Osteoinductive Moldable and Curable Bone Substitutes Based on Collagen, BMP-2 and Highly Porous Polylactide Granules, or a Mix of HAP/β-TCP

Highly Porous Particles of Cellulose Derivatives for Advanced Applications

A chemical modification of cellulose diacetate by phthalate and nitrate was performed to increase solubility in organic solvents and change the electrical properties. The role of substituents on the conductivity, permittivity, and polarizability of cellulose films is revealed. It has been shown that highly porous micro particles can be obtained from cellulose derivatives by a simple and technological freeze-drying method. The resulting micro sized aerogels have a predominantly spherical morphology and amorphous structure. Suspensions of porous particles of nitro- and phthalylated cellulose derivatives in silicone oil have an increased dielectric permittivity compared to cellulose diacetate particles. Produced particles are novel promising material with tunable electrical properties for advanced applications in composites, including for electrorheological fluids.

Application of BMP-2 and its gene delivery vehicles in dentistry

The restoration of bone defects resulting from tooth loss, periodontal disease, severe trauma, tumour resection and congenital malformations is a crucial task in dentistry and maxillofacial surgery. Growth factor- and gene-activated bone graft substitutes can be used instead of traditional materials to solve these problems. New materials will overcome the low efficacy and difficulties associated with the use of traditional bone substitutes in complex situations. One of the most well-studied active components for bone graft substitutes is bone morphogenetic protein-2 (BMP-2), which has strong osteoinductive properties. The aim of this review was to examine the use of BMP-2 protein and gene therapy for bone regeneration in the oral and maxillofacial region and to discuss its future use.

Controlled release of a non-steroidal anti-inflammatory drug from a photocurable polymeric calcium phosphate cement

In this research, a photocurable composite based on tetracalcuim phosphate ceramic and, hydroxyethyl methacrylate-modified poly(acrylic-maleic acid) was developed and studied as a potential drug delivery system for bone defects. Different concentrations (5, 10 and 20 wt. %) of a non-steroidal anti-inflammatory drug, Indomethacin, were loaded on to the composite and its release behavior was investigated in phosphate buffered solution during 504 h. The obtained release data were fitted by both power law (Peppas) and Weibull equations. The composites were also characterized after different soaking periods using X-ray diffractometry (XRD), scanning electron microscopy (SEM) and Fourier transforming infrared spectroscopy. The results of XRD and SEM analyses revealed the formation of nanosized needle/flake-like apatite crystals on the composites surfaces; however, better apatite formation was observed for the composites loaded with higher amounts of Indomethacin. The morphological observations and quantitative estimations revealed that the loaded composites were gradually degraded in the phosphate-buffered saline. Moreover, a controlled release of Indomethacin was found from the composites in which a higher drug concentration led to a more drug level as well as sustained release profile. In drug release modeling, better regression coefficient was obtained from the Weibull equation, compared to the power law, meaning that the Weibull equation suggests a better description of the indomethacin release from the composites during the whole period of the test. In conclusion, the photocurable composite with apatite formation ability can be successfully used for the controlled release of indomethacin as an anti-inflammatory drug in bone defects.

Adenovirus-Based Gene Therapy for Bone Regeneration: A Comparative Analysis of In Vivo and Ex Vivo BMP2 Gene Delivery

Adenovirus-mediated gene therapy is a promising tool in bone regenerative medicine. In this work, gene-activated matrices (GAMs) composed of (1) polylactide granules (PLA), which serve as a depot for genetic constructs or matrices for cell attachment, (2) a PRP-based fibrin clot, which is a source of growth factors and a binding gel, and (3) a BMP2 gene providing osteoinductive properties were studied. The study aims to compare the effectiveness of in vivo and ex vivo gene therapy based on adenoviral constructs with the BMP2 gene, PLA particles, and a fibrin clot for bone defect healing. GAMs with Ad-BMP2 and MSC(Ad-BMP2) show osteoinductive properties both in vitro and in vivo. However, MSCs incubated with GAMs containing transduced cells showed a more significant increase in osteopontin gene expression, protein production, Alpl activity, and matrix mineralization. Implantation of the studied matrices into critical-size calvarial defects after 56 days promotes the formation of young bone. The efficiency of neoosteogenesis and the volume fraction of newly formed bone tissue are higher with PLA/PRP-MSC(Ad-BMP2) implantation (33%) than PLA/PRP-Ad-BMP2 (28%). Thus, ex vivo adenoviral gene therapy with the BMP2 gene has proven to be a more effective approach than the in vivo delivery of gene constructs for bone regeneration.

Remotely Temporal Scheduled Macrophage Phenotypic Transition Enables Optimized Immunomodulatory Bone Regeneration

Precise timing of macrophage polarization plays a pivotal role in immunomodulation of tissue regeneration, yet most studies mainly focus on M2 macrophages for their anti-inflammatory and regenerative effects while the essential proinflammatory role of the M1 phenotype on the early inflammation stage is largely underestimated. Herein, a superparamagnetic hydrogel capable of timely controlling macrophage polarization is constructed by grafting superparamagnetic nanoparticles on collagen nanofibers. The magnetic responsive hydrogel network enables efficient polarization of encapsulated macrophage to the M2 phenotype through the podosome/Rho/ROCK mechanical pathway in response to static magnetic field (MF) as needed. Taking advantage of remote accessibility of magnetic field together with the superparamagnetic hydrogels, a temporal engineered M1 to M2 transition course preserving the essential role of M1 at the early stage of tissue healing, as well as enhancing the prohealing effect of M2 at the middle/late stages is established via delayed MF switch. Such precise timing of macrophage polarization matching the regenerative process of injured tissue eventually leads to optimized immunomodulatory bone healing in vivo. Overall, this study offers a remotely time-scheduled approach for macrophage polarization, which enables precise manipulation of inflammation progression during tissue healing.