Dynamic culture of droplet-confined cell arrays

Cell Seeding Technology for Microarray-Based Quantitative Human Primary Skeletal Muscle Cell Analysis

Pipetting techniques play a crucial role in obtaining reproducible and reliable results, especially when seeding cells on small target areas, such as on microarrays, biochips or microfabricated cell culture systems. For very rare cells, such as human primary skeletal muscle cells (skMCs), manual (freehand) cell seeding techniques invariably result in nonuniform cell spreading and heterogeneous cell densities, giving rise to undesirable variations in myogenesis and differentiation. To prevent such technique-dependent variation, we have designed and fabricated a simple, low-cost pipet guidance device (PGD), and holder that works with hand-held pipettes. This work validates the accuracy and reproducibility of the PGD platform and compares its effectiveness with manual and robotic seeding techniques. The PGD system ensures reproducibility of cell seeding, comparable to that of more expensive robotic dispensing systems, resulting in a high degree of cell uniformity and homogeneous cell densities, while also enabling cell community studies. As compared to freehand pipetting, PGD-assisted seeding of C2C12 mouse myoblasts showed 5.3 times more myotube formation and likewise myotubes derived from PGD-seeded human primary skMCs were 3.6 times thicker and 2.2 times longer. These results show that this novel, yet simple PGD-assisted pipetting technique provides precise cell seeding on small targets, ensuring reproducible and reliable high-throughput cell assays.

Rapid assessment of migration and proliferation: a novel 3D high-throughput platform for rational and combinatorial screening of tissue-specific biomaterials

Designing an ideal biomaterial supportive of multicellular tissue repair is challenging, especially with a poor understanding of the synergy between constituent proteins and growth factors. A brute-force approach, based on screening all possible combinations of proteins and growth factors, is inadequate due to the prohibitively large experimental space coupled with current low-throughput screening techniques. A high-throughput screening platform based on rational and combinatorial strategies for design and testing of proteins and growth factors can significantly impact the discovery of novel tissue-specific biomaterials. Here, we report the development of a flexible high-throughput screening platform, Rapid Assessment of Migration and Proliferation (RAMP), to rapidly investigate cell viability, proliferation, and migration in response to highly miniaturized three-dimensional biomaterial cultures (4-20 μL) with sparingly low cell densities (63-1000 cells per μL for cell arrays; 1 μL of 1000-10,000 cells per μL for migration arrays). The predictions made by RAMP on the efficacy and potency of the biomaterials are in agreement with the predictions made by conventional assays but at a throughput that is at least 100-1000-fold higher. The RAMP assay is therefore a novel approach for the rapid discovery of tissue-specific biomaterials for tissue engineering and regenerative medicine.

A versatile automated platform for micro-scale cell stimulation experiments

Study of cells in culture (in vitro analysis) has provided important insight into complex biological systems. Conventional methods and equipment for in vitro analysis are well suited to study of large numbers of cells (≥ 10(5)) in milliliter-scale volumes (≥ 0.1 ml). However, there are many instances in which it is necessary or desirable to scale down culture size to reduce consumption of the cells of interest and/or reagents required for their culture, stimulation, or processing. Unfortunately, conventional approaches do not support precise and reproducible manipulation of micro-scale cultures, and the microfluidics-based automated systems currently available are too complex and specialized for routine use by most laboratories. To address this problem, we have developed a simple and versatile technology platform for automated culture, stimulation, and recovery of small populations of cells (100-2,000 cells) in micro-scale volumes (1-20 μl). The platform consists of a set of fibronectin-coated microcapillaries ("cell perfusion chambers"), within which micro-scale cultures are established, maintained, and stimulated; a digital microfluidics (DMF) device outfitted with "transfer" microcapillaries ("central hub"), which routes cells and reagents to and from the perfusion chambers; a high-precision syringe pump, which powers transport of materials between the perfusion chambers and the central hub; and an electronic interface that provides control over transport of materials, which is coordinated and automated via pre-determined scripts. As an example, we used the platform to facilitate study of transcriptional responses elicited in immune cells upon challenge with bacteria. Use of the platform enabled us to reduce consumption of cells and reagents, minimize experiment-to-experiment variability, and re-direct hands-on labor. Given the advantages that it confers, as well as its accessibility and versatility, our platform should find use in a wide variety of laboratories and applications, and prove especially useful in facilitating analysis of cells and stimuli that are available in only limited quantities.

Overview of micro- and nano-technology tools for stem cell applications: micropatterned and microelectronic devices

In the past few decades the scientific community has been recognizing the paramount role of the cell microenvironment in determining cell behavior. In parallel, the study of human stem cells for their potential therapeutic applications has been progressing constantly. The use of advanced technologies, enabling one to mimic the in vivo stem cell microenviroment and to study stem cell physiology and physio-pathology, in settings that better predict human cell biology, is becoming the object of much research effort. In this review we will detail the most relevant and recent advances in the field of biosensors and micro- and nano-technologies in general, highlighting advantages and disadvantages. Particular attention will be devoted to those applications employing stem cells as a sensing element.