Endothelium-induced proliferation and electrophysiological differentiation of human embryonic stem cell-derived neuronal precursors

Impact of Matrix Gel Variations on Primary Culture of Microvascular Endothelial Cell Function

OBJECTIVE

The endothelium regulates crucial aspects of vascular function, including hemostasis, vasomotor tone, proliferation, immune cell adhesion, and microvascular permeability. Endothelial cells (ECs), especially in arterioles, are pivotal for flow distribution and peripheral resistance regulation. Investigating vascular endothelium physiology, particularly in microvascular ECs, demands precise isolation and culturing techniques.

METHODS

Freshly isolated ECs are vital for examining protein expression, ion channel behavior, and calcium dynamics. Establishing primary endothelial cell cultures is crucial for unraveling vascular functions and understanding intact microvessel endothelium roles. Despite the significance, detailed protocols and comparisons with intact vessels are scarce in microvascular research. We developed a reproducible method to isolate microvascular ECs, assessing substrate influence by cultivating cells on fibronectin and gelatin matrix gels. This comparative approach enhances our understanding of microvascular endothelial cell biology.

RESULTS

Microvascular mesenteric ECs expressed key markers (VE-cadherin and eNOS) in both matrix gels, confirming cell culture purity. Under uncoated conditions, ECs were undetected, whereas proteins linked to smooth muscle cells and fibroblasts were evident. Examining endothelial cell (EC) physiological dynamics on distinct matrix substrates revealed comparable cell length, shape, and Ca2+ elevations in both male and female ECs on gelatin and fibronectin matrix gels. Gelatin-cultured ECs exhibited analogous membrane potential responses to acetylcholine (ACh) or adenosine triphosphate (ATP), contrasting with their fibronectin-cultured counterparts. In the absence of stimulation, fibronectin-cultured ECs displayed a more depolarized resting membrane potential than gelatin-cultured ECs.

CONCLUSIONS

Gelatin-cultured ECs demonstrated electrical behaviors akin to intact endothelium from mouse mesenteric arteries, thus advancing our understanding of endothelial cell behavior within diverse microenvironments.

Electrophysiology Read-Out Tools for Brain-on-Chip Biotechnology

Brain-on-Chip (BoC) biotechnology is emerging as a promising tool for biomedical and pharmaceutical research applied to the neurosciences. At the convergence between lab-on-chip and cell biology, BoC couples in vitro three-dimensional brain-like systems to an engineered microfluidics platform designed to provide an in vivo-like extrinsic microenvironment with the aim of replicating tissue- or organ-level physiological functions. BoC therefore offers the advantage of an in vitro reproduction of brain structures that is more faithful to the native correlate than what is obtained with conventional cell culture techniques. As brain function ultimately results in the generation of electrical signals, electrophysiology techniques are paramount for studying brain activity in health and disease. However, as BoC is still in its infancy, the availability of combined BoC-electrophysiology platforms is still limited. Here, we summarize the available biological substrates for BoC, starting with a historical perspective. We then describe the available tools enabling BoC electrophysiology studies, detailing their fabrication process and technical features, along with their advantages and limitations. We discuss the current and future applications of BoC electrophysiology, also expanding to complementary approaches. We conclude with an evaluation of the potential translational applications and prospective technology developments.

Human-Derived Neurons and Neural Progenitor Cells in High Content Imaging Applications

Due to advances in the fields of stem cell biology and cellular engineering, a variety of commercially available human-derived neurons and neural progenitor cells (NPCs) are now available for use in research applications, including small molecule efficacy or toxicity screening. The use of human-derived neural cells is anticipated to address some of the uncertainties associated with the use of nonhuman culture models or transformed cell lines derived from human tissues. Many of the human-derived neurons and NPCs currently available from commercial sources recapitulate critical process of nervous system development including NPC proliferation, neurite outgrowth, synaptogenesis, and calcium signaling, each of which can be evaluated using high content image analysis (HCA). Human-derived neurons and NPCs are also amenable to culture in multiwell plate formats and thus may be adapted for use in HCA-based screening applications. This article reviews various types of HCA-based assays that have been used in conjunction with human-derived neurons and NPC cultures. This article also highlights instances where lower throughput analysis of neurodevelopmental processes has been performed and which demonstrate a potential for adaptation to higher-throughout imaging methods. Finally, a generic protocol for evaluating neurite outgrowth in human-derived neurons using a combination of immunocytochemistry and HCA is presented. The information provided in this article is intended to serve as a resource for cell model and assay selection for those interested in evaluating neurodevelopmental processes in human-derived cells.

