Abstract
While stem cell transplantation could potentially treat a variety of disorders, clinical studies have not yet demonstrated conclusive benefits. This may be partly because transplanted stem cells have low survival rates, potentially due to host inflammation. The system described herein used two different gene therapy techniques to improve retention of rat mesenchymal stem cells. In the first, stem cells were transfected with interleukin-10 (IL-10) before being loaded into a collagen scaffold. In the second, unmodified stem cells were loaded into a collagen scaffold along with polymer-complexed IL-10 plasmids. The scaffolds were surgically implanted into the dorsum of syngeneic rats. At each endpoint, the scaffolds were explanted and cell retention, IL-10 level and inflammatory response were quantified. All treatment groups had statistically significant increases in cell retention after 7 days, but the group treated with 2 µg of IL-10 polyplexes had a significant improvement even at 21 days. This cell retention was associated with increased IL-10 and decreased levels of proinflammatory cytokines and apoptosis. The primary effect on the inflammatory response appeared to be on macrophage differentiation, encouraging the regulatory phenotype over the cytotoxic lineage. Improving cell survival may be an important step toward realization of the therapeutic potential of stem cells.