Pearl extract enhances the migratory ability of fibroblasts in a wound healing model.

CONTEXT: For 2000 years, traditional Chinese medicine has been used as a remedy for general health improvement, including the fight against aging. Pearl powder has recently been used as a health food that has antioxidant, antiaging, antiradioactive, and tonic activities for cells; it is also applied to cure aphthous ulcer, gastric ulcer, and duodenal ulcer on clinical therapy. In addition, the mother of pearl, nacre, could enhance the cell adhesion and tissue regeneration of skin fibroblasts. OBJECTIVE: Fibroblast is regarded as indispensable in the processes of wound healing. Therefore, the effect of pearl extract (PL) on fibroblasts is investigated in this study. MATERIALS AND METHODS: PL is produced by a room temperature super extraction system (Taiwan patent no. I271 220). DMEM medium containing PL (300 µg/mL) was used to examine the effect of migration-promoting potential on human fibroblast cell line or human primary fibroblast cells in a wound healing model in vitro. RESULTS: Medium containing PL (300 µg/mL) demonstrated that the migratory cell numbers of fibroblasts were three times more than that without PL, and mRNA expression of collagen type III was higher than in collagen type I in fibroblasts. It revealed a migration-promoting potential of human fibroblasts in a wound healing model in vitro. DISCUSSION AND CONCLUSION: The present study found that the migration-promoting effect in PL, which could be a supplement in cell culture. These data suggest PL could be useful for enhancing the wound healing of fibroblasts.

Change in neuron aggregation and neurite fasciculation on EVAL membranes modified with different diamines.

In this study, we modified poly(ethylene-co-vinyl alcohol) (EVAL) membranes by the covalent bonding of diamines via epoxidation of surface hydroxyl groups of EVAL to analyze the effect of immobilized diamines with different carbon chain length on the cultured cerebellar granule neurons. Morphological studies showed that neurons seeded on the diamine-immobilized EVAL membrane were able to survive and regenerate with formation of an extensive neuritic network. Furthermore, cultured neurons showed that the presence of diamine with different carbon chain length was able to effectively regulate the neuron adhesion, migration, aggregation, and neurite growth pattern, but mediated neuronal activity with equal efficacy. The short-chain amine stimulated neuron migration, aggregation, and neurite fasciculation, whereas the long carbon chain diamine maintained single neuron distribution with the defasciculated feature of the neurite. Although it is known that positively charged amine molecules can interact directly with cell surface proteoglycans to mediate cell attachment, this study further demonstrated that the terminal primary amine with different carbon chain length is involved in mediating cell-substrate interaction to further regulate neuron aggregation and neurite fasciculation. This indicates a delicate interaction of neuron with the immobilized diamine molecules on the EVAL membrane surface. This work is encouraging because the diamine- immobilized EVAL membranes can be applied for the establishment of different neural culture systems useful for future investigations of neuron biology under in vitro conditions.

Gallium nitride induces neuronal differentiation markers in neural stem/precursor cells derived from rat cerebral cortex.

In the present study, gallium nitride (GaN) was used as a substrate to culture neural stem/precursor cells (NSPCs), isolated from embryonic rat cerebral cortex, to examine the effect of GaN on the behavior of NSPCs in the presence of basic fibroblast growth factor (bFGF) in serum-free medium. Morphological studies showed that neurospheres maintained their initial shape and formed many long and thick processes with the fasciculate feature on GaN. Immunocytochemical characterization showed that GaN could induce the differentiation of NSPCs into neurons and astrocytes. Compared to poly-d-lysine (PDL), the most common substrate used for culturing neurons, there was considerable expression of synapsin I for differentiated neurons on GaN, suggesting GaN could induce the differentiation of NSPCs towards the mature differentiated neurons. Western blot analysis showed that the suppression of glycogen synthase kinase-3beta (GSK-3beta) activity was one of the effects of GaN-promoted NSPC differentiation into neurons. Finally, compared to PDL, GaN could significantly improve cell survival to reduce cell death after long-term culture. These results suggest that GaN potentially has a combination of electric characteristics suitable for developing neuron and/or NSPC chip systems.

The effect of gallium nitride on long-term culture induced aging of neuritic function in cerebellar granule cells.

Gallium nitride (GaN) has been developed for a variety of microelectronic and optical applications due to its unique electric property and chemical stability. In the present study, n-type and p-type GaN were used as substrates to culture cerebellar granule neurons to examine the effect of GaN on cell response for a long-term culture period. It was found that GaN could rapidly induce cultured neurons to exhibit a high phosphorylated Akt level after 20h of incubation. It was assumed that the anti-apoptotic effect of Akt phosphorylation could be correlated with cell survival, neurite growth and neuronal function for up to 35 days of incubation. Morphological studies showed GaN induced larger neuronal aggregates and neurite fasciculation to exhibit a dense fiber network after 8 days of incubation. Western blot analysis and immunocytochemical characterization showed that GaN still exhibited the expression of neurite growth and function, such as high levels of GAP-43, synapsin I and synaptophysin even after 35 days of incubation. In addition, survival of cerebellar granule neurons on GaN was improved by the analysis of lactate dehydrogenase (LDH) release from damaged cells. These results indicated that neuronal connections were formed on GaN by a gradual process from Akt activation and cell aggregation to develop neurite growth, fasciculation and function. Therefore, GaN offers a good model system to identify a well-characterized pattern of neuronal behavior for a long-term culture period, consistent with the development of a neurochip requiring the integration of biological system and semiconductor material.

Assessment of GaN chips for culturing cerebellar granule neurons.

In this work, the behaviors of cerebellar granule neurons prepared from 7-day-old Wistar rats on gallium nitride (GaN) were investigated. We believe that this is the first time that the GaN has been used as a substrate for neuron cultures to examine its effect on cell response in vitro. The GaN surface structure and its relationship with cells were examined by atomic force microscopy (AFM), metallography microscopy, scanning electron microscopy (SEM), lactate dehydrogenase (LDH) release and Western blot analysis. GaN is a so-called III-V compound semiconductor material with a wide bandgap and a relatively high bandgap voltage. Compared with silicon used for most neural chips, neurons seeded on GaN were able to form an extensive neuritic network and expressed very high levels of GAP-43 coincident with the neurite outgrowth. Therefore, the GaN structure may spatially mediate cellular response that can promote neuronal cell attachment, differentiation and neuritic growth. The favorable biocompatibility characteristics of GaN can be used to measure electric signals from networks of neuronal cells in culture to make it a possible candidate for use in a microelectrode array.