Wnt3a is critical for endothelial progenitor cell-mediated neural stem cell proliferation and differentiation

The present study aimed to determine whether co-culture with bone marrow‑derived endothelial progenitor cells (EPCs) affects the proliferation and differentiation of spinal cord-derived neural stem cells (NSCs), and to investigate the underlying mechanism. The proliferation and differentiation of the NSCs were evaluated by an MTT cell proliferation and cytotoxicity assay, and immunofluorescence, respectively. The number of neurospheres and the number of β‑tubulin III‑positive cells were detected by microscopy. The wingless‑type MMTV integration site family, member 3a (Wnt3a)/β-catenin signaling pathway was analyzed by western blot analysis and reverse transcription‑quantitative polymerase chain reaction to elucidate the possible mechanisms of EPC‑mediated NSC proliferation and differentiation. The results revealed that co‑culture with EPCs significantly induced NSC proliferation and differentiation. In addition, co‑culture with EPCs markedly induced the expression levels of Wnt3a and β‑catenin and inhibited the phosphorylation of glycogen synthase kinase 3β (GSK‑3β). By contrast, Wnt3a knockdown using a short hairpin RNA plasmid in the EPCs reduced EPC‑mediated NSC proliferation and differentiation, accompanied by inhibition of the EPC‑mediated expression of β‑catenin, and its phosphorylation and activation of GSK‑3β. Taken together, the findings of the present study demonstrated that Wnt3a was critical for EPC‑mediated NSC proliferation and differentiation.

Cellular responses to Sindbis virus infection of neural progenitors derived from human embryonic stem cells

Background

Sindbis virus (SINV) causes age-dependent encephalitis in mice, and therefore serves as a model to study viral encephalitis. SINV is used as a vector for the delivery of genes into selected neural stem cell lines; however, the toxicity and side effects of this vector have rarely been discussed. In this context, we investigated the cellular responses of human embryonic stem cell (hESCs) derived neural progenitors (hNPCs) to SINV infection by assessing susceptibility of the cells to SINV infection, analyzing the effect of infection on cell proliferation and cell death, and examining the impact of SINV infection on hNPCs markers of stemness.

Findings

We found that hNPCs are highly susceptible to SINV infection. Upon infection, the viruses induced apoptosis to hNPCs while not affecting the expression of cell proliferation markers. Lastly, SINV infections result in significant changes in the expression of key regulators of hNPCs’ plasticity and homeostasis.

Conclusion

The robust and versatile signaling, proliferation, and other cell responses of hESCs-derived hNPCs to virus infection demonstrated that it is a good model to study the pathogenesis of viral-induced neurodevelopmental and degenerative diseases. On the other hand, the toxicity of SINV to hNPCs cells cannot be ignored, and therefore extra care should be taken when using SINV as a vector to deliver genes into human stem cell lines.

SSEA4-positive pig induced pluripotent stem cells are primed for differentiation into neural cells

Neural cells derived from induced pluripotent stem cells (iPSCs) have the potential for autologous cell therapies in treating patients with severe neurological disorders or injury. However, further study of efficacy and safety are needed in large animal preclinical models that have similar neural anatomy and physiology to humans such as the pig. The pig model for pluripotent stem cell therapy has been made possible for the first time with the development of pig iPSCs (piPSCs) capable of in vitro and in vivo differentiation into tissues of all three germ layers. Still, the question remains if piPSCs are capable of undergoing robust neural differentiation using a system similar to those being used with human iPSCs. In this study, we generated a new line of piPSCs from fibroblast cells that expressed pluripotency markers and were capable of embryoid body differentiation into all three germ layers. piPSCs demonstrated robust neural differentiation forming βIII-TUB/MAP2+ neurons, GFAP+ astrocytes, and O4+ oligodendrocytes and demonstrated strong upregulation of neural cell genes representative of all three major neural lineages of the central nervous system. In the presence of motor neuron signaling factors, piPSC-derived neurons showed expression of transcription factors associated with motor neuron differentiation (HB9 and ISLET1). Our findings demonstrate that SSEA4 expression is required for piPSCs to differentiate into neurons, astrocytes, and oligodendrocytes and furthermore develop specific neuronal subtypes. This indicates that the pigs can fill the need for a powerful model to study autologous neural iPSC therapies in a system similar to humans.

