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1.
Biomacromolecules ; 25(1): 188-199, 2024 01 08.
Article in English | MEDLINE | ID: mdl-38102990

ABSTRACT

Gelatin methacryloyl (GelMA) hydrogels have gained significant attention due to their biocompatibility and tunable properties. Here, a new approach to engineer GelMA-based matrices to mimic the osteoid matrix is provided. Two cross-linking methods were employed to mimic the tissue stiffness: standard cross-linking (SC) based on visible light exposure (VL) and dual cross-linking (DC) involving physical gelation, followed by VL. It was demonstrated that by reducing the GelMA concentration from 10% (G10) to 5% (G5), the dual-cross-linked G5 achieved a compressive modulus of ∼17 kPa and showed the ability to support bone formation, as evidenced by alkaline phosphatase detection over 3 weeks of incubation in osteogenic medium. Moreover, incorporating poly(ethylene) oxide (PEO) into the G5 and G10 samples was found to hinder the fabrication of highly porous hydrogels, leading to compromised cell survival and reduced osteogenic differentiation, as a consequence of incomplete PEO removal.


Subject(s)
Hydrogels , Osteogenesis , Tissue Engineering/methods , Bone and Bones , Methacrylates , Gelatin , Polyethylene Glycols , Tissue Scaffolds
2.
J Mech Behav Biomed Mater ; 139: 105665, 2023 03.
Article in English | MEDLINE | ID: mdl-36640542

ABSTRACT

Reproducing both the mechanical and biological performance of native blood vessels remains an ongoing challenge in vascular tissue engineering. Additive-lathe printing offers an attractive method of fabricating long tubular constructs as a potential vascular graft for the treatment of cardiovascular diseases. Printing hydrogels onto rotating horizontal mandrels often leads to sagging, resulting in poor and variable mechanical properties. In this study, an additive-lathe printing system with a vertical mandrel to fabricate tubular constructs is presented. Various concentrations of gelatin methacryloyl (gelMA) hydrogel were used to print grafts on the rotating mandrel in a helical pattern. The printing parameters were selected to achieve the bonding of consecutive gelMA filaments to improve the quality of the printed graft. The hydrogel filaments were fused properly under the action of gravity on the vertical mandrel. Thus, the vertical additive-lathe printing system was used to print uniform wall thickness grafts, eliminating the hydrogel sagging problem. Tensile testing performed in both circumferential and longitudinal direction revealed that the anisotropic properties of printed gelMA constructs were similar to those observed in the native blood vessels. In addition, no leakage was detected through the walls of the gelMA grafts during burst pressure measurement. Therefore, the current printing setup could be utilized to print vascular grafts for the treatment of cardiovascular diseases.


Subject(s)
Bioprinting , Cardiovascular Diseases , Humans , Tissue Scaffolds , Hydrogels , Printing, Three-Dimensional , Bioprinting/methods , Tissue Engineering/methods , Gelatin , Methacrylates
3.
Front Endocrinol (Lausanne) ; 14: 1308604, 2023.
Article in English | MEDLINE | ID: mdl-38169965

ABSTRACT

Introduction: Bioassembly techniques for the application of scaffold-free tissue engineering approaches have evolved in recent years toward producing larger tissue equivalents that structurally and functionally mimic native tissues. This study aims to upscale a 3-dimensional bone in-vitro model through bioassembly of differentiated rat osteoblast (dROb) spheroids with the potential to develop and mature into a bone macrotissue. Methods: dROb spheroids in control and mineralization media at different seeding densities (1 × 104, 5 × 104, and 1 × 105 cells) were assessed for cell proliferation and viability by trypan blue staining, for necrotic core by hematoxylin and eosin staining, and for extracellular calcium by Alizarin red and Von Kossa staining. Then, a novel approach was developed to bioassemble dROb spheroids in pillar array supports using a customized bioassembly system. Pillar array supports were custom-designed and printed using Formlabs Clear Resin® by Formlabs Form2 printer. These supports were used as temporary frameworks for spheroid bioassembly until fusion occurred. Supports were then removed to allow scaffold-free growth and maturation of fused spheroids. Morphological and molecular analyses were performed to understand their structural and functional aspects. Results: Spheroids of all seeding densities proliferated till day 14, and mineralization began with the cessation of proliferation. Necrotic core size increased over time with increased spheroid size. After the bioassembly of spheroids, the morphological assessment revealed the fusion of spheroids over time into a single macrotissue of more than 2.5 mm in size with mineral formation. Molecular assessment at different time points revealed osteogenic maturation based on the presence of osteocalcin, downregulation of Runx2 (p < 0.001), and upregulated alkaline phosphatase (p < 0.01). Discussion: With the novel bioassembly approach used here, 3D bone macrotissues were successfully fabricated which mimicked physiological osteogenesis both morphologically and molecularly. This biofabrication approach has potential applications in bone tissue engineering, contributing to research related to osteoporosis and other recurrent bone ailments.


