| 1. |
- Fursatz, Marian, et al.
(författare)
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Functionalization of bacterial cellulose wound dressings with the antimicrobial peptide ε-poly-L-Lysine
- 2018
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Ingår i: Biomedical Materials. - : Institute of Physics Publishing (IOPP). - 1748-6041 .- 1748-605X. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Wound dressings based on bacterial cellulose (BC) can form a soft and conformable protective layer that can stimulate wound healing while preventing bacteria from entering the wound. Bacteria already present in the wound can, however, thrive in the moist environment created by the BC dressing which can aggravate the healing process. Possibilities to render the BC antimicrobial without affecting the beneficial structural and mechanical properties of the material would hence be highly attractive. Here we present methods for functionalization of BC with ε-Poly-L-Lysine (ε-PLL), a non-toxic biopolymer with broad-spectrum antimicrobial activity. Low molecular weight ε-PLL was cross-linked in pristine BC membranes and to carboxymethyl cellulose (CMC) functionalized BC using carbodiimide chemistry. The functionalization of BC with ε-PLL inhibited growth of S. epidermidis on the membranes but did not affect the cytocompatibility to cultured human fibroblasts as compared to native BC. The functionalization had no significant effects on the nanofibrous structure and mechanical properties of the BC. The possibility to functionalize BC with ε-PLL is a promising, green and versatile approach to improve the performance of BC in wound care and other biomedical applications.
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| 2. |
- Gallinetti, Sara, 1985-, et al.
(författare)
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Titanium reinforced calcium phosphate improves bone formation and osteointegration in ovine calvaria defects : a comparative 52 weeks study
- 2021
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Ingår i: Biomedical Materials. - : Institute of Physics Publishing (IOPP). - 1748-6041 .- 1748-605X. ; 16:3
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Tidskriftsartikel (refereegranskat)abstract
- In a 52 week ovine calvaria implantation model, the restoration of cranial defects with a bare titanium mesh (Ti-mesh) and a titanium mesh embedded in a calcium phosphate (CaP-Ti) were evaluated in seven animals. During the study, no major clinical abnormalities were observed, and all sheep presented a normal neurologic assessment. Blood and cerebrospinal fluid analysis, made at termination, did not show any abnormalities. No indentation of the soft tissue was observed for either test article; however, the Ti-mesh burr-hole covers were associated with filling of the calvarial defect by fibrous tissue mainly. Some bone formation was observed at the bottom of the created defect, but no significant bone was formed in the proximity of the implant. The defect sites implanted with CaP-Ti were characterized by a moderate degradation of the calcium phosphate (CaP) that was replaced by mature bone tissue. Calcium-phosphate-filled macrophages were observed in all animals, indicating that they might play a vital role in osteogenesis. The newly formed bone was present, especially at the bony edges of the defect and on the dura side. Integration of the Ti-mesh in a CaP improved bone formation and osteointegration in comparison to a bare Ti-mesh.
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| 3. |
- Guillet, Claire, et al.
(författare)
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Bone formation beyond the skeletal envelope using calcium phosphate granules packed into a collagen pouch-a pilot study
- 2023
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Ingår i: Biomedical Materials. - : Institute of Physics Publishing (IOPP). - 1748-6041 .- 1748-605X. ; 18:3
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Tidskriftsartikel (refereegranskat)abstract
- In this proof-of-concept, bone neoformation beyond the skeletal envelope is explored by using a collagen pouch (n = 6) packed with calcium phosphate (CaP) granules placed over the frontal bone in sheep (n = 3). At 13 weeks, macroscopic examination showed specimens covered by an adherent fibrinous envelope with slight vascularization. Histology revealed colonization of the implant by newly formed woven bone and fibrous connective tissue. Surface osteoblasts as well as material-filled macrophages, lymphocytes, polymorphonuclear cells and giant cells were also found in large quantities surrounding the newly formed bone tissue inside the collagen pouch. On the side facing the recipient bone, the collagen membrane had to a large extent been resorbed and bridging bone formation was clearly visible between the test article and recipient bone. On the other side facing soft tissue, the collagen pouch remained intact with a visible fibrous capsule. This study demonstrated that the use of a collagen sleeve as a container for CaP granules allows for good neoformation beyond the skeletal envelope with bridging bone formation clearly visible between the test article and recipient bone. Additionally, in this model, macrophages rather than osteoclasts appear to modulate CaP granule resorption and remodeling into new bone. This construct opens new perspectives for treatment methods that could be used for bone augmentation and restoration of cranio-maxillofacial defects and malformations.
