This is only an early result from a very small study, but coming on the heels of reports just a few months ago, in which adult stem cells restored heart function to patients with advanced heart failure, the promise of stem cells again got just a bit brighter.

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But he cannot point to any reason the old promise might now become a reality after five years of failure.

BBC: Obama offers a promise on Guantanamo but no direction

Those are the facts necessary to satisfy the elements of a claim for, say, breach of contract: promise, consideration, failure to perform, causation and damages, or the requirements of an affirmative defense: impossibility of performance, for instance.

FORBES: Relevance and Strategy