Brain natriuretic peptide modulates the delayed rectifier outward K(+) current and promotes the proliferation of mouse Schwann cells

hESC- and hiPSC-derived Schwann cells are molecularly comparable and functionally equivalent

Establishing robust models of human myelinating Schwann cells is critical for studying peripheral nerve injury and disease. Stem cell differentiation has emerged as a key human cell model and disease motivating development of Schwann cell differentiation protocols. Human embryonic stem cells (hESCs) are considered the ideal pluripotent cell but ethical concerns regarding their use have propelled the popularity of human induced pluripotent stem cells (hiPSCs). Given that the equivalence of hESCs and hiPSCs remains controversial, we sought to compare the molecular and functional equivalence of hESC- and hiPSC-derived Schwann cells generated with our previously reported protocol. We identified only modest transcriptome differences by RNA sequencing and insignificant proteome differences by antibody array. Additionally, both cell types comparably improved nerve regeneration and function in a chronic denervation and regeneration animal model. Our findings demonstrate that Schwann cells derived from hESCs and hiPSCs with our protocol are molecularly comparable and functionally equivalent.

CNS Schwann cells display oligodendrocyte precursor-like potassium channel activation and antigenic expression in vitro

Central nervous system (CNS) injury triggers production of myelinating Schwann cells from endogenous oligodendrocyte precursors (OLPs). These CNS Schwann cells may be attractive candidates for novel therapeutic strategies aiming to promote endogenous CNS repair. However, CNS Schwann cells have been so far mainly characterized in situ regarding morphology and marker expression, and it has remained enigmatic whether they display functional properties distinct from peripheral nervous system (PNS) Schwann cells. Potassium channels (K+) have been implicated in progenitor and glial cell proliferation after injury and may, therefore, represent a suitable pharmacological target. In the present study, we focused on the function and expression of voltage-gated K+ channels Kv(1-12) and accessory β-subunits in purified adult canine CNS and PNS Schwann cell cultures using electrophysiology and microarray analysis and characterized their antigenic phenotype. We show here that K+ channels differed significantly in both cell types. While CNS Schwann cells displayed prominent K D-mediated K+ currents, PNS Schwann cells elicited K(D-) and K(A-type) K+ currents. Inhibition of K+ currents by TEA and Ba2+ was more effective in CNS Schwann cells. These functional differences were not paralleled by differential mRNA expression of Kv(1-12) and accessory β-subunits. However, O4/A2B5 and GFAP expressions were significantly higher and lower, respectively, in CNS than in PNS Schwann cells. Taken together, this is the first evidence that CNS Schwann cells display specific properties not shared by their peripheral counterpart. Both Kv currents and increased O4/A2B5 expression were reminiscent of OLPs suggesting that CNS Schwann cells retain OLP features during maturation.

The significance of natriuretic peptide in treatment of pulmonary hypertension after mitral valve replacement

OBJECTIVES

To compare the therapeutic efficacy of recombinant human brain natriuretic peptide and prostaglandin E1 in the treatment of pulmonary hypertension after mitral valve replacement.

METHODS

Sixty patients with postoperative pulmonary hypertension were divided randomly into 3 groups that received saline, prostaglandin E1, and natriuretic peptide infusions for 12 hours each. The hemodynamics data were monitored consecutively, and the levels of thromboxane A2 and cyclic guanosine monophosphate were detected pretreatment, after treatment, and 1 week after surgery.

RESULTS

The arterial pressure, pulmonary arterial pressure, and pulmonary capillary wedge pressure decreased 1 hour after prostaglandin E1 treatment and rebounded after treatment discontinuation. The pulmonary arterial pressure and pulmonary capillary wedge pressure in the natriuretic peptide group decreased 3 hours after treatment; pulmonary arterial pressure decreased less than that of the prostaglandin group, and there was no evidence of hemodynamic rebound after treatment discontinuation. The natriuretic peptide had no significant effects on arterial pressure. In both the prostaglandin and natriuretic peptide groups, cyclic guanosine monophosphate increased after the treatment, which was even higher in the latter group. Prostaglandin E1 could lead to the decrease of thromboxane A2, which was not seen in the natriuretic peptide group.

CONCLUSIONS

Both brain natriuretic peptide and prostaglandin E1 can effectively reduce pulmonary hypertension; however, natriuretic peptide has a slower and milder efficacy. The effects of these 2 drugs in reducing the pulmonary arterial pressure may be mediated through different pathways.