Cardiomyocyte cell cycle activation improves cardiac function after myocardial infarction.

AIMS: Cardiomyocyte loss is a major contributor to the decreased cardiac function observed in diseased hearts. Previous studies have shown that cardiomyocyte-restricted cyclin D2 expression resulted in sustained cell cycle activity following myocardial injury in transgenic (MHC-cycD2) mice. Here, we investigated the effects of this cell cycle activation on cardiac function following myocardial infarction (MI). METHODS AND RESULTS: MI was induced in transgenic and non-transgenic mice by left coronary artery occlusion. At 7, 60, and 180 days after MI, left ventricular pressure-volume measurements were recorded and histological analysis was performed. MI had a similar adverse effect on cardiac function in transgenic and non-transgenic mice at 7 days post-injury. No improvement in cardiac function was observed in non-transgenic mice at 60 and 180 days post-MI. In contrast, the transgenic animals exhibited a progressive and marked increase in cardiac function at subsequent time points. Improved cardiac function in the transgenic mice at 60 and 180 days post-MI correlated positively with the presence of newly formed myocardial tissue which was not apparent at 7 days post-MI. Intracellular calcium transient imaging indicated that cardiomyocytes present in the newly formed myocardium participated in a functional syncytium with the remote myocardium. CONCLUSION: These findings indicate that cardiomyocyte cell cycle activation leads to improvement of cardiac function and morphology following MI and may represent an important clinical strategy to promote myocardial regeneration.

S2 connector versus suture: distal coronary anastomosis remodeling, patency, and function in the pig.

BACKGROUND: Anastomotic connectors could be the key to less invasive bypass surgery, including endoscopic procedures, but equivalence to conventional suturing needs to be established. A novel distal coronary connector was tested pre-clinically for safety and efficacy in comparison to conventional suturing. METHODS AND RESULTS: Left internal thoracic to left anterior descending coronary artery bypasses were constructed off-pump in 35 pigs (73+/-8 kg). An intraluminal metal connector (S2AS) was used in 21 and conventional suturing in 14 animals. S2AS anastomosis construction was easier achieved in one-fourth of the conventional construction time (3.7+/-0.7 versus 16.5+/-2.6 minutes; P<0.001). Acute patency tended to be better (P=0.15). All anastomoses were evaluated intraoperatively, and subgroups at 90 and at 180 days. Patency was 100%. An effective remodeling response was observed in all groups, resulting in unobstructed anastomoses with excellent hemodynamic performance (fractional flow reserve > or = 0.93 at 180 days). At 6 months, the noncompliant connector was covered with stabilized neointima that was thinner than found on the suture line (0.10+/-0.04 versus 0.31+/-0.13 mm; P=0.01). The connector induced less lumen loss (-0.6+/-6.5 versus 21.6+/-19%; P=0.03). The initial side-to-side configuration had remodeled to an end-to-side shape as intended. CONCLUSIONS: In the porcine model, the connector rapidly and consistently produced high-quality anastomoses that fully met current standards on patency and function. Unconventional aspects like a noncompliant intraluminal ring and a side-to-side to end-to-side converted configuration did not interfere with favorable anastomosis remodeling. These findings shed a new light on the anatomical prerequisites for anastomosis patency.

Increased cardiomyocyte differentiation from human embryonic stem cells in serum-free cultures.

Human embryonic stem cells (hESCs) can differentiate into cardiomyocytes, but the efficiency of this process is low. We routinely induce cardiomyocyte differentiation of the HES-2 cell line by coculture with a visceral endoderm-like cell line, END-2, in the presence of 20% fetal calf serum (FCS). In this study, we demonstrate a striking inverse relationship between cardiomyocyte differentiation and the concentration of FCS during HES-2-END-2 coculture. The number of beating areas in the cocultures was increased 24-fold in the absence of FCS compared with the presence of 20% FCS. An additional 40% increase in the number of beating areas was observed when ascorbic acid was added to serum-free cocultures. The increase in serum-free cocultures was accompanied by increased mRNA and protein expression of cardiac markers and of Isl1, a marker of cardiac progenitor cells. The number of beating areas increased up to 12 days after initiation of coculture of HES-2 with END-2 cells. However, the number of alpha-actinin-positive cardiomyocytes per beating area did not differ significantly between serum-free cocultures (503 +/- 179; mean +/- standard error of the mean) and 20% FCS cocultures (312 +/- 227). The stimulating effect of serum-free coculture on cardiomyocyte differentiation was observed not only in HES-2 but also in the HES-3 and HES-4 cell lines. To produce sufficient cardiomyocytes for cell replacement therapy in the future, upscaling cardiomyocyte formation from hESCs is essential. The present data provide a step in this direction and represent an improved in vitro model, without interfering factors in serum, for testing other factors that might promote cardiomyocyte differentiation.