Subject(s)
Bone and Bones , Spheroids, Cellular , Rats , Animals , Cells, Cultured , Osteogenesis , Tissue Engineering/methods
4.
Pharmaceutics ; 13(3)2021 Mar 23.
Article in English | MEDLINE | ID: mdl-33807062

ABSTRACT

Single-administration vaccine delivery systems are intended to improve the efficiency and efficacy of immunisation programs in both human and veterinary medicine. In this work, an osmotically triggered delayed delivery device was developed that was able to release a payload after a delay of approximately 21 days, in a consistent and reproducible manner. The device was constructed out of a flexible poly(ε-caprolactone) photo-cured network fabricated into a hollow tubular shape, which expelled approximately 10% of its total payload within 2 days after bursting. Characterisation of the factors that control the delay of release demonstrated that it was advantageous to adjust material permeability and device wall thickness over manipulation of the osmogent concentration in order to maintain reproducibility in burst delay times. The photo-cured poly(ε-caprolactone) network was shown to be fully degradable in vitro, and there was no evidence of cytotoxicity after 11 days of direct contact with primary dermal fibroblasts. This study provides strong evidence to support further development of flexible biomaterials with the aim of continuing improvement of the device burst characteristics in order to provide the greatest chance of the devices succeeding with in vivo vaccine booster delivery.

5.
Chem Rev ; 120(19): 11128-11174, 2020 10 14.
Article in English | MEDLINE | ID: mdl-32937071

ABSTRACT

The lack of in vitro tissue and organ models capable of mimicking human physiology severely hinders the development and clinical translation of therapies and drugs with higher in vivo efficacy. Bioprinting allow us to fill this gap and generate 3D tissue analogues with complex functional and structural organization through the precise spatial positioning of multiple materials and cells. In this review, we report the latest developments in terms of bioprinting technologies for the manufacturing of cellular constructs with particular emphasis on material extrusion, jetting, and vat photopolymerization. We then describe the different base polymers employed in the formulation of bioinks for bioprinting and examine the strategies used to tailor their properties according to both processability and tissue maturation requirements. By relating function to organization in human development, we examine the potential of pluripotent stem cells in the context of bioprinting toward a new generation of tissue models for personalized medicine. We also highlight the most relevant attempts to engineer artificial models for the study of human organogenesis, disease, and drug screening. Finally, we discuss the most pressing challenges, opportunities, and future prospects in the field of bioprinting for tissue engineering (TE) and regenerative medicine (RM).


Subject(s)
Bioprinting , Polymers/chemistry , Precision Medicine , Printing, Three-Dimensional , Tissue Engineering , Tissue Scaffolds/chemistry , Humans
6.
APL Bioeng ; 4(3): 036105, 2020 Sep.
Article in English | MEDLINE | ID: mdl-32844139

ABSTRACT

Shape memory polymers are materials that are able to retain a deformed state until an external stimulus, most typically heat, triggers recovery to the original geometry. Whereas typically, shape memory polymers are required to recover fast (seconds to minutes), many applications, particularly in the medical field, would benefit from a slow recovery (days to weeks). In this work, we exploit the broad glass transition range of photo-cured poly(D,L-lactide) dimethacrylate networks to obtain recovery times of up to 2 weeks, at 11 °C below the peak glass transition temperature of 58 °C. Recovery times decreased considerably for higher recovery temperatures, down to ∼10 min at 55 °C. A large spread in glass transition values (53.3-61.0 °C) was observed between samples, indicating poor reproducibility in sample preparation and, hence, in predicting shape recovery kinetics for individual samples. Furthermore, a staged recovery was observed with different parts of the samples recovering at different times. The ability to prepare complex structures using digital light processing stereolithography 3D printing from these polymers was confirmed. To the best of our knowledge, this work provides the first experimental evidence of prolonged recovery of shape memory polymers.

