An innovative bioresorbable gelatin based 3D scaffold that maintains the stemness of adipose tissue derived stem cells and the plasticity of differentiated neurons

Neural tissue engineering aims at producing a simulated environment using a matrix that is suitable to grow specialized neurons/glial cells pertaining to CNS/PNS which replace damaged or lost tissues. The primary goal of this study is to design a compatible scaffold that supports the development of neural-lineage cells which aids in neural regeneration. The fabricated, freeze-dried scaffolds consisted of biocompatible, natural and synthetic polymers: gelatin and polyvinyl pyrrolidone. Physiochemical characterization was carried out using Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) imaging. The 3D construct retains good swelling proficiency and holds the integrated structure that supports cell adhesion and proliferation. The composite of PVP-gelatin is blended in such a way that it matches the mechanical strength of the brain tissue. The cytocompatibility analysis shows that the scaffolds are compatible and permissible for the growth of both stem cells as well as differentiated neurons. A change in the ratios of the scaffold components resulted in varied sizes of pores giving diverse surface morphology, greatly influencing the properties of the neurons. However, there is no change in stem cell properties. Different types of neurons are characterized by the type of gene associated with the neurotransmitter secreted by them. The change in the neuron properties could be attributed to neuroplasticity. The plasticity of the neurons was analyzed using quantitative gene expression studies. It has been observed that the gelatin-rich construct supports the prolonged proliferation of stem cells and multiple neurons along with their plasticity.

Grafted Miniature-Swine Neural Stem Cells of Early Embryonic Mesencephalic Neuroepithelial Origin can Repair the Damaged Neural Circuitry of Parkinson's Disease Model Rats

Although recent progress in the use of human iPS cell-derived midbrain dopaminergic progenitors is remarkable, alternatives are essential in the strategies of treatment of basal-ganglia-related diseases. Attention has been focused on neural stem cells (NSCs) as one of the possible candidates of donor material for neural transplantation, because of their multipotency and self-renewal characteristics. In the present study, miniature-swine (mini-swine) mesencephalic neuroepithelial stem cells (M-NESCs) of embryonic 17 and 18 days grafted in the parkinsonian rat striatum were assessed immunohistochemically, behaviorally and electrophysiologically to confirm their feasibility for the neural xenografting as a donor material. Grafted mini-swine M-NESCs survived in parkinsonian rat striatum at 8 weeks after transplantation and many of them differentiated into tyrosine hydroxylase (TH)-positive cells. The parkinsonian model rats grafted with mini-swine M-NESCs exhibited a functional recovery from their parkinsonian behavioral defects. The majority of donor-derived TH-positive cells exhibited a matured morphology at 8 weeks. Whole-cell recordings from donor-derived neurons in the host rat brain slices incorporating the graft revealed the presence of multiple types of neurons including dopaminergic. Glutamatergic and GABAergic post-synaptic currents were evoked in the donor-derived cells by stimulation of the host site, suggesting they receive both excitatory and inhibitory synaptic inputs from host area. The present study shows that non-rodent mammalian M-NESCs can differentiate into functionally active neurons in the diseased xenogeneic environment and could improve the parkinsonian behavioral defects over the species. Neuroepithelial stem cells could be an attractive candidate as a source of donor material for neural transplantation.

Strategies for bringing stem cell-derived dopamine neurons to the clinic: The Kyoto trial

Concerted efforts are realizing cell-based therapy for Parkinson's disease (PD). In this chapter, I describe efforts at the Center for iPS Cell Research and Application (CiRA), Kyoto University. These efforts use induced pluripotent stem cells (iPSCs) as donor cells. The iPSCs were established as human leukocyte antigen homozygous at CiRA and are intended for allogeneic transplantation. Our manufacturing protocol includes a feeder-free cell culture with laminin fragment LM511-E8 and the sorting of CORIN⁺ cells. Animal experiments, including those with monkey PD models, proved that the grafted cells survive and function as dopaminergic neurons in the brain without forming any tumors. Furthermore, I emphasize that not only the donor cells but also the host brain environment is critical for successful transplantation. To achieve optimization of the host environment, drug administration, gene modification, and rehabilitation are recommended. Based on these results, researchers plan to start a clinical trial at Kyoto University Hospital in the near future.

