Gelling Parameters of Alginate and Viability of Umbilical-Cord Stem Cells

Objective: To assess iono-gelling, ion concentration, and composition of pharmaceutical grade alginates on viability of human umbilical cord derived mesenchymal stem cells (hUMSCs), and to evaluate the use of alginate for tissue engineering purposes.

Method: Two pharmaceutical grade sodium alginates (containing high and low guluronic acid (G) groups) and calcium chloride were used in three different sets of experiments: 1) Monolayer of cells grown in a 12 well plate with 30-40% confluency were exposed to 30mg alginate beads prepared by extruding 2% w/v alginate solutions into individual calcium chloride (CaCl₂) solutions (50, 100, 150 and 200 mM); 2) The hUMSCs grown in 24 well culture plates were exposed to 30 mg of CaCl₂ (10, 50, 100 and 200 mM) solutions; and 3) The cells grown in  similar culture conditions were exposed to 30mg of high and low guluronic acid alginate solutions. For all experiments, the cell viability was estimated by MTT assay after 48 hours of incubation. A student’s test was used to evaluate the data and P<0.05 was considered statistically significant.

Result:

The viability of cells in the presence of alginate beads cross-linked with 50mM and 100mM CaCl₂ solutions was comparable to control (P>0.05). At concentrations greater than 100mM, viability was decreased significantly. Viability of cells treated with only CaCl₂ (50-200mM range) was found comparable to that of control. Nevertheless, cells grown in the presence of high and low G alginate solutions respectively showed 33% and 18% loss in viability.

Conclusion:

High hUMSCs survival rate in the presence of alginate gels was found primarily dependent on the alginate backbone structure (G content), and the concentration of calcium during ionogelation. The results suggest feasibility of using G rich alginates for tissue engineering purposes.