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| 4. |
- Han, Yuanyuan, et al.
(författare)
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Flexible conductive silk-PPy hydrogel toward wearable electronic strain sensors
- 2022
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Ingår i: Biomedical Materials. - : IOP Publishing Ltd. - 1748-6041 .- 1748-605X. ; 17:2
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Tidskriftsartikel (refereegranskat)abstract
- Conductive hydrogels have been studied as promising materials for the flexible and wearable bioelectronics, because of their unique electrical and mechanical properties. Addition of conducting polymers in biomaterial-based hydrogel matrix is a simple yet effective way to construct hydrogels with good conductivity and flexibility. In this work, a conductive hydrogel composed by a silk hydrogel and a conducting polymer, polypyrrole (PPy), is developed via in situ polymerization of pyrrole into the silk fibroin network. The silk-PPy hydrogel shows high conductivity (26 S m(-1)), as well as sensitive and fast responses to corresponding conformation changes. Taking advantages of these properties, flexible and wearable strain sensors are proposed for the monitoring of various body movements, which can detect both the large and subtle human motions with good sensitivity, reproducibility and stability. The hybridization of biomaterials and conducting polymers endows the multifunctions of the conductive hydrogels, thus showing considerable potentials in the advancement of the wearable electronics.
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| 5. |
- Ji, Zhenbing, et al.
(författare)
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Effects of surface morphology and composition of titanium implants on osteogenesis and inflammatory responses : a review
- 2023
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Ingår i: Biomedical Materials. - : IOP Publishing. - 1748-6041 .- 1748-605X. ; 18:4
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Forskningsöversikt (refereegranskat)abstract
- Titanium and its alloys have been widely used in bone tissue defect treatment owing to their excellent comprehensive properties. However, because of the biological inertness of the surface, it is difficult to achieve satisfactory osseointegration with the surrounding bone tissue when implanted into the body. Meanwhile, an inflammatory response is inevitable, which leads to implantation failure. Therefore, solving these two problems has become a new research hotspot. In current studies, various surface modification methods were proposed to meet the clinical needs. Yet, these methods have not been classified as a system to guide the follow-up research. These methods are demanded to be summarized, analyzed, and compared. In this manuscript, the effect of physical signal regulation (multi-scale composite structure) and chemical signal regulation (bioactive substance) generated by surface modification in promoting osteogenesis and reducing inflammatory responses was generalized and discussed. Finally, from the perspective of material preparation and biocompatibility experiments, the development trend of surface modification in promoting titanium implant surface osteogenesis and anti-inflammatory research was proposed.
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| 6. |
- Lewin, Susanne, et al.
