Main branch stent deformation following difficult side branch rewiring and balloon dilatation. Rare complication of provisional T stenting.

Coronary artery bifurcations are one of the largest challenges in interventional cardiology. Presented is the case of a patient in whom restenosis of a drug-eluting stent (DES) occurred as a consequence of guide wire re-crossing between the main vessel stent struts and the vessel wall in the proximal part of DES, and consequential balloon crushing of the proximal portion of the DES. Initially, the complication was not recognized because of a good angiographic result and absence of intravascular ultrasound (IVUS) guidance during the procedure. During the second procedure, IVUS analysis explained the mechanism of the DES failure. The problem was solved with the implantation of a new DES.

Lower limb salvage surgery: modular endoprosthesis in bone tumour treatment.

We retrospectively analysed 90 patients who underwent "en bloc" resection and modular endoprosthesis reconstruction in the lower limbs between 1987-2003. After proximal femur resection, reconstruction was performed with a modular endoprosthesis by Howmedica (KFTR, designed by Kotz) and modular revision endoprosthesis by W. Link or Lima-Lto (Revision system, designed by Wagner). The knee joint was reconstructed with a modular endoprosthesis (Howmedica, KFTR designed by Kotz) after distal femur or proximal tibia resection. Malignant bone tumours were present in 58 patients (64.5%), benign tumours in 16 (17.8%), metastases in 8 (8.9%), tumour-like lesions in 4 (4.4 %) and non-tumour-related destruction of the femur in 4 patients (4.4%). High-grade tumours were found in the majority of malignant bone tumours (70.7%). Treatment complications, which occurred in 26 patients, were: local recurrence of the tumour, deep infection, acetabular destruction following hemiarthroplasty, recurrent dislocations of endoprosthesis, periprosthetic fracture and hardware problems. In total, 23 patients (25.6%) died due to tumours. Endoprostheses should be considered as a treatment of choice for bone tumours in the hip and knee joint region. Advances in limb salvage surgery are, and will long continue to be, a great challenge for orthopaedic oncologists of the 21st century.

BM stem cells and cardiac repair: where do we stand in 2004?

Adult BM stem cells are being investigated for their potential to regenerate injured tissues by a process referred to as plasticity or transdifferentiation. Although data supporting stem cell plasticity is extensive, a controversy has emerged based on findings that propose cell-cell fusion as a more appropriate interpretation for this phenomenon. A major focus of this controversy is the claim that acutely infarcted myocardium in adult hearts can be regenerated by BM stem cells. Many researchers consider the adult heart to be a post-mitotic organ, whereas others believe that a low level of cardiomyocyte renewal occurs throughout life. If renewal occurs, it may be in response to cardiac stem cell activity or to stem cells that migrate from distant tissues. Post-mortem microscopic analysis of experimentally induced myocardial infarctions in several rodent models suggests that cardiomyocyte renewal is achieved by stem cells that infiltrate the damaged tissue. For a better understanding of the possible involvement of stem cells in myocardial regeneration, it is important to develop appropriate technologies to monitor myocardial repair over time with an emphasis on large animal models. Studies on non-human primate, swine and canine models of acute myocardial infarctions would enable investigators to utilize clinical quality cell-delivery devices, track labeled donor cells after precision transplantation and utilize non-invasive imaging for functional assays over time with clinical accuracy. In addition, if stem cell plasticity is to reach the next level of acceptance, it is important to identify the environmental cues needed for stem cell trafficking and to define the genetic and cellular mechanisms that initiate transdifferentiation. Only then will it be possible to determine if, and to what extent, BM stem cells are involved in myocardial regeneration and to begin to regulate precisely tissue repair.

The use of drug eluting stents in single and multivessel disease: results from a single centre experience.

