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Nanoengineering Neural Cells for Regenerative Medicine
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
Christopher F. Adams, Stuart I. Jenkins
In terms of its cytoarchitecture, the CNS consists of two major classes of cells: the neurons and their supporting glia. Neurons transmit electrical signals and reside in groups forming multiple connections with other neurons to make up neural circuits, which perform a common function, for example, vision or movement (Bear, Connors and Paradiso, 2015). Neurons extend axons which are highly specialized structures unique to neuronal cells and adapted to relay information within the body. Axons are ensheathed by layers of an electrically-insulating fatty deposit called myelin. CNS myelin is made and maintained by the oligodendrocytes, each of which can myelinate multiple axons. Astrocytes are the major supporting cell type within the CNS, with new roles regularly being discovered. Their currently accepted functions include: maintaining CNS homeostasis; clearance and recycling of neurotransmitters; providing metabolic support to neurons; roles in synapse formation and maintenance (Bear, Connors and Paradiso, 2015; Liddelow and Barres, 2015; Verkhratsky and Butt, 2013).
Nanovations in Neuromedicine for Shaping a Better Future
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
Jyotirekha Das, G. K. Rajanikant
Neural stimulation is a fundamental technique used to restore neural functions and disordered neural circuits in neurological disorders. It has multiple applications such as restoring auditory, bladder, visual, and limb functions and, moreover, treatment of PD, dystonia, tremor, epilepsy, obsessive-compulsive disorder, and depression (Cogan 2008). The conventional electrical stimulation has several limitations as the biocompatibility of the implanted electrodes as well as the surgery-induced trauma. In contrast, the non-invasive electrical stimulation undergoes even poorer resolution with the high power which can cause complications to the intermediate tissues. These limitations are addressed by using light, magnetic fields, or ultrasound to directly stimulate neurons in the contactless way (Wells et al. 2005). However, these techniques are constrained by poor spatial resolution which is highly depended on the ultrasound frequency. Conversely, for the stimulation of deep neural tissue like in the brain requires low ultra-sound frequency for deep tissue penetration which again leads to low spatial resolution (Menz et al. 2013). High spatial resolution neural stimulation is required for the clinical diagnosis and treatment of neurological diseases and neuroscience research (Menz et al. 2013). Neural stimulation occurs through two mechanisms proposed: the thermal effect on the cell membrane changes the membrane capacity and/or activates temperature-gated ion channels of the transient receptor potential vanilloid (TRPV) channels (Paviolo et al. 2014). To achieve this, the unique properties of the nanomaterials are to be explored, and surface modification can be done.
Culture of pyramidal neural precursors, neural stem cells, and fibroblasts on various biomaterials
Published in Journal of Biomaterials Science, Polymer Edition, 2018
Mo Li, Ying Wang, Jidi Zhang, Zheng Cao, Shuo Wang, Wei Zheng, Qian Li, Tianqi Zheng, Xiumei Wang, Qunyuan Xu, Zhiguo Chen
Pyramidal neurons have a potential of neural circuit reconstruction due to the strong projection and synapse forming ability [11]. A biomaterial that could guide axon growth in a desired direction would be conducive in this regard. However, all the aligned materials tested in the current study failed to meet this purpose. One problem was that pyramidal precursors had difficulty attaching to the aligned materials. Coating with 0.05 mg/ml PDL could improve attachment of pyramidal precursor, but apparently not to a sufficient level to allow cell growth and directional axon/neurite extension. Further modification of these or other materials in structure, possibly by graft copolymerization, is needed to enhance the adhesion and other supportive capacity. Three dimentional co-culture in matrigel allowed for pyramidal cell survival and neurite extension, although this extension was not aligned. However, matrigel was extracted from a murine sacoma cell line, and contained undefined components, which may render it inappropriate for clinical applications. Matrigel mainly contains structural proteins such as laminin, entactin, collagen and heparan sulfate proteoglycans, and various growth factors, such as fibroblast growth factor (FGF), transforming growth factor β (TGFβ) and epidermal growth factor (EGF). Laminin constitutes around 45% of matrigel and may possibly contribute to the growth of PNPs in matrigel. Scaffold made of laminin alone or in combination with HA or collagen should be tested for the supportive capacity in future studies.
Design of a RADA16-based self-assembling peptide nanofiber scaffold for biomedical applications
Published in Journal of Biomaterials Science, Polymer Edition, 2019
Rongrong Wang, Zhaoyue Wang, Yayuan Guo, Hongmin Li, Zhuoyue Chen
The functional peptides linked to the C-terminus of RADA16 are derived from the active center of the functional protein. For example, Sun et al. [23] inserted the spider silk protein noncrystalline motif GGAGGS or GPGGY at the C-terminus of RADA16-I, which effectively enhanced the mechanical strength and hydrophobicity of the peptide. Shi et al. [24] linked the neurotrophic factor (BDNF) functional peptide to the C-terminus of the RADA16 hydrogel to promote neural circuit reconstruction by stimulating the growth of axons, dendrites and the induction of synapse formation, the results of which were confirmed again in 2018 [25]. Wu et al. [3] modified RADA16 with IKVAV and RGD peptides, and they found that the RADA16 mixed hydrogel induced better axonal regeneration and Schwann cell migration than the RADA16 hydrogel alone. Wu et al. linked an active peptide sequence KPSSAPTQLN in BMP-7 at the C-terminus of RADA16 and found that (RADA)4-KPSSAPTQLN was more conducive to nucleus pulposus regeneration than RADA16 alone [29]. In 2017, Wang et al. [33] linked RADA16 to the functional motif SVVYGLR to form the self-assembling peptide RADA16-SVVYGLR. The RADA16-SVVYGLR hydrogel was implanted into zebrafish and was found can promote angiogenesis in a brain injury site. Horii et al. [35] combined RADA16 with three functional motifs: osteogenic growth peptide ALK (ALKRQGRTLYGF), osteopontin cell adhesion motif DGR (DGRGDSVAYG) and RGD binding sequence PGR (PRGDSGYGDS). The results showed that these RADA16 fused peptides can accelerate the proliferation and differentiation of the mouse osteoblasts MC3T3-E1, promote the activity of alkaline phosphatase (ALP) and the secretion of osteocalcin. In 2017, He et al. [36] modified D-type RADA 16 with functional motif RGD sequence to obtain the self-assembling peptide D-RADA16-RGD hydrogel, which obviously promoted bone regeneration.
Biological function simulation in neuromorphic devices: from synapse and neuron to behavior
Published in Science and Technology of Advanced Materials, 2023
Hui Chen, Huilin Li, Ting Ma, Shuangshuang Han, Qiuping Zhao
Except for the above two, other biological behaviors are also demonstrated in artificial synapses and neurons. For example, sleep-wake cycle autoregulation is simulated in neural circuit of Bi2O2Se synapse reported by Zhang et al. [172]. However, more biologically intelligent behaviors will need to be developed in neuromorphic devices.