Application of stem cell derived neuronal cells to evaluate neurotoxic chemotherapy

Modeling mechanisms of chemotherapy-induced peripheral neuropathy and chemotherapy transport using induced pluripotent stem cell-derived sensory neurons

BACKGROUND

and Purpose: Chemotherapy-induced peripheral neuropathy (CIPN) constitutes a significant health problem due to the increasing prevalence and lack of therapies for treatment and prevention. While pivotal for routine cancer treatment, paclitaxel and vincristine frequently cause CIPN and impact the quality of life among cancer patients and survivors. Here, we investigate molecular mechanisms and drug transport in CIPN.

EXPERIMENTAL APPROACH

Human sensory neurons were derived from induced pluripotent stem cells (iPSC-SNs), which were characterized using flow cytometry and immunolabeling. These iPSC-SNs were exposed to different concentrations of the two microtubule-targeting agents, paclitaxel and vincristine, with and without pre-exposure to inhibitors and inducers of efflux transporters. Neuronal networks were quantified via fluorescent staining against sensory neuron markers. Transcriptional effects of the chemotherapeutics were examined using quantitative polymerase chain reactions (qPCR).

KEY RESULTS

Paclitaxel exposure resulted in axonal retraction and thickening, while vincristine caused fragmentation and abolishment of axons. Both agents increased the mRNA expression of the pain receptor, transient receptor potential vanilloid (TRPV1), and highly induced neuronal damage, as measured by activating transcription factor 3 (ATF3) mRNA. iPSC-SNs express the efflux transporters, P-glycoprotein (P-gp, encoded by ABCB1) and multidrug resistance-associated protein 1 (MPR1, encoded by ABCC1). Modulation of efflux transporters indicate that P-gp and MRP1 play a role in modulating neuronal accumulation and neurotoxicity in preliminary experiments.

CONCLUSION

and Implications: iPSC-SNs are a valuable and robust model to study the role of efflux transporters and other mechanistic targets in CIPN. Efflux transporters may play a role in CIPN pathogenesis as they regulate the disposition of chemotherapy to the peripheral nervous system, and they may present potential therapeutic targets for CIPN.

Chemotherapy-induced peripheral neuropathy models constructed from human induced pluripotent stem cells and directly converted cells: a systematic review

ABSTRACT

Developments in human cellular reprogramming now allow for the generation of human neurons for in vitro disease modelling. This technique has since been used for chemotherapy-induced peripheral neuropathy (CIPN) research, resulting in the description of numerous CIPN models constructed from human neurons. This systematic review provides a critical analysis of available models and their methodological considerations (ie, used cell type and source, CIPN induction strategy, and validation method) for prospective researchers aiming to incorporate human in vitro models of CIPN in their research. The search strategy was developed with assistance from a clinical librarian and conducted in MEDLINE (PubMed) and Embase (Ovid) on September 26, 2023. Twenty-six peer-reviewed experimental studies presenting original data about human reprogrammed nonmotor neuron cell culture systems and relevant market available chemotherapeutics drugs were included. Virtually, all recent reports modeled CIPN using nociceptive dorsal root ganglion neurons. Drugs known to cause the highest incidence of CIPN were most used. Furthermore, treatment effects were almost exclusively validated by the acute effects of chemotherapeutics on neurite dynamics and cytotoxicity parameters, enabling the extrapolation of the half-maximal inhibitory concentration for the 4 most used chemotherapeutics. Overall, substantial heterogeneity was observed in the way studies applied chemotherapy and reported their findings. We therefore propose 6 suggestions to improve the clinical relevance and appropriateness of human cellular reprogramming-derived CIPN models.

Exploration for Blood Biomarkers of Human Long Non-coding RNAs Predicting Oxaliplatin-Induced Chronic Neuropathy Through iPS Cell-Derived Sensory Neuron Analysis

Oxaliplatin, a platinum-based chemotherapeutic agent, frequently causes acute and chronic peripheral sensory neuropathy, for which no effective treatment has been established. In particular, chronic neuropathy can persist for years even after treatment completion, thus worsening patients' quality of life. To avoid the development of intractable adverse effects, a predictive biomarker early in treatment is awaited. In this study, we explored extracellular long non-coding RNAs (lncRNAs) released from primary sensory neurons as biomarker candidates for oxaliplatin-induced peripheral neuropathy. Because many human-specific lncRNA genes exist, we induced peripheral sensory neurons from human induced pluripotent stem cells. Oxaliplatin treatment changed the levels of many lncRNAs in extracellular vesicles (EVs) released from cultured primary sensory neurons. Among them, the levels of release of lncRNAs that were considered to be selectively expressed in dorsal root ganglia were correlated with those of lncRNAs in plasma EV obtained from healthy individuals. Several lncRNAs in plasma EVs early after the initiation of treatment showed greater changes in patients who did not develop chronic neuropathy that persisted for more than 1 year than in those who did. Therefore, these extracellular lncRNAs in plasma EVs may represent predictive biomarkers for the development of chronic peripheral neuropathy induced by oxaliplatin.

Sensitivity of Human Induced Pluripotent Stem Cells and Thereof Differentiated Kidney Proximal Tubular Cells towards Selected Nephrotoxins

Proximal tubular epithelial cells (PTEC) are constantly exposed to potentially toxic metabolites and xenobiotics. The regenerative potential of the kidney enables the replacement of damaged cells either via the differentiation of stem cells or the re-acquisition of proliferative properties of the PTEC. Nevertheless, it is known that renal function declines, suggesting that the deteriorated cells are not replaced by fully functional cells. To understand the possible causes of this loss of kidney cell function, it is crucial to understand the role of toxins during the regeneration process. Therefore, we investigated the sensitivity and function of human induced pluripotent stem cells (hiPSC), hiPSC differentiating, and hiPSC differentiated into proximal tubular epithelial-like cells (PTELC) to known nephrotoxins. hiPSC were differentiated into PTELC, which exhibited similar morphology to PTEC, expressed prototypical PTEC markers, and were able to undergo albumin endocytosis. When treated with two nephrotoxins, hiPSC and differentiating hiPSC were more sensitive to cisplatin than differentiated PTELC, whereas all stages were equally sensitive to cyclosporin A. Both toxins also had an inhibitory effect on albumin uptake. Our results suggest a high sensitivity of differentiating cells towards toxins, which could have an unfavorable effect on regenerative processes. To study this, our model of hiPSC differentiating into PTELC appears suitable.

An In Vitro Assessment Method for Chemotherapy-Induced Peripheral Neurotoxicity Caused by Anti-Cancer Drugs Based on Electrical Measurement of Impedance Value and Spontaneous Activity

Chemotherapy-induced peripheral neurotoxicity (CIPN) is a major adverse event of anti-cancer drugs, which still lack standardized measurement and treatment methods. In the present study, we attempted to evaluate neuronal dysfunctions in cultured rodent primary peripheral neurons using a microelectrode array system. After exposure to typical anti-cancer drugs (i.e., paclitaxel, vincristine, oxaliplatin, and bortezomib), we successfully detected neurotoxicity in dorsal root ganglia neurons by measuring electrical activities, including impedance value and spontaneous activity. The impedance value decreased significantly for all compounds, even at low concentrations, which indicated cell loss and/or neurite degeneration. The spontaneous activity was also suppressed after exposure, which suggested neurotoxicity again. However, an acute response was observed for paclitaxel and bortezomib before toxicity, which showed different mechanisms based on compounds. Therefore, MEA measurement of impedance value could provide a simple assessment method for CIPN, combined with neuronal morphological changes.