OBJECTIVE: Drug eluting stents have been shown to reduce the rate of in-stent restenosis in cases where single lesions are treated. The performance of these stents, in patients with multivessel disease and complex lesions, however, remains unknown. Our experience with sirolimus eluting stents in such patients is presented. DESIGN AND PATIENTS: This study includes all consecutive patients treated at San Raffaele Hospital and EMO Centro Cuore Columbus, Milan, Italy treated with sirolimus eluting stents. RESULTS: Between April 2002 and March 2003, 486 patients with 1027 lesions were treated (437 males, 49 females) with a mean (SD) age of 62.2 (10.5) years. Of all patients studied, 19.1% had single vessel disease, 33.8% had two vessel disease, and 47.1% had three vessel disease. Of the whole study group, 20.3% of patients had diabetes mellitus. A mean (SD) of 2.3 (0.4) stents per patient and 1.1 (0.2) stents per lesion were implanted. The baseline mean reference diameter was 2.7 (0.6) mm with a mean minimal luminal diameter of 0.9 (0.5) mm. Post-stenting, the acute gain was 1.8 (0.6) mm. During hospital stay one patient died (0.2%) and 13 (2.7%) patients had in-hospital myocardial infarction (MI). One patient required urgent repeat percutaneous coronary intervention. Six months clinical follow up was performed in all 347 eligible patients. Six months mortality was 2.0% (n = 7) and acute MI occurred in 0.3% (n = 1). Target lesion revascularisation occurred in 9.5% (n = 33) of the patients and target vessel revascularisation (TVR) in 11.5% (n = 40) of the patients. Major adverse cardiac event rate was 13.8% (n = 48). TVR was 4.5% for single vessel disease and 13.2% for multivessel disease. Diabetes mellitus was the only significant predictor for TVR. CONCLUSION: The use of drug eluting stents in single and multivessel coronary disease produces good short and medium term results with a low rate of revascularisation. Longer term follow-up is required to confirm these observations.

Mobilized bone marrow cells repair the infarcted heart, improving function and survival.

Attempts to repair myocardial infarcts by transplanting cardiomyocytes or skeletal myoblasts have failed to reconstitute healthy myocardium and coronary vessels integrated structurally and functionally with the remaining viable portion of the ventricular wall. The recently discovered growth and transdifferentiation potential of primitive bone marrow cells (BMC) prompted us, in an earlier study, to inject in the border zone of acute infarcts Lin(-) c-kit(POS) BMC from syngeneic animals. These BMC differentiated into myocytes and vascular structures, ameliorating the function of the infarcted heart. Two critical determinants seem to be required for the transdifferentiation of primitive BMC: tissue damage and a high level of pluripotent cells. On this basis, we hypothesized here that BMC, mobilized by stem cell factor and granulocyte-colony stimulating factor, would home to the infarcted region, replicate, differentiate, and ultimately promote myocardial repair. We report that, in the presence of an acute myocardial infarct, cytokine-mediated translocation of BMC resulted in a significant degree of tissue regeneration 27 days later. Cytokine-induced cardiac repair decreased mortality by 68%, infarct size by 40%, cavitary dilation by 26%, and diastolic stress by 70%. Ejection fraction progressively increased and hemodynamics significantly improved as a consequence of the formation of 15 x 10(6) new myocytes with arterioles and capillaries connected with the circulation of the unaffected ventricle. In conclusion, mobilization of primitive BMC by cytokines might offer a noninvasive therapeutic strategy for the regeneration of the myocardium lost as a result of ischemic heart disease and, perhaps, other forms of cardiac pathology.

Transplanted adult bone marrow cells repair myocardial infarcts in mice.

Occlusion of the anterior descending left coronary artery leads to ischemia, infarction, and loss of function in the left ventricle. We have studied the repair of infarcted myocardium in mice using highly enriched stem/progenitor cells from adult bone marrow. The left coronary artery was ligated and 5 hours later Lin- c-kit+ bone marrow cells obtained from transgenic male mice expressing enhanced green fluorescent protein (EGFP) were injected into the healthy myocardium adjacent to the site of the infarct. After 9 days the damaged hearts were examined for regenerating myocardium. A band of new myocardium was observed in 12 surviving mice. The developing myocytes were small and resembled fetal and neonatal myocytes. They were positive for EGFP, Y chromosome, and several myocyte-specific proteins including cardiac myosin, and the transcription factors GATA-4, MEF2, and Csx/Nkx2.5. The cells were also positive for connexin 43, a gap junction/intercalated disc component indicating the onset of intercellular communication. Myocyte proliferation was demonstrated by incorporation of BrdU into the DNA of dividing cells and by the presence of the cell cycle-associated protein K167 in their nuclei. Neo-vascularization was also observed in regenerating myocardium. Endothelial and smooth muscle cells in developing capillaries and small arterioles were EGFP-positive. These cells were positive for Factor VIII and alpha smooth muscle actin, respectively. No myocardial regeneration was observed in damaged hearts transplanted with Lin- c-kit- bone marrow cells, which lack bone marrow-regenerating activity. Functional competence of the repaired left ventricle was improved for several hemodynamic parameters. These in vivo findings demonstrate the capacity of highly enriched Lin- c-kit+ adult bone marrow cells to acutely regenerate functional myocardium within an infarcted region.

