Lecithinized brain-derived neurotrophic factor promotes the differentiation of embryonic stem cells in vitro and in vivo

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Abstract

The addition of lecithin molecules to brain-derived neurotrophic factor (BDNF) has been reported to markedly enhance its pharmacological effect in vivo. In the current study, we show that lecithinized BDNF (PC-BDNF) has a higher affinity than BDNF for neural precursor cells. Although BDNF only slightly increased the expression of the genes for Mash-1, p35, 68 kDa neurofilament, and TrkB receptor, PC-BDNF caused a significant increase in their expression. PC-BDNF also increased the level of neurofilament protein and dramatically increased TrkB mRNA gene expression, which was followed by a sustained activation of the p42/p44 extracellular-regulated kinases. Finally, transplantation of PC-BDNF-treated cells was more effective than BDNF-treated cells at improving impaired motor function caused by spinal cord injury. These findings showed that PC-BDNF has a better potential than BDNF for promoting neural differentiation, partly due to a higher cellular affinity. Furthermore, PC-BDNF-treated cells could be useful for transplantation therapy for central nervous system injuries.

Section snippets

Materials and methods

Animals. All animals were housed at a constant temperature (23 ± 1 °C) and humidity (50–60%) with free access to a standard diet and water. The animal room had a 12-h light/dark cycle. All of the experimental procedures were in accordance with the St. Marianna University guidelines for the welfare of animals.

Synthesis of PC-BDNF. BDNF was kindly provided by Sumitomo Pharmaceutical (Osaka, Japan). PC-BDNF was synthesized according to the method of Igarashi et al. [13]. Analysis by matrix-assisted

Results

First, the affinity of the retinoic acid-treated neural precursor cells for BDNF and PC-BDNF was examined (Table 1). The incubation of 3 × 105 cells with 1 ng/ml 125I-BDNF resulted in the binding of 0.007 ± 0.001 ng ligand. The same dose of 125I-PC-BDNF resulted in the binding of 0.028 ± 0.001 ng ligand, which is 4-fold higher than for BDNF. Similar results were obtained regardless of the amount of 125I-BDNF added. At 100 ng/ml of 125I-BDNF, there was a total binding of 0.164 ± 0.022 ng of ligand, of which

Discussion

The present study demonstrated that PC-BDNF not only had a much higher affinity for neural precursor cells but was also a more potent inducer for neural differentiation. Of particular importance is that transplanted PC-BDNF-treated cells were more effective than BDNF-treated cells at promoting functional motor recovery following SCI.

The fact that PC-BDNF had improved affinity for the neural cells is not surprising because we have already shown that derivatization of other proteins, such as

Acknowledgments

This study was supported by grants from the Ministry of Education, Culture, Sports, Science and Technology of Japan.

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