Chemical Control of Grafted Human PSC-Derived Neurons in a Mouse Model of Parkinson's Disease

Cryopreservation Maintains Functionality of Human iPSC Dopamine Neurons and Rescues Parkinsonian Phenotypes In Vivo

A major challenge for clinical application of pluripotent stem cell therapy for Parkinson's disease (PD) is large-scale manufacturing and cryopreservation of neurons that can be efficiently prepared with minimal manipulation. To address this obstacle, midbrain dopamine neurons were derived from human induced pluripotent stem cells (iPSC-mDA) and cryopreserved in large production lots for biochemical and transplantation studies. Cryopreserved, post-mitotic iPSC-mDA neurons retained high viability with gene, protein, and electrophysiological signatures consistent with midbrain floor-plate lineage. To test therapeutic efficacy, cryopreserved iPSC-mDA neurons were transplanted without subculturing into the 6-OHDA-lesioned rat and MPTP-lesioned non-human-primate models of PD. Grafted neurons retained midbrain lineage with extensive fiber innervation in both rodents and monkeys. Behavioral assessment in 6-OHDA-lesioned rats demonstrated significant reversal in functional deficits up to 6 months post transplantation with reinnervation of the host striatum and no aberrant growth, supporting the translational development of pluripotent cell-based therapies in PD.

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Cryopreserved human iPSC-mDA neurons retain high viability and midbrain lineage

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iPSC-mDA neurons secrete dopamine and possess typical electrophysiological parameters

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Grafted iPSC-mDA neurons survive and innervate rodent and monkey PD models

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Cryopreserved iPSC-mDA neurons reverse functional motor deficits in 6-OHDA rats

Piezoelectric Effects of Materials on Bio-Interfaces

Electrical stimulation of cells and tissues is an important approach of interaction with living matter, which has been traditionally exploited in the clinical practice for a wide range of pathological conditions, in particular, related to excitable tissues. Standard methods of stimulation are, however, often invasive, being based on electrodes and wires used to carry current to the intended site. The possibility to achieve an indirect electrical stimulation, by means of piezoelectric materials, is therefore of outstanding interest for all the biomedical research, and it emerged in the latest decade as a most promising tool in many bioapplications. In this paper, we summarize the most recent achievements obtained by our group and by others in the exploitation of piezoelectric nanoparticles and nanocomposites for cell stimulation, describing the important implications that these studies present in nanomedicine and tissue engineering. A particular attention will be also dedicated to the physical modeling, which can be extremely useful in the description of the complex mechanisms involved in the mechanical/electrical transduction, yet also to gain new insights at the base of the observed phenomena.

Differentiation of Human Induced Pluripotent Stem Cell (hiPSC)-Derived Neurons in Mouse Hippocampal Slice Cultures

Potential clinical applications of neurons derived from human induced pluripotent stem cells (hiPSC-neurons) for drug screening and transplantation therapies have received considerable attention. However, it remains unclear whether and how transplanted hiPSC-neurons are incorporated into pre-existing neural circuits. Here we developed a co-culture system of hiPSC-neurons and mouse hippocampal slices to examine the differentiation of hiPSC-neurons in pre-existing neural circuits. hiPSC-neurons transplanted in mouse hippocampal slices expressed the hippocampal neuron-specific markers HuB and Prox1 after 7 days of culture, while those markers were scarcely expressed in hiPSC-neurons cultured on glass dishes. Furthermore, hiPSC-neurons transplanted in the dentate gyrus (DG) of slice cultures grew to exhibit dentate granule cell-like morphologies, including besom-shaped dendrites. Similarly, hiPSC-neurons transplanted in the CA1 region of slice cultures grew to exhibit CA1 pyramidal cell-like morphologies, including primary apical and multiple basal dendrites with synaptic spines. Additionally, these cells projected axons toward the entorhinal cortex (EC) as observed in vivo. These data suggest that hiPSC-neurons were anatomically integrated into pre-existing neural circuits in a region-specific manner. Thus, the co-culture system will be useful for the study of efficient strategies to differentiate transplanted hiPSC-neurons.

The role of nonhuman primate models in the development of cell-based therapies for Parkinson's disease

Through the course of over three decades, nonhuman primate (NHP) studies on cell-based therapies (CBTs) for Parkinson’s disease (PD) have provided insight into the feasibility, safety and efficacy of the approach, methods of cell collection and preparation, cell viability, as well as potential brain targets. Today, NHP research continues to be a vital source of information for improving cell grafts and analyzing how the host affects graft survival, integration and function. Overall, this article aims to discuss the role that NHP models of PD have played in CBT development and highlights specific issues that need to be considered to maximize the value of NHP studies for the successful clinical translation of CBTs.

Ex vivo gene therapy for the treatment of neurological disorders

Ex vivo gene therapy involves the genetic modification of cells outside of the body to produce therapeutic factors and their subsequent transplantation back into patients. Various cell types can be genetically engineered. However, with the explosion in stem cell technologies, neural stem/progenitor cells and mesenchymal stem cells are most often used. The synergy between the effect of the new cell and the additional engineered properties can often provide significant benefits to neurodegenerative changes in the brain. In this review, we cover both preclinical animal studies and clinical human trials that have used ex vivo gene therapy to treat neurological disorders with a focus on Parkinson's disease, Huntington's disease, Alzheimer's disease, ALS, and stroke. We highlight some of the major advances in this field including new autologous sources of pluripotent stem cells, safer ways to introduce therapeutic transgenes, and various methods of gene regulation. We also address some of the remaining hurdles including tunable gene regulation, in vivo cell tracking, and rigorous experimental design. Overall, given the current outcomes from researchers and clinical trials, along with exciting new developments in ex vivo gene and cell therapy, we anticipate that successful treatments for neurological diseases will arise in the near future.

