Editors' ChoiceStem Cells

A graphene security blanket

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Science Translational Medicine  27 May 2015:
Vol. 7, Issue 289, pp. 289ec89
DOI: 10.1126/scitranslmed.aac5088

Stem cells become “homesick” and undergo apoptosis after detachment from the extracellular matrix (ECM), a phenomenon known as anoikis. For instance, mesenchymal stem cells (MSC) are unsettled by excessive reactive oxygen species (ROS), which degrade cell-matrix attachments. These inhospitable conditions can arise after the restoration of blood flow to infarcted heart tissue, curbing the survival, engraftment, and therapeutic efficacy of MSCs.

Park et al. hypothesized that anoikis could be thwarted by substituting cellular adhesion for a nanomaterial “security blanket” that would present familiar ECM-like cues and resist ROS damage. The authors used graphene oxide (GO), a carbon-based nanomaterial with hydrophilic surface groups that promote protein adsorption. GO was prepared in the form of sheet-like flakes with a thickness of 1.5 nm. In serum, GO flakes became coated with ECM proteins such as fibronectin and wrapped conformably around stem cells. GO-adherent MSCs implanted into a rat model of heart ischemia and reperfusion survived much longer than unwrapped MSCs, with sevenfold more MSCs engrafted after 14 days. Consequently, GO-adherent MSC secreted greater quantities of reparative paracrine factors, which curbed apoptosis in damaged cardiac tissue, encouraged new blood vessel growth, and improved overall heart function.

Overall, GO promoted MSC engraftment by increasing survival, which is more efficient than simply administering greater numbers of MSCs. Such GO security blankets could be used more generally to reduce anoikis in cell-based therapies for treating inflammation and regenerating damaged tissues. Further work will be needed to characterize the long-term biocompatibility and biodegradation of these dispersed carbon nanomaterials, which will vary with size, geometry, and surface chemistry.

J. Park et al., Graphene oxide flakes as a cellular adhesive: Prevention of reactive oxygen species mediated death of implanted cells for cardiac repair. ACS Nano.10.1021/nn507149w (2015). [Abstract]

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