(författare)
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Evaluation of bone formation in calcium phosphate scaffolds with μCT-method validation using SEM
- 2017
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Ingår i: Biomedical Materials. - : Institute of Physics (IOP). - 1748-6041 .- 1748-605X. ; 12:6
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Tidskriftsartikel (refereegranskat)abstract
- There is a plethora of calcium phosphate (CaP) scaffolds used as synthetic substitutes to bone grafts. The scaffold performance is often evaluated from the quantity of bone formed within or in direct contact with the scaffold. Micro-computed tomography (mu CT) allows three-dimensional evaluation of bone formation inside scaffolds. However, the almost identical x-ray attenuation of CaP and bone obtrude the separation of these phases in mu CT images. Commonly, segmentation of bone in mu CT images is based on gray scale intensity, with manually determined global thresholds. However, image analysis methods, and methods for manual thresholding in particular, lack standardization and may consequently suffer from subjectivity. The aim of the present study was to provide a methodological framework for addressing these issues. Bone formation in two types of CaP scaffold architectures (foamed and robocast), obtained from a larger animal study (a 12 week canine animal model) was evaluated by mu CT. In addition, cross-sectional scanning electron microscopy (SEM) images were acquired as references to determine thresholds and to validate the result. mu CT datasets were registered to the corresponding SEM reference. Global thresholds were then determined by quantitatively correlating the different area fractions in the mu CT image, towards the area fractions in the corresponding SEM image. For comparison, area fractions were also quantified using global thresholds determined manually by two different approaches. In the validation the manually determined thresholds resulted in large average errors in area fraction (up to 17%), whereas for the evaluation using SEM references, the errors were estimated to be less than 3%. Furthermore, it was found that basing the thresholds on one single SEM reference gave lower errors than determining them manually. This study provides an objective, robust and less error prone method to determine global thresholds for the evaluation of bone formation in CaP scaffolds.
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| 7. |
- Li, Ya, et al.
(författare)
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Click chemistry-based biopolymeric hydrogels for regenerative medicine
- 2021
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Ingår i: Biomedical Materials. - : Institute of Physics Publishing (IOPP). - 1748-6041 .- 1748-605X. ; 16:2
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Forskningsöversikt (refereegranskat)abstract
- Click chemistry is not a single specific reaction, but describes ways of generating products which emulate examples in nature. Click reactions occur in one pot, are not disturbed by water, generate minimal and inoffensive byproducts, and are characterized by a high thermodynamic driving force, driving the reaction quickly and irreversibly towards a high yield of a single reaction product. As a result, over the past 15 years it has become a very useful bio-orthogonal method for the preparation of chemical cross-linked biopolymer-based hydrogel, in the presence of e.g. growth factors and live cells, or in-vivo. Biopolymers are renewable and non-toxic, providing a myriad of potential backbone toolboxes for hydrogel design. The goal of this review is to summarize recent advances in the development of click chemistry-based biopolymeric hydrogels, and their applications in regenerative medicine. In particular, various click chemistry approaches, including copper-catalyzed azide-alkyne cycloaddition reactions, copper-free click reactions (e.g. the Diels-Alder reactions, the strain-promoted azide-alkyne cycloaddition reactions, the radical mediated thiol-ene reactions, and the oxime-forming reactions), and pseudo-click reactions (e.g. the thiol-Michael addition reactions and the Schiff base reactions) are highlighted in the first section. In addition, numerous biopolymers, including proteins (e.g. collagen, gelatin, silk, and mucin), polysaccharides (e.g. hyaluronic acid, alginate, dextran, and chitosan) and polynucleotides (e.g. deoxyribonucleic acid), are discussed. Finally, we discuss biopolymeric hydrogels, cross-linked by click chemistry, intended for the regeneration of skin, bone, spinal cord, cartilage, and cornea. This article provides new insights for readers in terms of the design of regenerative medicine, and the use of biopolymeric hydrogels based on click chemistry reactions.
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| 8. |
- Mellgren, Torbjörn, 1986-, et al.
(författare)
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Guided bone tissue regeneration using a hollow calcium phosphate based implant in a critical size rabbit radius defect
- 2021
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Ingår i: Biomedical Materials. - : Institute of Physics Publishing (IOPP). - 1748-6041 .- 1748-605X. ; 16:3
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Tidskriftsartikel (refereegranskat)abstract
- Long bone fractures are common and sometimes difficult to treat. Autologous bone (AB), bovine bone and calcium phosphates are used to stimulate bone growth with varying results. In the present study, a calcium phosphate cement (CPC) that previously showed promising grafting capabilities was evaluated for the first time in a long bone defect. A radius defect of 20 mm was created in 20 rabbits. The defect was filled by either a hollow CPC implant that had been manufactured as a replica of a rabbit radius through indirect 3D printing, or by particulate AB as control. Defect filling and bone formation was evaluated after 12 weeks by combining micro computed tomography (mu CT) and scoring of 3D images, together with histomorphometry and histology. The mu CT and histomorphometric evaluations showed a similar amount of filling of the defect (combining graft and bone) between the CPC and AB group, but the scoring of 3D images showed that the filling in the CPC group was significantly larger. Histologically the AB graft could not be distinguished from the new bone. The AB treated defects were found to be composed of more bone than the CPC group, including reorganised cancellous and cortical bone. Both the CPC and AB material was associated with new bone formation, also in the middle of the defect, which could result in closing of the otherwise critically sized gap. This study shows the potential for an indirectly 3D printed implant in guided bone regeneration in critically sized long bone defects.
