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Biomedical subjects

Derrick C Wan

Publications and source records attributed to Derrick C Wan.

7 recordsLinked to original sources
PubMed2007

Bilateral macrostomia as an isolated pathology.

OBJECTIVE: Congenital macrostomia is a lateral orofacial cleft between the maxillary and mandibular components of the first branchial arch. Bilateral macrostomia is a poorly characterized malformation, with only 14 cases reported in the literature. The purpose of this study was to compare our experience with the world literature. METHOD: A retrospective analysis of 20 cases of bilateral congenital macrostomia was conducted; 6 cases were drawn from 2 maxillofacial surgery units and 14 cases from the world literature. Cases of bilateral congenital macrostomia were compared with cases of unilateral forms using a review of the literature post-1954. Among the six cases identified from the two maxillofacial surgery units, three were treated with linear sutures and three with Z-plasty. Subsequent aesthetic and functional results were analyzed. RESULTS: Compared to unilateral forms, bilateral macrostomia is more often isolated without ear or skin deformities. Moreover, there are a greater proportion of larger defects among cases with bilateral macrostomia when compared to unilateral macrostomia. Alimentation, phonation, and mouth opening were always normal. The two sides were always symmetric. Only one case presented with the complication of skin contractions during lip movement. CONCLUSION: The etiopathogenesis of bilateral macrostomia is unclear. Although over 50% of the reported cases of bilateral macrostomia are isolated, this condition presents a therapeutic challenge. In the case of bilateral forms, the surgeon must define the commissure position without a normal side. Repair thus requires extraoral landmarks and normal measurements.

Adult↗
PubMed2006

Differential gene expression between juvenile and adult dura mater: a window into what genes play a role in the regeneration of membranous bone.

BACKGROUND: Although reossification of large calvarial defects is possible in children, adults lack this tissue engineering capacity. In this study, the authors compared the differences in gene expression between juvenile and adult dura mater using a mouse cDNA microarray with 42,000 unique elements. METHODS: Non-suture-associated parietal bone was harvested from 6-day-old and 60-day-old mice. The dura mater was carefully dissected from the calvarial disk and snap-frozen. RNA was extracted from pooled dura mater for microarray analysis. The 25 most differentially expressed genes were listed, as were selected bone-related genes. In addition, quantitative real-time reverse-transcriptase polymerase chain reaction confirmation of selected genes-BMP-2, BMP-4, and BMP-7; and osteopontin (OP), osteocalcin (OC), and FGFR-1-was performed. RESULTS: Juvenile dura mater expressed significantly greater amounts of BMP-2 and OP. Minimal difference in OC expression was observed between juvenile and adult dura mater. Extracellular matrix proteins (Col3a1, 5a1, 6a1, and fibronectin 1), osteoblast differentiation markers (Runx2/Cbfa1, Itm2a, and FGFR-1), and the growth factor Ptn were among other genes with greater expression in juvenile dura mater. Markers of osteoclasts (Acp5, MMP9, Ctsk) and the multiple candidate gene Ntrk2 were also expressed at higher levels in the juvenile dura mater. CONCLUSIONS: These findings suggest a more differentiated osteoprogenitor population to exist along with a greater presence of osteoclasts in the juvenile dura mater relative to adults. In addition to establishing a baseline difference in gene expression between juvenile and adult dura mater, new genes potentially critical to the regenerative potential of juvenile calvaria were identified.

Age Factors↗
PubMed2006

Osteogenic differentiation of mouse adipose-derived adult stromal cells requires retinoic acid and bone morphogenetic protein receptor type IB signaling.

Although the multilineage potential of human adipose-derived adult stromal cells (ADAS) has been well described, few published studies have investigated the biological and molecular mechanisms underlying osteogenic differentiation of mouse ADAS. We report here that significant osteogenesis, as determined by gene expression and histological analysis, is induced only when mouse ADAS are cultured in the presence of retinoic acid with or without recombinant human bone morphogenetic protein (BMP)-2 supplementation. Furthermore, a dynamic expression profile for the BMP receptor (BMPR) isoform IB was observed, with dramatic up-regulation during osteogenesis. Western blot analysis revealed that retinoic acid enhanced levels of BMPR-IB protein during the first 7 days of osteogenic differentiation and that RNAi-mediated suppression of BMPR-IB dramatically impaired the ability of ADAS to form bone in vitro. In contrast, absence of BMPR-IA did not significantly diminish ADAS osteogenesis. Our data therefore demonstrate that the osteogenic commitment of multipotent mouse ADAS requires retinoic acid, which enhances expression of the critical BMPR-IB isoform.

3T3 Cells↗
PubMed2006

Craniofacial bone tissue engineering.

Repair and reconstruction of the craniofacial skeleton represents a significant biomedical burden, with thousands of procedures per-formed annually secondary to injuries and congenital malformations. Given the multitude of current approaches, the need for more effective strategies to repair these bone deficits is apparent. This article explores two major modalities for craniofacial bone tissue engineering: distraction osteogenesis and cellular based therapies. Current understanding of the guiding principles for each of these modalities is elaborated on along with the knowledge gained from clinical and investigative studies. By laying this foundation, future directions for craniofacial distraction and cell-based bone engineering have emerged with great promise for the advancement of clinical practice.

Biomechanical Phenomena↗
PubMed2005

New developments in pediatric plastic surgery research.

Pediatric plastic surgery research is a rapidly expanding field. Unique in many ways, researchers in this field stand at the union of multiple scientific specialties, including biomedical engineering, tissue engineering, polymer science, molecular biology, developmental biology, and genetics. The goal of this scientific effort is to translate research advances into improved treatments for children with congenital and acquired defects. Although the last decade has seen a dramatic acceleration in research related to pediatric plastic surgery, the next 10 years will no doubt lead to novel treatment strategies with improved clinical outcomes.

Animals↗