Terminal differentiation, advanced organotypic maturation, and modeling of hypertrophic growth in engineered heart tissue.

RATIONALE: Cardiac tissue engineering should provide "realistic" in vitro heart muscle models and surrogate tissue for myocardial repair. For either application, engineered myocardium should display features of native myocardium, including terminal differentiation, organotypic maturation, and hypertrophic growth. OBJECTIVE: To test the hypothesis that 3D-engineered heart tissue (EHT) culture supports (1) terminal differentiation as well as (2) organotypic assembly and maturation of immature cardiomyocytes, and (3) constitutes a methodological platform to investigate mechanisms underlying hypertrophic growth. METHODS AND RESULTS: We generated EHTs from neonatal rat cardiomyocytes and compared morphological and molecular properties of EHT and native myocardium from fetal, neonatal, and adult rats. We made the following key observations: cardiomyocytes in EHT (1) gained a high level of binucleation in the absence of notable cytokinesis, (2) regained a rod-shape and anisotropic sarcomere organization, (3) demonstrated a fetal-to-adult gene expression pattern, and (4) responded to distinct hypertrophic stimuli with concentric or eccentric hypertrophy and reexpression of fetal genes. The process of terminal differentiation and maturation (culture days 7-12) was preceded by a tissue consolidation phase (culture days 0-7) with substantial cardiomyocyte apoptosis and dynamic extracellular matrix restructuring. CONCLUSIONS: This study documents the propensity of immature cardiomyocytes to terminally differentiate and mature in EHT in a remarkably organotypic manner. It moreover provides the rationale for the utility of the EHT technology as a methodological bridge between 2D cell culture and animal models.

Cardiac grafting of engineered heart tissue in syngenic rats.

BACKGROUND: Cell grafting has emerged as a novel approach to treat heart diseases refractory to conventional therapy. We hypothesize that survival and functional and electrical integration of grafts may be improved by engineering cardiac tissue constructs in vitro before grafting. METHODS AND RESULTS: Engineered heart tissue (EHT) was reconstituted by mixing cardiac myocytes from neonatal Fischer 344 rats with liquid collagen type I, matrigel, and serum-containing culture medium. EHTs were designed in circular shape (inner/outer diameter: 8/10 mm; thickness: 1 mm) to fit around the circumference of hearts from syngenic rats. After 12 days in culture and before implantation on uninjured hearts, contractile function of EHT was measured under isometric conditions. Baseline twitch tension amounted to 0.34+/-0.03 mN (n=33) and was stimulated by Ca(2+) and isoprenaline to 200+/-12 and 185+/-10% of baseline values, respectively. Despite utilization of a syngenic model immunosuppression (mg/kg BW: azathioprine 2, cyclosporine A 5, methylprednisolone 2) was necessary for EHT survival in vivo. Echocardiography conducted 7, 14, and 28 days after implantation demonstrated no change in left ventricular function compared with pre-OP values (n=9). Fourteen days after implantation, EHTs were heavily vascularized and retained a well organized heart muscle structure as indicated by immunolabeling of actinin, connexin 43, and cadherins. Ultrastructural analysis demonstrated that implanted EHTs surpassed the degree of differentiation reached before implantation. Contractile function of EHT grafts was preserved in vivo. CONCLUSIONS: EHTs can be employed for tissue grafting approaches and might serve as graft material to repair diseased myocardium.

[BQS1 indicators as a monitoring tool for guideline implementation using selected quality indicators in the treatment of patients with breast cancer and femoral neck fractures]. / Qualitätsindikatoren der BQS als Monitoring--Instrument zur Leitlinienimplementierung am Beispiel ausgewählter Qualitätsindikatoren bei Mammakarzinom und Schenkelhalsfraktur.

Successfully implemented clinical guidelines can contribute to improvement in the quality of care. In the context of clinical guidelines, quality indicators play an important role. Quality indicators can contribute to the further development and updating of existing guidelines by analysing their results. In addition, these results support internal and external quality improvement activities and supply information on the implementation status of guideline recommendations giving an impression of the actual quality of care. In this paper the data of the mandatory German performance measurement (specimen radiograph of impalpable breast lesions, preoperative waiting time with femoral neck fracture) were analysed in respect to the extent that guideline recommendations have been implemented in clinical care. We analysed a database of 189,756 and 331,087 patients for the quality indicators 'specimen radiograph' and 'preoperative waiting time', respectively. Depending on the quality of the clinical guideline the results varied. After the publication of this recommendation as part of the German high-quality guideline for neoplasms of the breast in 2004 the proportion of radiographic controls of specimens after breast cancer surgery increased from initially 36% to 84% in 2006, and the variance as a measure of the variability of care decreased considerably. By contrast, the percentage of patients with femoral neck fracture undergoing surgery within 48h did not change noticeably (2003: 19%; 2006: 16%). A German high-quality guideline making a clear recommendation for early surgery does not yet exist. Quality indicators of the German mandatory performance measurement system are suitable for measuring the extent to which guideline recommendations have been implemented and for supporting their (further) development.