Cryoinjury models of the adult and neonatal mouse heart for studies of scarring and regeneration.

A major limitation in studies of the injured heart is animal-to-animal variability in wound size resulting from commonly used techniques such as left anterior descending coronary artery ligation. This variability can make standard errors sufficiently large that mean separation between treatment and control groups can be difficult without replicating numbers (n) of animals in groups by excessive amounts. Here, we describe the materials and protocol necessary for delivering a standardized non-transmural cryoinjury to the left ventricle of an adult mouse heart that may in part obviate the issue of injury variance between animals. As reported previously, this cryoinjury model generates a necrotic wound to the ventricle of consistent size and shape that resolves into a scar of uniform size, shape, and organization. The cryo-model also provides an extended injury border zone that exhibits classic markers of remodeling found in surviving cardiac tissue at the edge of a myocardial infarction, including connexin43 (Cx43) lateralization. In a further extension of the method, we describe how we have adapted the model to deliver a cryoinjury to the apex of the heart of neonatal mice-a modification that may be useful for studies of myocardial regeneration in mammals.