[Oro-maxillofacial bone tissue engineering combining biomaterials, stem cells, and gene therapy]

New Generation of Hybrid Materials Based on Gelatin and Bioactive Glass Particles for Bone Tissue Regeneration

Hybrid scaffolds based on bioactive glass (BAG) particles (<38 µm), covalently linked to gelatin (G*) using 3-glycidoxypropyltrimethoxysilane (GPTMS), have been studied for bone bioengineering. In this study, two glass compositions (13-93 and 13-93B20 (where 20% of the SiO₂ was replaced with B₂O₃)) were introduced in the gelatin matrix. The C_factor (gelatin/GPTMS molar ratio) was kept constant at 500. The hybrids obtained were found to be stable at 37 °C in solution, the condition in which pure gelatin is liquid. All hybrids were characterized by in vitro dissolution in Tris(hydroxymethyl)aminomethane (TRIS) solution (for up to 4 weeks) and Simulated Body Fluid (SBF) (for up to 2 weeks). Samples processed with 13-93B20 exhibited faster initial dissolution and significantly faster precipitation of a hydroxyapatite (HA) layer. The faster ion release and HA precipitation recorded from the G*/13-93B20 samples are attributable to the higher reactivity of borosilicate compared to silicate glass. The MC3T3-E1 cell behavior in direct contact with the hybrids was investigated, showing that the cells were able to proliferate and spread on the developed biomaterials. Tailoring the glass composition allows us to better control the material’s dissolution, biodegradability, and bioactivity. Bioactive (especially with 13-93B20 BAG) and biocompatible, the hybrids are promising for bone application.

Improvements in biomaterial matrices for neural precursor cell transplantation

Progress is being made in developing neuroprotective strategies for traumatic brain injuries; however, there will never be a therapy that will fully preserve neurons that are injured from moderate to severe head injuries. Therefore, to restore neurological function, regenerative strategies will be required. Given the limited regenerative capacity of the resident neural precursors of the CNS, many investigators have evaluated the regenerative potential of transplanted precursors. Unfortunately, these precursors do not thrive when engrafted without a biomaterial scaffold. In this article we review the types of natural and synthetic materials that are being used in brain tissue engineering applications for traumatic brain injury and stroke. We also analyze modifications of the scaffolds including immobilizing drugs, growth factors and extracellular matrix molecules to improve CNS regeneration and functional recovery. We conclude with a discussion of some of the challenges that remain to be solved towards repairing and regenerating the brain.

[CT-scan evaluation of calvarial bone donor site reconstruction using calcium phosphate cement]

The aim of reconstructing a calvarial donor site with biomaterial is to reconstruct the skull vault. The aim of this retrospective study was to assess the quality of reconstruction of calvarial bone with Hydroset™ (Stryker™) in patients having undergone monocortical parietal bone graft harvesting.

PATIENTS AND METHOD

The donor sites of patients having undergone calvarial bone harvesting had been reconstructed with Hydroset™ cement over a period of four years. Calvarial bone reconstruction and the thickness of the parietal bone were evaluated by CT scan.

RESULTS

Twenty-six patients had undergone reconstruction. The CT scan revealed a good integration of Hydroset™ with maintained thickness of the biomaterial. The parietal bone thickness was increased by 0.67 mm on average (P=0.002).

DISCUSSION

The reconstruction of calvarial donor site bone defect with Hydroset™, after a monocortical harvesting, demonstrates parietal osseous thickness maintained in time.

[Membranes in pre-implantation surgery]

The use of membranes in pre-implantation surgery is part of the guided bone regeneration (GBR) concept, one of the usual bone augmentation techniques. Membranes for GBR procedures have two main uses: a mechanical function to maintain bone regeneration space and a physical function as cellular barrier. The goal is to promote colonization of the regeneration space located under the membrane, by osteogenic cells from the residual bone walls. GBR was the subject of numerous publications and protocols since its first use in the 1980s. These protocols are mainly supported by team experience and the level of evidence is poor. Few indications are truly validated. The goal of our study was to review the recent literature on membrane use for pre-implantations surgery, and, in the absence of any consensus, to provide some arguments for their rational use.