Safety and Biocompatibility of the Myosplint System—A Passive Implantable Device That Alters Ventricular Geometry for the Treatment of Heart Failure

Decellularized amniotic membrane attenuates postinfarct left ventricular remodeling

BACKGROUND

Placenta and amnion have been suggested as sources of juvenile cells and tissues for use in surgical regenerative medicine. We previously determined the impact of amniotic epithelial cells induced to undergo epithelial-to-mesenchymal transition (EMT) on myocardial remodeling processes and now evaluated the effects of naïve and processed amniotic membrane (AM) on postischemic left ventricular (LV) geometry and function.

METHODS

Human AM was used in unmodified form (AM), after EMT induction by transforming growth factor β (EMT-AM), and after decellularization (Decell-AM). After characterization by histology, electron microscopy, splenocyte proliferation assay, and cytokine release, myocardial infarction was induced in 6-8-week old male BALB/c mice by permanent left anterior descending coronary occlusion, and AM patches were sutured to the anterior LV surface (n = 10 per group). Infarcted hearts without AM or sham-operated mice were used as controls (n = 10 each). After 4 weeks, LV pressure-volume curves were recorded using a conductance catheter before the animals were sacrificed and the hearts analyzed by histology.

RESULTS

TGF-ß treatment induced EMT-like changes in amniotic epithelial cells but increased AM xenoreactivity in vitro (splenocyte proliferation) and in vivo (CD4+ cell invasion). Moreover, in vitro interleukin-6 release from AM and from cardiac fibroblasts co-incubated with AM was 300- or 100-fold higher than that of interleukin-10, whereas Decell-AM did not release any cytokines. AM- and Decell-AM-treated hearts had smaller infarct size and greater infarct scar thickness than infarct control hearts, but there was no difference in myocardial capillary density or the number of TUNEL positive apoptotic cells. LV contractile function was better in the AM and EMT-AM groups than in infarcted control hearts, but dP/dt max, dP/dt min, stroke work, and cardiac output were best preserved in mice treated with Decell-AM. Volume-based parameters (LV end-systolic and end-diastolic volume as well as LV ejection fraction) did not differ between AM and Decell-AM.

CONCLUSIONS

Decellularized AM supports postinfarct ventricular dynamics independent of the actual regeneration processes. As a cell-free approach to support the infarcted heart, this concept warrants further investigation.

Device therapy for remodeling in congestive heart failure

Heart failure is a progressive condition which begins after an inciting event that leads to neurohormonal activation and cardiac remodeling. Medical therapy with beta-blockers and angiotensin-converting enzyme inhibitors has been shown to attenuate neurohormonal changes and left ventricular remodeling. Despite optimal medical therapy, patients often progress, and other therapeutic modalities have been sought to interrupt and reverse the process of remodeling. Various devices have been developed and entered into clinical trials with the intent of promoting reverse remodeling by directly altering the mechanical properties or shape of the left ventricle. This article reviews devices currently undergoing clinical trials.

Initial Safety and Feasibility Clinical Trial of the Myosplint Device

BACKGROUND

The Myocor Myosplint device is a passive implantable device for the treatment of heart failure by changing the geometry of the left ventricle (LV).

AIM

The purpose of this evaluation was to describe the first human experience with the Myosplint device to demonstrate safety and feasibility.

METHODS

Of the first consecutive 21 patients, 9 patients received a Myosplint device alone while 12 patients underwent a mitral valve repair as well. Safety and efficacy data were gathered at enrollment and during follow-up.

RESULTS

No serious device-related adverse events or device failures were observed. Three patients died during the follow-up period, and 2 patients underwent heart transplantation. There was a significant improvement in the New York Heart Association (NYHA) functional class from 3.0 +/- 0.3 at baseline to 2.1 +/- 0.7 at 6 months (p = 0.001). Both LV end-diastolic and end-systolic volumes had decreased at follow-up. The LV ejection fraction significantly increased in the Myosplint alone group (from 17.1 +/- 4.0% at baseline to 21.8 +/- 4.1% at 3 months and 23.1 +/- 7.2% at 6 months) but not in the Myosplint and mitral valve repair group. The mitral regurgitation (MR) grade had a significant (p = 0.002) linear relationship with the NYHA functional class.

CONCLUSIONS

The initial clinical experience of the Myosplint device demonstrated both safety and feasibility, validating the LV shape change concept in humans. A remodeling solution must, however, include MR resolution, to illustrate the need for a device that can simultaneously reduce or eliminate functional MR off-pump.