Editors' ChoiceNanomedicine

Banking on Carbon

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Science Translational Medicine  26 Jun 2013:
Vol. 5, Issue 191, pp. 191ec104
DOI: 10.1126/scitranslmed.3006770

Umbilical cord blood is becoming an increasingly popular source of hematopoetic stem and progenitor cells for treating a wide variety of blood disorders, including cancers and metabolic diseases. In the absence of reliable methods for ex vivo expansion of stem cells, however, cord blood–based treatments are limited mostly to children and adults with low body weights. In response, Bari and colleagues showed that carbon nanotubes could be used as scaffolds to improve the expansion and viability of hematopoetic stem and progenitor cells from human umbilical cord blood.

For cord blood cell expansion, scaffolding materials should have limited adverse effects on stem cell differentiation while supporting the overall viability and expansion of cord blood cells. By dispersing carboxylated carbon nanotubes in serum-free supplemented medium, Bari et al. were able to achieve an increase in expansion of human hematopoetic progenitor and stem cells as compared with using supplemented medium alone. Culturing cord blood cells in the presence of carbon nanotubes also led to an observable reduction in cord blood–derived mesenchymal stromal cells as compared with that of controls, indicating an ability of carbon nanotubes to limit differentiation during expansion. Expanded cells were then transplanted into immunodeficient mice in order to see whether they could reconstitute human blood. Only the cells cultured in the presence of carbon nanotubes led to a more than 100-fold increase in human CD45+ cells in mouse peripheral blood 8 weeks after transplantation. These cells also reduced mortality associated with host rejection of transplanted cells as compared with that of nonexpanded cord blood cells.

This study by Bari et al. demonstrates that functionalized carbon nanotubes can be used for scaffold-based expansion of umbilical cord blood cells ex vivo, with minimal differentiation and enhanced engraftment of expanded cells. The long-term in vivo safety of carbon nanotubes is not yet known, and the exact mechanism of stem cell protection is still needed. With this study, however, there is new evidence of the clinical potential of carbon nanotubes as a scaffold for the expansion of human stem and progenitor cells in cord blood.

S. Bari et al., Protective role of functionalized single walled carbon nanotubes enhance ex vivo expansion of hematopoietic stem and progenitor cells in human umbilical cord blood. Nanomed. Nanotechnol. Biol. Med., 3 June 2013 (10.1016/j.nano.2013.05.009). [Abstract]

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