Faculty Bibliography

OBJECTIVE: Radiotherapy, an essential modality in cancer treatment, frequently induces fibrotic processes in the skin, including accumulation of extracellular matrix. Transforming growth factor-beta is essential in regulating extracellular matrix gene expression and is dependent on Smad3, an intracellular mediator/transcription factor. Our study characterized the genetic expression involved in extracellular matrix accumulation during radiation-induced fibrosis. We performed Smad3 gene silencing in an attempt to abrogate the effects of radiation. STUDY DESIGN: Laboratory research. SETTING: University laboratory. SUBJECTS AND METHODS: C57 murine dermal fibroblasts were irradiated with 20 Gy RNA isolated (0, 6, 12, 24, 48, 72 hours postirradiation) and mRNA analyzed (reverse transcriptase polymerase chain reaction) for known regulators (Smad3, interleukin-13 [IL-13]), tumor necrosis factor-alpha [TNF-alpha]) and mediators of fibrosis (collagen 1A1 [Col1A1]), TGF-beta, matrix metalloprotease-1 and -2 (MMP-1, MMP-2), and tissue inhibitor of metalloprotease-1 (TIMP-1). Smad3 gene expression was silenced using siRNA in an effort to restore an unirradiated gene profile. RESULTS: Following irradiation, there was a steady increase in mRNA expression of Smad3, IL-13, TGF-beta, Col1A1, MMP-2, TIMP-1, with peak at 12 to 24 hours and subsequent decline by 72 hours. TNF-alpha expression remained elevated throughout. MMP-1 showed minimal expression initially, which decreased to negligible by 72 hours. Inhibition of Smad3 significantly decreased expression of Col1A1, TGF-beta, MMP-2, and TIMP-1. IL-13 and TNF-alpha expression was not affected by Smad3 silencing. CONCLUSION: We have characterized the early-phase mRNA expression profiles of the major mediators of radiation-induced fibrosis. Smad3 siRNA effectively abrogated the elevation of Col1A1, TGF-beta, TIMP-1, and MMP-2. IL-13 and TNF-alpha were unaffected by Smad3 silencing and appear to be minor regulators in fibrosis. These findings suggest a therapeutic rationale for Smad3 silencing in vivo

Large temple and suprabrow lesions can pose a reconstructive challenge. When the lesion extends anterior to the hairline, esthetically acceptable local flaps may be difficult to design. We describe a modified scalp flap (ie, part Converse scalping flap and part scalp rotation flap) that can be tailored to reconstruct a variety of difficult temple and suprabrow lesions while simultaneously maintaining eyebrow position.The modified scalp flap is raised in a subgaleal plane until approximately 2.5 cm above the brow. At this level, dissection proceeds in the subcutaneous plane to protect the frontal branch of the facial nerve and to keep the flap thin. (The key to the modified scalp flap is the dissection plane change that protects the frontal branch of the facial nerve.) The extent of posterior subgaleal dissection is dictated by the amount of anterior rotation necessary. A temporal dog-ear is removed subfollicularly to permit modified flap rotation and preserve the superficial temporal artery.The modified scalp flap has been used to reconstruct temple and suprabrow lesions in 10 patients ranging in age from 4 months to 22 years. There were no complications. Four typical cases are presented.Temple and suprabrow lesions can be excised and successfully reconstructed in one stage using a modified scalp flap that is extended from the hair-bearing scalp onto the glabrous skin of the forehead. This novel modified scalp flap prevents eyebrow/hairline distortion and avoids facial nerve injury

OBJECTIVE: To attempt to mitigate the effects of irradiation on murine skin after high-dose radiation using a novel transcutaneous topical delivery system to locally inhibit gene expression with small interfering RNA (siRNA) against Smad3. DESIGN: Laboratory investigation. SETTING: University laboratory. SUBJECTS: Twenty-five wild-type C57 mice. INTERVENTION: In an isolated skin irradiation model, the dorsal skin of C57 wild-type mice was irradiated (45 Gy). Just before irradiation, Smad3 and nonsense siRNA were applied to 2 separate dorsal skin areas and then reapplied weekly. Skin was harvested after 1 and 4 weeks. Smad3 expression were assessed by immunohistochemistry, and collagen deposition and architecture was examined using picrosirius red collagen staining. MAIN OUTCOME MEASURES: Epidermal thickness was measured semiquantitatively at 4 weeks. Radiation-induced fibrosis was measured quantitatively via tensiometry. The Young modulus, a measure of cutaneous rigidity inversely related to elasticity, was determined, with normal irradiated skin serving as a control specimen. RESULTS: Murine skin treated with topical Smad3 siRNA demonstrated effective Smad3 inhibition at 1 week and persistent suppression at 4 weeks. Collagen deposition and epidermal thickness were significantly decreased in skin treated with Smad3 siRNA compared with control irradiated skin. Tensiometry demonstrated decreased tension in Smad3 siRNA-treated skin, with a Young modulus of 9.29 MPa (nonirradiated normal skin, 7.78 MPa) compared with nonsense (control) siRNA-treated skin (14.68 MPa). CONCLUSIONS: Smad3 expression can be effectively silenced in vivo using a novel topical delivery system. Moreover, cutaneous Smad3 inhibition mitigates radiation-induced changes in tissue elasticity, restoring a near-normal phenotype

