UCLA

Tissue engineering is a combination of advanced technologies with a goal to fabricate better materials for the repair or replacement of damaged tissue. This is accomplished with the help of cells, biomaterials, and other physiological and chemical cues. In tissue engineering, human mesenchymal stem cells (hMSCs) have huge potential as they can differentiate into many cell types, reduce immune response, be isolated from adult bone marrow, and are easily available. The present study analyzes the gene expression profile of hMSCs when cultured under different conditions: two-dimensional (2D) versus three-dimensional (3D) culture systems; presence or absence of radicals, and exposure to ultra violet (UV) radiation. In our experiments, cells were cultured on 2D substrates and in 3D hydrogel systems fabricated with and without free-radicals. Total RNA was extracted from cells cultured under each condition and the differential expression of genes was analyzed using the Human U133 plus 2.0 Affymetrix gene chip. We observed that the largest difference in gene expression occurs in cells cultured in 3D as compared to 2D systems. UV radiation did not have a significant effect on gene expression but, when combined with the free-radicals generated during fabrication, significant variations in the hMSC gene expression profile were observed. Therefore, can conclude that, while all three factors (2D vs. 3D, free-radicals, and UV light) can influence the gene expression profile of hMSCs, switching from 2D to 3D cell culture system results in the largest change in gene expression.