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The fabrication of scaffolds for tissue engineering requires elements of customization depending on the application and is often limited due to the flexibility of the processing technique. This investigation seeks to address this obstacle by utilizing an open-source three-dimensional printing (3DP) system that allows vast customizability and facilitates reproduction of experiments. The effects of processing parameters on printed poly(ε-caprolactone) scaffolds with uniform and gradient pore architectures have been characterized with respect to fiber and pore morphology and mechanical properties. The results demonstrate the ability to tailor the fiber diameter, pore size, and porosity through modification of pressure, printing speed, and programmed fiber spacing. A model was also used to predict the compressive mechanical properties of uniform and gradient scaffolds, and it was found that modulus and yield strength declined with increasing porosity. The use of open-source 3DP technologies for printing tissue-engineering scaffolds provides a flexible system that can be readily modified at a low cost and is supported by community documentation. In this manner, the 3DP system is more accessible to the scientific community, which further facilitates the translation of these technologies toward successful tissue-engineering strategies. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 4326-4335, 2014. [ABSTRACT FROM AUTHOR]

The ability to regulate the proliferation of normal cells in a reversible manner would be a useful adjunct to some clinical therapies, including many types of cancer chemotherapy and surgery for periodontal regeneration. While the application of recombinant growth factors and cytokines to target cells is a logical approach to regulate cell proliferation, the high turnover rates of these peptide factors often make this approach impractical. Recombinant adenoviral vectors can be used to direct the expression of transgene products such as growth factors in many cell types in vitro and in vivo. We have adapted the tetracycline‐regulated expression system to allow regulated transforming growth factor (TGF)‐β1 expression using recombinant adenovirus. We demonstrate that infection with a recombinant TGF‐β‐encoding virus system in primary human oral keratinocytes and in a lung epithelial cell line is sufficient to allow a cell cycle arrest that is reversible upon tetracycline addition. This inhibition is efficient even after the infection of a minority of cells in a population. These results highlight the possibility of using low level infection with recombinant adenovirus to cause short‐term blocks on cell proliferation. [ABSTRACT FROM AUTHOR]