Figure 2

Biomechanical loading in myocardial tissue engineering. Circular engineered heart muscle (gray) can be subjected to different loading protocols [16]. (A) Suspension between static holders facilitates isometric contractions under highly controlled conditions; preloading can be adapted by increasing or decreasing the holder distance. (B) Suspension between motorized holders enables defined extensions at a defined cycle length; engineered heart muscle ideally adapts to the motorized cycle to contract and relax in phase with the narrowing and widening of the holders (quasi-isotonic contractions). (C) Suspension against a bias force supports auxotonic contractions; that is, contraction against increasing load followed by extension under a defined bias force. L0, slack length at diastole; L + 1, extension from slack length; L-1, length at peak systole. Black arrows indicate displacement forced upon engineered heart muscle either by a motorized device with fixed cycle length (B) or defined biasing force elicited by a resilient mount (C).