Ultrasound-aided fixation of biodegradable implants in pediatric craniofacial surgery.

PURPOSE: Bioresorbable implant systems have been used for the rigid fixation of cranial and facial bones. A relatively recent advancement has been the fixation of these implants using an ultrasonic device. Published reports with such a device in pediatric craniofacial surgery have been limited. We report our experience with ultrasound-aided fixation of bioresorbable implants in the craniofacial surgery of children. METHODS: We retrospectively examined the clinical information, complications and outcome following the use of a commercially available ultrasound-aided bioresorbable implant system (SonicWeld Rx™, KLS Martin, Jacksonville, Fla., USA) during craniofacial surgery by University of Florida College of Medicine Jacksonville surgeons. Follow-up was obtained via clinical examination or telephone interview. RESULTS: Over a period of 3 years, 37 pediatric patients (age range: 2 months to 16 years) had placement of these implants for immediate bony fixation during craniofacial procedures. Pathology consisted mainly of craniosynostosis (n = 19), and trauma (n = 16). Twenty-eight had combined craniofacial procedures; 9 patients had facial procedures. Reoperation was performed for: wound infection (n = 1), plate extrusion (n = 1). Delayed subcutaneous plate-related swelling was seen in 5 patients (4 were infants) and had a benign clinical course. Good cosmetic outcomes were seen in all patients. CONCLUSIONS: The use of a bioresorbable implant system with ultrasound-aided pin fixation in pediatric craniofacial surgery achieves rapid fixation with minimal morbidity and good cosmetic outcome. This system is easy to use and provides reliable stability in the setting of pediatric trauma and craniosynostosis.

Optimization of reporter cells for expression profiling in a microfluidic device.

The emergence of green fluorescence protein (GFP) technologies has enabled non-invasive monitoring of cell function and gene expression. GFP-based expression studies are typically performed in traditional single-dish or multi-well formats to monitor a small number of genes or conditions that do not lend well to scaling, high-throughput analysis, or single-cell measurements. We have recently developed a microfluidic device, the Living Cell Array (LCA), for monitoring GFP-based gene expression in a high-throughput manner. Here, we report the optimization of GFP reporter cell characteristics in this microfluidic device for gene expression profiling. A reporter cell line for the transcription factor NF-kappa B was generated and used as the model cell line. Reporter cells were seeded in the LCA and NF-kappa B activated by addition of the cytokine TNF-alpha . Our studies show that the fluorescence kinetics from the reporter cell line in response to both single and repeated TNF-alpha stimulation in the LCA is similar to that observed in standard tissue culture. In addition, our data also indicate that multiple expression waves can be reliably monitored from a small population of reporter cells. Using reporter cell line subcloning and cell cycle synchronization, we demonstrate that the kinetics and magnitude of induced fluorescence in the reporter cell lines can be further improved to maximize the fluorescence readout from reporter cell lines, thereby improving their applicability to live cell expression profiling. Our studies establish some of the important criteria to be considered when using reporter cell lines for dynamic expression profiling in microfluidic devices.

Dynamic gene expression profiling using a microfabricated living cell array.

We describe the development of a microfluidic platform for continuous monitoring of gene expression in live cells. This optically transparent microfluidic device integrates high-throughput molecular stimulation with nondestructive monitoring of expression events in individual living cells, hence, a living cell array (LCA). Several concentrations of a soluble molecular stimulus are generated in an upstream microfluidic network and used to stimulate downstream reporter cells, each containing a green fluorescence reporter plasmid for a gene of interest. Cellular fluorescence is continuously monitored and quantified to infer the expression dynamics of the gene being studied. We demonstrate this approach by profiling the activation of the transcription factor NF-kappaB in HeLa S3 cells in response to varying doses of the inflammatory cytokine TNF-alpha. The LCA platform offers a unique opportunity to simultaneously control dynamic inputs and measure dynamic outputs from adherent mammalian cells in a high-throughput fashion. This approach to profiling expression dynamics, in conjunction with complementary techniques such as DNA microarrays, will help provide a more complete picture of the dynamic cellular response to diverse soluble stimuli.