7.
Trends Biotechnol ; 38(6): 584-593, 2020 06.
Article in English | MEDLINE | ID: mdl-31955894

ABSTRACT

Extrusion-based 3D printers have been adopted in pursuit of engineering functional tissues through 3D bioprinting. However, we are still a long way from the promise of fabricating constructs approaching the complexity and function of native tissues. A major challenge is presented by the competing requirements of biomimicry and manufacturability. This opinion article discusses 3D printing in suspension baths as a novel strategy capable of disrupting the current bioprinting landscape. Suspension baths provide a semisolid medium to print into, voiding many of the inherent flaws of printing onto a flat surface in air. We review the state-of-the-art of this approach and extrapolate toward future possibilities that this technology might bring, including the fabrication of vascularized tissue constructs.


Subject(s)
Biocompatible Materials/chemistry , Bioprinting/trends , Printing, Three-Dimensional/trends , Tissue Engineering/trends , Biocompatible Materials/therapeutic use , Humans , Hydrogels/chemistry , Hydrogels/therapeutic use
8.
Ned Tijdschr Geneeskd ; 1632019 05 22.
Article in Dutch | MEDLINE | ID: mdl-31166096

ABSTRACT

5 years ago, we described the emergence of 3D printing in medicine. It was about 3D printing of anatomical structures, patient-specific drilling guides, cutting templates and implants and printing of living cells, growth factors and biomaterials ('bioprinting'). Surgeons are increasingly making use of 3D printing possibilities in preparation of surgeries on patients with complicated anatomies. Using tangible 3D models, it is easier for surgeons to prepare for surgeries and discussions with patients. They can also use 3D models as a tool to help with the training of young surgeons. Permanent titanium implants are increasingly being printed. Bioprinting is still in its infancy and there are no direct clinical applications yet. As we already predicted 5 years ago, many hurdles still have to be taken before broad clinical application of bioprinted products will become a reality.


Subject(s)
Bioprinting , Models, Anatomic , Preoperative Care/methods , Printing, Three-Dimensional , Prostheses and Implants , Humans
9.
Macromol Biosci ; 19(6): e1900098, 2019 06.
Article in English | MEDLINE | ID: mdl-31026127

ABSTRACT

In this study, the cyto-compatibility and cellular functionality of cell-laden gelatin-methacryloyl (Gel-MA) hydrogels fabricated using a set of photo-initiators which absorb in 400-450 nm of the visible light range are investigated. Gel-MA hydrogels cross-linked using ruthenium (Ru) and sodium persulfate (SPS), are characterized to have comparable physico-mechanical properties as Gel-MA gels photo-polymerized using more conventionally adopted photo-initiators, such as 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (Irgacure 2959) and lithium phenyl(2,4,6-trimethylbenzoyl) phosphinate (LAP). It is demonstrated that the Ru/SPS system has a less adverse effect on the viability and metabolic activity of human articular chondrocytes encapsulated in Gel-MA hydrogels for up to 35 days. Furthermore, cell-laden constructs cross-linked using the Ru/SPS system have significantly higher glycosaminoglycan content and re-differentiation capacity as compared to cells encapsulated using I2959 and LAP. Moreover, the Ru/SPS system offers significantly greater light penetration depth as compared to the I2959 system, allowing thick (10 mm) Gel-MA hydrogels to be fabricated with homogenous cross-linking density throughout the construct. These results demonstrate the considerable advantages of the Ru/SPS system over traditional UV polymerizing systems in terms of clinical relevance and practicability for applications such as cell encapsulation, biofabrication, and in situ cross-linking of injectable hydrogels.