Local production of reactive oxygen species drives vincristine-induced axon degeneration

Neurological side effects arising from chemotherapy, such as severe pain and cognitive impairment, are a major concern for cancer patients. These major side effects can lead to reduction or termination of chemotherapy medication in patients, negatively impacting their prognoses. With cancer survival rates improving dramatically, addressing side effects of cancer treatment has become pressing. Here, we use iPSC-derived human neurons to investigate the molecular mechanisms that lead to neurotoxicity induced by vincristine, a common chemotherapeutic used to treat solid tumors. Our results uncover a novel mechanism by which vincristine causes a local increase in mitochondrial proteins that produce reactive oxygen species (ROS) in the axon. Vincristine triggers a cascade of axon pathology, causing mitochondrial dysfunction that leads to elevated axonal ROS levels and SARM1-dependent axon degeneration. Importantly, we show that the neurotoxic effect of increased axonal ROS can be mitigated by the small molecule mitochondrial division inhibitor 1 (mdivi-1) and antioxidants glutathione and mitoquinone, identifying a novel therapeutic avenue to treat the neurological effects of chemotherapy.

Neurofilament light chain as a biomarker of axonal damage in sensory neurons and paclitaxel-induced peripheral neuropathy in patients with ovarian cancer

ABSTRACT

Paclitaxel-induced peripheral neuropathy (PIPN) is a barrier to effective cancer treatment and impacts quality of life among patients with cancer. We used a translational approach to assess the utility of neurofilament light chain (NFL) as a biomarker of PIPN in a human cell model and in patients with ovarian cancer. We measured NFL in medium from human induced pluripotent stem cell-derived sensory neurons (iPSC-SNs) exposed to paclitaxel. Serum NFL (sNFL) levels were quantified in 190 patients with ovarian cancer receiving paclitaxel/carboplatin chemotherapy at baseline and after each of the following 2 or 6 cycles. Adverse outcomes related to PIPN were retrospectively obtained, and Cox regression model was performed with different sNFL cut-offs after first cycle. The apparent elimination half-life of sNFL was estimated in patients who discontinued paclitaxel. Paclitaxel neurotoxicity in iPSC-SNs was accompanied by NFL release in a concentration-dependent manner ( P < 0.001, analysis of variance). Serum NFL levels increased substantially in patients during paclitaxel/carboplatin chemotherapy with considerable interindividual variability. Patients with sNFL >150 pg/mL after first cycle had increased risk to discontinue paclitaxel early (unadjusted HR: 2.47 [95% CI 1.16-5.22], adjusted HR: 2.25 [95% CI: 0.88-5.79]). Similar trends were shown for risk of severe PIPN and paclitaxel dose reduction because of PIPN. The median elimination half-life of sNFL was 43 days (IQR 27-82 days). Neurofilament light chain constitutes an objective biomarker of neurotoxicity in iPSC-SNs and in ovarian cancer patients with high sNFL predicting PIPN-related adverse outcomes. If prospectively validated, NFL can be used to study PIPN and may guide clinical decision making and personalize treatment with paclitaxel.

Large-Area Field Potential Imaging Having Single Neuron Resolution Using 236 880 Electrodes CMOS-MEA Technology

The electrophysiological technology having a high spatiotemporal resolution at the single-cell level and noninvasive measurements of large areas provide insights on underlying neuronal function. Here, a complementary metal-oxide semiconductor (CMOS)-microelectrode array (MEA) is used that uses 236 880 electrodes each with an electrode size of 11.22 × 11.22 µm and 236 880 covering a wide area of 5.5 × 5.9 mm in presenting a detailed and single-cell-level neural activity analysis platform for brain slices, human iPS cell-derived cortical networks, peripheral neurons, and human brain organoids. Propagation pattern characteristics between brain regions changes the synaptic propagation into compounds based on single-cell time-series patterns, classification based on single DRG neuron firing patterns and compound responses, axonal conduction characteristics and changes to anticancer drugs, and network activities and transition to compounds in brain organoids are extracted. This detailed analysis of neural activity at the single-cell level using the CMOS-MEA provides a new understanding of the basic mechanisms of brain circuits in vitro and ex vivo, on human neurological diseases for drug discovery, and compound toxicity assessment.

Bortezomib-induced neurotoxicity in human neurons is the consequence of nicotinamide adenine dinucleotide depletion

The proteosome inhibitor bortezomib has revolutionized the treatment of multiple hematologic malignancies, but in many cases, its efficacy is limited by a dose-dependent peripheral neuropathy. We show that human induced pluripotent stem cell (hiPSC)-derived motor neurons and sensory neurons provide a model system for the study of bortezomib-induced peripheral neuropathy, with promising implications for furthering the mechanistic understanding of and developing treatments for preventing axonal damage. Human neurons in tissue culture displayed distal-to-proximal neurite degeneration when exposed to bortezomib. This process coincided with disruptions in mitochondrial function and energy homeostasis, similar to those described in rodent models of bortezomib-induced neuropathy. Moreover, although the degenerative process was unaffected by inhibition of caspases, it was completely blocked by exogenous nicotinamide adenine dinucleotide (NAD+), a mediator of the SARM1-dependent axon degeneration pathway. We demonstrate that bortezomib-induced neurotoxicity in relevant human neurons proceeds through mitochondrial dysfunction and NAD+ depletion-mediated axon degeneration, raising the possibility that targeting these changes might provide effective therapeutics for the prevention of bortezomib-induced neuropathy and that modeling chemotherapy-induced neuropathy in human neurons has utility.

Passage number affects differentiation of sensory neurons from human induced pluripotent stem cells

Induced pluripotent stem cells (iPSCs) are a valuable resource for neurological disease-modeling and drug discovery due to their ability to differentiate into neurons reflecting the genetics of the patient from which they are derived. iPSC-derived cultures, however, are highly variable due to heterogeneity in culture conditions. We investigated the effect of passage number on iPSC differentiation to optimize the generation of sensory neurons (iPSC-dSNs). Three iPSC lines reprogrammed from the peripheral blood of three donors were differentiated into iPSC-dSNs at passage numbers within each of the following ranges: low (5-10), intermediate (20-26), and high (30-38). Morphology and pluripotency of the parent iPSCs were assessed prior to differentiation. iPSC-dSNs were evaluated based on electrophysiological properties and expression of key neuronal markers. All iPSC lines displayed similar morphology and were similarly pluripotent across passage numbers. However, the expression levels of neuronal markers and sodium channel function analyses indicated that iPSC-dSNs differentiated from low passage numbers better recapitulated the sensory neuron phenotype than those differentiated from intermediate or high passage numbers. Our results demonstrate that lower passage numbers may be better suited for differentiation into peripheral sensory neurons.

Bridging the Translational Gap in Chemotherapy-Induced Peripheral Neuropathy with iPSC-Based Modeling

Simple Summary

Chemotherapy-induced peripheral neuropathy (CIPN) remains a clinical challenge with a considerable impact on the effective treatment of cancers and quality of life during and after concluding chemotherapy. Given the limited understanding of CIPN, there are no options for the treatment and prevention of CIPN. Decades of research with the unsuccessful translation of preclinical findings to clinical studies argue for the requirement of human model systems. This review focuses on the translational potential of human induced pluripotent stem cells (iPSCs) in CIPN research. We provide an overview of the current studies and discuss important aspects to improve the translation of in vitro findings. We identified distinct effects on the neurite network and cell viability upon exposure to different classes of chemotherapy. Our study revealed considerable variability between donors and between neurons of the central and peripheral nervous system. Translational success may be improved by including multiple iPSC donors with known clinical data and selecting clinically relevant concentrations.

