At the Meeting: Fresh-Dried Stem Cells ‘To Go’

Newswise — If the promise of stem cell therapy is ever to become a practical reality, the handling of stem cells must first become more practical, according to the Center for Biostabilization at the University of California, Davis. Researchers there are developing ways to desiccate and store mesenchymal stem cells (MSCs). These stem cells can be isolated from adult bone marrow and have the potential to produce bone, cartilage, muscle, fat, and even neural tissue. The hope is to use MSCs clinically for tissue engineering and regenerative medicine. However, this goal will be feasible only if MSCs are available in a form that is easily and reliably transported, stored and used. The Davis researchers proposed that desiccation might be the best approach, and tested ways to make a stable dry mesenchymal stem cell product.

Mammalian cells need their water, and usually die when dehydrated. To protect cells during dehydration, protective substances must be delivered into the cells. Trehalose, a sugar found in extremely high concentrations in organisms that can naturally survive drying, is one such protective compound. Previously, the Davis researchers had successfully loaded MSCs with trehalose by exploiting the machinery that the cells normally use to take up nutrients from their environment.

In new work presented at the American Society for Cell Biology's 43rd Annual Meeting in San Francisco, Ann Oliver, Fern Tablin and colleagues explained how they took the trehalose-loaded MSCs one step further, air-drying them until their water content was in the range of 0.1-0.2 gram H2O per gram dry weight. The issue of residual water content in "dried" samples has been controversial recently, so the researchers applied rigorous quantitative analysis by weight, in triplicate, to confirm water contents. Remarkably, the desiccated cells maintained 20-50 percent viability, as measured by trypan blue exclusion, a marker for membrane integrity. This is the highest viability ever achieved in cells desiccated to this degree, the researchers say. Strikingly, the dried and rehydrated cells were also metabolically active as measured by the fluorescent dye alamar blue, and were able to incorporate nucleotides (assayed by BrdU) suggesting they are capable of cell division.

Clinical MSC treatments may still be miles away. However these promising results bring us a large step closer to the day when doctors might be able to order fresh-dried stem cells 'to go'.

Survival and Growth of Dried and Rehydrated Human Mesenchymal Stem Cells 1,2Ann Oliver, 1,3Kamran Jamil, 1,2John Crowe, and 1,3Fern Tablin 1Center for Biostabilization, UCD; 2Section of Molecular and Cellular Biology, UCD; 3Department of Anatomy Physiology and Cell Biology, School of Veterinary Medicine; University of California, Davis, CA 95616 Funding: This work was supported by DARPA grant # N66001-02-C-8055.