Subject(s)
Cell Differentiation/drug effects , Cellular Microenvironment/drug effects , Hydrogels/pharmacology , Tissue Engineering , Cell Differentiation/radiation effects , Cell Survival/drug effects , Cells, Cultured , Chondrocytes/drug effects , Cross-Linking Reagents/chemistry , Cross-Linking Reagents/radiation effects , Gelatin/chemistry , Gelatin/pharmacology , Gelatin/radiation effects , Humans , Hydrogels/chemistry , Hydrogels/radiation effects , Light , Polymerization/drug effects , Polymerization/radiation effects , Polymers/chemistry , Polymers/pharmacology
10.
Biofabrication ; 10(3): 034101, 2018 05 11.
Article in English | MEDLINE | ID: mdl-29693552

ABSTRACT

Lithography-based three-dimensional (3D) printing technologies allow high spatial resolution that exceeds that of typical extrusion-based bioprinting approaches, allowing to better mimic the complex architecture of biological tissues. Additionally, lithographic printing via digital light processing (DLP) enables fabrication of free-form lattice and patterned structures which cannot be easily produced with other 3D printing approaches. While significant progress has been dedicated to the development of cell-laden bioinks for extrusion-based bioprinting, less attention has been directed towards the development of cyto-compatible bio-resins and their application in lithography-based biofabrication, limiting the advancement of this promising technology. In this study, we developed a new bio-resin based on methacrylated poly(vinyl alcohol) (PVA-MA), gelatin-methacryloyl (Gel-MA) and a transition metal-based visible light photoinitiator. The utilization of a visible light photo-initiating system displaying high molar absorptivity allowed the bioprinting of constructs with high resolution features, in the range of 25-50 µm. Biofunctionalization of the resin with 1 wt% Gel-MA allowed long term survival (>90%) of encapsulated cells up to 21 d, and enabled attachment and spreading of endothelial cells seeded on the printed hydrogels. Cell-laden hydrogel constructs of high resolution with complex and ordered architecture were successfully bioprinted, where the encapsulated cells remained viable, homogenously distributed and functional. Bone and cartilage tissue synthesis was confirmed by encapsulated stem cells, underlining the potential of these DLP-bioprinted hydrogels for tissue engineering and biofabrication. Overall, the PVA-MA/Gel-MA bio-resin is a promising material for biofabrication and provides important cues for the further development of lithography-based bioprinting of complex, free-form living tissue analogues.


Subject(s)
Acrylic Resins/chemistry , Bioprinting/methods , Cell Culture Techniques/methods , Tissue Scaffolds/chemistry , Cell Differentiation , Cell Survival , Cells, Cultured , Gelatin/chemistry , Humans , Hydrogels/chemistry , Light , Methacrylates/chemistry , Polyvinyl Alcohol/chemistry , Tissue Engineering/methods
11.
Tissue Eng Part C Methods ; 24(4): 222-232, 2018 04.
Article in English | MEDLINE | ID: mdl-29457534

ABSTRACT

Hydrogels can facilitate nucleus pulposus (NP) regeneration, either for clinical application or research into mechanisms of regeneration. However, many different hydrogels and culture conditions for human degenerated NP have been employed, making literature data difficult to compare. Therefore, we compared six different hydrogels of natural polymers and investigated the role of serum in the medium and of osmolarity during expansion or redifferentiation in an attempt to provide comparators for future studies. Human NP cells of Thompson grade III discs were cultured in alginate, agarose, fibrin, type II collagen, gelatin methacryloyl (gelMA), and hyaluronic acid-poly(ethylene glycol) hydrogels. Medium containing fetal bovine serum and a serum-free (SF) medium were compared in agarose, gelMA, and type II collagen hydrogels. Isolation and expansion of NP cells in low compared to high osmolarity medium were performed before culture in agarose and type II collagen hydrogels in media of varying osmolarity. NP cells in agarose produced the highest amounts of proteoglycans, followed by cells in type II collagen hydrogels. The absence of serum reduced the total amount of proteoglycans produced by the cells, although incorporation efficiency was higher in type II collagen hydrogels in the absence than in the presence of serum. Isolation and expansion of NP cells in high osmolarity medium improved proteoglycan production during culture in hydrogels, but variation in osmolarity during redifferentiation did not have any effect. Agarose hydrogels seem to be the best option for in vitro culture of human NP cells, but for clinical application, type II collagen hydrogels may be better because, as opposed to agarose, it degrades in time. Although culture in SF medium reduces the amount of proteoglycans produced during redifferentiation culture, isolating and expanding the cells in high osmolarity medium can largely compensate for this loss.


