Research Tools : Media


Controlling the Formation of Stem Cell Colonies with Tailored SAM Array

Building on their previous work, the researchers have developed a new feature to make SAM arrays an even better tool to control cell aggregation. Specifically, the spots on the array consist of cellular adhesive peptides stuck to the surface by an easy-to-cleave labile bond. The peptides enable layers of cell to form and detach from the array without scraping or other external manipulation.

Any peptide capable of forming such a bond (e.g., a thioester bond) with the SAM surface could be employed.

Controlling Size and Shape of Stem Cell Colonies with SAM Array

UW–Madison researchers have developed a method for generating colonies of stem cells in controlled shapes and sizes.

The method uses self-assembled monolayer (SAM) arrays, which are metal-coated slides patterned with small adherent spots. These tools enable researchers to systematically expose cells to various surface-bound molecules — such as proteins, nucleic acids and polysaccharides — and study how they interact.

The SAM spots can have specified diameters and shapes (e.g., circle, oval or star), and the cells that come in contact with them will adhere accordingly. The cells can be cultured for a sufficient time to form a layer that undergoes a morphogenesis process and then detaches so it can be collected for further analysis.

Investigating Cell-Surface Interactions via Chemical Array

UW–Madison researchers have developed an improved approach to SAM-based experiments using simple methods to construct arrays of SAMs that can be used to rapidly investigate how selected types and densities of ligands impact cell behaviors such as adhesion, spreading, proliferation, migration and differentiation.

The substrate comprises a slide coated with metal such as gold onto which a polymer stencil is fitted. Through small holes in the stencil, alkanethiol solutions are deposited, forming micrometer-sized spots (up to 120 or more) of SAM. During this deposition process, a range of biological molecules can be tethered to each SAM spot (at varied densities and mixtures), allowing researchers to examine a wide range of possible biological ligands on a single surface. Furthermore, arrays formed using alkanethiolates that prevent biofouling allow researchers to carefully examine the effects of a particular ligand on the behavior of cells cultured on each array spot. Importantly, array fabrication and subsequent examination of cell behavior can be carried out using tools that are standard in biological laboratories such as pipettes and light/fluorescent microscopes.

Culturing Human Embryonic Stem Cells in Well Defined and Controlled Conditions

UW-Madison researchers have developed culture conditions for human ES cells that are entirely free of animal products, feeder cells and conditioned medium. These conditions permit the indefinite culture and proliferation of human ES cells in an undifferentiated state.

The medium includes high levels of a fibroblast growth factor, salts, vitamins, amino acids, glucose, gamma-aminobutyric acid, transforming growth factor beta, pipecholic acid, a lithium salt and lipids. It has been shown to support undifferentiated ES cell proliferation through at least thirteen passages and has proven sufficient to support the derivation of new lines of human ES cells.

The culture conditions also include a biological matrix in the culture vessel. The biological matrix is composed of four human proteins - collagen, laminin, fibronectin, and vitronectin.

No animal products of any kind and no fibroblasts from any species, including humans, are necessary in the culture. Instead, only purified, well characterized components are used to provide a more consistent culture system.

Nuclease Inhibitors and Methods for Their Use

UW-Madison researchers have identified a class of anionic oligomers and polymers that inhibit nucleases, particularly ribonucleases. The inhibitors are polymers of vinyl sulfonate. When nucleases are brought into contact with them in vitro, the polymers are capable of reversibly inhibiting or inactivating the nucleases. The researchers also have developed a method for purifying commercial buffers of these inhibitors.

Protectant Mixture for Use During Freezing and Drying of Human Platelets

UW-Madison researchers have developed an improved protectant mixture for preserving blood platelets. The mixture includes the platelets, at least one polyhydroxy compound, such as trehalose, and phosphate ions. It may also include human serum albumin. The mixture can be used with a variety of preservation processes, including freezing and drying, to provide a stable, preserved composition of platelets.

Use of White Yolk to Preserve Gametes and Embryos

UW-Madison researchers have developed compositions containing white yolk for preserving and storing gametes and embryos. The white yolk can be included in media for keeping gametes and embryos alive in vitro, inducing gametes and embryos to mature in vitro, fertilizing oocytes in vitro, or for any combination of the above. Embryos cultured in white yolk are more “in vivo-like” than embryos cultured on bovine serum albumin (BSA) and fetal calf serum. White yolk also is more likely than serum to provide the various factors needed for embryo development and survival and may ameliorate the adverse effects of temperature change on cultured embryos.

Preservation and Storage Medium for Biological Materials

UW-Madison researchers have developed a preservation medium composed of at least one polyhydroxy compound (monosaccarides and polysaccarides like trehalose, maltose, lactose and sucrose are preferred) and phosphate ions, all of which are approved for use in foods.

Serum-Free Cultivation of Primate Embryonic Stem Cells

A UW-Madison researcher has developed methods for stably culturing primate embryonic stem cells in serum-free media. The researcher discovered that adding basic fibroblast growth factor (bFGF) to serum-free media allows undifferentiated ES cells to proliferate in culture for long periods of time.