This study investigated the effects of dual delivery of vascular endothelial growth factor (VEGF) and bone morphogenetic protein-2 (BMP-2) for bone regeneration in a rat cranial critical size defect. Four groups of scaffolds were generated with VEGF (12 μg), BMP-2 (2 μg), both VEGF (12 μg) and BMP-2 (2 μg), or no growth factor released from gelatin microparticles incorporated within the scaffold pores. These scaffolds were implanted within an 8 mm rat cranial critical size defect (n = 8-9 for each group). At 4 and 12 weeks, implants were retrieved and evaluated by microcomputed tomography (microCT) and histological scoring analysis. Additionally, 4 week animals were perfused with a radiopaque material to visualize and quantify blood vessel formation. Histological analysis revealed that for all groups at 4 weeks, a majority of the porous scaffold volume was filled with vascularized fibrous tissue; however, bone formation appeared most abundant in the dual release group at this time. At 12 weeks, both dual release and BMP-2 groups showed large amounts of bone formation within the scaffold pores and along the outer surfaces of the scaffold; osteoid secretion and mineralization were apparent, and new bone was often in close or direct contact with the scaffold interface. MicroCT results showed no significant difference among groups for blood vessel formation at 4 weeks (<4% blood vessel volume); however, the dual release group showed significantly higher bone formation (16.1±9.2% bone volume) than other groups at this time. At 12 weeks, dual release and BMP-2 groups exhibited significantly higher bone formation (39.7 ± 14.1% and 37.4 ± 18.8% bone volume, respectively) than either the VEGF group or blank scaffolds (6.3 ± 4.8% and 7.8 ± 7.1% bone volume, respectively). This work indicates a synergistic effect of the dual delivery of VEGF and BMP-2 on bone formation at 4 weeks and suggests an interplay between these growth factors for early bone regeneration. For the doses investigated, the results show that the addition of VEGF does not affect the amount of bone formation achieved by BMP-2 at 12 weeks; however, they also indicate that delivery of both growth factors may enhance bone bridging and union of the critical size defect compared to delivery of BMP-2 alone.

Engineering complex tissues requires a precisely formulated combination of cells, spatiotemporally released bioactive factors, and a specialized scaffold support system. Injectable materials, particularly those delivered in aqueous solution, are considered ideal delivery vehicles for cells and bioactive factors and can also be delivered through minimally invasive methods and fill complex 3D shapes. In this review, we examine injectable materials that form scaffolds or networks capable of both replacing tissue function early after delivery and supporting tissue regeneration over a time period of weeks to months. The use of these materials for tissue engineering within the craniofacial complex is challenging but ideal as many highly specialized and functional tissues reside within a small volume in the craniofacial structures and the need for minimally invasive interventions is desirable due to aesthetic considerations. Current biomaterials and strategies used to treat craniofacial defects are examined, followed by a review of craniofacial tissue engineering, and finally an examination of current technologies used for injectable scaffold development and drug and cell delivery using these materials.

The increased use of immunohistochemistry (IHC) in both clinical and basic research settings has led to the development of techniques for acquiring quantitative information from immunostains. Staining correlates with absolute protein levels and has been investigated as a clinical tool for patient diagnosis and prognosis. For these reasons, automated imaging methods have been developed in an attempt to standardize IHC analysis. We propose a novel imaging technique in which brightfield images of diaminobenzidene (DAB)-labeled antigens are converted to normalized blue images, allowing automated identification of positively stained tissue. A statistical analysis compared our method with seven previously published imaging techniques by measuring each one's agreement with manual analysis by two observers. Eighteen DAB-stained images showing a range of protein levels were used. Accuracy was assessed by calculating the percentage of pixels misclassified using each technique compared with a manual standard. Bland-Altman analysis was then used to show the extent to which misclassification affected staining quantification. Many of the techniques were inconsistent in classifying DAB staining due to background interference, but our method was statistically the most accurate and consistent across all staining levels.

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The calcifying epithelial odontogenic tumor (CEOT) is a rare benign odontogenic neoplasm which was first described by Pindborg in 1955 and accounts for less than 1% of all odontogenic lesions. Recently, a clear cell variant of CEOT has been identified with only eight well-documented cases in the literature. We present an additional case of clear cell CEOT of the mandible and review the salient clinical, radiologic, and histopathologic features of this entity and CEOTs in general. The differential diagnosis of clear cell tumors in the mandible includes: clear cell odontogenic tumor, clear cell ameloblastoma (odontogenic carcinoma), metastatic clear cell adenocarcinoma, primary intraosseous mucoepidermoid carcinoma, acinic cell carcinoma, epithelial-myoepithelial carcinoma, clear cell salivary gland tumors, and clear cell variant of squamous cell carcinoma. Because of the belief that clear cell odontogenic tumors are locally aggressive neoplasms, definitive resection of the entire mass with tumor-free surgical margins and long-term follow-up are recommended.