Dopaminergic-primed fetal liver mesenchymal stromal-like cells can reverse parkinsonian symptoms in 6-hydroxydopamine-lesioned mice.

BACKGROUND AIMS: Cell replacement therapy is considered a promising alternative in the treatment of degenerative diseases, and in this context, mesenchymal stromal cells (MSCs) have been proposed for transplantation in Parkinson disease (PD). Thus far, the results of animal studies are found to be inconsistent and inconclusive regarding the therapeutic ability of the cells. This study investigated the efficacy of fetal liver (FL)-MSC-derived dopaminergic (DA) neuronal primed cells for correction of parkinsonian symptoms in mice. METHODS: FL-MSCs were differentiated for 21 days in the presence of a combination of neurotropic factors. The extent of cellular reprogramming was analyzed by quantitative polymerase chain reaction for DA-specific neuronal gene expressions and protein expressions by immuno-cytochemistry. The functionality of the cells was determined by electrophysiology and dopamine release assays. Ten-day-primed neuron-like cells or unprimed MSCs were transplanted into the 6-hydroxydopamine (6-OHDA)-lesioned striatum using a stereotaxic device. Dopamine-secreting properties and behavioral studies were used to assess improvement of parkinsonian symptoms. RESULTS: The differentiated cells expressed DA-specific genes and proteins, while exhibiting a high level of voltage-gated potassium current. Furthermore, neuronal primed cells differentiated into tyrosine hydroxylase immunoreactive and dopamine-secreting functional neuron-like cells. Symptomatic correction of PD in the recipient mice within 2 months of transplantation was also observed. DISCUSSION: FL-MSC-derived primed neuron-like cells integrated into the striatum of PD mice, improving parkinsonian symptoms. This study demonstrates an effective cell-based therapy for PD.

All four subunits of HCN2 channels contribute to the activation gating in an additive but intricate manner.

Hyperpolarization-activated cyclic nucleotide-modulated (HCN) channels are tetramers that elicit electrical rhythmicity in specialized brain neurons and cardiomyocytes. The channels are dually activated by voltage and binding of cyclic adenosine monophosphate (cAMP) to their four cyclic nucleotide-binding domains (CNBDs). Here we analyze the effects of cAMP binding to different concatemers of HCN2 channel subunits, each having a defined number of functional CNBDs. We show that each liganded CNBD promotes channel activation in an additive manner and that, in the special case of two functional CNBDs, functionality does not depend on the arrangement of the subunits. Correspondingly, the reverse process of deactivation is slowed by progressive liganding, but only if four and three ligands as well as two ligands in trans position (opposite to each other) are bound. In contrast, two ligands bound in cis positions (adjacent to each other) and a single bound ligand do not affect channel deactivation. These results support an activation mechanism in which each single liganded CNBD causes a turning momentum on the tetrameric ring-like structure formed by all four CNBDs and that at least two liganded subunits in trans positions are required to maintain activation.