Application of osteoinductive calcium phosphate ceramics in children's endoscopic neurosurgery: report of five cases

An In Vitro Study of Chitosan-Coated Bovine Pericardium as a Dural Substitute Candidate

Defects in the dura matter can be caused by head injury, and many cases require neurosurgeons to use artificial dura matter. Bovine pericardium is an option due to its abundant availability, adjustable size and characteristics, and because it has more collagen than porcine or equine pericardia. Nevertheless, the drawback of bovine pericardium is that it has a higher inflammatory effect than other synthetic dura matters. Chitosan has been shown to have a strong anti-inflammatory effect and has good tensile strength; thus, the idea was formulated to use chitosan as a coating for bovine pericardium. This study used decellularized bovine pericardial membranes with 0.5% sodium dodecyl sulphate and coatings containing chitosan at concentrations of 0.25%, 0.5%, 0.75%, and 1%. An FTIR test showed the presence of a C=N functional group as a bovine pericardium-chitosan bond. Morphological tests of the 0.25% and 0.5% chitosan concentrations showed standard pore sizes. The highest tensile strength percentage was shown by the membrane with a chitosan concentration of 1%. The highest degradation rate of the membrane was observed on the 7th and 14th days for 0.75% and 1% concentrations, and the lowest swelling ratio was observed for the 0.25% concentration. The highest level of cell viability was found for 0.75% chitosan. The bovine pericardium membrane with a 0.75% concentration chitosan coating was considered the optimal sample for use as artificial dura matter.

Core-Shell Structured Porous Calcium Phosphate Bioceramic Spheres for Enhanced Bone Regeneration

Adequate new bone regeneration in bone defects has always been a challenge as it requires excellent and efficient osteogenesis. Calcium phosphate (CaP) bioceramics, including hydroxyapatite (HA) and biphasic calcium phosphates (BCPs), have been extensively used in clinical bone defect filling due to their good osteoinductivity and biodegradability. Here, for the first time, we designed and fabricated two porous CaP bioceramic granules with core-shell structures, named in accordance with their composition as BCP@HA and HA@BCP (core@shell). The spherical shape and the porous structure of these granules were achieved by the calcium alginate gel molding technology combined with a H₂O₂ foaming process. These granules could be stacked to build a porous structure with a porosity of 65-70% and a micropore size distribution between 150 and 450 μm, which is reported to be good for new bone ingrowth. In vitro experiments confirmed that HA@BCP bioceramic granules could promote the proliferation and osteogenic ability when cocultured with bone marrow mesenchymal stem cells, while inhibiting the differentiation of RAW264.7 cells into osteoclasts. In vivo, 12 weeks of implantation in a critical-sized femoral bone defect animal model showed a higher bone volume fraction and bone mineral density in the HA@BCP group than in the BCP@HA or pure HA or BCP groups. From histological analysis, we discovered that the new bone tissue in the HA@BCP group was invading from the surface to the inside of the granules, and most of the bioceramic phase was replaced by the new bone. A higher degree of vascularization at the defect region repaired by HA@BCP was revealed by 3D microvascular perfusion angiography in terms of a higher vessel volume fraction. The current study demonstrated that the core-shell structured HA@BCP bioceramic granules could be a promising candidate for bone defect repair.

Application of osteoinductive calcium phosphate ceramics in giant cell tumor of the sacrum: report of six cases

This study aimed at evaluating the possibility and effectiveness of osteoinductive bioceramics to fill the tumor cavity following the curettage of sacral giant cell tumor (GCT). Six patients (four females and two males, 25–45 years old) underwent nerve-sparing surgery, in which the tumor was treated by denosumab, preoperative arterial embolization and extensive curettage. The remaining cavity was filled with commercial osteoinductive calcium phosphate (CaP) bioceramics, whose excellent osteoinductivity was confirmed by intramuscular implantation in beagle canine. All patients were followed by computed tomography (CT) scans postoperatively. According to the modified Neer criterion, five cases obtained Type I healing status, and one case had Type II. At the latest follow-up, no graft-related complications and local recurrence were found. The CT scan indicated a median time of healing initiation of 3 months postoperatively, and the median time for relatively complete healing was 12 months. The excellent bone regenerative ability of the ceramics was also confirmed by increased CT attenuation value, blurred boundary and cortical rim rebuilding. In conclusion, osteoinductive CaP bioceramics could be an ideal biomaterial to treat the large remaining cavity following extensive curettage of sacral GCT. However, further investigation with more cases and longer follow-up was required to confirm the final clinical effect.

Hyaluronic Acid/Bone Substitute Complex Implanted on Chick Embryo Chorioallantoic Membrane Induces Osteoblastic Differentiation and Angiogenesis, but not Inflammation

Microscopic and molecular events related to alveolar ridge augmentation are less known because of the lack of experimental models and limited molecular markers used to evaluate this process. We propose here the chick embryo chorioallantoic membrane (CAM) as an in vivo model to study the interaction between CAM and bone substitutes (B) combined with hyaluronic acid (BH), saline solution (BHS and BS, respectively), or both, aiming to point out the microscopic and molecular events assessed by Runt-related transcription factor 2 (RUNX 2), osteonectin (SPARC), and Bone Morphogenic Protein 4 (BMP4). The BH complex induced osteoprogenitor and osteoblastic differentiation of CAM mesenchymal cells, certified by the RUNX2 +, BMP4 +, and SPARC + phenotypes capable of bone matrix synthesis and mineralization. A strong angiogenic response without inflammation was detected on microscopic specimens of the BH combination compared with an inflammatory induced angiogenesis for the BS and BHS combinations. A multilayered organization of the BH complex grafted on CAM was detected with a differential expression of RUNX2, BMP4, and SPARC. The BH complex induced CAM mesenchymal cells differentiation through osteoblastic lineage with a sustained angiogenic response not related with inflammation. Thus, bone granules resuspended in hyaluronic acid seem to be the best combination for a proper non-inflammatory response in alveolar ridge augmentation. The CAM model allows us to assess the early events of the bone substitutes–mesenchymal cells interaction related to osteoblastic differentiation, an important step in alveolar ridge augmentation.