| 1. |
- Yan, Hongji, et al.
(författare)
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Synthetic design of growth factor sequestering extracellular matrix mimetic hydrogel for promoting in vivo bone formation
- 2018
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Ingår i: Biomaterials. - : Elsevier. - 0142-9612 .- 1878-5905. ; 161, s. 190-202
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Tidskriftsartikel (refereegranskat)abstract
- Synthetic scaffolds that possess an intrinsic capability to protect and sequester sensitive growth factors is a primary requisite for developing successful tissue engineering strategies. Growth factors such as recombinant human bone morphogenetic protein-2 (rhBMP-2) is highly susceptible to premature degradation and to provide a meaningful clinical outcome require high doses that can cause serious side effects. We discovered a unique strategy to stabilize and sequester rhBMP-2 by enhancing its molecular interactions with hyaluronic acid (HA), an extracellular matrix (ECM) component. We found that by tuning the initial protonation state of carboxylic acid residues of HA in a covalently crosslinked hydrogel modulate BMP-2 release at physiological pH by minimizing the electrostatic repulsion and maximizing the Van der Waals interactions. At neutral pH, BMP-2 release is primarily governed by Fickian diffusion, whereas at acidic pH both diffusion and electrostatic interactions between HA and BMP-2 become important as confirmed by molecular dynamics simulations. Our results were also validated in an in vivo rat ectopic model with rhBMP-2 loaded hydrogels, which demonstrated superior bone formation with acidic hydrogel as compared to the neutral counterpart. We believe this study provides new insight on growth factor stabilization and highlights the therapeutic potential of engineered matrices for rhBMP-2 delivery and may help to curtail the adverse side effects associated with the high dose of the growth factor.
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| 2. |
- Martinez-Sanz, Elena, et al.
(författare)
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Bone reservoir : Injectable hyaluronic acid hydrogel for minimal invasive bone augmentation
- 2011
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Ingår i: Journal of Controlled Release. - : Elsevier BV. - 0168-3659 .- 1873-4995. ; 152:2, s. 232-240
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Tidskriftsartikel (refereegranskat)abstract
- A strategy has been designed to develop hyaluronic acid (HA) hydrogel for in vivo bone augmentation using minimal invasive technique. A mild synthetic procedure was developed to prepare aldehyde modified HA by incorporating an amino-glycerol side chain via amidation reaction and selective oxidation of the pendent group. This modification, upon mixing with hydrazide modified HA formed hydrazone-crosslinked hydrogel within 30 s that was stable at physiological pH. In vitro experiments showed no cytotoxicity of hydrogel with the controlled release of active bone morphogenic protein-2 (BMP-2). In vivo evaluation of this gel as a BMP-2 carrier was performed by injecting gels over the rat calvarium and showed bone formation in 8 weeks in correlation with the amount of BMP-2 loaded (0, 1 and 30 pig) within the gel. Furthermore, hydrogels with 30 Kg of BMP-2 induced less bone formation upon subcutaneous injection in comparison with subperiosteal implantation. Histological examination showed newly formed bone with a high expression of osteocalcin, osteopontin and with angiogenic bone marrow when higher BMP-2 concentration was employed. Our result suggests that novel HA hydrogels could be used as a BMP-2 carrier and can promote bone augmentation for potential orthopedic applications.
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| 3. |
- Paidikondala, Maruthibabu, 1985-, et al.
(författare)
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Impact of Hydrogel Cross-Linking Chemistry on the in Vitro and in VivoBioactivity of Recombinant Human Bone Morphogenetic Protein-2
- 2019
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Ingår i: ACS Applied Bio Materials. - : American Chemical Society (ACS). - 2576-6422.
