Orthop. Surgery & Tissue engineering

Scaffolds made of polycaprolactone and nanocrystalline silicon-substituted hydroxyapatite have been fabricated by 3D printing rapid prototyping technique. To asses that the scaffolds fulfill the requirements to be considered for bone grafting applications, they were implanted in New Zealand rabbits. Histological and radiological studies have demonstrated that the scaffolds implanted in bone exhibited an excellent osteointegration without the interposition of fibrous tissue between bone and implants and without immune response after 4 months of implantation. In addition, we have evaluated the possibility of improving the scaffolds efficiency by incorporating demineralized bone matrix during the prepa-ration by 3D printing. When demineralized bone matrix (DBM) is incorporated, the efficacy of the scaffolds is enhanced, as new bone formation occurs not only in the peripheral portions of the scaffolds but also within its pores after 4 months of implantation. This enhanced performance can be explained in terms of the osteoinductive properties of the DBM in the scaffolds, which have been assessed through the new bone tissue formation when the scaffolds are ectopically implanted. V C 2012

Biomaterial pieces with osteogenic properties, suitable for use in the treatment of bone defects, were synthesized. The materials, which avoid bone infections, are exclusively composed of gentamicin sulfate and bioactive SiO 2 -CaO-P 2 O 5 sol-gel glass (synthesized previously), and were manufactured by means of uniaxial and isostatic pressure of the mixed components. After implanting the pieces into rabbit femur, we studied (1) antibiotic release, determining the concentration in proximal and distal bone, liver, kidney, and lung as a function of time, and (2) bone growth as a consequence of the glass reactivity in the biological environment. The results demonstrated that the implants are good carriers for local gentamicin release into the local osseous tissue, where they show excellent biocompatibility and bone integration. Moreover, these implants are able to promote bone growth during the resorption process. ß

Scaffolds constituted by micro and nanofibers of silk fibroin were obtained by electrospinning. Fibers of fibroin meshes were coated with polypyrrole (pPy) by chemical polymerization; chemical linkages between polymers were observed by SEM and IR spectroscopy. Mechanical resistance of the meshes was improved by polypyrrole coating. Furthermore, coated meshes present a high electroactivity allowing anion storage and delivery during oxidation/reduction reactions in aqueous solutions. Uncoated and pPy coated materials support the adherence and proliferation of adult human mesenchymal stem cells (ahMSCs) or human fibroblasts (hFb). The bioactivity of fibroin mesh overcomes that of the polypyrrole coated meshes.

Materials 2016, 9, 474; doi:10.3390/ma90
The  characterization  process  of  a  new  porous  Nurse’s  A  ceramic  and  the  physico  chemical nature of the remodeled interface between the implant and the surrounding bone were studied after in vivo implantation. Scaffolds were prepared by a solid‐state reaction and implanted in New Zealand rabbits. Animals were sacrificed on days 15, 30, and 60. The porous biomaterial displayed biocompatible, bioresorbable, and osteoconductive capacity. The degradation processes of  implants  also  encouraged  osseous  tissue  ingrowths  into  the  material’s  pores,  and  drastically  changed the macro‐ and microstructure of the implants. After 60 healing days, the resorption rates were 52.62% ± 1.12% for the ceramic and 47.38% ± 1.24% for the residual biomaterial. The elemental analysis  showed  a  gradual  diffusion  of  the  Ca  and  Si  ions  from  the  materials  into  the  newly  forming  bone  during  the  biomaterial’s  resorption  process.  The  energy  dispersive  spectroscopy (EDS) analysis of the residual ceramic revealed some particle categories with different mean Ca/P ratios  according  to  size,  and  indicated  various  resorption  process  stages.  Since  osteoconductive  capacity was indicated for this material and bone ingrowth was possible, it could be applied to progressively substitute an implant.
Materials 2016, 9, 474; doi:10.3390/ma90