Bone marrow cells regenerate infarcted myocardium.

Myocardial infarction leads to loss of tissue and impairment of cardiac performance. The remaining myocytes are unable to reconstitute the necrotic tissue, and the post-infarcted heart deteriorates with time. Injury to a target organ is sensed by distant stem cells, which migrate to the site of damage and undergo alternate stem cell differentiation; these events promote structural and functional repair. This high degree of stem cell plasticity prompted us to test whether dead myocardium could be restored by transplanting bone marrow cells in infarcted mice. We sorted lineage-negative (Lin-) bone marrow cells from transgenic mice expressing enhanced green fluorescent protein by fluorescence-activated cell sorting on the basis of c-kit expression. Shortly after coronary ligation, Lin- c-kitPOS cells were injected in the contracting wall bordering the infarct. Here we report that newly formed myocardium occupied 68% of the infarcted portion of the ventricle 9 days after transplanting the bone marrow cells. The developing tissue comprised proliferating myocytes and vascular structures. Our studies indicate that locally delivered bone marrow cells can generate de novo myocardium, ameliorating the outcome of coronary artery disease.

Dipyridamole-atropine-induced myocardial infarction in a patient with patent epicardial coronary arteries.

BACKGROUND: The diagnostic accuracy of the physical and pharmacological stress echocardiography tests is higher than routine exercise electrocardiography. They have an acceptable safety profile and have been rarely associated with severe adverse effects. CASE REPORT: We present a case of acute anterior myocardial reinfarction immediately after exercise and pharmacological (dipyridamole-atropine) stress echocardiography testing 1 month after successful stent implantation in LAD. Our patient was a 43-year-old man with a history of heavy smoking and hypertension. Remarkably, the stress echocardiogram was non-diagnostic few hours before the infarction occurred. Angiography performed 4 months after the reinfarction revealed neither a culprit lesion nor stent thrombosis. CONCLUSION: Aggressive "last generation" pharmacological stress testing may provide optimal diagnostic accuracy, but as in our case, complications may occur, even after negative stress testing. To our knowledge, this is the first reported case of an acute myocardial infarction as a severe complication of stress testing, which developed in a patient after stent implantation.

Superior transduction of mouse hematopoietic stem cells with 10A1 and VSV-G pseudotyped retrovirus vectors.

The inefficient transduction of human hematopoietic stem cells (HSC) with amphotropic retroviral vectors has been an obstacle to gene therapy for hematopoietic diseases. We have previously reported low levels of amphotropic retrovirus receptor (Pit-2) mRNA and higher levels of gibbon ape leukemia virus (GALV) or 10A1 retrovirus receptor (Pit-1) mRNA in mouse and human HSC. The vesicular stomatitis virus (VSV-G) uses an abundant membrane phospholipid as a receptor. We hypothesized that transduction of HSC requires relatively high levels of retrovirus receptor molecules. Because mouse HSC can be efficiently transduced by ecotropic virus through the abundant ecotropic receptor, the mouse is an ideal model to compare receptor levels and transduction. We have developed a cotransduction assay where ecotropic retrovirus transduction is a positive internal control for downstream steps in retrovirus transduction. A comparison of mouse HSC transduction with amphotropic, 10A1, and VSV-G envelopes showed that the level of amphotropic and 10A1 receptor mRNA in HSC correlated with the frequency of transduction. Transduction with VSV-G vectors was similar to that with 10A1 vectors. We conclude that the level of retrovirus receptor on HSC is critical for HSC transduction and that GALV or VSV-G vectors would be better for human HSC transduction.

Osteochondroma in a skeleton from an 11th century Croatian cemetery.

We present a case of a well-preserved bone tumor in a skeleton from a Croatian skeletal series dated to the 11th century AD. The tumor is located on the anterior side of the neck of the right femur. The gross morphology of the tumor - a round, lumpy, cauliflower-like appearance with a fairly smooth external surface - is consistent with osteochondroma. The diagnosis is supported by x-ray and CAT-scan findings, which show thickened trabeculae and an internal structure of cancellous bone interspersed with areas of dense compact bone. Comparison with x-rays from a patient surgically treated in 1999 for an osteochondroma with the same localization shows that the characteristics of the tumor have remained unchanged from the 11th century.

Quadricepsplasty after war fractures.