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| 9. |
- Oskarsdotter, Kristin, 1995, et al.
(författare)
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Autologous endothelialisation by the stromal vascular fraction on laminin-bioconjugated nanocellulose-alginate scaffolds
- 2023
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Ingår i: Biomedical Materials (Bristol). - 1748-605X .- 1748-6041. ; 18:4
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Tidskriftsartikel (refereegranskat)abstract
- Establishing a vascular network in biofabricated tissue grafts is essential for ensuring graft survival. Such networks are dependent on the ability of the scaffold material to facilitate endothelial cell adhesion; however, the clinical translation potential of tissue-engineered scaffolds is hindered by the lack of available autologous sources of vascular cells. Here, we present a novel approach to achieving autologous endothelialisation in nanocellulose-based scaffolds by using adipose tissue-derived vascular cells on nanocellulose-based scaffolds. We used sodium periodate-mediated bioconjugation to covalently bind laminin to the scaffold surface and isolated the stromal vascular fraction and endothelial progenitor cells (EPCs; CD31+CD45−) from human lipoaspirate. Additionally, we assessed the adhesive capacity of scaffold bioconjugation in vitro using both adipose tissue-derived cell populations and human umbilical vein endothelial cells. The results showed that the bioconjugated scaffold exhibited remarkably higher cell viability and scaffold surface coverage by adhesion regardless of cell type, whereas control groups comprising cells on non-bioconjugated scaffolds exhibited minimal cell adhesion across all cell types. Furthermore, on culture day 3, EPCs seeded on laminin-bioconjugated scaffolds showed positive immunofluorescence staining for the endothelial markers CD31 and CD34, suggesting that the scaffolds promoted progenitor differentiation into mature endothelial cells. These findings present a possible strategy for generating autologous vasculature and thereby increase the clinical relevance of 3D-bioprinted nanocellulose-based constructs.
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| 10. |
- Safarpour, F., et al.
(författare)
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Kappa-carrageenan based hybrid hydrogel for soft tissue engineering applications
- 2023
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Ingår i: Biomedical Materials. - : IOP Publishing. - 1748-6041 .- 1748-605X. ; 18:5
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Tidskriftsartikel (refereegranskat)abstract
- Biological materials such as cell-derived membrane vesicles have emerged as alternative sources for molecular delivery systems, owing to multicomponent features, the inherent functionalities and signaling networks, and easy-to-carry therapeutic agents with various properties. Herein, red blood cell membrane (RBCM) vesicle-laden methacrylate kappa-carrageenan (KaMA) composite hydrogel is introduced for soft tissue engineering. Results revealed that the characteristics of hybrid hydrogels were significantly modulated by changing the RBCM vesicle content. For instance, the incorporation of 20% (v/v) RBCM significantly enhanced compressive strength from 103 & PLUSMN; 26 kPa to 257 & PLUSMN; 18 kPa and improved toughness under the cyclic loading from 1.0 & PLUSMN; 0.4 kJ m(-3) to 4.0 & PLUSMN; 0.5 kJ m(-3) after the 5(th) cycle. RBCM vesicles were also used for the encapsulation of curcumin (CUR) as a hydrophobic drug molecule. Results showed a controlled release of CUR over three days of immersion in PBS solution. The RBCM vesicles laden KaMA hydrogels also supported in vitro fibroblast cell growth and proliferation. In summary, this research sheds light on KaMA/RBCM hydrogels, that could reveal fine-tuned properties and hydrophobic drug release in a controlled manner.
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