Abstract

Chemotherapy-induced peripheral neuropathy (CIPN) is a common and potentially serious adverse effect of a wide range of chemotherapeutics. The lack of understanding of the molecular mechanisms underlying CIPN limits the efficacy of chemotherapy and development of therapeutics for treatment and prevention of CIPN. Human induced pluripotent stem cells (iPSCs) have become an important tool to generate the cell types associated with CIPN symptoms in cancer patients. We reviewed the literature for iPSC-derived models that assessed neurotoxicity among chemotherapeutics associated with CIPN. Furthermore, we discuss the gaps in our current knowledge and provide guidance for selecting clinically relevant concentrations of chemotherapy for in vitro studies. Studies in iPSC-derived neurons revealed differential sensitivity towards mechanistically diverse chemotherapeutics associated with CIPN. Additionally, the sensitivity to chemotherapy was determined by donor background and whether the neurons had a central or peripheral nervous system identity. We propose to utilize clinically relevant concentrations that reflect the free, unbound fraction of chemotherapeutics in plasma in future studies. In conclusion, iPSC-derived sensory neurons are a valuable model to assess CIPN; however, studies in Schwann cells and motor neurons are warranted. The inclusion of multiple iPSC donors and concentrations of chemotherapy known to be achievable in patients can potentially improve translational success.

Establishment of Neurotoxicity Assessment Using Microelectrode Array (MEA) with hiPSC-Derived Neurons and Evaluation of New Psychoactive Substances (NPS)

Background and Objectives

Currently, safety pharmacological tests for the central nervous system depend on animal behavioral analysis. However, due to the subjectivity of behavioral analysis and differences between species, there is a limit to appropriate nervous system toxicity assessment, therefore a new neurotoxicity assessment that can simulate the human central nervous system is required.

Methods and Results

In our study, we developed an in vitro neurotoxicity assessment focusing on neuronal function. To minimize the differences between species and fast screening, hiPSC-derived neurons and a microelectrode array (MEA) that could simultaneously measure the action potentials of the neuronal networks were used. After analyzing the molecular and electrophysiological characters of our neuronal network, we conducted a neurotoxicity assessment on neurotransmitters, neurotoxicants, illicit drugs, and new psychoactive substances (NPS). We found that most substances used in our experiments responded more sensitively to our MEA-based neurotoxicity assessment than to the conventional neurotoxicity assessment. Also, this is the first paper that evaluates various illicit drugs and NPS using MEA-based neurotoxicity assessment using hiPSC-derived neurons.

Conclusions

Our study expanded the scope of application of neurotoxicity assessment using hiPSC-derived neurons to NPS, and accumulated evaluation data of various toxic substances for hiPSC-derived neurons.

Specific Attenuation of Purinergic Signaling during Bortezomib-Induced Peripheral Neuropathy In Vitro

Human peripheral neuropathies are poorly understood, and the availability of experimental models limits further research. The PeriTox test uses immature dorsal root ganglia (DRG)-like neurons, derived from induced pluripotent stem cells (iPSC), to assess cell death and neurite damage. Here, we explored the suitability of matured peripheral neuron cultures for the detection of sub-cytotoxic endpoints, such as altered responses of pain-related P2X receptors. A two-step differentiation protocol, involving the transient expression of ectopic neurogenin-1 (NGN1) allowed for the generation of homogeneous cultures of sensory neurons. After >38 days of differentiation, they showed a robust response (Ca2+-signaling) to the P2X3 ligand α,β-methylene ATP. The clinical proteasome inhibitor bortezomib abolished the P2X3 signal at ≥5 nM, while 50−200 nM was required in the PeriTox test to identify neurite damage and cell death. A 24 h treatment with low nM concentrations of bortezomib led to moderate increases in resting cell intracellular Ca2+ concentration but signaling through transient receptor potential V1 (TRPV1) receptors or depolarization-triggered Ca2+ influx remained unaffected. We interpreted the specific attenuation of purinergic signaling as a functional cell stress response. A reorganization of tubulin to form dense structures around the cell somata confirmed a mild, non-cytotoxic stress triggered by low concentrations of bortezomib. The proteasome inhibitors carfilzomib, delanzomib, epoxomicin, and MG-132 showed similar stress responses. Thus, the model presented here may be used for the profiling of new proteasome inhibitors in regard to their side effect (neuropathy) potential, or for pharmacological studies on the attenuation of their neurotoxicity. P2X3 signaling proved useful as endpoint to assess potential neurotoxicants in peripheral neurons.

The Effect of Schwann Cells/Schwann Cell-Like Cells on Cell Therapy for Peripheral Neuropathy

Peripheral neuropathy is a common neurological issue that leads to sensory and motor disorders. Over time, the treatment for peripheral neuropathy has primarily focused on medications for specific symptoms and surgical techniques. Despite the different advantages of these treatments, functional recovery remains less than ideal. Schwann cells, as the primary glial cells in the peripheral nervous system, play crucial roles in physiological and pathological conditions by maintaining nerve structure and functions and secreting various signaling molecules and neurotrophic factors to support both axonal growth and myelination. In addition, stem cells, including mesenchymal stromal cells, skin precursor cells and neural stem cells, have the potential to differentiate into Schwann-like cells to perform similar functions as Schwann cells. Therefore, accumulating evidence indicates that Schwann cell transplantation plays a crucial role in the resolution of peripheral neuropathy. In this review, we summarize the literature regarding the use of Schwann cell/Schwann cell-like cell transplantation for different peripheral neuropathies and the potential role of promoting nerve repair and functional recovery. Finally, we discuss the limitations and challenges of Schwann cell/Schwann cell-like cell transplantation in future clinical applications. Together, these studies provide insights into the effect of Schwann cells/Schwann cell-like cells on cell therapy and uncover prospective therapeutic strategies for peripheral neuropathy.

Systems Pharmacology Modeling Identifies a Novel Treatment Strategy for Bortezomib-Induced Neuropathic Pain

Chemotherapy-induced peripheral neurotoxicity is a common dose-limiting side effect of several cancer chemotherapeutic agents, and no effective therapies exist. Here we constructed a systems pharmacology model of intracellular signaling in peripheral neurons to identify novel drug targets for preventing peripheral neuropathy associated with proteasome inhibitors. Model predictions suggested the combinatorial inhibition of TNFα, NMDA receptors, and reactive oxygen species should prevent proteasome inhibitor-induced neuronal apoptosis. Dexanabinol, an inhibitor of all three targets, partially restored bortezomib-induced reduction of proximal action potential amplitude and distal nerve conduction velocity in vitro and prevented bortezomib-induced mechanical allodynia and thermal hyperalgesia in rats, including a partial recovery of intraepidermal nerve fiber density. Dexanabinol failed to restore bortezomib-induced decreases in electrophysiological endpoints in rats, and it did not compromise bortezomib anti-cancer effects in U266 multiple myeloma cells and a murine xenograft model. Owing to its favorable safety profile in humans and preclinical efficacy, dexanabinol might represent a treatment option for bortezomib-induced neuropathic pain.