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Tidskriftsartikel (refereegranskat)abstract
- Designing strategies to deliver functional proteins at physiologically relevant concentrations using chemically cross-linked biocompatible hydrogels is a major field of research. However, the impact of cross-linking chemistry on the encapsulated protein bioactivity is rarely studied. Here we examine the two well-known cross-linking reactions namely; hydrazone cross-linking chemistry and thiol-Michael addition reaction to form hyaluronic acid (HA) hydrogels. As a therapeutic protein, we employed recombinant human bone morphogenetic protein-2 (rhBMP-2) for this study. Incubation of rhBMP-2 with HA functionalized with a thiol diminished phosphorylation of Smad 1/5/8, a signal transducer for osteogenic differntiation, whereas an aldehyde functionalized HA had no effect. This indicates that thiol functionalized polymers indeed has an impact on protein function. To validate this result in an in vivo setting we performed BMP-2 induced bone formation in a rat ectopic model. These experiments revealed that the hydrazone-cross-linked HA-hydrogel induced significantly higher bone formation (18.90 ± 4.25 mm3) as compared to the HA-thiol-Michael hydrogels (1.25 ± 0.52 mm3) after 8 weeks as determined by micro-computed tomography. The histological examination of the neo-bone indicated that hydrazone-hydrogels promoted a better quality of bone formation with improved mineralization and collagen formation as compared to the thiol-Michael hydrogels. We believe such a direct comparison of two cross-linking chemistries will provide new insight for developing biomaterials for protein delivery for in vivo applications.
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| 4. |
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| 5. |
- Yan, Hongji, et al.
(författare)
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The choice of crosslinking chemistry for hydrogel development influences BMP-2 stability and bioactivity in vivo
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Annan publikation (populärvet., debatt m.m.)abstract
- Site-specific administration of bone morphogenetic protein-2 (BMP-2) at the site of a bone fracture via scaffolds can minimise systemic side-effects and exhibit sustained biological effects. While this method requires sufficient scaffolds to preserve the BMP-2 structure and tuned release patterns, the incorporation of thiol-acrylate chemistry has shown great success in scaffold synthesis. However, thiolates attack the sulphur atoms of disulphide bonds, displacing the other sulphur atom and forming a new disulphide bond, hence at physiological conditions, thiol-modified scaffold components could potentially attack inter-chain disulphide bonds of BMP-2 by thiol-exchange reactions. This therefore led us to compare hyaluronic acid (HA) hydrogels synthesised via thiol-acrylate (HA-S) and hydrazone crosslinking chemistry (HA-H) formed BMP-2 carriers. The study revealed the integrity of BMP-2 dimer structures can be disrupted and reveals the osteogenic capacity of BMP-2 by HA derivatives (HA-SH). BMP-2 bioactivity released from HA-S hydrogels are decreased when compared to HA-H hydrogels. This was further confirmed via the rat ectopic bone model, showing that bone volume was significantly higher when induced by HA-H hydrogels with BMP-2 than compared to HA-S hydrogel with BMP-2. This study gives new insights into scaffolds synthesis, showing that biomolecule bioactivity needs to be considered when choosing a chemistry for scaffolds synthesis.
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| 6. |
- Yan, Hongji, et al.
(författare)
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Tuning biomaterial pH for regulating BMP-2 stability and bioactivity in vitro and in vivo
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Annan publikation (populärvet., debatt m.m.)abstract
- The poor affinity of rhBMP-2 to the scaffolds leads to high dose administration requirement resulted in massive side effects has been the hurdle for successful clinic translation for treating delayed unions or remained non-union at bone defect. Optimizing the scaffolds with the purpose of obtaining optimal BMP2 dose and release have been addressed as critical for BMP-2 administration, however, the results are contradictory concerning whether bone formation is more beneficial from burst or controlled release of BMP2. While this might be due to these studies incorporated other bioactive molecules onto scaffolds to immobilize BMP-2. In this study, we report the affinities of rhBMP-2 to the scaffolds can be improved by only tuning the pH of hyaluronic acid (HA) hydrazone crosslinking hydrogel without addition of other molecules. Neo bone induced by BMP-2 showed significantly higher volume with more impact structure and vascularization in pH 4.5 HA hydrogel compared to that in pH7 HA hydrogel. The mechanisms were demonstrated by In vitro BMP-2 release followed by diffusion quantitative calculation and computational simulation methods. Initial burst release of BMP-2 from pH 7 HA hydrogels with the fitting of Fickian behavior while sustained release from pH 4.5 HA hydrogel was observed. Computational stimulation revealed this is due to the protonation state of BMP2 at pH 4.5 resulted in stronger electrostatic interaction with negatively charged groups along the backbone of hyaluronic acid molecules compared to at pH 7. This study gives new direction to scaffolds designing for basic bioactive protein applications in future.
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