Scaffolds Based on Poly(3-Hydroxybutyrate) and Its Copolymers for Bone Tissue Engineering (Review)

Innovative Biocompatible Blend Scaffold of Poly(hydroxybutyrate-co-hydroxyvalerate) and Poly(ε-caprolactone) for Bone Tissue Engineering: In Vitro and In Vivo Evaluation

This study evaluated the biocompatibility of dense and porous forms of Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), Poly(ε-caprolactone) (PCL), and their 75/25 blend for bone tissue engineering applications. The biomaterials were characterized morphologically using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), and the thickness and porosity of the scaffolds were determined. Functional assessments of mesenchymal stem cells (MSCs) included the MTT assay, alkaline phosphatase (ALP) production, and morphological and cytochemical analyses. Moreover, these polymers were implanted into rats to evaluate their in vivo performance. The morphology and FTIR spectra of the scaffolds were consistent with the expected results. Porous polymers were thicker than dense polymers, and porosity was higher than 92% in all samples. The cells exhibited good viability, activity, and growth on the scaffolds. A higher number of cells was observed on dense polymers, likely due to their smaller surface area. ALP production occurred in all samples, but enzyme activity was more intense in PCL samples. The scaffolds did not interfere with the osteogenic capacity of MSCs, and mineralized nodules were present in all samples. Histological analysis revealed new bone formation in all samples, although pure PHBV exhibited lower results compared to the other blends. In vivo results indicated that dense PCL and the dense 75/25 blend were the best materials tested, with PCL tending to improve the performance of PHBV in vivo.

Efficacy of Poly-3-Hydroxybutyrate Enriched with Simvastatin in Bone Regeneration after Tooth Extraction (Experimental Study)

Physiological resorption of bone tissue after tooth extraction leads to a decrease in the volume of bone tissue available for implantation and makes it difficult to install dental implants. Preservation of the well after tooth extraction is the solution to this problem, with the choice of bone plastic material playing an important role. The development of an "ideal" bone plastic material with osteoinductive properties that promotes reparative bone regeneration remains an urgent task. The aim of the study was to evaluate the regeneration of bone tissue of the alveolar ridge during implantation of a new osteoinductive bone plastic material containing simvastatin into the wells of extracted teeth in sheep using microcomputer tomography.

MATERIALS AND METHODS

The study was conducted on 24 adult sheep with a total of 48 teeth removed. 12 wells were filled with material based on poly(3-hydroxybutyrate) (PHB) with simvastatin; 12 wells were filled with PHB-based material without simvastatin, 24 wells were used as a control. Micro-CT was used for comparative analysis of bone tissue formation between the test groups after 3 and 6 months.

RESULTS

The results of the study confirm the positive effect of simvastatin released from the PHB-based osteoplastic material on the volume of the formed bone tissue and the total bone volume in the defect area (BV/TV) and bone mineral density (BMD) 3 and 6 months after surgery.

CONCLUSION

The study demonstrated that simvastatin, released from the PHB-based osteoplastic material, has an osteoinductive effect, promoting bone tissue regeneration in the wells left after tooth removal. Higher BV/TV and BMD values in the wells indicate better efficacy of the material in terms of regeneration support.

Evaluation of Chemical and Biological Properties of Biodegradable Composites Based on Poly(3-hydroxybutyrate) and Chitosan

In this study, composite films and scaffolds of polyester poly(3-hydroxybutyrate) and polysaccharide chitosan obtained via a simple and reproducible blending method using acetic acid as a solvent were considered. The degradation process of the films was studied gravimetrically in a model biological medium in the presence of enzymes in vitro for 180 days. The kinetics of weight reduction depended on the amount of chitosan in the composition. The biocompatibility of the films was evaluated using the Alamar blue test and fluorescence microscopy. The materials were non-cytotoxic, and the addition of poly(3-hydroxybutyrate) to chitosan improved its matrix properties on mesenchymal stem cells. Then, the 3D composites were prepared by freeze-drying. Their structure (using SEM), rheological behavior, moisture absorption, and porosity were investigated. The addition of different amounts of chitosan allowed us to vary the chemical and biological properties of poly(3-hydroxybutyrate) materials and their degradation rate, which is extremely important in the development of biomedical poly(3-hydroxybutyrate) materials, especially implantable ones.

Preparation and characterization of poly(3-hydroxybutyrate)/chitosan composite films using acetic acid as a solvent

Poly(3-hydroxybutyrate) and chitosan are among the most widely used polymers for biomedical applications due to their biocompatibility, renewability and low toxicity. The creation of composite materials based on biopolymers belonging to different classes makes it possible to overcome the disadvantages of each of the components and to obtain a material with specific properties. Solving this problem is associated with difficulties in the selection of conditions and solvents for obtaining the composite material. In our study, acetic acid was used as a common solvent for hydrophobic poly(3-hydroxybutyrate) and chitosan. Mechanical, thermal, physicochemical and surface properties of the composites and homopolymers were investigated. The composite films had less crystallinity and hydrophobicity than poly(3-hydroxybutyrate), and the addition of chitosan caused an increase in moisture absorption, a decrease in contact angle and changes in mechanical properties of the poly(3-hydroxybutyrate). The inclusion of varying amounts of chitosan controlled the properties of the composite, which will be important in the future for its specific biomedical applications.