IDN-1965

Background— Although the occurrence of cardiac myocyte apoptosis during heart failure has been documented, its importance in pathogenesis is unknown. Transgenic mice with cardiac-restricted overexpression of Gαq exhibit a lethal, peripartum cardiomyopathy accompanied by apoptosis. To test whether apoptosis is causally linked to heart failure, we assessed whether inhibiting this cell death would improve left ventricular function and survival in the Gαq peripartum cardiomyopathy model. Methods and Results— The potent polycaspase inhibitor IDN-1965 or vehicle was administered subcutaneously to Gαq mice by osmotic minipump beginning on day 12 of pregnancy and continuing through euthanasia at day 14 postpartum. As expected, IDN-1965 markedly suppressed cardiac caspase-3–like activity (86.5%; P <0.01), accompanied by reduction in the frequency of cardiac myocyte apoptosis from 1.9±0.3% to 0.2±0.1% ( P <0.01). Animals receiving IDN-1965 exhibited significant improvements in left ventricular end-diastolic dimension (vehicle, 4.7±0.1 mm; IDN-1965, 4.2±0.1 mm; P <0.01), fractional shortening (vehicle, 30.7±1.2%; IDN-1965, 38.9±1.0%; P <0.01), positive (vehicle, 3972±412; IDN-1965, 5870±295; P <0.01) and negative (vehicle, 2365±213; IDN-1965, 3413±201; P <0.01) dP/dt, and complete suppression of mortality (vehicle, 6 of 20 died; IDN-1965, 0 of 14 died; P <0.05). Conclusions— Reduction in cardiac myocyte apoptosis by caspase inhibition improved left ventricular function and survival in pregnant Gαq mice. These data indicate that cardiac myocyte apoptosis plays a causal role in the pathogenesis of cardiomyopathy in this model. Caspase inhibition may provide a novel therapeutic target for heart failure.

We have previously shown that cryopreservation leads to increased apoptotic death of porcine hepatocytes intended for use in a bioartificial liver (BAL). This study was designed to determine if a broad-spectrum caspase inhibitor, IDN–1965, reduced apoptosis and increased function of cryopreserved porcine hepatocytes in static culture or in a BAL. Porcine hepatocytes were studied immediately after isolation and after 2 weeks of cryopreservation in liquid nitrogen using medium supplemented with 25 μmol/L IDN-1965 or vehicle. Both apoptotic and necrotic cells were observed in cultures of fresh and cryopreserved hepatocytes, but the percentage of apoptotic cells increased after cryopreservation. Cryopreservation in IDN-1965 improved hepatocyte viability and reduced apoptotic cell death determined by TUNEL assay. Cryopreservation of hepatocytes in IDN-1965 was also associated with reduced caspase 3-like activity, decreased release of cytochrome c from mitochondria, and a slower decline in mitochondrial membrane potential after thawing. These markers of apoptosis were lowest after cryopreservation when IDN-1965 was added to both the culture and cryopreservation medium. Functional markers of hepatocyte activity (albumin production, diazepam metabolism, urea production) were also increased after cryopreservation and culture of hepatocytes in medium supplemented with 25 μmol/L IDN-1965. Cryopreservation of porcine hepatocytes in the presence of caspase inhibitor IDN-1965 was associated with reduced apoptosis and improved function of porcine hepatocytes in both static culture and a perfused BAL. These data demonstrate that inhibition of apoptosis also preserves cell function.