Identification of Neurexophilin 3 as a Novel Supportive Factor for Survival of Induced Pluripotent Stem Cell-Derived Dopaminergic Progenitors

Successful cell transplantation for Parkinson's disease (PD) depends on both an optimal host brain environment and ideal donor cells. We report that a secreted peptide, neurexophilin 3 (NXPH3), supports the survival of mouse induced pluripotent stem cell-derived (iPSC-derived) dopaminergic (DA) neurons in vitro and in vivo. We compared the gene expression profiles in the mouse striatum from two different environments: a supportive environment, which we defined as 1 week after acute administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), and a nonsupportive environment, defined as 8 weeks after chronic administration of MPTP. NXPH3 expression was higher in the former condition and lower in the latter compared with untreated controls. When we injected mouse iPSC-derived neural cells along with NXPH3 into the mouse striatum, the ratio of tyrosine hydroxylase-positive DA neurons per graft volume was higher at 8 weeks compared with cell injections that excluded NXPH3. In addition, quantitative polymerase chain reaction analyses of the postmortem putamen revealed that the expression level of NXPH3 was lower in PD patients compared with normal controls. These findings will contribute to optimizing the host brain environment and patient recruitment in cell therapy for PD.

Mitomycin-treated undifferentiated embryonic stem cells as a safe and effective therapeutic strategy in a mouse model of Parkinson's disease

Parkinson’s disease (PD) is an incurable progressive neurodegenerative disorder. Clinical presentation of PD stems largely from the loss of dopaminergic neurons in the nigrostriatal dopaminergic pathway, motivating experimental strategies of replacement based on cell therapy. Transplantation of dopaminergic neurons derived from embryonic stem cells significantly improves motor functions in rodent and non-human primate models of PD. However, protocols to generate dopaminergic neurons from embryonic stem cells generally meet with low efficacy and high risk of teratoma formation upon transplantation. To address these issues, we have pre-treated undifferentiated mouse embryonic stem cells (mESCs) with the DNA alkylating agent mitomycin C (MMC) before transplantation. MMC treatment of cultures prevented tumorigenesis in a 12 week follow-up after mESCs were injected in nude mice. In 6-OH-dopamine-lesioned mice, intrastriatal injection of MMC-treated mESCs markedly improved motor function without tumor formation for as long as 15 months. Furthermore, we show that halting mitotic activity of undifferentiated mESCs induces a four-fold increase in dopamine release following in vitro differentiation. Our findings indicate that treating mESCs with MMC prior to intrastriatal transplant is an effective to strategy that could be further investigated as a novel alternative for treatment of PD.

Salsolinol induced apoptotic changes in neural stem cells: amelioration by neurotrophin support

Salsolinol (SAL), a catechol isoquinoline has invited considerable attention due to its structural similarity with dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Its high endogenous presence in Parkinsonian brain implicated its possible association with the disease process. SAL is also present in alcohol beverages and certain food materials and can get access to brain especially in conditions of immature or impaired BBB. Besides this, the effect of SAL on neural stem cells (NSCs) which are potential candidates for adult neurogenesis and transplantation mediated rejuvenating attempts for Parkinson's disease (PD) brain has not been known so far. NSCs in both the cases have to overcome suppressive cues of diseased brain for their survival and function. In this study we explored the toxicity of SAL toward NSCs focusing on apoptosis and status of PI3K survival signaling. NSCs cultured from embryonic day 11 rat fetal brain including those differentiated to TH(+ve) colonies, when challenged with SAL (1-100μM), elicited a concentration and time dependent cell death/loss of mitochondrial viability. 10μM SAL on which significant mitochondrial impairment initiated was further used to study mechanism of toxicity. Morphological impairment, enhanced TUNEL positivity, cleaved caspase-3 and decreased Bcl-2:Bax suggested apoptosis. Sal toxicity coincided with reduced pAkt level and its downstream effectors: pCREB, pGSK-3β, Bcl-2 and neurotrophins GDNF, BDNF suggesting repressed PI3K/Akt signaling. Multiple neurotrophic factor support in the form of Olfactory Ensheathing Cell's Conditioned Media (OEC CM) potentially protected NSCs against SAL through activating PI3K/Akt pathway. This was confirmed on adding LY294002 the PI3K inhibitor which abolished the protection. We inferred that SAL exerts substantial toxicity toward NSCs. These findings will lead to better understanding of endogenous threats that might affect the fate of transplanted NSCs and their probable antidotes.

Stem Cells for the Treatment of Neurodegenerative Diseases

Neurodegenerative diseases are characterized by neurodegenerative changes or apoptosis of neurons involved in networks, leading to permanent paralysis and loss of sensation below the site of the injury. Cell replacement therapy has provided the basis for the development of potentially powerful new therapeutic strategies for a broad spectrum of human neurological diseases. In recent years, neurons and glial cells have successfully been generated from stem cells, and extensive efforts by investigators to develop stem cell-based brain transplantation therapies have been carried out. We review here notable previously published experimental and preclinical studies involving stem cell-based cell for neurodegenerative diseases and discuss the future prospects for stem cell therapy of neurological disorders in the clinical setting. Steady and solid progress in stem cell research in both basic and preclinical settings should support the hope for development of stem cell-based cell therapies for neurological diseases.