A Delay between Motor Cortex Lesions and Neuronal Transplantation Enhances Graft Integration and Improves Repair and Recovery

We previously reported that embryonic motor cortical neurons transplanted immediately after lesions in the adult mouse motor cortex restored damaged motor cortical pathways. A critical barrier hindering the application of transplantation strategies for a wide range of traumatic injuries is the determination of a suitable time window for therapeutic intervention. Here, we report that a 1 week delay between the lesion and transplantation significantly enhances graft vascularization, survival, and proliferation of grafted cells. More importantly, the delay dramatically increases the density of projections developed by grafted neurons and improves functional repair and recovery as assessed by intravital dynamic imaging and behavioral tests. These findings open new avenues in cell transplantation strategies as they indicate successful brain repair may occur following delayed transplantation.SIGNIFICANCE STATEMENT Cell transplantation represents a promising therapy for cortical trauma. We previously reported that embryonic motor cortical neurons transplanted immediately after lesions in the adult mouse motor cortex restored damaged cortical pathways. A critical barrier hindering the application of transplantation strategies for a wide range of traumatic injuries is the determination of a suitable time window for therapeutic intervention. We demonstrate that a 1 week delay between the lesion and transplantation significantly enhances graft vascularization, survival, proliferation, and the density of the projections developed by grafted neurons. More importantly, the delay has a beneficial impact on functional repair and recovery. These results impact the effectiveness of transplantation strategies in a wide range of traumatic injuries for which therapeutic intervention is not immediately feasible.

Predictive Markers Guide Differentiation to Improve Graft Outcome in Clinical Translation of hESC-Based Therapy for Parkinson's Disease

Stem cell treatments for neurodegenerative diseases are expected to reach clinical trials soon. Most of the approaches currently under development involve transplantation of immature progenitors that subsequently undergo phenotypic and functional maturation in vivo, and predicting the long-term graft outcome already at the progenitor stage remains a challenge. Here, we took an unbiased approach to identify predictive markers expressed in dopamine neuron progenitors that correlate with graft outcome in an animal model of Parkinson's disease through gene expression analysis of >30 batches of grafted human embryonic stem cell (hESC)-derived progenitors. We found that many of the commonly used markers did not accurately predict in vivo subtype-specific maturation. Instead, we identified a specific set of markers associated with the caudal midbrain that correlate with high dopaminergic yield after transplantation in vivo. Using these markers, we developed a good manufacturing practice (GMP) differentiation protocol for highly efficient and reproducible production of transplantable dopamine progenitors from hESCs.

The Stagnant Adaptation of Defined and Xeno-Free Culture of iPSCs in Academia

Pluripotent Stem Cells were originally derived and cultured using a feeder layer of cells. Movements have been undertaken to transition from this method to one more defined, high-throughput, and without xenogenic factors. Tremendous research has been done in this area and many products have been developed, however, based on our analysis of recent publications in stem cell related journals many in academia are still using older methods like a feeder layer. In this short communication, we discuss the feasibility of transitioning to defined, xeno-free methods, how a standardized method could improve the field and industry, and that a study bringing together multiple institutions comparing culture methods could be done to evaluate the efficacy of these new methods.

Using Induced Pluripotent Stem Cells to Investigate Complex Genetic Psychiatric Disorders

PURPOSE OF REVIEW

Induced pluripotent stem cells (iPSCs) can be generated from human patient tissue samples, differentiated into any somatic cell type, and studied under controlled culture conditions. We review how iPSCs are used to investigate genetic factors and biological mechanisms underlying psychiatric disorders, and considerations for synthesizing data across studies.

RECENT FINDINGS

Results from patient specific-iPSC studies often reveal cellular phenotypes consistent with postmortem and brain imaging studies. Unpredicted findings illustrate the power of iPSCs as a discovery tool, but may also be attributable to limitations in modeling dynamic neural networks or difficulty in identifying the most affected neural subtype or developmental stage.

SUMMARY

Technological advances in differentiation protocols and organoid generation will enhance our ability to model the salient pathology underlying psychiatric disorders using iPSCs. The field will also benefit from context-driven interpretations of iPSC studies that recognize all potential sources of variability, including differences in patient symptomatology, genetic risk factors and affected cellular subtype.

Applications of CRISPR/Cas9 for Gene Editing in Hereditary Movement Disorders

Gene therapy is a potential therapeutic strategy for treating hereditary movement disorders, including hereditary ataxia, dystonia, Huntington’s disease, and Parkinson’s disease. Genome editing is a type of genetic engineering in which DNA is inserted, deleted or replaced in the genome using modified nucleases. Recently, clustered regularly interspaced short palindromic repeat/CRISPR associated protein 9 (CRISPR/Cas9) has been used as an essential tool in biotechnology. Cas9 is an RNA-guided DNA endonuclease enzyme that was originally associated with the adaptive immune system of Streptococcus pyogenes and is now being utilized as a genome editing tool to induce double strand breaks in DNA. CRISPR/Cas9 has advantages in terms of clinical applicability over other genome editing technologies such as zinc-finger nucleases and transcription activator-like effector nucleases because of easy in vivo delivery. Here, we review and discuss the applicability of CRISPR/Cas9 to preclinical studies or gene therapy in hereditary movement disorders.