Abstract: Cryopreservation of endothelial cell monolayers is one of the major challenges in the cryopreservation of complex tissues. Human umbilical vein endothelial cells (HUVECs) in suspension are available commercially and recently their post-thaw cell membrane integrity was significantly improved by cryopreservation in 5% dimethyl sulfoxide (DMSO) and 6% hydroxyethyl starch (HES). However, cryopreservation of cells in monolayers has been elusive. The exact mechanisms of damage during cell monolayer cryopreservation are still under investigation. Here, we show that a combination of different factors contribute to significant progress in cryopreservation of cell monolayers. The addition of 2% chondroitin sulfate to 5% DMSO and 6% HES and cooling at 0.2 or 1° C./min led to high membrane integrity (97.3±3.2%) immediately after thaw when HUVECs were cultured on a substrate with a coefficient of thermal expansion similar to that of ice.

Abstract: Methodology is provided for the production of uniformly transformed plants capable of transmitting a foreign gene to progeny by sexual reproduction. A foreign gene is introduced into the zygote in an isolated embryo sac and a transformed plant is recovered. Alternatively, a foreign gene is introduced into an egg cell in an isolated embryo sac, the egg cell is fertilized with an isolated sperm cell and a transformed plant is recovered. Sperm cells may be transformed with a foreign gene, an egg cell in an isolated embryo sac is fertilized with the transformed sperm cells, or nuclei isolated from the transformed sperm cells, and a transgenic plant is recovered. Another method for the production of transgenic plants is transformation of an embryo in an isolated embryo sac. The transgenic plant produced by any one of these methods is homogeneously transformed and capable of transmitting the foreign gene to progeny by sexual reproduction.