Ceramics International 41 (2015) 6631–6644
We investigated the effect of the ceramic chemistry and surface roughness of pure α-tricalcium phosphate, and also αTCP doped with either 1.5 wt% or 3.0 wt% of dicalcium silicate (C2S), on the response of adult human mesenchymal stem cells (ahMSCs). AhMSCs were plated onto ceramic discs, prepared by a solid-state reaction. After being sintered, some samples were polished up to 1 μm, while others were kept as manufactured, which resulted in two surface roughness grades. Viability, proliferation and osteoinductive capacity were determined following various incubation periods.
The results showed a non-cytotoxic effect after an indirect apoptosis test. Cell adhesion and proliferation were surface roughness-sensitive and increased proportionally to the roughness of materials. These observations became more evident in the unpolished αTCP ceramic doped with 1.5 wt% C2S, which induced osteoblastic differentiation as a result of the roughness and increased concentration of the C2S solid solution in αTCP.

Scaffolds constituted by micro and nanofibers of silk fibroin were obtained by electrospinning. Fibers of fibroin meshes were coated with polypyrrole (pPy) by chemical polymerization; chemical linkages between polymers were observed by SEM and IR spectroscopy. Mechanical resistance of the meshes was improved by polypyrrole coating. Furthermore, coated meshes present a high electroactivity allowing anion storage and delivery during oxidation/reduction reactions in aqueous solutions. Uncoated and pPy coated materials support the adherence and proliferation of adult human mesenchymal stem cells (ahMSCs) or human fibroblasts (hFb). The bioactivity of fibroin mesh overcomes that of the polypyrrole coated meshes.

In this work a new kind of a-tricalcium phosphate (a-Ca 3 (PO 4 ) 2 ) doped with dicalcium silicate (Ca 2 SiO 4 ) ceramic materials, with compositions lying in the field of the Ca 3 (PO 4 ) 2 solid solution in the system Ca 3 (PO 4 ) 2 -Ca 2 SiO 4 , were obtained. The properties of the sintered ceramics were discussed in detail as well as some in vitro relevant properties for bone repairing. Crystalline a-Ca 3 (PO 4 ) 2 solid solution (a-TCPss) was the only phase in the ceramics containing from 1 wt% to 4 wt% of Ca 2 SiO 4 . The release of ionic Si in simulated body fluid increased with the content of Ca 2 SiO 4 and favoured a-Ca 3 (PO 4 ) 2 surface transformation. In addition, cell attachment test showed that the a-TCPss supported the mesenchymal stem cells adhesion and spreading, and the cells established close contact with the ceramics after 24 h of culture. According to the results, the investigated a-TCPss ceramics possesses good bioactivity, biocompatibility and mechanical properties, and might be a promising bone implant material. #

Silicate Tricalcium phosphate Powder-solid state reaction Adult human mesenchymal stem cells Electron microscopy Biomedical applications Bioceramic samples with osteogenic properties, suitable for use in the regeneration of hard tissue, were synthesized. The materials consisting of α-tricalcium phosphate (αTCP) and also αTCP doped with either 1.5 wt.% or 3.0 wt.% of dicalcium silicate (C 2 S) in the system Dicalcium Silicate-Tricalcium Phosphate (C 2 S-TCP) were obtained by solid state reaction. All materials were composed of a single phase, αTCP in the case of a pure material, or solid solution of C 2 S in αTCP (αTCPss) for the doped αTCP. Viability, proliferation and in vitro osteoinductive capacity were investigated by seeding, adult mesenchymal stem cells of human origin (ahMSCs) which were CD73 + , CD90 + , CD105 + , CD34 − and CD45 − onto the 3 substrates for 30 days. Results show a non-cytotoxic effect after applying an indirect apoptosis test (Annexin V/7-AAD staining), so ahMSCs adhered, spread, proliferated and produced extracellular matrix (Heparan-sulfate proteoglycan (HS) and osteopontin (OP)) on all the ceramics studied. Finally, the cells lost the cluster differentiation marker expression CD73, CD90 y CD105 characteristic of ahMSCs and they showed an osteoblastic phenotype (Alkaline phosphatase activity (ALP), Osteocalcin production (OC), Collagen type I expression (Col-I), and production of mineralization nodules on the extracellular matrix). These observations were more evident in the αTCP ceramic doped with 1.5 wt.% C 2 S, indicating osteoblastic differentiation as a result of the increased concentration of solid solution of C 2 S in αTCP (αTCPss). Overall, these results suggest that the ceramics studied are cytocompatible and they are able to induce osteoblastic differentiation of undifferentiated ahMSCs.

