The encapsulation of mammalian cells within the bulk material of microfluidic channels may be beneficial for applications ranging from tissue engineering to cell-based diagnostic assays. In this work, we present a technique for fabricating microfluidic channels from cell-laden agarose hydrogels. Using standard soft lithographic techniques, molten agarose was molded against a SU-8 patterned silicon wafer. To generate sealed and water-tight microfluidic channels, the surface of the molded agarose was heated at 71 degrees C for 3 s and sealed to another surface-heated slab of agarose. Channels of different dimensions were generated and it was shown that agarose, though highly porous, is a suitable material for performing microfluidics. Cells embedded within the microfluidic molds were well distributed and media pumped through the channels allowed the exchange of nutrients and waste products. While most cells were found to be viable upon initial device fabrication, only those cells near the microfluidic channels remained viable after 3 days, demonstrating the importance of a perfused network of microchannels for delivering nutrients and oxygen to maintain cell viability in large hydrogels. Further development of this technique may lead to the generation of biomimetic synthetic vasculature for tissue engineering, diagnostics, and drug screening applications.

Microscale hydrogels with dimensions of 200 µm or less are powerful tools for various biomedical applications such as tissue engineering, drug delivery, and biosensors, due to their size, biocompatibility, and their controllable biological, chemical, and mechanical properties. In this review, we provide a broad overview of the approaches used to synthesize and characterize microgels, as well as their applications. We discuss the various methods used to fabricate microgels, such as emulsification, micromolding, microfluidics, and photolithography. Furthermore, we discuss the effects of porosity and crosslinking density on the mechanical and biological properties of hydrogels. In addition, we give specific examples of the use of hydrogels, such as scaffolds and cell encapsulation for tissue engineering, controlled release materials for drug delivery, and environmentally sensitive sensors for microdevices. Finally, we will discuss the future applications of this technology.

The original article to which this Erratum refers was published in Developmental Dynamics 236:1347-1357.On page 1348 in the original published article, top of 3rd column, the tr241 allele mutation location is incorrect. The paper states that the C to T mutation is at position 491, which results in a premature stop codon at amino acid position 167. The mutation is actually at position 499. The amino acid position is correct. The authors regret this error.

Organogenesis involves both the development of specific cell types and their organization into a functional three-dimensional structure. We are using the zebrafish to assess the genetic basis for brain organogenesis. We show that the whitesnake mutant corresponds to the sfpq (splicing factor, proline/glutamine rich) gene, encoding the PSF protein (polypyrimidine tract-binding protein-associated splicing factor). In vitro studies have shown that PSF is important for RNA splicing and transcription and is a candidate brain-specific splicing factor, however, the in vivo function of this gene is unclear. sfpq is expressed throughout development and in the adult zebrafish, with strong expression in the developing brain, particularly in regions enriched for neuronal progenitors. In the whitesnake mutant, a brain phenotype is visible by 28 hr after fertilization, when it becomes apparent that the midbrain and hindbrain are abnormally shaped. Neural crest, heart, and muscle development or function is also abnormal. sfpq function appears to be required in two distinct phases during development.