Although fundamentally similar to other bones, the jaws demonstrate discrete responses to developmental, mechanical, and homeostatic regulatory signals. Here, we hypothesized that rat mandible vs. long-bone marrow-derived cells possess different osteogenic potential. We established a protocol for rat mandible and long-bone marrow stromal cell (BMSC) isolation and culture. Mandible BMSC cultures formed more colonies, suggesting an increased CFU-F population. Both mandible and long-bone BMSCs differentiated into osteoblasts. However, mandible BMSCs demonstrated augmented alkaline phosphatase activity, mineralization, and osteoblast gene expression. Importantly, upon implantation into nude mice, mandible BMSCs formed 70% larger bone nodules containing three-fold more mineralized bone compared with long-bone BMSCs. Analysis of these data demonstrates an increased osteogenic potential and augmented capacity of mandible BMSCs to induce bone formation in vitro and in vivo. Our findings support differences in the mechanisms underlying mandible homeostasis and the pathophysiology of diseases unique to the jaws.

In this work, we fabricated injectable bone substitutes modified with the addition of bioactive glass powders synthesized via ultrasonic energy-assisted hydrothermal method to the calcium phosphate-based bone cement to improve its biocompatibility. The injectable bone substitutes was initially composed of a powder component (tetracalcium phosphate, dicalcium phosphate dihydrate and calcium sulfate dehydrate) and a liquid component (citric acid, chitosan and hydroxyl-propyl-methyl-cellulose) upon which various concentrations of bioactive glass were added: 0%, 10%, 20% and 30%. Setting time and compressive strength of the injectable bone substitutes were evaluated and observed to improve with the increase of bioactive glass content. Surface morphologies were observed via scanning electron microscope before and after submersion of the samples to simulated body fluid and increase in apatite formation was detected using x-ray diffraction machine. In vitro biocompatibility of the injectable bone substitutes was observed to improve with the addition of bioactive glass as the proliferation/adhesion behavior of cells on the material increased. Human gene markers were successfully expressed using real time-polymerase chain reaction and the samples were found to promote cell viability and be more biocompatible as the concentration of bioactive glass increases. In vivo biocompatibility of the samples containing 0% and 30% bioactive glass were evaluated using Micro-CT and histological staining after 3 months of implantation in male rabbits' femurs. No inflammatory reaction was observed and significant bone formation was promoted by the addition of bioactive glass to the injectable bone substitute system.

In this study, two distinct systems of biomaterials were fabricated and their potential use as a bilayer scaffold (BS) for skin bioengineering applications was assessed. The initial biomaterial was a polycaprolactone/poly(lacto-co-glycolic acid) (PCL/PLGA) membrane fabricated using the electrospinning method. The PCL/PLGA membrane M-12 (12% PCL/10% PLGA, 80:20) displayed strong mechanical properties (stress/strain values of 3.01 ± 0.23 MPa/225.39 ± 7.63%) and good biocompatibility as demonstrated by adhesion of keratinocyte cells on the surface and ability to support cell proliferation. The second biomaterial was a hydrogel composed of 2% chitosan and 15% gelatin (50:50) crosslinked with 5% glutaraldehyde. The CG-3.5 hydrogel (with 3.5% glutaraldehyde (v/v)) displayed a high porosity, ≥97%, good compressive strength (2.23 ± 0.25 MPa), ability to swell more than 500% of its dry weight and was able to support fibroblast cell proliferation. A BS was fabricated by underlaying the membrane and hydrogel casting method to combine these two materials. The physical properties and biocompatibility were preliminarily investigated and the properties of the two biomaterials were shown to be complementary when combined. The upper layer membrane provided mechanical support in the scaffold and reduced the degradation rate of the hydrogel layer. Cell viability was similar to that in the hydrogel layer which suggests that addition of the membrane layer did not affect the biocompatibility.

In this study, a novel bilayer scaffold composed of electrospun polycaprolactone and poly(lacto-co-glycolic acid) (PCL/PLGA) membrane and glutaraldehyde (3.5% v/v) cross-linked chitosan/gelatin hydrogel was fabricated using two methods: electrospinning of the membrane onto the lyophilized hydrogel (BS-1) and membrane underlaying and casting method (BS-2). The morphology of the fabricated scaffolds was examined by scanning electron microscope (SEM). Mechanical strength, porosity, swelling capacity, and biodegradation rates of the scaffolds were also characterized. The in vitro biocompatibility of the materials was investigated by assessing cytotoxicity and cell proliferation on the material was measured using MTT assay. In addition, cell adhesion on the material was investigated by SEM. The BS-2 was grafted in Sprague-Dawley rats to determine its in vivo behavior and biocompatibility. The experimental results showed that the addition of the membrane layer to the hydrogel decreased swelling and degradation rates and provided ease of handling during implantation. Grafted BS-2 showed normal wound healing and no major inflammatory reaction was observed.

In this study, a novel porous hydroxyapatite scaffold was designed and fabricated to imitate natural bone through a multipass extrusion process. The conceptual design manifested unidirectional microchannels at the exterior part of the scaffold to facilitate rapid biomineralization and a central canal that houses the bone marrow. External and internal fissures were minimized during microwave sintering at 1,100°C. No deformation was noted, and a mechanically stable scaffold was fabricated. Detailed microstructure of the fabricated artificial bone was examined by scanning electron microscope and X-ray diffractometer, and material properties like compressive strength were evaluated. The initial biocompatibility was examined by the cell proliferation of MG-63 osteoblast-like cells using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Preliminary in vivo investigation in a rabbit model after 4 weeks and 8 weeks of implantation showed full osteointegration of the scaffold with the native tissue, and formation of bone tissue within the pore network, as examined by microcomputed tomography analyses and histological staining. Osteon-like bone microarchitecture was observed along the unidirectional channel with microblood vessels. These confirm a biomimetic regeneration model in the implanted bone scaffold, which can be used as an artificial alternative for damaged bone.