OUP accepted manuscript

In vitro models of the peripheral nervous system would benefit from further refinements to better support studies on neuropathies. In particular, the assessment of pain-related signals is still difficult in human cell cultures. Here, we harnessed induced pluripotent stem cells (iPSCs) to generate peripheral sensory neurons enriched in nociceptors. The objective was to generate a culture system with signaling endpoints suitable for pharmacological and toxicological studies. Neurons generated by conventional differentiation protocols expressed moderate levels of P2X3 purinergic receptors and only low levels of TRPV1 capsaicin receptors, when maturation time was kept to the upper practically useful limit of 6 weeks. As alternative approach, we generated cells with an inducible NGN1 transgene. Ectopic expression of this transcription factor during a defined time window of differentiation resulted in highly enriched nociceptor cultures, as determined by functional (P2X3 and TRPV1 receptors) and immunocytochemical phenotyping, complemented by extensive transcriptome profiling. Single cell recordings of Ca²⁺-indicator fluorescence from >9000 cells were used to establish the “fraction of reactive cells” in a stimulated population as experimental endpoint, that appeared robust, transparent and quantifiable. To provide an example of application to biomedical studies, functional consequences of prolonged exposure to the chemotherapeutic drug oxaliplatin were examined at non-cytotoxic concentrations. We found (i) neuronal (allodynia-like) hypersensitivity to otherwise non-activating mechanical stimulation that could be blocked by modulators of voltage-gated sodium channels; (ii) hyper-responsiveness to TRPV1 receptor stimulation. These findings and several other measured functional alterations indicate that the model is suitable for pharmacological and toxicological studies related to peripheral neuropathies.

Mechanistic insights into the pathogenesis of microtubule-targeting agent-induced peripheral neuropathy from pharmacogenetic and functional studies

Chemotherapy-induced peripheral neuropathy (CIPN) is a common dose-limiting toxicity that affects 30%-40% of patients undergoing cancer treatment. Although multiple mechanisms of chemotherapy-induced neurotoxicity have been described in preclinical models, these have not been translated into widely effective strategies for the prevention or treatment of CIPN. Predictive biomarkers to inform therapeutic approaches are also lacking. Recent studies have examined genetic risk factors associated with CIPN susceptibility. This review provides an overview of the clinical and pathologic features of CIPN and summarizes efforts to identify target pathways through genetic and functional studies. Structurally and mechanistically diverse chemotherapeutics are associated with CIPN; however, the current review is focused on microtubule-targeting agents since these are the focus of most pharmacogenetic association and functional studies of CIPN. Genome-wide pharmacogenetic association studies are useful tools to identify not only causative genes and genetic variants but also genetic networks implicated in drug response or toxicity and have been increasingly applied to investigations of CIPN. Induced pluripotent stem cell-derived models of human sensory neurons are especially useful to understand the mechanistic significance of genomic findings. Combined genetic and functional genomic efforts to understand CIPN hold great promise for developing therapeutic approaches for its prevention and treatment.

The impact of SBF2 on taxane-induced peripheral neuropathy

Taxane-induced peripheral neuropathy (TIPN) is a devastating survivorship issue for many cancer patients. In addition to its impact on quality of life, this toxicity may lead to dose reductions or treatment discontinuation, adversely impacting survival outcomes and leading to health disparities in African Americans (AA). Our lab has previously identified deleterious mutations in SET-Binding Factor 2 (SBF2) that significantly associated with severe TIPN in AA patients. Here, we demonstrate the impact of SBF2 on taxane-induced neuronal damage using an ex vivo model of SBF2 knockdown of induced pluripotent stem cell-derived sensory neurons. Knockdown of SBF2 exacerbated paclitaxel changes to cell viability and neurite outgrowth while attenuating paclitaxel-induced sodium current inhibition. Our studies identified paclitaxel-induced expression changes specific to mature sensory neurons and revealed candidate genes involved in the exacerbation of paclitaxel-induced phenotypes accompanying SBF2 knockdown. Overall, these findings provide ex vivo support for the impact of SBF2 on the development of TIPN and shed light on the potential pathways involved.

Considerations for a Reliable In Vitro Model of Chemotherapy-Induced Peripheral Neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is widely recognized as a potentially severe toxicity that often leads to dose reduction or discontinuation of cancer treatment. Symptoms may persist despite discontinuation of chemotherapy and quality of life can be severely compromised. The clinical symptoms of CIPN, and the cellular and molecular targets involved in CIPN, are just as diverse as the wide variety of anticancer agents that cause peripheral neurotoxicity. There is an urgent need for extensive molecular and functional investigations aimed at understanding the mechanisms of CIPN. Furthermore, a reliable human cell culture system that recapitulates the diversity of neuronal modalities found in vivo and the pathophysiological changes that underlie CIPN would serve to advance the understanding of the pathogenesis of CIPN. The demonstration of experimental reproducibility in a human peripheral neuronal cell system will increase confidence that such an in vitro model is clinically useful, ultimately resulting in deeper exploration for the prevention and treatment of CIPN. Herein, we review current in vitro models with a focus on key characteristics and attributes desirable for an ideal human cell culture model relevant for CIPN investigations.

Mechanisms of peripheral neurotoxicity associated with four chemotherapy drugs using human induced pluripotent stem cell-derived peripheral neurons

The awareness of the long-term toxicities of cancer survivors after chemotherapy treatment has been gradually strengthened as the population of cancer survivors grows. Generally, chemotherapy-induced peripheral neurotoxicity (CIPN) is studied by animal models which are not only expensive and time-consuming, but also species-specific differences. The generation of human induced pluripotent stem cells (hiPSCs) and differentiation of peripheral neurons have provided an in vitro model to elucidate the risk of CIPN. Here, we developed a drug-induced peripheral neurotoxicity model using hiPSC-derived peripheral neurons (hiPSC-PNs) to study the mechanisms of different chemotherapeutic agents on neuronal viability using LDH assay, a cell apoptosis assay determined by caspase 3/7 activation, neurite outgrowth, ion channel expression and neurotransmitter release following treatment of cisplatin, bortezomib, ixabepilone, or pomalidomide. Our data showed that the multiple endpoints of the hiPSC-PNs model had different sensitivity to various chemotherapeutic agents. Furthermore, the chemotherapeutics separated cell viability from the decrease in neurite lengthand changed levels of ion channels and neurotransmitters to a certain extent. Thus, we study the mechanisms of peripheral neurotoxicity induced by chemotherapeutic agents through changes in these indicators.

An Electrophysiological and Pharmacological Study of the Properties of Human iPSC-Derived Neurons for Drug Discovery

Human stem cell-derived neurons are increasingly considered powerful models in drug discovery and disease modeling, despite limited characterization of their molecular properties. Here, we have conducted a detailed study of the properties of a commercial human induced Pluripotent Stem Cell (iPSC)-derived neuron line, iCell [GABA] neurons, maintained for up to 3 months in vitro. We confirmed that iCell neurons display neurite outgrowth within 24 h of plating and label for the pan-neuronal marker, βIII tubulin within the first week. Our multi-electrode array (MEA) recordings clearly showed neurons generated spontaneous, spike-like activity within 2 days of plating, which peaked at one week, and rapidly decreased over the second week to remain at low levels up to one month. Extracellularly recorded spikes were reversibly inhibited by tetrodotoxin. Patch-clamp experiments showed that iCell neurons generated spontaneous action potentials and expressed voltage-gated Na and K channels with membrane capacitances, resistances and membrane potentials that are consistent with native neurons. Our single neuron recordings revealed that reduced spiking observed in the MEA after the first week results from development of a dominant inhibitory tone from GABAergic neuron circuit maturation. GABA evoked concentration-dependent currents that were inhibited by the convulsants, bicuculline and picrotoxin, and potentiated by the positive allosteric modulators, diazepam, chlordiazepoxide, phenobarbital, allopregnanolone and mefenamic acid, consistent with native neuronal GABA_A receptors. We also show that glycine evoked robust concentration-dependent currents that were inhibited by the neurotoxin, strychnine. Glutamate, AMPA, Kainate and NMDA each evoked concentration-dependent currents in iCell neurons that were blocked by their selective antagonists, consistent with the expression of ionotropic glutamate receptors. The NMDA currents required the presence of the co-agonist glycine and were blocked in a highly voltage-dependent manner by Mg²⁺ consistent with the properties of native neuronal NMDA receptors. Together, our data suggest that such human iPSC-derived neurons may have significant value in drug discovery and development and may eventually largely replace the need for animal tissues in human biomedical research.

