Effect of osmotic pressure on neurogenesis in cultures of chich embryo spinal cords

Effects of High Glucose on Cell Viability and Differentiation in Primary Cultured Schwann Cells: Potential Role of ERK Signaling Pathway

Diabetic peripheral neuropathy (DPN) is one of the most common complications of diabetes mellitus and hyperglycemia is considered to be the major factor in the development and progression of DPN. Because of the contribution of Schwann cells (SCs) to the pathology of DPN, we investigated the effects of high glucose on cell proliferation, apoptosis and differentiation in primary cultured SCs. Cell Counting Kit-8 (CCK-8) assay and Hoechst staining showed that high glucose inhibited SCs proliferation and increased apoptosis ratio in time and concentration dependent manner. Western blot and real-time quantitative PCR analysis revealed that the major myelin proteins and genes expressions including P0, MAG and Krox-20, were downregulated time dependently in SCs exposed to high glucose from 48 to 96 h. To further elucidate the underlying pathogenic mechanisms, we also explored the role of ERK signaling pathway in high glucose induced SC injury, which has been proved to drive demyelination of peripheral nerves. The western blot analysis showed that compared with control group phosphorylation level of ERK was increased by 14.3 % in SCs exposed to high glucose for 72 h (P < 0.01). Using immunocytochemistry analysis, we observed that the ERK specific inhibitor U0126 blocked the ERK activation induced by high glucose and reversed the inhibitory effect of high glucose on P0 expression. Taken together, these results suggest that high glucose can cause damage in primary cultured SCs and may exert the inhibitory effect on SC differentiation and myelination through ERK signaling activation.

A modified roller tube technique for organotypic cocultures of embryonic rat spinal cord, sensory ganglia and skeletal muscle

The roller tube technique as initially described in the literature in 1981, was modified in several aspects for the coexplantation of embryonic rat spinal cord with attached dorsal root ganglia and skeletal muscle from newborn rats. The high metabolic activity of this coculture system required a particular culturing protocol to stabilize pH and osmotic pressure. The appropriate adjustment of the partial pressure of carbon dioxide gas in the incubator proved to be essential for the control of the pH within narrow limits (7.3 +/- 0.1). The adjustment of the osmotic pressure of the medium (290-300 mOsm) improved the growth of the cultures considerably. Roller drum speed was set to 120 revolutions per hour for enhanced flattening of the culture. A simple rating system was used to evaluate neuronal and non-neuronal outgrowth under different modifications of the culture system. Furthermore, morphological and electrophysiological criteria were defined for evaluating individual neurons. The technique described insures the growth of long-term organotypic cocultures of spinal cord, sensory ganglia and skeletal muscle.

The development of chick spinal cord in tissue culture. III. Neuronal precursor cells in culture

On culturing fragments of neural tube of Hamilton and Hamburger (H & H) Stage 10 chick embryos, large multipolar neurons developed. The aim of this investigation was to determine whether these neurons in culture developed from dividing neuronal precursor cells, from postmitotic precursor cells, or both. Of the neurons formed during the 20 d of culturing in the presence of [3H]thymidine, 26% were unlabeled, indicating that they originated from cells that were already postmitotic at the time of explantation. By labeling cells of the neural tube in vivo and determining the total number of cells in the neural tube, we estimated that the neural tube of chick embryos of H & H Stage 10 contained approximately 1000 (3.3%) postmitotic cells. By estimating the total number of neurons that formed in 20-d cultures and the percentage of labeled and unlabeled neurons, we concluded that the postmitotic neuronal precursor cells survived well in cultures and proceeded on their predetermined path of differentiation. By considering the number of neurons found in the spinal cord in vivo and the number of labeled neurons found in cultures, we concluded that only a relatively small fraction of the dividing neuronal precursor cells entered the postmitotic stages of differentiation and formed neurons in cultures. The majority of cells that did this, entered the postmitotic stage of differentiation during the first 5 d in culture.