Subject(s)
Biocompatible Materials/chemistry , Hydrogels/chemistry , Intervertebral Disc/cytology , Nucleus Pulposus/cytology , Regeneration , Aged , Cells, Cultured , Collagen Type II/metabolism , Glycosaminoglycans/metabolism , Humans , Intervertebral Disc/metabolism , Middle Aged , Nucleus Pulposus/metabolism , Osmolar Concentration
12.
Acta Biomater ; 66: 238-247, 2018 01 15.
Article in English | MEDLINE | ID: mdl-29174589

ABSTRACT

Hydrogel-based 3D cell cultures are an emerging strategy for the regeneration of cartilage. In an attempt to regenerate dysfunctional intervertebral discs, nucleus pulposus (NP) cells can be cultured in hydrogels of various kinds and physical properties. Stiffness sensing through focal adhesions is believed to direct chondrogenesis, but the mechanisms by which this works are largely unknown. In this study we compared focal adhesion formation and glycosaminoglycan (GAG) deposition by NP cells in a range of hydrogels. Using a focal adhesion kinase (FAK) inhibitor, we demonstrated that focal adhesion signaling is involved in the response of NP cells in hydrogels that contain integrin binding sites (i.e. methacrylated gelatin (gelMA) and type II collagen), but not in hydrogels deplete from integrin binding sites such as alginate and agarose, or CD44-binding hydrogels based on hyaluronic acid. As a result of FAK inhibition we observedenhanced proteoglycan production in gelMA, but decreased production in type II collagen hydrogels, which could be explained by alteration in cell fate as supported by the increase in the adipogenic marker peroxisome proliferator-activated receptor gamma (PPARy). Furthermore, GAG deposition was inversely proportional to polymer concentration in integrin-binding gelMA, while no direct relationship was found for the non-integrin binding gels alginate and agarose. This corroborates our finding that focal adhesion formation plays an important role in NP cell response to its surrounding matrix. STATEMENT OF SIGNIFICANCE: Biomaterials are increasingly being investigated for regenerative medicine applications, including regeneration of the nucleus pulposus. Cells interact with their environment and are influenced by extracellular matrix or polymer properties. Insight in these interactions can improve regeneration and helps to understand degeneration processes. The role of focal adhesion formation in the regenerative response of nucleus pulposus cells is largely unknown. Therefore, the relation between materials, stiffness and focal adhesion formation is studied here.


Subject(s)
Carbohydrates/pharmacology , Collagen/pharmacology , Focal Adhesions/metabolism , Hydrogels/pharmacology , Nucleus Pulposus/cytology , Regeneration/drug effects , Signal Transduction , Actins/metabolism , Adult , Aged , Compressive Strength , DNA/metabolism , Focal Adhesion Protein-Tyrosine Kinases/antagonists & inhibitors , Focal Adhesion Protein-Tyrosine Kinases/metabolism , Gene Expression Regulation/drug effects , Glycosaminoglycans/metabolism , Humans , Intervertebral Disc Degeneration/genetics , Intervertebral Disc Degeneration/pathology , Middle Aged , Protein Kinase Inhibitors/pharmacology , Staining and Labeling , Vinculin/metabolism
13.
PLoS One ; 12(6): e0177628, 2017.
Article in English | MEDLINE | ID: mdl-28586346

ABSTRACT

In bone regenerative medicine there is a need for suitable bone substitutes. Hydrogels have excellent biocompatible and biodegradable characteristics, but their visco-elastic properties limit their applicability, especially with respect to 3D bioprinting. In this study, we modified the naturally occurring extracellular matrix glycosaminoglycan hyaluronic acid (HA), in order to yield photo-crosslinkable hydrogels with increased mechanical stiffness and long-term stability, and with minimal decrease in cytocompatibility. Application of these tailor-made methacrylated hyaluronic acid (MeHA) gels for bone tissue engineering and 3D bioprinting was the subject of investigation. Visco-elastic properties of MeHA gels, measured by rheology and dynamic mechanical analysis, showed that irradiation of the hydrogels with UV light led to increased storage moduli and elastic moduli, indicating increasing gel rigidity. Subsequently, human bone marrow derived mesenchymal stromal cells (MSCs) were incorporated into MeHA hydrogels, and cell viability remained 64.4% after 21 days of culture. Osteogenic differentiation of MSCs occurred spontaneously in hydrogels with high concentrations of MeHA polymer, in absence of additional osteogenic stimuli. Addition of bone morphogenetic protein-2 (BMP-2) to the culture medium further increased osteogenic differentiation, as evidenced by increased matrix mineralisation. MeHA hydrogels demonstrated to be suitable for 3D bioprinting, and were printed into porous and anatomically shaped scaffolds. Taken together, photosensitive MeHA-based hydrogels fulfilled our criteria for cellular bioprinted bone constructs within a narrow window of concentration.