Identification of small molecules that mitigate vincristine-induced neurotoxicity while sensitizing leukemia cells to vincristine

Vincristine (VCR) is one of the most widely prescribed medications for treating solid tumors and acute lymphoblastic leukemia (ALL) in children and adults. However, its major dose-limiting toxicity is peripheral neuropathy that can disrupt curative therapy. Peripheral neuropathy can also persist into adulthood, compromising quality of life of childhood cancer survivors. Reducing VCR-induced neurotoxicity without compromising its anticancer effects would be ideal. Here, we show that low expression of NHP2L1 is associated with increased sensitivity of primary leukemia cells to VCR, and that concomitant administration of VCR with inhibitors of NHP2L1 increases VCR cytotoxicity in leukemia cells, prolongs survival of ALL xenograft mice, but decreases VCR effects on human-induced pluripotent stem cell-derived neurons and mitigates neurotoxicity in mice. These findings offer a strategy for increasing VCR's antileukemic effects while reducing peripheral neuropathy in patients treated with this widely prescribed medication.

Investigation Into the Role of ERK in Tyrosine Kinase Inhibitor-Induced Neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is a common and debilitating adverse event that can alter patient treatment options and halt candidate drug development. A case study is presented here describing the preclinical and clinical development of CC-90003, a small molecule extracellular signal-regulated kinase (ERK)1/2 inhibitor investigated as an oncology therapy. In a Phase Ia clinical trial, CC-90003 elicited adverse drug-related neuropathy and neurotoxicity that contributed to discontinued development of CC-90003 for oncology therapy. Preclinical evaluation of CC-90003 in dogs revealed clinical signs and electrophysiological changes consistent with peripheral neuropathy that was reversible. Mice did not exhibit signs of neuropathy upon daily dosing with CC-90003, supporting that rodents generally poorly predict CIPN. We sought to investigate the mechanism of CC-90003-induced peripheral neuropathy using a phenotypic in vitro assay. Translating preclinical neuropathy findings to humans proves challenging as no robust in vitro models of CIPN exist. An approach was taken to examine the influence of CIPN-associated drugs on human-induced pluripotent stem cell-derived peripheral neuron (hiPSC-PN) electrophysiology on multielectrode arrays (MEAs). The MEA assay with hiPSC-PNs was sensitive to CIPN-associated drugs cisplatin, sunitinib, colchicine, and importantly, to CC-90003 in concordance with clinical neuropathy incidence. Biochemical data together with in vitro MEA data for CC-90003 and 12 of its structural analogs, all having similar ERK inhibitory activity, revealed that CC-90003 disrupted in vitro neuronal electrophysiology likely via on-target ERK inhibition combined with off-target kinase inhibition and translocator protein inhibition. This approach could prove useful for assessing CIPN risk and interrogating mechanisms of drug-induced neuropathy.

Neuropathic pain: Spotlighting anatomy, experimental models, mechanisms, and therapeutic aspects

The International Association for the Study of Pain defines neuropathic pain as "pain arising as a direct consequence of a lesion or disease affecting the somatosensory system". The associated changes can be observed in the peripheral as well as the central nervous system. The available literature discusses a wide variety of causes as predisposing for the development and amplification of neuropathic pain. Further, key interactions within sensory pathways have been discovered, but no common molecular mechanism leading to neuropathic pain has been identified until now. In the first part of this review, the pain mediating lateral spinothalamic tract is described. Different in vivo models are presented that allow studying trauma-, chemotherapy-, virus-, and diabetes-induced neuropathic pain in rodents. We furthermore discuss approaches to assess neuropathic pain in these models. Second, the current knowledge about cellular and molecular mechanisms suggested to underlie the development of neuropathic pain is presented and discussed. A summary of established therapies that are already applied in the clinic and novel, promising approaches closes the paper. In conclusion, the established animal models are able to emulate the diversity of neuropathic pain observed in the clinics. However, the assessment of neuropathic pain in the presented in vivo models should be improved. The determination of common molecular markers with suitable in vitro models would simplify the assessment of neuropathic pain in vivo. This would furthermore provide insights into common molecular mechanisms of the disease and establish a basis to search for satisfying therapeutic approaches.

Modeling chemotherapy induced neurotoxicity with human induced pluripotent stem cell (iPSC) -derived sensory neurons

Chemotherapy-induced peripheral neuropathy (CIPN) is a frequent, potentially irreversible adverse effect of cytotoxic chemotherapy often leading to a reduction or discontinuation of treatment which negatively impacts patients' prognosis. To date, however, neither predictive biomarkers nor preventive treatments for CIPN are available, which is partially due to a lack of suitable experimental models. We therefore aimed to evaluate whether sensory neurons derived from induced pluripotent stem cells (iPSC-DSN) can serve as human disease model system for CIPN. Treatment of iPSC-DSN for 24 h with the neurotoxic drugs paclitaxel, bortezomib, vincristine and cisplatin led to axonal blebbing and a dose dependent decline of cell viability in clinically relevant IC₅₀ ranges, which was not observed for the non-neurotoxic compounds doxorubicin and 5-fluorouracil. Paclitaxel treatment effects were less pronounced after 24 h but prominent when treatment was applied for 72 h. Global transcriptome analyses performed at 24 h, i.e. before paclitaxel-induced cell death occurred, revealed the differential expression of genes of neuronal injury, cellular stress response, and sterol pathways. We further evaluated if known neuroprotective strategies can be reproduced in iPSC-DSN and observed protective effects of lithium replicating findings from rodent dorsal root ganglia cells. Comparing sensory neurons derived from two different healthy donors, we found preliminary evidence that these cell lines react differentially to neurotoxic drugs as expected from the variable presentation of CIPN in patients. In conclusion, iPSC-DSN are a promising platform to study the pathogenesis of CIPN and to evaluate neuroprotective treatment strategies. In the future, the application of patient-specific iPSC-DSN could open new avenues for personalized medicine with individual risk prediction, choice of chemotherapeutic compounds and preventive treatments.

Vincristine- and bortezomib-induced neuropathies - from bedside to bench and back

Vincristine and bortezomib are effective chemotherapeutics widely used to treat hematological cancers. Vincristine blocks tubulin polymerization, whereas bortezomib is a proteasome inhibitor. Despite different mechanisms of action, the main non-hematological side effect of both is peripheral neuropathy that can last long after treatment has ended and cause permanent disability. Many different cellular and animal models of various aspects of vincristine and bortezomib-induced neuropathies have been generated to investigate underlying molecular mechanisms and serve as platforms to develop new therapeutics. These models revealed that bortezomib induces several transcriptional programs in dorsal root ganglia that result in the activation of different neuroinflammatory pathways and secondary central sensitization. In contrast, vincristine has direct toxic effects on the axon, which are accompanied by changes similar to those observed after nerve cut. Axon degeneration following both vincristine and bortezomib is mediated by a phylogenetically ancient, genetically encoded axon destruction program that leads to the activation of the Toll-like receptor adaptor SARM1 (sterile alpha and TIR motif containing protein 1) and local decrease of nicotinamide dinucleotide (NAD+). Here, I describe current in vitro and in vivo models of vincristine- and bortezomib induced neuropathies, present discoveries resulting from these models in the context of clinical findings and discuss how increased understanding of molecular mechanisms underlying different aspects of neuropathies can be translated to effective treatments to prevent, attenuate or reverse vincristine- and bortezomib-induced neuropathies. Such treatments could improve the quality of life of patients both during and after cancer therapy and, accordingly, have enormous societal impact.