The Carpentier-Edwards Classic and Physio mitral annuloplasty rings: a randomized trial.

OBJECTIVE: To evaluate clinical and echocardiographic outcomes for the semi-flexible Carpentier-Edwards Physio and the rigid Classic mitral annuloplasty ring. METHODS: Ninety-six patients were randomized for either a Classic (n = 53) or a Physio (n = 43) ring from October 1995 through July 1997. Mean follow-up was 5.1 years (range .1-6.6). We included standard patient characteristics at baseline and during follow-up. Analyses were adjusted for age and gender, and for factors that differed across groups at baseline. In 2002, echocardiography was performed in 74% of the survivors. RESULTS: We found a 16% difference in mortality: 14% in the Physio group (n = 6) and 30% in the Classic group (n = 16) (adjusted P = .41). Life table analysis shows that the absolute risk of death after 30 months is lower in the Physio group. Intra-operative repair failure occurred in 3 patients (6%) of the Classic group, and in 4 (9%) of the Physio group, resulting in mitral valve replacement. Late failure occurred in 1 patient (2%) in the Classic group, and in 4 (9%) in the Physio group. At follow-up, left ventricular function did not differ across groups (ejection fraction 45% and 48% (adjusted P = .65)). The combined NYHA class III-IV had improved for the Classic group in 42% and for the Physio group in 34%. CONCLUSION: Although the 16% difference in mortality did not reach statistical significance, it is considered clinically important. No differences in morbidity, valve function, and left ventricular function were found. Further research to explain the difference in mortality is required.

Surgical treatment of Pancoast tumours.

Due to its localisation in the apex of the lung with invasion of the lower part of the brachial plexus, first ribs, vertebrae, subclavian vessels or stellate ganglion, a superior sulcus tumour causes characteristic symptoms, like arm or shoulder pain or Horner's syndrome. If rib invasion is the only feature, lysis of the rib must be evident on the chest radiograph; otherwise the tumour cannot be defined as a Pancoast tumour. It is important to adequately stage the tumour, because staging significantly influences survival. Survival is better for T3 than T4 tumours and mediastinal lymph node involvement has been found to be a negative prognostic factor. Also Horner's syndrome and incompleteness of resection worsen survival. The management of superior sulcus tumours has evolved over the past 50 years. Before 1950 it was considered to be inoperable and uniformly fatal. Shaw and Paulson introduced combined modality treatment and for many years, this combination of radiotherapy and surgery was the treatment of choice with a mean 5-year survival of approximately 30%. Postoperative radiotherapy or brachytherapy does not improve survival in patients with complete or incomplete resection. The tumour can be resected through the classic posterior Shaw-Paulson approach or the newer anterior transcervical approach, introduced by Dartevelle. This method facilitates better exposure of the extreme apex of the lung, brachial plexus and subclavian vessels. Regarding the extent of pulmonary resection, en bloc resection of the involved ribs with a lobectomy is recommended. Recent multimodality studies, involving chemoradiotherapy and surgical resection, show promising results regarding completeness of resection, local recurrence and survival, provided that appropriate staging has been carried out. However, careful patient selection and adequate perioperative management with protection of the bronchial stump or anastomosis are important to achieve reasonable rates of morbidity and mortality. As brain metastases remain one of the most common forms of relapse, further studies are needed to examine the role of prophylactic cranial irradiation in patients with complete resection. Also the addition of other chemotherapy agents or biologic agents such as angiogenesis inhibitors or tyrosine kinase inhibitors gives a new perspective in the treatment of Pancoast tumours.

Differentiation of human embryonic stem cells to cardiomyocytes: role of coculture with visceral endoderm-like cells.

