Cell fiber-based 3D tissue array for drug response assay.

For the establishment of a reproducible and sensitive assay system for three-dimensional (3D) tissue-based drug screening, it is essential to develop 3D tissue arrays with uniform shapes and high cell numbers that prevent cell death in the center of the tissue. In recent years, 3D tissue arrays based on spheroids have attracted increased attention. However, they have only been used in specific tissues with hypoxic regions, such as cancer tissues, because nutrient deprivation and hypoxic regions are formed in the core as spheroids grow. Herein, we propose a method to array cell-encapsulated tube-like tissue (cell fiber (CF)) with diameters < 150 µm to prevent nutrient deprivation and hypoxia using a device that can fix the CFs, section them in uniform sizes, and transfer them to a 96-well plate. We fabricated the arrays of CF fragments from cell lines (GT1-7), cancer cells (HeLa), mouse neural stem cells (mNSCs) and differentiated mNSCs, and performed drug response assays. The array of CF fragments assessed the drug response differences among different cell types and drug responses specific to 3D tissues. The array of CF fragments may be used as a versatile drug screening system to detect drug sensitivities in various types of tissues.

Neural stem/progenitor cell-laden microfibers promote transplant survival in a mouse transected spinal cord injury model.

Previous studies have demonstrated that transplantation of neural stem/progenitor cells (NS/PCs) into the lesioned spinal cord can promote functional recovery following incomplete spinal cord injury (SCI) in animal models. However, this strategy is insufficient following complete SCI because of the gap at the lesion epicenter. To obtain functional recovery in a mouse model of complete SCI, this study uses a novel collagen-based microfiber as a scaffold for engrafted NS/PCs. We hypothesized that the NS/PC-microfiber combination would facilitate lesion closure as well as transplant survival in the transected spinal cord. NS/PCs were seeded inside the novel microfibers, where they maintained their capacity to differentiate and proliferate. After transplantation, the stumps of the transected spinal cord were successfully bridged by the NS/PC-laden microfibers. Moreover, the transplanted cells migrated into the host spinal cord and differentiated into three neural lineages (astrocytes, neurons, and oligodendrocytes). However, the NS/PC-laden scaffold could not achieve a neural connection between the rostral end of the injury and the intact caudal area of the spinal cord, nor could it achieve recovery of motor function. To obtain optimal functional recovery, a microfiber design with a modified composition may be useful. Furthermore, combinatorial therapy with rehabilitation and/or medications should also be considered for practical success of biomaterial/cell transplantation-based approaches to regenerative medicine.

Metre-long cell-laden microfibres exhibit tissue morphologies and functions.

Artificial reconstruction of fibre-shaped cellular constructs could greatly contribute to tissue assembly in vitro. Here we show that, by using a microfluidic device with double-coaxial laminar flow, metre-long core-shell hydrogel microfibres encapsulating ECM proteins and differentiated cells or somatic stem cells can be fabricated, and that the microfibres reconstitute intrinsic morphologies and functions of living tissues. We also show that these functional fibres can be assembled, by weaving and reeling, into macroscopic cellular structures with various spatial patterns. Moreover, fibres encapsulating primary pancreatic islet cells and transplanted through a microcatheter into the subrenal capsular space of diabetic mice normalized blood glucose concentrations for about two weeks. These microfibres may find use as templates for the reconstruction of fibre-shaped functional tissues that mimic muscle fibres, blood vessels or nerve networks in vivo.

Link between Aluminum and the Pathogenesis of Alzheimer's Disease: The Integration of the Aluminum and Amyloid Cascade Hypotheses.

Whilst being environmentally abundant, aluminum is not essential for life. On the contrary, aluminum is a widely recognized neurotoxin that inhibits more than 200 biologically important functions and causes various adverse effects in plants, animals, and humans. The relationship between aluminum exposure and neurodegenerative diseases, including dialysis encephalopathy, amyotrophic lateral sclerosis and Parkinsonism dementia in the Kii Peninsula and Guam, and Alzheimer's disease (AD) has been suggested. In particular, the link between aluminum and Alzheimer's disease has been the subject of scientific debate for several decades. However, the complex characteristics of aluminum bioavailability make it difficult to evaluate its toxicity and therefore, the relationship remains to be established. Mounting evidence has suggested that significance of oligomerization of ß-amyloid protein and neurotoxicity in the molecular mechanism of AD pathogenesis. Aluminum may play crucial roles as a cross-linker in ß-amyloid oligomerization. Here, we review the detailed characteristics of aluminum neurotoxicity based on our own studies and the recent literatures. Our aim is to revisit the link between aluminum and AD and to integrate aluminum and amyloid cascade hypotheses in the context of ß-amyloid oligomerization and the interactions with other metals.

A neurospheroid network-stamping method for neural transplantation to the brain.

Neural transplantation therapy using neural stem cells has received as potential treatments for neurodegenerative diseases. Indeed, this therapy is thought to be effective for replacement of degenerating neurons in restricted anatomical region. However, because injected neural stem cells integrate randomly into the host neural network, another approach is needed to establish a neural pathway between selective areas of the brain or treat widespread degeneration across multiple brain regions. One of the promising approaches might be a therapy using pre-made neural network in vitro by the tissue engineering technique. In this study, we engineered a three-dimensional (3D) tissue with a neuronal network that can be easily manipulated and transplanted onto the host brain tissue in vivo. A polydimethylsiloxane microchamber array facilitated the formation of multiple neurospheroids, which in turn interconnected via neuronal processes to form a centimeter-sized neurospheroid network (NSN). The NSN was transferable onto the cortical surface of the brain without damage of the neuronal network. After transfer onto the cortical tissue, the NSN showed neural activity for more than 8 days. Moreover, neurons of the transplanted NSN extended their axons into the host cortical tissue and established synaptic connections with host neurons. Our findings suggest that this method could lay the foundation for treating severe degenerative brain disease.

Brain-derived neurotrophic factor protects cultured rat hippocampal neurons from aluminum maltolate neurotoxicity.

Aluminum is environmentally abundant but not an essential trace element. Although there is increasing evidence suggesting the implication of aluminum in the pathogenesis of Alzheimer's disease, it is still controversial. We found and report here that aluminum maltolate, a stable and hydrophilic aluminum complex, causes death of primary cultured rat hippocampal neurons in a time- and dose-dependent manner. Degenerated neurons were TUNEL-positive. Immunohistochemical detection of synapsin I and microtubule associated protein 2 revealed the synapse loss between neurons intoxicated by aluminum maltolate. To explore the mechanism underlying its neurotoxicity, we administered various pharmacological compounds prior to the application of aluminum maltolate, and found that brain-derived neurotrophic factor (BDNF) markedly attenuated the neurotoxicity. Furthermore, aluminum maltolate inhibited the elevation of intracellular calcium levels caused by BDNF. Our results suggest the involvement of BDNF in the molecular mechanism underlying neurotoxicity induced by aluminum maltolate.