Pathological Mechanisms of Bortezomib-Induced Peripheral Neuropathy

Bortezomib, a first-generation proteasome inhibitor widely used in chemotherapy for hematologic malignancy, has effective anti-cancer activity but often causes severe peripheral neuropathy. Although bortezomib-induced peripheral neuropathy (BIPN) is a dose-limiting toxicity, there are no recommended therapeutics for its prevention or treatment. One of the most critical problems is a lack of knowledge about pathological mechanisms of BIPN. Here, we summarize the known mechanisms of BIPN based on preclinical evidence, including morphological abnormalities, involvement of non-neuronal cells, oxidative stress, and alterations of transcriptional programs in both the peripheral and central nervous systems. Moreover, we describe the necessity of advancing studies that identify the potential efficacy of approved drugs on the basis of pathological mechanisms, as this is a convincing strategy for rapid translation to patients with cancer and BIPN.

Drug Repositioning for the Prevention and Treatment of Chemotherapy-Induced Peripheral Neuropathy: A Mechanism- and Screening-Based Strategy

Chemotherapy-induced peripheral neuropathy (CIPN) is a severe adverse effect observed in most patients treated with neurotoxic anti-cancer drugs. Currently, there are no therapeutic options available for the prevention of CIPN. Furthermore, few drugs are recommended for the treatment of existing neuropathies because the mechanisms of CIPN remain unclear. Each chemotherapeutic drug induces neuropathy by distinct mechanisms, and thus we need to understand the characteristics of CIPN specific to individual drugs. Here, we review the known pathogenic mechanisms of oxaliplatin- and paclitaxel-induced CIPN, highlighting recent findings. Cancer chemotherapy is performed in a planned manner; therefore, preventive strategies can be planned for CIPN. Drug repositioning studies, which identify the unexpected actions of already approved drugs, have increased in recent years. We have also focused on drug repositioning studies, especially for prevention, because they should be rapidly translated to patients suffering from CIPN.

Human Induced Pluripotent Stem Cell Derived Sensory Neurons are Sensitive to the Neurotoxic Effects of Paclitaxel

Chemotherapy‐induced peripheral neuropathy (CIPN) is a dose‐limiting adverse event associated with treatment with paclitaxel and other chemotherapeutic agents. The prevention and treatment of CIPN are limited by a lack of understanding of the molecular mechanisms underlying this toxicity. In the current study, a human induced pluripotent stem cell–derived sensory neuron (iPSC‐SN) model was developed for the study of chemotherapy‐induced neurotoxicity. The iPSC‐SNs express proteins characteristic of nociceptor, mechanoreceptor, and proprioceptor sensory neurons and show Ca²⁺ influx in response to capsaicin, α,β‐meATP, and glutamate. The iPSC‐SNs are relatively resistant to the cytotoxic effects of paclitaxel, with half‐maximal inhibitory concentration (IC₅₀) values of 38.1 µM (95% confidence interval (CI) 22.9–70.9 µM) for 48‐hour exposure and 9.3 µM (95% CI 5.7–16.5 µM) for 72‐hour treatment. Paclitaxel causes dose‐dependent and time‐dependent changes in neurite network complexity detected by βIII‐tubulin staining and high content imaging. The IC₅₀ for paclitaxel reduction of neurite area was 1.4 µM (95% CI 0.3–16.9 µM) for 48‐hour exposure and 0.6 µM (95% CI 0.09–9.9 µM) for 72‐hour exposure. Decreased mitochondrial membrane potential, slower movement of mitochondria down the neurites, and changes in glutamate‐induced neuronal excitability were also observed with paclitaxel exposure. The iPSC‐SNs were also sensitive to docetaxel, vincristine, and bortezomib. Collectively, these data support the use of iPSC‐SNs for detailed mechanistic investigations of genes and pathways implicated in chemotherapy‐induced neurotoxicity and the identification of novel therapeutic approaches for its prevention and treatment.

A human induced pluripotent stem cell-derived cortical neuron human-on-a chip system to study Aβ42 and tau-induced pathophysiological effects on long-term potentiation

INTRODUCTION

The quest to identify an effective therapeutic strategy for neurodegenerative diseases, such as mild congitive impairment (MCI) and Alzheimer's disease (AD), suffers from the lack of good human-based models. Animals represent the most common models used in basic research and drug discovery studies. However, safe and effective compounds identified in animal studies often translate poorly to humans, yielding unsuccessful clinical trials.

METHODS

A functional in vitro assay based on long-term potentiation (LTP) was used to demonstrate that exposure to amyloid beta (Aβ42) and tau oligomers, or brain extracts from AD transgenic mice led to prominent changes in human induced pluripotent stem cells (hiPSC)-derived cortical neurons, notably, without cell death.

RESULTS

Impaired information processing was demonstrated by treatment of neuron-MEA (microelectrode array) systems with the oligomers and brain extracts by reducing the effects of LTP induction. These data confirm the neurotoxicity of molecules linked to AD pathology and indicate the utility of this human-based system to model aspects of AD in vitro and study LTP deficits without loss of viability; a phenotype that more closely models the preclinical or early stage of AD.

DISCUSSION

In this study, by combining multiple relevant and important molecular and technical aspects of neuroscience research, we generated a new, fully human in vitro system to model and study AD at the preclinical stage. This system can serve as a novel drug discovery platform to identify compounds that rescue or alleviate the initial neuronal deficits caused by Aβ42 and/or tau oligomers, a main focus of clinical trials.

Elimination of Teratogenic Human Induced Pluripotent Stem Cells by Bee Venom via Calcium-Calpain Pathway

Induced pluripotent stem cells (iPSCs) are regarded as a promising option for cell-based regenerative medicine. To obtain safe and efficient iPSC-based cell products, it is necessary to selectively eliminate the residual iPSCs prior to in vivo implantation due to the risk of teratoma formation. Bee venom (BV) has long been used in traditional Chinese medicine to treat inflammatory diseases and relieve pain, and has been shown to exhibit anti-cancer, anti-mutagenic, anti-nociceptive, and radioprotective activities. However, the potential benefits of BV in iPSC therapy, particularly its anti-teratoma activity, have not been examined. In this study, we found that BV selectively induced cell death in iPSCs, but not in iPSC-derived differentiated cells (iPSCs-Diff). BV rapidly disrupted cell membrane integrity and focal adhesions, followed by induction of apoptosis and necroptosis in iPSCs. We also found that BV remarkably enhanced intracellular calcium levels, calpain activation, and reactive oxygen speciesgeneration in iPSCs. BV treatment before in ovo grafting efficiently prevented iPSC-derived teratoma formation. In contrast, no DNA damage was observed in iPSCs-Diff following BV treatment, further demonstrating the safety of BV for use with iPSCs-Diff. Taken together, these findings show that BV has potent anti-teratoma activity by eliminating residual iPSCs, and can be used for the development of effective and safe iPSC-based cell therapies.

Pathogenesis of paclitaxel-induced peripheral neuropathy: A current review of in vitro and in vivo findings using rodent and human model systems

Paclitaxel (Brand name Taxol) is widely used in the treatment of common cancers like breast, ovarian and lung cancer. Although highly effective in blocking tumor progression, paclitaxel also causes peripheral neuropathy as a side effect in 60-70% of chemotherapy patients. Recent efforts by numerous labs have aimed at defining the underlying mechanisms of paclitaxel-induced peripheral neuropathy (PIPN). In vitro models using rodent dorsal root ganglion neurons, human induced pluripotent stem cells, and rodent in vivo models have revealed a number of molecular pathways affected by paclitaxel within axons of sensory neurons and within other cell types, such as the immune system and peripheral glia, as well skin. These studies revealed that paclitaxel induces altered calcium signaling, neuropeptide and growth factor release, mitochondrial damage and reactive oxygen species formation, and can activate ion channels that mediate responses to extracellular cues. Recent studies also suggest a role for the matrix-metalloproteinase 13 (MMP-13) in mediating neuropathy. These diverse changes may be secondary to paclitaxel-induced microtubule transport impairment. Human genetic studies, although still limited, also highlight the involvement of cytoskeletal changes in PIPN. Newly identified molecular targets resulting from these studies could provide the basis for the development of therapies with which to either prevent or reverse paclitaxel-induced peripheral neuropathy in chemotherapy patients.