Knee movements after fractures caused by explosive devices, as well as after intra-articular fractures of the knee, are often inadequate. This paper presents the results of quadriceps-plasty performed in 10 patients with the purpose of improving knee function. All of the patients were treated by the external fixation method, either after femoral fractures caused by explosive devices or for intra-articular knee fractures. All of them manifested markedly decreased knee flexion (15-70 degrees, with an average of 32 degrees). After quadricepsplasty and physical therapy, the achieved knee flexion was enough for normal walking (80-130 degrees, average 97.5 degrees). Mean knee mobility was increased 65.5 degrees. Our paper presents indications, methods, results, and complications for quadricepsplasty performed after war injuries.

Alternative viral envelopes for oncoretroviruses to increase gene transfer into hematopoietic stem cells.

The hematopoietic stem cell is the target for gene therapy of human blood disease. Low retroviral receptors for the commonly used vectors and quiescence of hematopoietic stem cells are believed to be major obstacles to the success of gene therapy. The development of new stem cell assays has allowed better understanding of the biology and phenotype of hematopoietic stem cells, leading to selection of highly enriched populations of hematopoietic stem cells. Quantitation of retrovirus receptors on these enriched populations of hematopoietic stem cells has resulted in the identification of subpopulations of cells expressing high levels of retrovirus receptors. New promising retrovirus envelopes are being developed. In this review, we discuss those issues that may help to resolve the problem of low gene transfer efficiency into human hematopoietic stem cells.

Granulocyte colony-stimulating factor mobilized peripheral blood stem cells enter into G1 of the cell cycle and express higher levels of amphotropic retrovirus receptor mRNA.

We compared the cell cycle status and expression of mRNA for the amphotropic retroviral receptor in hematopoietic stem cells isolated from bone marrow and cytokine mobilized peripheral blood. CD34+ cells from six normal volunteers were enriched by immune selection from steady-state bone marrow and granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood (10 microg/kg/day for 5 days). Cell cycle status of the phenotypically primitive CD34+CD38- hematopoietic stem cell population was analyzed using a four-color flow cytometry technique that distinguished the G0, G1, and S/IG2/M phases of the cell cycle. Semiquantitative reverse transcriptase-polymerase chain reaction was performed to measure mRNA expression of the amphotropic retroviral receptor. Peripheral blood hematopoietic stem cells had 2.6-fold more cells in the G1 phase of the cell cycle compared to steady-state bone marrow. Furthermore, lineage CD34+CD38- cells from G-CSF mobilized peripheral blood had a fourfold higher level of amphotropic retrovirus receptor mRNA. In conclusion, we found that CD34+ CD38- hematopoietic stem cells isolated from G-CSF mobilized peripheral blood differ from those isolated from steady-state bone marrow in that a significant proportion have entered the G1 phase of the cell cycle and express higher levels of amphotropic receptor mRNA. These biologic properties are consistent with the reported rapid recovery of hematopoietic function following transplantation with peripheral blood hematopoietic stem cells and make these cells a preferred target for retroviral-based gene transfer.

Amphotropic retrovirus transduction of hematopoietic stem cells.

Mice treated with cytokines for 5 days have large numbers of hematopoietic stem cells (HSCs) in their peripheral blood and bone marrow at 1 and 14 days after the last injection. We fractionated the HSCs from the bone marrow of these mice using elutriation at flow rates of 25, 30 and 35 ml/min. The subpopulations of HSCs from cytokine-treated mice show a 3- to 8-fold higher level of mRNA encoding the amphotropic retrovirus receptor (amphoR) compared with the corresponding HSC subpopulation from untreated mouse bone marrow. In an earlier study with mouse HSCs we showed a direct correlation between high levels of amphoR mRNA and efficient retrovirus transduction. We have now utilized our gene transfer protocol to assay amphotropic retrovirus transduction efficiency using HSCs from the bone marrow of mice treated with granulocyte-colony stimulating factor/stem cell factor (G-CSF/SCF). To extend these findings to a more clinically relevant protocol we analyzed the amphoR mRNA levels in HSCs from human cord blood and adult bone marrow. The amphoR mRNA level in HSCs from human bone marrow and fresh cord blood was detectable at an extremely low level compared with the HSC population in cryopreserved cord blood samples. The 12- to 22-fold increase in amphoR mRNA in HSCs from cryopreserved cord blood renders these HSCs likely candidates for high efficiency, gene transfer.