OBJECTIVE: Progenitor cells (PCs) contribute to postnatal neovascularization and tissue repair. Here, we explore the mechanism contributing to decreased diabetic circulating PC number and propose a novel treatment to restore circulating PC number, peripheral neovascularization, and tissue healing. RESEARCH DESIGN AND METHODS: Cutaneous wounds were created on wild-type (C57BL/J6) and diabetic (Lepr(db/db)) mice. Blood and bone marrow PCs were collected at multiple time points. RESULTS: Significantly delayed wound closure in diabetic animals was associated with diminished circulating PC number (1.9-fold increase vs. 7.6-fold increase in lin(-)/sca-1(+)/ckit(+) in wild-type mice; P < 0.01), despite adequate numbers of PCs in the bone marrow at baseline (14.4 +/- 3.2% lin(-)/ckit(+)/sca1(+) vs. 13.5 +/- 2.8% in wild-type). Normal bone marrow PC mobilization in response to peripheral wounding occurred after a necessary switch in bone marrow stromal cell-derived factor-1alpha (SDF-1alpha) expression (40% reduction, P < 0.01). In contrast, a failed switch mechanism in diabetic bone marrow SDF-1alpha expression (2.8% reduction) resulted in impaired PC mobilization. Restoring the bone marrow SDF-1alpha switch (54% reduction, P < 0.01) with plerixafor (Mozobil, formerly known as AMD3100) increased circulating diabetic PC numbers (6.8 +/- 2.0-fold increase in lin(-)/ckit(+), P < 0.05) and significantly improved diabetic wound closure compared with sham-treated controls (32.9 +/- 5.0% vs. 11.9 +/- 3% at day 7, P > 0.05; 73.0 +/- 6.4% vs. 36.5 +/- 7% at day 14, P < 0.05; and 88.0 +/- 5.7% vs. 66.7 +/- 5% at day 21, P > 0.05, respectively). CONCLUSIONS: Successful ischemia-induced bone marrow PC mobilization is mediated by a switch in bone marrow SDF-1alpha levels. In diabetes, this switch fails to occur. Plerixafor represents a potential therapeutic agent for improving ischemia-mediated pathology associated with diabetes by reducing bone marrow SDF-1alpha, restoring normal PC mobilization and tissue healing

BACKGROUND/AIMS: Neovascularization involves angiogenesis and vasculogenesis mediated by cytokines and soluble chemokines. The predominant stimulus is ischemia, however, recent data suggest that ionizing radiation (IR) has angiogenic potential. In this study we evaluated whether IR increases vascularity and perfusion in vivo. METHODS: In wild-type mice, a full-thickness, pedicled skin flap was created and isolated for localized irradiation at a dose of 5 Gy. Serial Doppler analysis of the flap was performed. The skin flaps were then harvested at various time points for vascularity and histologic analysis. Blood was concurrently harvested for serum and hematopoietic progenitor cell population analysis. RESULTS: IR to an ischemic flap augmented the angiogenic cytokines SDF-1 and VEGF. Serum MMP-9 and s-kit levels, which are critical for progenitor cell mobilization, were also increased. When hematopoietic progenitor cells were evaluated by Sca1+/Flk1+ cells, a correlate 2-fold increase was seen compared to controls. When the flaps were examined, both vascularity and perfusion were increased. CONCLUSION: In this study we demonstrate that local, low-dose IR upregulates angiogenic chemokines and results in progenitor cell mobilization to the systemic circulation. There is a resultant increase in the vascularity of the irradiated flap, suggesting that the pro-angiogenic effects of IR can be harnessed locally

Bony defects in the craniomaxillofacial skeleton remain a major and challenging health concern. Surgeons have been trying for centuries to restore functionality and aesthetic appearance using autografts, allografts, and even xenografts without entirely satisfactory results. As a result, physicians, scientists, and engineers have been trying for the past few decades to develop new techniques to improve bone growth and bone healing. In this review, the authors summarize the advantages and limitations of current animal models; describe current materials used as scaffolds, cell-based, and protein-based therapies; and lastly highlight areas for future investigation. The purpose of this review is to highlight the major scaffold-, cell-, and protein-based preclinical tools that are currently being developed to repair cranial defects