Laura E. Niklason

Surface hydrolysis of poly(glycolic acid) meshes increases the seeding density of vascular smooth muscle cells

A procedure for surface hydrolysis of poly(glycolic acid) (PGA) meshes was developed to increase cell seeding density and improve attachment of vascular smooth muscle cells. Hydrolysis of PGA in 1N NaOH transformed ester groups on the surface of PGA fibers to carboxylic acid and hydroxyl groups. After hydrolysis, the polymer scaffold retained its original gross appearance and dimensions while the fiber diameter decreased. A plot of fiber diameter versus the hydrolysis time showed a linear relationship, with a rate of decrease in fiber diameter of 0.65 microm/min. The molecular weight and thermal properties of the polymer did not change significantly following surface hydrolysis. In cell seeding experiments, surface-hydrolyzed mesh was seeded with more than twice as many cells as unmodified PGA mesh. Vascular smooth muscle cells attached to the surface-hydrolyzed PGA mesh both as individual cells and as cell aggregates while only cell aggregates were observed on the unmodified mesh. Control experiments indicated that adsorption of serum proteins onto the surface-hydrolyzed PGA fibers was correlated with the increase in cell seeding density. These results demonstrate that optimization of biomaterial-cell interactions provides a strategy for increasing the initial cell seeding density for the engineering of tissues of high cell density.

Digital Breast Tomosynthesis: Potentially a New Method for Breast Cancer Screening

Despite recent advances in mammography imaging, it has been shown that many cancers are missed by mammography [1–4]. One of the main reasons cancers are missed is that they are masked by radiographically dense fibroglandular breast tissue which may be overlying or encompassing the cancer [5–11]. Standard mammography techniques, either analog (film) or digital, suffer from the limitation that despite breast compression, three-dimensional anatomical information is projected onto a two-dimensional detector. Tomosynthesis is a technique that allows the radiologist to view individual planes of the breast, potentially reducing the problem of superimposed structures which may limit conventional mammography techniques.