Silk fibroin (SF) was regenerated using three of the most common protocols described in the bibliography for the dissolution of raw SF (LiBr 9.3 M, CaCl 2 50 wt.% or CaCl 2 :EtOH:H 2 O 1:2:8 in molar ratio). The integrity of regenerated SF in aqueous solution was analyzed by SDS-PAGE and different profiles of degradation were observed depending on the protocol used. This fact was found to affect also the aqueous solubility of the freeze dried protein. These different SFs were used to produce electrospun mats using SF solutions of SF 17 wt.% in 1,1,1,1′,1′,1′-hexafluoro-2-propanol (HFIP) and significant differences in fiber sizes, elongation and ultimate strength values were found. This work provides a global overview of the manner that different methods of SF extraction can affect the properties of electrospun SF-mats and consequently it should be considered depending on the use they are going to be made for.

In this work a new kind of a-tricalcium phosphate (a-Ca 3 (PO 4 ) 2 ) doped with dicalcium silicate (Ca 2 SiO 4 ) ceramic materials, with compositions lying in the field of the Ca 3 (PO 4 ) 2 solid solution in the system Ca 3 (PO 4 ) 2 -Ca 2 SiO 4 , were obtained. The properties of the sintered ceramics were discussed in detail as well as some in vitro relevant properties for bone repairing. Crystalline a-Ca 3 (PO 4 ) 2 solid solution (a-TCPss) was the only phase in the ceramics containing from 1 wt% to 4 wt% of Ca 2 SiO 4 . The release of ionic Si in simulated body fluid increased with the content of Ca 2 SiO 4 and favoured a-Ca 3 (PO 4 ) 2 surface transformation. In addition, cell attachment test showed that the a-TCPss supported the mesenchymal stem cells adhesion and spreading, and the cells established close contact with the ceramics after 24 h of culture. According to the results, the investigated a-TCPss ceramics possesses good bioactivity, biocompatibility and mechanical properties, and might be a promising bone implant material. #

The subsystem Nurse's A-phase-silicocarnotite within the system Ca 3 (PO 4) 2 –Ca 2 SiO 4 was conducted as a preliminary step toward obtaining new biomaterials with controlled microstructures. Phase composition of the resulting ceramics was studied by X-ray diffraction, differential thermal analysis, and scanning electron microscopy with attached wavelength dispersive spectroscopy. The results showed that the subsystem presents an invariant eutectoid point at 1366 ˘ 4 ˝ C with a composition of 59.5 wt % Ca 3 (PO 4) 2 and 40.5 wt % Ca 2 SiO 4 , and typical eutectoid microstructure of lamellae morphology. These results are in disagreement with the previous reported data, which locate the invariant eutectoid point at 1250 ˘ 20 ˝ C with a composition of 55 wt % Ca 3 (PO 4) 2 and 45 wt % Ca 2 SiO 4. In addition, cell attachment testing showed that the new eutectoid material supported the mesenchymal stem cell adhesion and spreading, and the cells established close contact with the ceramic after 28 days of culture. These findings indicate that the new ceramic material with eutectoid microstructure of lamellae morphology possesses good bioactivity and biocompatibility and might be a promising bone implant material.