Subject(s)
Bioprinting , Hydrogel, Polyethylene Glycol Dimethacrylate/pharmacology , Mesenchymal Stem Cells/drug effects , Osteogenesis/drug effects , Bone Regeneration , Cell Differentiation/drug effects , Cell Survival/drug effects , Cells, Cultured/drug effects , Glycosaminoglycans/chemical synthesis , Glycosaminoglycans/chemistry , Glycosaminoglycans/pharmacology , Humans , Hyaluronic Acid/chemical synthesis , Hyaluronic Acid/chemistry , Hyaluronic Acid/pharmacology , Hydrogel, Polyethylene Glycol Dimethacrylate/chemical synthesis , Hydrogel, Polyethylene Glycol Dimethacrylate/chemistry , Polymethacrylic Acids/chemical synthesis , Polymethacrylic Acids/chemistry , Polymethacrylic Acids/pharmacology , Rheology , Tissue Engineering , Tissue Scaffolds
14.
Biofabrication ; 8(3): 035003, 2016 07 19.
Article in English | MEDLINE | ID: mdl-27431733

ABSTRACT

Bioprinting of chondrocyte-laden hydrogels facilitates the fabrication of constructs with controlled organization and shape e.g. for articular cartilage implants. Gelatin-methacryloyl (gelMA) supplemented with gellan gum is a promising bio-ink. However, the rheological properties governing the printing process, and the influence of gellan gum on the mechanical properties and chondrogenesis of the blend, are still unknown. Here, we investigated the suitability of gelMA/gellan for cartilage bioprinting. Multiple concentrations, ranging from 3% to 20% gelMA with 0%-1.5% gellan gum, were evaluated for their printability, defined as the ability to form filaments and to incorporate cells at 15 °C-37 °C. To support the printability assessment, yield stress and viscosity of the hydrogels were measured. Stiffness of UV-cured constructs, as well as cartilage-like tissue formation by embedded chondrocytes, were determined in vitro. A large range of gelMA/gellan concentrations were printable with inclusion of cells and formed the bioprinting window. The addition of gellan gum improved filament deposition by inducing yielding behavior, increased construct stiffness and supported chondrogenesis. High gellan gum concentrations, however, did compromise cartilage matrix production and distribution, and even higher concentrations resulted in too high yield stresses to allow cell encapsulation. This study demonstrates the high potential of gelMA/gellan blends for cartilage bioprinting and identifies yield stress as a dominant factor for bioprintability.


Subject(s)
Bioprinting/methods , Cartilage, Articular , Hydrogels/chemistry , Polysaccharides, Bacterial/chemistry , Tissue Engineering , Biocompatible Materials , Chondrocytes , Gelatin , Materials Testing , Printing, Three-Dimensional , Tissue Scaffolds
15.
Nat Protoc ; 11(4): 727-46, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26985572

ABSTRACT

Progress in advancing a system-level understanding of the complexity of human tissue development and regeneration is hampered by a lack of biological model systems that recapitulate key aspects of these processes in a physiological context. Hence, growing demand by cell biologists for organ-specific extracellular mimics has led to the development of a plethora of 3D cell culture assays based on natural and synthetic matrices. We developed a physiological microenvironment of semisynthetic origin, called gelatin methacryloyl (GelMA)-based hydrogels, which combine the biocompatibility of natural matrices with the reproducibility, stability and modularity of synthetic biomaterials. We describe here a step-by-step protocol for the preparation of the GelMA polymer, which takes 1-2 weeks to complete, and which can be used to prepare hydrogel-based 3D cell culture models for cancer and stem cell research, as well as for tissue engineering applications. We also describe quality control and validation procedures, including how to assess the degree of GelMA functionalization and mechanical properties, to ensure reproducibility in experimental and animal studies.


