Behavior of adult human mesenchymal stem cells entrapped in alginate-GRGDY beads.

This study demonstrates that adult human mesenchymal cells (MSC) can be encapsulated in alginate beads with a substantially retained viability (>80%) and that a Gly-Arg-Gly-Asp-Tyr (GRGDY) derivative encourages attachment and elongation to form a dense network of cells that is required for a tissue substitute. Because the availability of autologous human material is severely limited, we used and examined the beads in this study as a proxy for larger constructs. These bead constructs were assessed using phase contrast microscopy and standard histological preparations. In addition, we used a modified MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay to examine cell proliferation by dissociating the cell/alginate constructs using trisodium citrate and trypsin/EDTA. MSCs did not proliferate within the alginate-GRGDY matrix during the 2 weeks examined. These results were further substantiated by concurrent cell density measurements using a hemocytometer. In addition, the glucose consumption rate was measured and compared to that of MSCs grown in two-dimensional culture vessels, indicating steady consumption albeit at a lower level in the entrapped MSCs.