Background Three-dimensional (3D) printing is a capable approach for the fabrication of bone tissue scaffolds. Nevertheless, a purely made scaffold such as polylactic acid (PLA) may suffer from shortcomings and be restricted due to its biological behavior. Gelatin, hydroxyapatite and platelet-rich plasma (PRP) have been revealed to be of potential to enhance the osteogenic effect. In this study, it was tried to improve the properties of 3D-printed PLA scaffolds by infilling them with gelatin-nano-hydroxyapatite (PLA/G-nHA) and subsequent coating with PRP. For comparison, bare PLA and PLA/G-nHA scaffolds were also fabricated. The printing accuracy, the scaffold structural characterizations, mechanical properties, degradability behavior, cell adhesion, mineralization, systemic effect of the scaffolds on the liver enzymes, osteocalcin level in blood serum and in vivo bone regeneration capability in rat critical-sized calvaria defect were evaluated. Results High printing accuracy (printing error of < 11%) was obtained for all measured parameters including strut thickness, pore width, scaffold density and porosity%. The highest mean ultimate compression strength (UCS) was associated with PLA/G-nHA/PRP scaffolds, which was 10.95 MPa. A slow degradation rate was observed for all scaffolds. The PLA/G-nHA/PRP had slightly higher degradation rate, possibly due to PRP release, with burst release occurred at week 4. The MTT results showed that PLA/G-nHA/PRP provided the highest cell proliferation at all time points, and the serum biochemistry (ALT and AST level) results indicated no abnormal/toxic influence caused by scaffold biomaterials. Superior cell adhesion and mineralization were obtained for PLA/G-nHA/PRP. Furthermore, all the developed scaffolds showed bone repair capability. The PLA/G-nHA/PRP scaffolds could better support bone regeneration than bare PLA and PLA/G-nHA scaffolds. Conclusion The PLA/G-nHA/PRP scaffolds can be considered as potential for hard tissue repair.

In this paper, the in-vivo healing of critical-sized bony defects by cell-free and stem cell-seeded 3D-printed PLA scaffolds was studied in rat calvaria bone. The scaffolds were implanted in the provided defect sites and histological analysis was conducted after 8 and 12 weeks. The results showed that both cell-free and stem cell-seeded scaffolds exhibited superb healing compared with the empty defect controls, and new bone and connective tissues were formed in the healing site after 8 and 12 weeks, postoperatively. The higher filled area, bone formation and bone maturation were observed after 12 weeks, particularly for PLA + Cell scaffolds.

Background Alumina-titanium (Al2O3-Ti) biocomposites have been recently developed with improved mechanical properties for use in heavily loaded orthopedic sites. Their biological performance, however, has not been investigated yet. Methods The aim of the present study was to evaluate the in vivo biological interaction of Al2O3-Ti. Spark plasma sintering (SPS) was used to fabricate Al2O3-Ti composites with 25 vol.%, 50 vol.%, and 75 vol.% Ti content. Pure alumina and titanium were also fabricated by the same procedure for comparison. The fabricated composite disks were cut into small bars and implanted into medullary canals of rat femurs. The histological analysis and scanning electron microscopy (SEM) observation were carried out to determine the bone formation ability of these materials and to evaluate the bone-implant interfaces. Results The histological observation showed the formation of osteoblast, osteocytes with lacuna, bone with lamellar structures, and blood vessels indicating that the healing and remodeling of the bone, and vasculature reconstruction occurred after 4 and 8 weeks of implantation. However, superior bone formation and maturation were obtained after 8 weeks. SEM images also showed stronger interfaces at week 8. There were differences between the composites in percentages of bone area (TB%) and the number of osteocytes. The 50Ti composite showed higher TB% at week 4, while 25Ti and 75Ti represented higher TB% at week 8. All the composites showed a higher number of osteocytes compared to 100Ti, particularly 75Ti. Conclusions The fabricated composites have the potential to be used in load-bearing orthopedic applications.

is a common and popular biomaterial for bone regeneration. About 70% of bone structure and essentially all of the enamel in teeth are composed of HA. It has been used in orthopedic and dental applications such as dental implants, bone grafts, orthopedic implants, and bone scaffolds. [1][2][3][4][5] The reason is the excellent bioactivity, adequate mechanical characteristics, osteoconductive, and angiogenic properties, without toxicity, inflammatory, or antigenic reactions. 6 Nano-hydroxyapatite (nano-HA), particularly, is considered as one of the most biocompatible and bioactive materials that has been used and accepted in orthopedics and dentistry. [7][8][9] For example, it has been extensively used in periodontics and in oral and maxillofacial surgical procedures. The inorganic part of bone extra cellular matrix (ECM) contains nano-sized crystallites of calcium phosphate similar to HA. 10 Nano-HA has an outstanding osteoinductive capacity and improves bone-to-implant integration. 11 This nanomaterial also has been employed in the products used for oral care to treat the dentin hypersensitivity (DH) and promote enamel demineralization. It has been shown that nano-HA is capable of reducing the pain associated with DH because the nanoparticles are very small and can readily enter and fill the tubules in dentin. These nanoparticles precipitate inside the dentin tubules and block the nerves interaction with the external stimuli. They can also set down onto the surface of enamel and demineralize the early enamel caries, leading to a new apatite layer formation, which subsequently increases the enamel surface hardness and therefore prevents the tooth decay. These benefits are due to high similarity of morphology and crystal structure of nano-HA with tooth enamel. 12,13 HA can be simply synthesized or extracted from the natural sources, including eggshell, seashell, bovine, or fish bones. [14][15][16][17][18] Fish bone as an alternative natural source for HA production recently has received a lot of attention because of low cost and easy manufacturing regarding the many