BACKGROUND: Cardiomyocytes derived from human embryonic stem (hES) cells could be useful in restoring heart function after myocardial infarction or in heart failure. Here, we induced cardiomyocyte differentiation of hES cells by a novel method and compared their electrophysiological properties and coupling with those of primary human fetal cardiomyocytes. METHODS AND RESULTS: hES cells were cocultured with visceral-endoderm (VE)-like cells from the mouse. This initiated differentiation to beating muscle. Sarcomeric marker proteins, chronotropic responses, and ion channel expression and function were typical of cardiomyocytes. Electrophysiology demonstrated that most cells resembled human fetal ventricular cells. Real-time intracellular calcium measurements, Lucifer yellow injection, and connexin 43 expression demonstrated that fetal and hES-derived cardiomyocytes are coupled by gap junctions in culture. Inhibition of electrical responses by verapamil demonstrated the presence of functional alpha1c-calcium ion channels. CONCLUSIONS: This is the first demonstration of induction of cardiomyocyte differentiation in hES cells that do not undergo spontaneous cardiogenesis. It provides a model for the study of human cardiomyocytes in culture and could be a step forward in the development of cardiomyocyte transplantation therapies.

A comparison of on-pump and off-pump coronary bypass surgery in low-risk patients.

BACKGROUND: The performance of coronary bypass surgery without cardiopulmonary bypass ("off pump") may reduce perioperative morbidity and costs, but it is uncertain whether the outcome is similar to that involving the use of cardiopulmonary bypass ("on pump"). METHODS: In a multicenter, randomized trial, we randomly assigned 139 patients with predominantly single- or double-vessel coronary disease to on-pump surgery and 142 to off-pump surgery. Cardiac outcome and cost effectiveness were determined one year after surgery. The uncertainty surrounding the cost-effectiveness ratio (cost differences per quality-adjusted year of life gained) was addressed by bootstrapping. RESULTS: At one year, the rate of freedom from death, stroke, myocardial infarction, and coronary reintervention was 90.6 percent after on-pump surgery and 88.0 percent after off-pump surgery (absolute difference, 2.6 percent; 95 percent confidence interval, - 4.6 to 9.8). Graft patency in a randomized subgroup of patients was 93 percent after on-pump surgery and 91 percent after off-pump surgery (absolute difference, 2.0 percent; 95 percent confidence interval, - 6.5 to 10.4). On-pump surgery was associated with $1,839 in additional direct costs per patient ($14,908 vs. $13,069--a difference of 14.1 percent) and an increase in quality-adjusted years of life of 0.83 as compared with 0.82 (difference, 0.01 year; 95 percent confidence interval, - 0.03 to 0.04). Off-pump surgery was more cost effective than on-pump surgery in 95 percent of bootstrap estimates. CONCLUSIONS: In low-risk patients, there was no difference in cardiac outcome at one year between those who underwent on-pump bypass surgery and those who underwent off-pump surgery. Off-pump surgery was more cost effective.

Surgery as part of combined modality treatment in stage IIIB non-small cell lung cancer.

BACKGROUND: The role of surgery after neoadjuvant chemotherapy in patients with stage IIIB non-small cell lung cancer (NSCLC) remains unclear. METHODS: A prospective multicenter trial of neoadjuvant chemotherapy followed by surgery or radiotherapy or both was conducted with 41 patients with stage IIIB NSCLC. End points were toxicity, response, downstaging, complete resectability, and survival. The diagnostic value of repeat mediastinoscopy after neoadjuvant chemotherapy (three courses of gemcitabine/cisplatin) was also studied. RESULTS: Response rate after neoadjuvant chemotherapy was 66% (27 of 41). Fifteen patients underwent repeat mediastinoscopy, which proved to be inadequate in 6 patients. Two repeat mediastinoscopies were false negative. Resection was performed in 18 patients, of which 10 proved to be radical. Hospital mortality was 2.4% (n = 1). Major complications occurred in 6 patients (fistula, empyema, hemorrhage). Histopathologically proven downstaging was seen in 16 patients (39%). Twenty-five patients underwent radiotherapy of whom 14 were diagnosed with stable/progressive disease and 9 with partial/complete response. Median survival for all patients was 15.1 months, for nonresponders 8.4 months and for responders 16.8 months (p = 0.11). Patients with partial/complete response had a mean survival of 21.5 months after resection and 13.0 months after radiotherapy (p = 0.0003). CONCLUSIONS: Radical surgery can be performed in 37% (10 of 27) of the responders resulting in a prolonged survival. Surgery as part of combined modality treatment is feasible in stage IIIB NSCLC. Results of a repeat mediastinoscopy are disappointing and proved to be a not-so-effective restaging tool because of the high number of incomplete procedures and because it yields false negative results.