Both ion channels and calcium signals regulate proliferation in human adult mesenchymal stem cells from bone marrow

BACKGROUND: It has been recognized that human bone marrow-derived mesenchymal stem cells (MSCs) are present within the bone marrow cavity and serve as a reservoir for the ...postprintThe 9th Annual Meeting of the International Society for Stem Cell Research (ISSCR 2011), Toronto, Canada, 15-18 June 2011. In Thursday Poster Abstracts of ISSCR, 2011, p. 156, poster board no. 301

Roles of Functional Ion Channels In Human Cardiac C-Kit+ Progenitor Cells

Poster PresentationBackground and objectives: Cardiac progenitor cells play an important role in cardiac repair and regeneration; however, cellular biology and electrophysiology are not understood. The present study was to investigate the functional ion channel expression in human cardiac c-kit+ progenitor cells and the 53 potential roles of these ion channels in regulating proliferation and migration. Methods: Multiple experimental approaches were employed in this study, including whole-cell patch voltage-clamp, RT-PCR, Western blots, cell proliferation and migration assays, etc. Results: Several ionic currents were heterogeneously expressed in human cardiac c-kit+ progenitor cells, including a large conductance Ca2+-activated K+ current (BKCa) in most (93%) of cells, an inwardly-rectifying K+ current (IKir) in 87% of cells, a transient outward K+ current (Ito) in 39% of cells, a voltage-gated tetrodotoxin-sensitive Na+ currents (INa,TTX) in 76% of cells. Molecular identities of these ionic currents were determined with RT-PCR and Western blot analysis. KCa.1.1 (for BKCa), Kir2.1 (for IKir), Kv4.2, Kv4.3 (for Ito), NaV1.2, NaV1.3, NaV1.6, NaV1.7 (for INa.TTX) were expressed in human cardiac progenitor cells. Inhibition of BKCa with paxilline, Ito with 4-aminopyridine, but not INa.TTX with TTX and IKir with Ba2+, decreased cell proliferation. Silencing of KCa.1.1, Kv4.2 or Kv4.3, but not Kir2.1, with siRNA targeting corresponding channels reduced proliferation. Inhibition of KCa1.1 or Kv4.2 or Kv4.3 channels accumulated cells at G0/G1 phase. Interestingly, down regulation of KCa1.1, Kv4.2 or Kv4.3 channels decreased, while of Kir2.1 channels increased migration in human c-kit+ progenitor cells. Conclusions: These results demonstrate for the first time that multiple ion channels are expressed in human cardiac c-kit+ cells. KCa1.1, Kv4.2, and Kv4.3 channels, but not Na+ channels and Kir 2.1 channels, participate in regulating proliferation. KCa1.1, Kv4.2 or Kv4.3 channels promote, while Kir2.1 channels reduce cell migration in human cardiac c-kit+ progenitor cells.published_or_final_versio

Human cardiac Kv4.3 channels are regulated by protein tyrosine kinases

Poster presentationpublished_or_final_versionThe 15th Annual Research Conference of the Department of Medicine, The University of Hong Kong, Hong Kong, 16 January 2010. In Hong Kong Medical Journal, 2010, v. 16, suppl. 1, p. 64, abstract no. 11

Regulation of cell proliferation by ion channels in human mesenchymal stem cells

Oral presentationpublished_or_final_versionThe 15th Annual Research Conference of the Department of Medicine, The University of Hong Kong, Hong Kong, 16 January 2010. In Hong Kong Medical Journal, 2010, v. 16, suppl. 1, p. 65, abstract no. 11

Star Formation in Violent and Normal Evolutionary Phases

Mergers of massive gas-rich galaxies trigger violent starbursts that - over timescales of $> 100$ Myr and regions $> 10$ kpc - form massive and compact star clusters comparable in mass and radii to Galactic globular clusters. The star formation efficiency is higher by 1 - 2 orders of magnitude in these bursts than in undisturbed spirals, irregulars or even BCDs. We ask the question if star formation in these extreme regimes is just a scaled-up version of the normal star formation mode of if the formation of globular clusters reveals fundamentally different conditions.Comment: 4 pages To appear in The Evolution of Galaxies. II. Basic building blocks, eds. M. Sauvage, G. Stasinska, L. Vigroux, D. Schaerer, S. Madde

