Human mesenchymal stem cells (hMSCs) were infected with an adenovirus expressing integrin-linked kinase (ILK) to understand the role of cell-ECM signal transduction cascades in suppressing anoikis. Survivability of ILK-infected hMSCs encapsulated in poly(ethylene glycol) (PEG) hydrogels, an anoikis-inducing environment, was sustained at 90% over 7 weeks, and survival was attributed to increased protein kinase B (PKB/Akt) activation. hMSCs encapsulated in RGD-modified hydrogels induced an upregulation in ILK production, PKB/Akt activation, and subsequent survival to the same extent of ILK-infected, encapsulated hMSCs. As negative controls, encapsulated hMSCs were infected with cyclization recombinase (a protein not associated with cell survival)-expressing virus, and uninfected hMSCs exhibited very little ILK production, PKB/Akt activation, and survival ( approximately 55% after 7 weeks). As a measure of cell-matrix interactions, vinculin was also quantified for the encapsulated hMSCs and found to be 30-fold greater for cells encapsulated in RGD-modified hydrogels and fivefold greater for ILK-infected hMSCs than controls, indicating that cell-material interactions are inducing the cell survivability of hMSCs encapsulated in RGD-modified hydrogels. In sum, ILK infection can support cell survival in the absence of matrix interactions and enable fundamental studies of three-dimensional cell function in response to extrinsic signals, independently of matrix-ligand interactions.
Copyright 2007 Wiley Periodicals, Inc.