Influence of Polyethylene Glycol on Biochemical Assays

To objectively assess the quality of tissue engineered constructs, researchers quantify cellular production of important extracellular matrix constituents, including DNA, collagen, elastin, and glycosaminoglycans (GAGs), using standard biochemical assays. The quality of these measurements is critically dependent on the standards accurately reflecting the sample treatments and conditions. In our experiments, cells are encapsulated within polyethylene glycol (PEG) based hydrogels. Based on initial results produced in our lab, it appears that PEG may be affecting the standard curves produced and hence the interpretation of our data. We have therefore conducted a series of experiments to try to assess the impact of PEG on our standard curves so that we can better control for its presence in our data interpretation. Specifically, we have examined the influence of gel degradation time and hydrogel composition in terms of PEG molecular weight and weight percent on DNA and GAG standard curves. We found that the molecular weight of the PEG influenced the results in DNA assays whereas the weight percentage did not create a large differentiation. In the GAG assays, the weight percent had a noticeable effect on results where the molecular weight did not.