BKca and hEAG channels modulate proliferation and differentiation of human marrow-derived mesenchymal stem cells

INTRODUCTION: Bone marrow–derived mesenchymal stem cells (MSCs) are a promising cell source for regenerative medicine. However, cellular physiology is not fully understood in human MSCs. The present study was to determine the potential role of the dominant functional ion channels, large-conductance Ca2+-activated potassium (BKCa) channel, ether-a-go-go potassium (hEAG1) channel in regulating cell functions, including ...published_or_final_versionThe 17th Medicial Research Conference, Department of Medicine, The University of Hong Kong, 14 January 2012. In Hong Kong Medical Journal, 2012, v. 18 n. 1, suppl. 1, p. 63, abstract no. 10

Theranostics for MRI‐guided therapy: Recent developments

Recent advances in bioimaging, biochemistry, and bioinformatics have facilitated the development of personalized and precision medicine. Theranostics, combining imaging modalities and therapeutic agents, have garnered a lot of attention in this context, owing to their potential to monitor and control treatment for individual patients. A promising strategy to achieve this goal involves the development of therapy guided by magnetic resonance imaging (MRI). MRI has a high degree of soft tissue contrast, low invasiveness, high depth of penetration and good spatial resolution. MRI-guided therapy could thus allow precise and time-resolved assessment of disease conditions and therapeutic progression. This article will give a brief introduction to the principles of MRI, and describe recently developed strategies to produce MRI-guided therapies. A number of theranostics based on T1, T2, or chemical exchange saturation transfer (CEST) MRI have been explored to track the route of drug carriers in vivo and image diseased tissue so as to enhance bioavailability, overcome complex delivery barriers, and assess therapeutic responses. In addition, the integration of thermal therapy and MRI imaging offers a strategy to noninvasively identify target areas, plan treatment, and provide real-time assessment of the efficacy of tumor ablation. We also discuss advances in intelligent nanoparticles combining small molecule drugs, thermal treatment and multimodal imaging, arguing that these multifunctional agents can further improve therapeutic outcomes

Identification of transient receptor potential channels in human atrial myocytes

In Hong Kong Medical Journal, 2011, v. 17, suppl. 1, p. 68, abstract no. 115published_or_final_versionThe 16th Medical Resarch Conference (MRC), The University of Hong Kong, Hong Kong, China, 22 January 2011. In Hong Kong Medical Journal, 2011, v. 17, suppl. 1, p. 68, abstract no. 11

Identification of wheat-Dasypyrum breviaristatum addition lines with stripe rust resistance using C-banding and genomic in situ hybridization

Older adults show more bilateral prefrontal activation during cognitive performance than younger adults, who typically show unilateral activation. This over-recruitment has been interpreted as compensation for declining structure and function of the brain. Here we examined how the relationship between behavioral performance and prefrontal activation is modulated by different levels of working-memory load. Eighteen healthy older adults (70.8 +/- 5.0 years; MMSE 29.3 +/- 0.9) performed a spatial working-memory task (n-back). Oxygenated ([O2Hb]) and deoxygenated ([HHb]) hemoglobin concentration changes were registered by two functional Near-Infrared Spectroscopy (fNIRS) channels located over the left and right prefrontal cortex. Increased working-memory load resulted in worse performance compared to the control condition. [O2Hb] increased with rising working-memory load in both fNIRS channels. Based on the performance in the high working-memory load condition, the group was divided into low and high performers. A significant interaction effect of performance level and hemisphere on [O2Hb] increase was found, indicating that high performers were better able to keep the right prefrontal cortex engaged under high cognitive demand. Furthermore, in the low performers group, individuals with a larger decline in task performance from the control to the high working-memory load condition had a larger bilateral increase of [O2Hb]. The high performers did not show a correlation between performance decline and working-memory load related prefrontal activation changes. Thus, additional bilateral prefrontal activation in low performers did not necessarily result in better cognitive performance. Our study showed that bilateral prefrontal activation may not always be successfully compensatory. Individual behavioral performance should be taken into account to be able to distinguish successful and unsuccessful compensation or declined neural efficiency