BackgroundCosmetic procedures are growing ever more common, and the use of soft tissue fillers is increasing. Practicing physicians need to be aware of the biological behavior of these products in tissue to enable them to respond to any safety concerns that their patients raise.ObjectivesTo provide an overview of the metabolism of 1,4-butanediol diglycidyl ether (BDDE)-crosslinked hyaluronic acid (HA) dermal fillers and to examine the safety of the resulting byproducts.MethodsA review of available evidence was conducted.ResultsAfter reaction with HA, the epoxide groups of BDDE are neutralized, and only trace amounts of unreacted BDDE remain in the product (<2 parts per million). When crosslinked HA, uncrosslinked HA, and unreacted BDDE degrade, they break down into harmless byproducts or into byproducts that are identical to substances already found in the skin.ConclusionClinical and biocompatibility data from longer than 15 years support the favorable clinical safety profile of BDDE-crosslinked HA and its degradation products. Given the strength of the empirical evidence, physicians should be confident in offering these products to their patients.

Lipid vesicles displaying RGD peptide amphiphiles were fused with glass coverslips to control the ability of these surfaces to support cell adhesion and growth. Cell adhesion was prevented on phosphatidylcholine bilayers in the absence of RGD, whereas cells adhered and grew in the presence of accessible RGD amphiphiles. This specific interaction between cells and RGD peptides was further explored in a concentration-dependent fashion by creating surface composition arrays using microfluidics. For the range of concentrations studied adhesion and growth were favored by increased peptide concentration, but this concentration dependence was found to diminish in the higher concentration regions of the array. Developing peptide composition gradients in a membrane environment is demonstrated as an effective method to screen biological probes for cell adhesion and growth.

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A general lattice Monte Carlo model is used for simulating the formation of Supported Lipid Bilayers (SLBs) from vesicle solutions. The model, based on a previously published paper, consists of adsorption, decomposition and lateral diffusion steps, and is derived from fundamental physical interactions and mass transport principles. The Monte Carlo simulation results are fit to experimental data at different vesicle bulk concentrations. A sensitivity analysis reveals that the process strongly depends on the bulk concentration C 0 , adsorption rate constant K and all vesicle radii parameters. A measure of "quality of coverage" is proposed. By this measure, the quality of the formed bilayers is found to increase with vesicle bulk concentration.1

In this study fusion of lipid-peptide amphiphile vesicles is employed to form biomimetic coating materials that can modify cellular adhesion and growth on solid substrates. Ellipsometry has been used to monitor vesicle fusion at different concentrations on hydrophilic surfaces and to identify adsorption as its limiting step. Incorporation of small amounts of RGD containing peptide amphiphiles in cell adhesion resistant PC lipid membranes is shown to promote adhesion and growth only when a sufficiently long spacer is used to control the distance of the peptide ligand from the surface.