Burst analysis tool for developing neuronal networks exhibiting highly varying action potential dynamics

In this paper we propose a firing statistics based neuronal network burst detection algorithm for neuronal networks exhibiting highly variable action potential dynamics. Electrical activity of neuronal networks is generally analyzed by the occurrences of spikes and bursts both in time and space. Commonly accepted analysis tools employ burst detection algorithms based on predefined criteria. However, maturing neuronal networks, such as those originating from human embryonic stem cells (hESCs), exhibit highly variable network structure and time-varying dynamics. To explore the developing burst/spike activities of such networks, we propose a burst detection algorithm which utilizes the firing statistics based on interspike interval (ISI) histograms. Moreover, the algorithm calculates ISI thresholds for burst spikes as well as for pre-burst spikes and burst tails by evaluating the cumulative moving average (CMA) and skewness of the ISI histogram. Because of the adaptive nature of the proposed algorithm, its analysis power is not limited by the type of neuronal cell network at hand. We demonstrate the functionality of our algorithm with two different types of microelectrode array (MEA) data recorded from spontaneously active hESC-derived neuronal cell networks. The same data was also analyzed by two commonly employed burst detection algorithms and the differences in burst detection results are illustrated. The results demonstrate that our method is both adaptive to the firing statistics of the network and yields successful burst detection from the data. In conclusion, the proposed method is a potential tool for analyzing of hESC-derived neuronal cell networks and thus can be utilized in studies aiming to understand the development and functioning of human neuronal networks and as an analysis tool for in vitro drug screening and neurotoxicity assays.

Cellular environment directs differentiation of human umbilical cord blood-derived neural stem cells in vitro

Cord blood-derived neural stem cells (NSCs) are proposed as an alternative cell source to repair brain damage upon transplantation. However, there is a lack of data showing how these cells are driven to generate desired phenotypes by recipient nervous tissue. Previous research indicates that local environment provides signals driving the fate of stem cells. To investigate the impact of these local cues interaction, the authors used a model of cord blood-derived NSCs co-cultured with different rat brain-specific primary cultures, creating the neural-like microenvironment conditions in vitro. Neuronal and astro-, oligo-, and microglia cell cultures were obtained by the previously described methods. The CMFDA-labeled neural stem cells originated from, non-transformed human umbilical cord blood cell line (HUCB-NSCs) established in a laboratory. The authors show that the close vicinity of astrocytes and oligodendrocytes promotes neuronal differentiation of HUCB-NSCs, whereas postmitotic neurons induce oligodendrogliogenesis of these cells. In turn, microglia or endothelial cells do not favor any phenotypes of their neural commitment. Studies have confirmed that HUCB-NSCs can read cues from the neurogenic microenvironment, attaining features of neurons, astrocytes, or oligodendrocytes. The specific responses of neurally committed cord blood-derived cells, reported in this work, are very much similar to those described previously for NSCs derived from other "more typical" sources. This further proves their genuine neural nature. Apart from having a better insight into the neurogenesis in the adult brain, these findings might be important when predicting cord blood cell derivative behavior after their transplantation for neurological disorders.

Endothelial cells support survival, proliferation, and neuronal differentiation of transplanted adult ischemia-induced neural stem/progenitor cells after cerebral infarction

Transplantation of neural stem cells (NSCs) has been proposed as a therapy for a range of neurological disorders. To realize the potential of this approach, it is essential to control survival, proliferation, migration, and differentiation of NSCs after transplantation. NSCs are regulated in vivo, at least in part, by their specialized microenvironment or "niche." In the adult central nervous system, neurogenic regions, such as the subventricular and subgranular zones, include NSCs residing in a vascular niche with endothelial cells. Although there is accumulating evidence that endothelial cells promote proliferation of NSCs in vitro, there is no description of their impact on transplanted NSCs. In this study, we grafted cortex-derived stroke-induced neural stem/progenitor cells, obtained from adult mice, onto poststroke cortex in the presence or absence of endothelial cells, and compared survival, proliferation, and neuronal differentiation of the neural precursors in vivo. Cotransplantation of endothelial cells and neural stem/progenitor cells increased survival and proliferation of ischemia-induced neural stem/progenitor cells and also accelerated neuronal differentiation compared with transplantation of neural precursors alone. These data indicate that reconstitution of elements in the vascular niche enhances transplantation of adult neural progenitor cells.