A paper from the Journal of Dental Research describes how scientists took frozen - cryopreserved - tissue, extracted stem cells and successfully put them through their paces. "These cryopreserved periodontal ligament stem cells maintained normal periodontal ligament stem cell characteristics ... . Collectively, this study provides valuable evidence demonstrating a practical approach to the preservation of solid-frozen human tissues for subsequent [adult] stem cell isolation and tissue regeneration." This research group has a good history of stem cell research for regenerative dental work. Work on cryopreserved stem cells is of wider interest for those people considering storage of their stem cells for use in later life.
Link: http://jdr.iadrjournals.org/cgi/content/abstract/84/10/907