Insights into platinum-induced peripheral neuropathy-current perspective

Cancer is a global health problem that is often successfully addressed by therapy, with cancer survivors increasing in numbers and living longer world around. Although new cancer treatment options are continuously explored, platinum based chemotherapy agents remain in use due to their efficiency and availability. Unfortunately, all cancer therapies affect normal tissues as well as cancer, and more than 40 specific side effects of platinum based drugs documented so far decrease the quality of life of cancer survivors. Chemotherapy-induced peripheral neuropathy is a frequent side effects of platinum-based chemotherapy agents. This cluster of complications is often so debilitating that patients occasionally have to discontinue the therapy. Sensory neurons of dorsal root ganglia are at the core of chemotherapy-induced peripheral neuropathy symptoms. In these postmitotic cells, DNA damage caused by platinum chemotherapy interferes with normal functioning. Accumulation of DNA-platinum adducts correlates with neurotoxic severity and development of sensation of pain. While biochemistry of DNA-platinum adducts is the same in all cell types, molecular mechanisms affected by DNA-platinum adducts are different in cancer cells and non-dividing cells. This review aims to raise awareness about platinum associated chemotherapy-induced peripheral neuropathy as a medical problem that has remained unexplained for decades. We emphasize the complexity of this condition both from clinical and mechanistical point of view and focus on recent findings about chemotherapy-induced peripheral neuropathy in in vitro and in vivo model systems. Finally, we summarize current perspectives about clinical approaches for chemotherapy-induced peripheral neuropathy treatment.

A Comparative Review of Chemotherapy-Induced Peripheral Neuropathy in In Vivo and In Vitro Models

Chemotherapy-induced peripheral neuropathy (CIPN) is an adverse effect caused by several classes of widely used anticancer therapeutics. Chemotherapy-induced peripheral neuropathy frequently leads to dose reduction or discontinuation of chemotherapy regimens, and CIPN symptoms can persist long after completion of chemotherapy and severely diminish the quality of life of patients. Differences in the clinical presentation of CIPN by widely diverse classifications of anticancer agents have spawned multiple mechanistic hypotheses that seek to explain the pathogenesis of CIPN. Despite its clinical relevance, common occurrence, and extensive investigation, the pathophysiology of CIPN remains unclear. Furthermore, there is no unequivocal gold standard for the prevention and treatment of CIPN. Herein, we review in vivo and in vitro models of CIPN with a focus on histopathological changes and morphological features aimed at understanding the pathophysiology of CIPN and identify gaps requiring deeper exploration. An elucidation of the underlying mechanisms of CIPN is imperative to identify potential targets and approaches for prevention and treatment.

Induced pluripotent stem cells for therapy personalization in pediatric patients: Focus on drug-induced adverse events

Adverse drug reactions (ADRs) are major clinical problems, particularly in special populations such as pediatric patients. Indeed, ADRs may be caused by a plethora of different drugs leading, in some cases, to hospitalization, disability or even death. In addition, pediatric patients may respond differently to drugs with respect to adults and may be prone to developing different kinds of ADRs, leading, in some cases, to more severe consequences. To improve the comprehension, and thus the prevention, of ADRs, the set-up of sensitive and personalized assays is urgently needed. Important progress is represented by the possibility of setting up groundbreaking patient-specific assays. This goal has been powerfully achieved using induced pluripotent stem cells (iPSCs). Due to their genetic and physiological species-specific differences and their ability to be differentiated ideally into all tissues of the human body, this model may be accurate in predicting drug toxicity, especially when this toxicity is related to individual genetic differences. This review is an up-to-date summary of the employment of iPSCs as a model to study ADRs, with particular attention to drugs used in the pediatric field. We especially focused on the intestinal, hepatic, pancreatic, renal, cardiac, and neuronal levels, also discussing progress in organoids creation. The latter are three-dimensional in vitro culture systems derived from pluripotent or adult stem cells simulating the architecture and functionality of native organs such as the intestine, liver, pancreas, kidney, heart, and brain. Based on the existing knowledge, these models are powerful and promising tools in multiple clinical applications including toxicity screening, disease modeling, personalized and regenerative medicine.

Neuropathic Pain in Taxane-Induced Peripheral Neuropathy: Evidence for Exercise in Treatment

One in 2 Canadians is expected to acquire cancer in their lifetime. Many cancers, including breast, ovarian, and lung cancer, are treated using taxane chemotherapy with curative intent. A major adverse effect with the use of taxane chemotherapeutic agents is taxane-induced peripheral neuropathy (TIPN). Both positive (spontaneous pain, heightened sensitivity with light touch, tingling, itching, burning) and negative (loss of touch, loss of hot/cold sensations, and loss of pain) sensory symptoms can be experienced in the hands and feet and worsen with increasing dose and treatment duration. The pathophysiology of TIPN is still unknown but likely involves multiple mechanisms, including microtubule impairment, neuroimmune and inflammatory changes, ion channel remodeling, impaired mitochondrial function, and genetic predisposition. This review highlights current theories on the pathophysiology for TIPN, the cellular responses thought to maintain neuropathic pain, and the growing support for exercise in the treatment and prevention of peripheral neuropathy and neuropathic pain in both animal and human models.

Human-Derived Brain Models: Windows into Neuropsychiatric Disorders and Drug Therapies

Human-derived neurons and brain organoids have revolutionized our ability to model brain development in a dish. In this review, we discuss the potential for human brain models to advance drug discovery for complex neuropsychiatric disorders. First, we address the advantages of human brain models to screen for new drugs capable of altering CNS activity. Next, we propose an experimental pipeline for using human-derived neurons and brain organoids to rapidly assess drug impact on key events in brain development, including neurite extension, synapse formation, and neural activity. The experimental pipeline begins with automated high content imaging for analysis of neurites, synapses, and neuronal viability. Following morphological examination, multi-well microelectrode array technology examines neural activity in response to drug treatment. These techniques can be combined with high throughput sequencing and mass spectrometry to assess associated transcriptional and proteomic changes. These combined technologies provide a foundation for neuropsychiatric drug discovery and future clinical assessment of patient-specific drug responses.

Chemotherapy-Induced Peripheral Neuropathy and Changes in Cytoskeleton

Despite the different antineoplastic mechanisms of action, peripheral neurotoxicity induced by all chemotherapy drugs (anti-tubulin agents, platinum compounds, proteasome inhibitors, thalidomide) is associated with neuron morphological changes ascribable to cytoskeleton modifications. The “dying back” degeneration of distal terminals (sensory nerves) of dorsal root ganglia sensory neurons, observed in animal models, in in vitro cultures and biopsies of patients is the most evident hallmark of the perturbation of the cytoskeleton. On the other hand, in highly polarized cells like neurons, the cytoskeleton carries out its role not only in axons but also has a fundamental role in dendrite plasticity and in the organization of soma. In the literature, there are many studies focused on the antineoplastic-induced alteration of microtubule organization (and consequently, fast axonal transport defects) while very few studies have investigated the effect of the different classes of drugs on microfilaments, intermediate filaments and associated proteins. Therefore, in this review, we will focus on: (1) Highlighting the fundamental role of the crosstalk among the three filamentous subsystems and (2) investigating pivotal cytoskeleton-associated proteins.