Subject(s)
Biopolymers , Gelatin , Hydrogels/chemistry , Methacrylates , Tissue Culture Techniques/methods , Tissue Scaffolds/chemistry , Animals , Humans , Tissue Engineering/methods
16.
Trends Biotechnol ; 34(5): 394-407, 2016 05.
Article in English | MEDLINE | ID: mdl-26867787

ABSTRACT

Research over the past decade on the cell-biomaterial interface has shifted to the third dimension. Besides mimicking the native extracellular environment by 3D cell culture, hydrogels offer the possibility to generate well-defined 3D biofabricated tissue analogs. In this context, gelatin-methacryloyl (gelMA) hydrogels have recently gained increased attention. This interest is sparked by the combination of the inherent bioactivity of gelatin and the physicochemical tailorability of photo-crosslinkable hydrogels. GelMA is a versatile matrix that can be used to engineer tissue analogs ranging from vasculature to cartilage and bone. Convergence of biological and biofabrication approaches is necessary to progress from merely proving cell functionality or construct shape fidelity towards regenerating tissues. GelMA has a critical pioneering role in this process and could be used to accelerate the development of clinically relevant applications.


Subject(s)
Biocompatible Materials , Gelatin , Hydrogels , Methacrylates , Tissue Engineering/methods , Wound Healing/physiology , Animals , Cartilage/physiology , Humans , Mice
17.
Plast Reconstr Surg Glob Open ; 4(12): e1146, 2016 Dec.
Article in English | MEDLINE | ID: mdl-28293505

ABSTRACT

BACKGROUND: The limited cranial skin covering auricular implants is an important yet underrated factor in auricular reconstruction for both reconstruction surgery and tissue engineering strategies. We report exact measurements on skin deficiency in microtia patients and propose an accessible preoperative method for these measurements. METHODS: Plaster ear models (n = 11; male:female = 2:1) of lobular-type microtia patients admitted to the University Medical Center Utrecht in The Netherlands were scanned using a micro-computed tomographic scanner or a cone-beam computed tomographic scanner. The resulting images were converted into mesh models from which the surface area could be calculated. RESULTS: The mean total skin area of an adult-size healthy ear was 47.3 cm2, with 49.0 cm2 in men and 44.3 cm2 in women. Microtia ears averaged 14.5 cm2, with 15.6 cm2 in men and 12.6 cm2 in women. The amount of skin deficiency was 25.4 cm2, with 26.7 cm2 in men and 23.1 cm2 in women. CONCLUSIONS: This study proposes a novel method to provide quantitative data on the skin surface area of the healthy adult auricle and the amount of skin deficiency in microtia patients. We demonstrate that the microtia ear has less than 50% of skin available compared with healthy ears. Limited skin availability in microtia patients can lead to healing problems after auricular reconstruction and poses a significant challenge in the development of tissue-engineered cartilage implants. The results of this study could be used to evaluate outcomes and investigate new techniques with regard to tissue-engineered auricular constructs.

18.
Nat Commun ; 6: 6933, 2015 Apr 28.
Article in English | MEDLINE | ID: mdl-25917746

ABSTRACT

Despite intensive research, hydrogels currently available for tissue repair in the musculoskeletal system are unable to meet the mechanical, as well as the biological, requirements for successful outcomes. Here we reinforce soft hydrogels with highly organized, high-porosity microfibre networks that are 3D-printed with a technique termed as melt electrospinning writing. We show that the stiffness of the gel/scaffold composites increases synergistically (up to 54-fold), compared with hydrogels or microfibre scaffolds alone. Modelling affirms that reinforcement with defined microscale structures is applicable to numerous hydrogels. The stiffness and elasticity of the composites approach that of articular cartilage tissue. Human chondrocytes embedded in the composites are viable, retain their round morphology and are responsive to an in vitro physiological loading regime in terms of gene expression and matrix production. The current approach of reinforcing hydrogels with 3D-printed microfibres offers a fundament for producing tissue constructs with biological and mechanical compatibility.


