Lineage Tracing of Cardiac Explant Derived Cells

AIMS: Cultured cardiac explants produce a heterogeneous population of cells including a distinctive population of refractile cells described here as small round cardiac explant derived cells (EDCs). The aim of this study was to explore the source, morphology and cardiogenic potential of EDCs. METHODS: Transgenic MLC2v-Cre/ZEG, and actin-eGFP mice were used for lineage-tracing of EDCs in vitro and in vivo. C57B16 mice were used as cell transplant recipients of EDCs from transgenic hearts, as well as for the general characterisation of EDCs. The activation of cardiac-specific markers were analysed by: immunohistochemistry with bright field and immunofluorescent microscopy, electron microscopy, PCR and RT-PCR. Functional engraftment of transplanted cells was further investigated with calcium transient studies. RESULTS: Production of EDCs was highly dependent on the retention of blood-derived cells or factors in the cultured explants. These cells shared some characteristics of cardiac myocytes in vitro and survived engraftment in the adult heart in vivo. However, EDCs failed to differentiate into functional cardiac myocytes in vivo as demonstrated by the absence of stimulation-evoked intracellular calcium transients following transplantation into the peri-infarct zone. CONCLUSIONS: This study highlights that positive identification based upon one parameter alone such as morphology or immunofluorescene is not adequate to identify the source, fate and function of adult cardiac explant derived cells

Early impact of aortic wrapping on patients undergoing aortic valve replacement with mild to moderate ascending aorta dilatation

<p>Abstract</p> <p>Background</p> <p>The management of mild to moderate dilatation of the ascending aorta of less than 5 cm is controversial, particularly when concomitant surgical correction of aortic valve is required. We investigate the impact of a simple method of aorta reduction using Dacron graft wrapping during aortic valve replacement on the rest of the aorta.</p> <p>Methods</p> <p>We studied 14 patients who had ascending aorta dilatation of 4-5 cm before undergoing aortic wrapping during their aortic valve replacement and compared with their post-operative imaging within a month.</p> <p>Results</p> <p>The diameters of the ascending aorta wrapped with the Dacron graft were significantly reduced within 4 weeks after surgery from 44.7 ± 2.6 to 33.6 ± 3.9 mm (p < 0.001). This was associated with significant reduction in the diameter of rest of ascending aorta: coronary sinuses (from 37.9 ± 4.9 mm to 33.3 ± 6.1 mm; p < 0.001), sinotubular junction (from 33.2 ± 4.7 mm to 30.6 ± 4.4 mm, p = 0.02), and aortic arch (from 34.7 ± 4.3 mm to 32.6 ± 4.1 mm, p = 0.03).</p> <p>Conclusions</p> <p>Reduction of ascending aortic dilatation by wrapping with a Dacron graft in this preliminary study is associated with favourable early reversed aortic remodelling. This supports the hypothesis that correction of mild-moderate dilatation of the ascending aorta with Dacron wrapping at the time of aortic valve surgery may prevent the progression of the dilatation, although the long-term study on a larger population is needed to confirm its benefits.</p

Cell therapy for the repair of the mammalian heart

There are immense interests in utilising cell therapy for myocardial repair. Although bone marrow cells are the most extensively studied cell type to-date, evidences of the benefits of using these cells are conflicting. In this thesis, I explore the methodologies used for in-vitro and in-vivo studies of cell therapy, and define the potential of bone marrow cells for myocardial repair. I have identified a potential drawback with the use of green fluorescent protein for the cell therapy studies. The use of cardiac explants was also not suitable for my in-vitro studies of cell therapy. I further demonstrated that there were limitations in the current microscopic techniques used for identifying myocyte nucleus, and this can be a potential source of error in in-vivo studies in which myocyte nuclear events, such as proliferation, and transdifferentiation are evaluated. With this in mind, lineage tracing was used to show that bone marrow cells did not differentiate into myocytes when transplanted immediately after acute myocardial infarction. In addition, no functional improvement was also observed on echocardiography. To compliment my pre-clinical work, two randomised trials were conducted. The first trial showed that intramuscular or intracoronary injections of bone marrow cells into scarred myocardium did not contribute to any meaningful regeneration. The second trial investigated the potential cardioprotective paracrine effects of bone marrow cells, and showed that they did not provide additional cardioprotection when used as an adjunct during cardiopulmonary bypass. While these studies contributed to our understanding and planning of future work in this field, many key questions remain unanswered – whether bone marrow cells can truly benefit the heart, and if so, what are the mechanisms? When and to whom it should be given? Hopefully, my final study on novel biomarkers will eventually aid the identification of patients who will benefit from cell therapy

ISO 14000 environmental management system : an exploratory research

78 p.With rising international concerns over the environment, global customers in the future may demand that their suppliers be ISO 14000 certified. As such, there is an increasing need for organisations to demonstrate greater concern over the potential impact of their activities, processes and products on the environment, in order to remain globally competitive.BUSINES

Impacts of additional cycles of neoadjuvant immunotherapy on surgery in non‐small‐cell lung cancer

Abstract Objective Whether cycle number influences the subsequent pathological or surgical outcomes remained unclear. This study aimed to assess the efficacy and surgical safety of neoadjuvant immunochemotherapy‐based treatment in the real‐world setting. Methods Clinical data of patients who received neoadjuvant immunochemotherapy for non‐small‐cell lung cancer between 2018 and 2021 were collected. Oncological outcomes such as objective response rate (ORR), major pathological response (MPR), and pathological complete response (pCR), and surgical outcomes including operating time, intraoperative bleeding, postoperative drainage, and hospital stay were analyzed. Results In total, 176 patients were included, among whom 102 cases were lung squamous carcinoma (LUSQ). After immunochemotherapy, 98 (56%) of patients achieved ORR. Notably, the ORR (63% vs. 46%, p = 0.039) and pCR (45% vs. 27%, p = 0.022) were significantly higher in patients with LUSQ. For patients who received two, three, four, and five or more cycles, the ORRs were 52%, 67%, 53%, and 50% (p = 0.36). In post hoc analysis, cycle numbers showed no significant association with MPR or pCR (p = 0.14 and p = 0.073). Treatment cycles showed no influence on operating time, postoperative drainage, and hospital stay (p = 0.79, 0.37, and 0.22). Notably, the blood loss index of patients who received more than four cycles was higher than those receiving four or fewer cycles (mean blood loss: two or fewer cycles 153.1, three cycles 113.8, four cycles 137.6, and five or more cycles 293.3, respectively). Conclusions This study indicated that cycles of neoadjuvant immunochemotherapy had no significant effect on the feasibility and safety of surgery. Although not statistically significant, patients who received five or more cycles of treatment experienced higher intraoperative blood loss