COA-Cl induces dopamine release and tyrosine hydroxylase phosphorylation: In vivo reverse microdialysis and in vitro analysis

We found that local perfusion of COA-Cl (0.1, 0.4, or 1.0 mM) into the dorsal striatum of living mice produced a significant and dose-dependent increase in extracellular DA levels, with the highest dose of 1.0 mM COA-Cl producing an approximately 5-fold increase in DA. Consistent with in vivo findings, 0.1 and 0.2 mM COA-Cl significantly and dose-dependently enhanced DA release 3.0 to 5.0-fold in PC12 cells, an in vitro model of DA-responsive neurons. Interestingly, the increase in striatal DA levels by COA-Cl in vivo was similar in magnitude to that observed in PC12 cells. Treatment with 0.1 mM COA-Cl significantly increased both Ser31 and Ser40 phosphorylation of tyrosine hydroxylase (TH) in PC12 cells, and Ser40 phosphorylation in iCell neurons, without altering total TH protein levels. Further, we examined whether COA-Cl could stimulate neurite outgrowth in PC12 cells and iCell neurons and found that COA-Cl significantly induced neurite outgrowth in both cell lines. Our results provide the first evidence that COA-Cl can stimulate dose-dependent DA release and activation of TH phosphorylation, suggesting that COA-Cl may be a promising therapeutic candidate for the treatment of neurological dysfunction associated with low DA.

Fabrication of a Co-Culture System with Human Sweat Gland-Derived Cells and Peripheral Nerve Cells

The interaction of peripheral nerves with different cells of the skin is a relevant aspect of many physiological processes including nociception, temperature control, and wound healing. Here we describe a protocol for the setup of an indirect co-culture system of peripheral nerve cells and sweat gland-derived stem cells, which can be used to quantify neurite outgrowth.

Concise Review: The Current State of Human In Vitro Cardiac Disease Modeling: A Focus on Gene Editing and Tissue Engineering

Until recently, in vivo and ex vivo experiments were the only means to determine factors and pathways involved in disease pathophysiology. After the generation of characterized human embryonic stem cell lines, human diseases could readily be studied in an extensively controllable setting. The introduction of human‐induced pluripotent stem cells, a decade ago, allowed the investigation of hereditary diseases in vitro. In the field of cardiology, diseases linked to known genes have successfully been studied, revealing novel disease mechanisms. The direct effects of various mutations leading to hypertrophic cardiomyopathy, dilated cardiomyopathy, arrythmogenic cardiomyopathy, or left ventricular noncompaction cardiomyopathy are discovered as a result of in vitro disease modeling. Researchers are currently applying more advanced techniques to unravel more complex phenotypes, resulting in state‐of‐the‐art models that better mimic in vivo physiology. The continued improvement of tissue engineering techniques and new insights into epigenetics resulted in more reliable and feasible platforms for disease modeling and the development of novel therapeutic strategies. The introduction of CRISPR‐Cas9 gene editing granted the ability to model diseases in vitro independent of induced pluripotent stem cells. In addition to highlighting recent developments in the field of human in vitro cardiomyopathy modeling, this review also aims to emphasize limitations that remain to be addressed; including residual somatic epigenetic signatures induced pluripotent stem cells, and modeling diseases with unknown genetic causes. Stem Cells Translational Medicine2019;8:66–74

Toxicological evaluation of convulsant and anticonvulsant drugs in human induced pluripotent stem cell-derived cortical neuronal networks using an MEA system

Functional evaluation assays using human induced pluripotent stem cell (hiPSC)-derived neurons can predict the convulsion toxicity of new drugs and the neurological effects of antiepileptic drugs. However, differences in responsiveness depending on convulsant type and antiepileptic drugs, and an evaluation index capable of comparing in vitro responses with in vivo responses are not well known. We observed the difference in synchronized burst patterns in the epileptiform activities induced by pentylentetrazole (PTZ) and 4-aminopryridine (4-AP) with different action mechanisms using multi-electrode arrays (MEAs); we also observed that 100 µM of the antiepileptic drug phenytoin suppressed epileptiform activities induced by PTZ, but increased those induced by 4-AP. To compare in vitro results with in vivo convulsive responses, frequency analysis of below 250 Hz, excluding the spike component, was performed. The in vivo convulsive firing enhancement of the high γ wave and β wave component were observed remarkably in in vitro hiPSC-derived neurons with astrocytes in co-culture. MEA measurement of hiPSC-derived neurons in co-culture with astrocytes and our analysis methods, including frequency analysis, appear effective for predicting convulsion toxicity, side effects, and their mechanism of action as well as the comparison of convulsions induced in vivo.

Cordycepin induces apoptotic cell death of human brain cancer through the modulation of autophagy

Brain cancer, in particular neuroblastoma and glioblastoma, is a global challenge to human health. Cordycepin, extracted from Cordyceps ssp., has been revealed as a strong anticancer agent through several ways; however, the mechanism, by which cordycepin counteracts brain cancers, is still poorly understood. In this study, the underlying mechanisms of cordycepin against human brain cancer cells were explored. SH-SY5Y and U251 cells were being a model to represent human neuroblastoma and glioblastoma, respectively. Here, it was found that cordycepin inhibited cell growth, and induced apoptosis in a dose-dependent manner in both SH-SY5Y and U-251 cell lines. The expression of pro-apoptotic genes, including P53, BAX, Caspase-3, and Caspase-9, were upregulated, whereas the expression of anti-apoptotic gene, BCL-2, was suppressed. Besides, cordycepin induced the generation of reactive oxygen species (ROS) along with the suppression of antioxidant genes, including GPX, SOD, and Catalase. Importantly, cordycepin was shown to involve in the activation of autophagy, which was evidenced by the increment of LC3I/II. The combination of cordycepin with chloroquine, an autophagy inhibitor, further inhibited the growth, and enhanced the death of brain cancer cells. Altogether, this finding suggested that cordycepin induced apoptosis of human brain cancer cells through mitochondrial-mediated intrinsic pathway and the modulation of autophagy. Therefore, cordycepin could be a promising candidate for the development of anticancer drugs targeting human brain cancers.

Utilization of iPSC-derived human neurons for high-throughput drug-induced peripheral neuropathy screening

As the number of cancer survivors continues to grow, awareness of long-term toxicities and impact on quality of life after chemotherapy treatment in cancer survivors has intensified. Chemotherapy-induced peripheral neuropathy (CIPN) is one of the most common side effects of modern chemotherapy. Animal models are used to study peripheral neuropathy and predict human risk; however, such models are labor-intensive and limited translatability between species has become a major challenge. Moreover, the mechanisms underlying CIPN have not been precisely determined and few human neuronal models to study CIPN exist. Here, we have developed a high-throughput drug-induced neurotoxicity screening model using human iPSC-derived peripheral-like neurons to study the effect of chemotherapy agents on neuronal health and morphology using high content imaging measurements (neurite length and neuronal cell viability). We utilized this model to test various classes of chemotherapeutic agents with known clinical liability to cause peripheral neuropathy such as platinum agents, taxanes, vinca alkaloids, proteasome inhibitors, and anti-angiogenic compounds. The model was sensitive to compounds that cause interference in microtubule dynamics, especially the taxane, epothilone, and vinca alkaloids. Conversely, the model was not sensitive to platinum and anti-angiogenic chemotherapeutics; compounds that are not reported to act directly on neuronal processes. In summary, we believe this model has utility for high-throughput screening and prediction of human risk for CIPN for novel chemotherapeutics.