Subject(s)
Chondrocytes/physiology , Hydrogels , Polyesters , Printing, Three-Dimensional , Tissue Scaffolds , Acrylamides , Alginates , Animals , Cartilage, Articular/physiology , Cells, Cultured , Chondrocytes/cytology , Chondrogenesis , Compressive Strength , Elasticity , Glucuronic Acid , Hexuronic Acids , Horses , Humans , Models, Theoretical
19.
Biotechnol Bioeng ; 112(9): 1927-35, 2015 Sep.
Article in English | MEDLINE | ID: mdl-25787134

ABSTRACT

Achieving the combination of delayed and immediate release of a vaccine from a delivery device without applying external triggers remains elusive in implementing single administration vaccination strategies. Here a means of vaccine delivery is presented, which exploits osmosis to trigger delayed burst release of an active compound. Poly(ε-caprolactone) capsules of 2 mm diameter were prepared by dip-coating, and their burst pressure and release characteristics were evaluated. Burst pressures (in bar) increased with wall thickness (t in mm) following Pburst = 131(.) t + 3(.) 4 (R(2) = 0.93). Upon immersion in PBS, glucose solution-filled capsules burst after 8.7 ± 2.9 days. Copolymers of hydrophobic ε -caprolactone and hydrophilic polyethylene glycol were synthesized and their physico-chemical properties were assessed. With increasing hydrophilic content, the copolymer capsules showed increased water uptake rates and maximum weight increase, while the burst release was earlier: 5.6 ± 2.0 days and 1.9 ± 0.2 days for 5 and 10 wt% polyethylene glycol, respectively. The presented approach enables the reproducible preparation of capsules with high versatility in materials and properties, while these vaccine delivery vehicles can be prepared separately from, and independently of the active compound.


Subject(s)
Drug Delivery Systems/instrumentation , Polyesters/chemistry , Polyethylene Glycols/chemistry , Vaccination/instrumentation , Osmosis , Pressure , Water
20.
Acta Biomater ; 10(6): 2551-62, 2014 Jun.
Article in English | MEDLINE | ID: mdl-24590158

ABSTRACT

Modern cancer research requires physiological, three-dimensional (3-D) cell culture platforms, wherein the physical and chemical characteristics of the extracellular matrix (ECM) can be modified. In this study, gelatine methacrylamide (GelMA)-based hydrogels were characterized and established as in vitro and in vivo spheroid-based models for ovarian cancer, reflecting the advanced disease stage of patients, with accumulation of multicellular spheroids in the tumour fluid (ascites). Polymer concentration (2.5-7% w/v) strongly influenced hydrogel stiffness (0.5±0.2kPa to 9.0±1.8kPa) but had little effect on solute diffusion. The diffusion coefficient of 70kDa fluorescein isothiocyanate (FITC)-labelled dextran in 7% GelMA-based hydrogels was only 2.3 times slower compared to water. Hydrogels of medium concentration (5% w/v GelMA) and stiffness (3.4kPa) allowed spheroid formation and high proliferation and metabolic rates. The inhibition of matrix metalloproteinases and consequently ECM degradability reduced spheroid formation and proliferation rates. The incorporation of the ECM components laminin-411 and hyaluronic acid further stimulated spheroid growth within GelMA-based hydrogels. The feasibility of pre-cultured GelMA-based hydrogels as spheroid carriers within an ovarian cancer animal model was proven and led to tumour development and metastasis. These tumours were sensitive to treatment with the anti-cancer drug paclitaxel, but not the integrin antagonist ATN-161. While paclitaxel and its combination with ATN-161 resulted in a treatment response of 33-37.8%, ATN-161 alone had no effect on tumour growth and peritoneal spread. The semi-synthetic biomaterial GelMA combines relevant natural cues with tunable properties, providing an alternative, bioengineered 3-D cancer cell culture in in vitro and in vivo model systems.


Subject(s)
Acrylamides/chemistry , Gelatin/chemistry , Hydrogels , Cell Division , Cell Line, Tumor , Cells, Cultured , Extracellular Matrix/enzymology , Extracellular Matrix/metabolism , Humans , Matrix Metalloproteinases/drug effects
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