The manipulation of calcium oscillations by harnessing self-organisation

Mesenchymal stem cell differentiation: Control by calcium-activated potassium channels

Mesenchymal stem cells (MSCs) are widely used in modern medicine for which understanding the mechanisms controlling their differentiation is fundamental. Ion channels offer novel insights to this process because of their role in modulating membrane potential and intracellular milieu. Here, we evaluate the contribution of calcium-activated potassium (K_Ca ) channels to the three main components of MSC differentiation: initiation, proliferation, and migration. First, we demonstrate the importance of the membrane potential (V_m ) and the apparent association of hyperpolarization with differentiation. Of K_Ca subtypes, most evidence points to activity of big-conductance channels in inducing initiation. On the other hand, intermediate-conductance currents have been shown to promote progression through the cell cycle. While there is no information on the role of K_Ca channels in migration of MSCs, work from other stem cells and cancer cells suggest that intermediate-conductance and to a lesser extent big-conductance channels drive migration. In all cases, these effects depend on species, tissue origin and lineage. Finally, we present a conceptual model that demonstrates how K_Ca activity could influence differentiation by regulating V_m and intracellular Ca²⁺ oscillations. We conclude that K_Ca channels have significant involvement in MSC differentiation and could potentially enable novel tissue engineering approaches and therapies.

Studies on the effect of adenosine on calcium oscillation in hippocampal neurons

Adenosine (Ade) is an antiepileptic agent. In order to investigate the possible mechanism of action of Ade, its effect on calcium (Ca²⁺) oscillations in hippocampal neurons of Sprague Dawley (SD) rats was explored. Primary hippocampal neurons were cultured from suckling neonatal SD rats. Cells were cultured for 7–9 days and the Ca²⁺ oscillations in response to perfusion with Ade were detected using confocal laser scanning microscopy in combination with Fluo-3/AM labeling. This study found that Ade inhibits the spontaneous synchronized Ca²⁺ oscillation frequency and amplitude in mature hippocampal neurons and such inhibition depends on the Ade dosage level to a certain extent. Ade also had a significant inhibitory effect on high potassium-induced Ca²⁺ oscillation frequency and amplitude. Ade had a significant inhibitory effect on high-voltage-activated Ca²⁺ channel-mediated Ca²⁺ influx and Ca²⁺ oscillations in neurons. This may be one of the mechanisms for Ade to exert antiepileptic effects as an endogenous substance.

Investigating the properties of self-organization and synchronization in electronic systems

Nonlinear cooperative behavior appears naturally in many systems, such as cardiac cell oscillations; cellular calcium oscillations; oscillatory chemical reactions, and fireflies. Such systems have been studied in detail due to their inherent properties of robustness, adaptability, scalability, and emergence. In this paper, such nonlinear cooperative behaviors are considered within the domain of electronic system design. We investigate these desirable properties in a system composed of electronic oscillators. The paper presents a series of circuit simulation results showing that self-organizing principles, which can be emulated in an electronic circuit, enable the systems to show a phase transition to synchronization, in a manner similar to those of natural systems. Circuit simulation results presented here show that the circuits are robust to the unreliable performance of the electronic oscillators and tolerant to their run-time faults. These are important findings for future engineering applications in which the system's elements are likely to be unreliable and faulty, such as in molecular- and nanoelectronic systems.