery (ESS). However, the CD-100 hydrogel showed moderate in vitro cytotoxicity to mammalian cell lines, with the DA-100 found to be the cytotoxic component. In order to extend the use of the hydrogel to abdominal surgeries, reformulation using a lower oxidized DA (DA-25) was pursued.

Characterization of the in vivo host response to a bi-labeled chitosan-dextran based hydrogel for postsurgical adhesion prevention.

In developing a chitosan/dextran-based (CD) hydrogel as an adhesion prevention postsurgical aid, the in vivo biodegradation rate, biodistribution, and inflammatory response are important parameters to the biomedical device design. Herein, for the first time, a CD hydrogel was prepared by mixing aqueous solutions of a near infrared (NIR) labeled succinylated chitosan (SC) and tritiated [(3) H] oxidized dextran (DA). The biodegradation and biodistribution of the NIR/[(3) H]-CD hydrogel was tracked noninvasively using NIR fluorescence imaging, and by liquid scintillation counting (LSC) of organs/tissues after subcutaneous injection in BALB/c mice.

Synthesis, physiochemical characterization, and biocompatibility of a chitosan/dextran-based hydrogel for postsurgical adhesion prevention.

An amine-functionalized succinyl chitosan and an oxidized dextran were synthesized and mixed in aqueous solution to form an in situ chitosan/dextran injectable, surgical hydrogel for adhesion prevention. Rheological characterization showed that the rate of gelation and moduli were tunable based on amine and aldehyde levels, as well as polymer concentrations. The CD hydrogels have been shown to be effective post-operative aids in prevention of adhesions in ear, nose, and throat surgeries and abdominal surgeries in vivo.

In vitro biocompatibility and cellular interactions of a chitosan/dextran-based hydrogel for postsurgical adhesion prevention.

In this paper, we report the in vitro biocompatibility and cellular interactions of a chitosan/dextran-based (CD) hydrogel and its components as determined by mutagenicity, cytotoxicity, cytokine/chemokine response, and wound healing assays. The CD hydrogel, developed for postsurgical adhesion prevention in ear, nose, and throat surgeries, was shown by previously published experiments in animal and human trials to be effective. The hydrogel was synthesized from the reaction between succinyl chitosan (SC) and oxidized dextran (DA).

Antimicrobial properties of a chitosan dextran-based hydrogel for surgical use.

A chitosan dextran-based (CD) hydrogel, developed for use in endoscopic sinus surgery, was tested for antimicrobial activity in vitro against a range of pathogenic microorganisms. The microdilution technique was used to determine minimum inhibitory, minimum bactericidal, and minimum fungicidal concentrations. In addition, the time-kill efficacy of CD hydrogel was determined for two bacterial species.