The serrulatane diterpenoid natural products RAD288 and RAD289 stimulate properties of olfactory ensheathing cells useful for neural repair therapies

Olfactory ensheathing cells (OECs) are crucial for promoting the regeneration of the primary olfactory nervous system that occurs throughout life. Transplantation of OECs has emerged as a promising therapy for nervous system injuries, in particular for spinal cord injury repair. Functional outcomes in both animals and humans are, however, highly variable, primarily because it is difficult to rapidly obtain enough OECs for transplantation. Compounds which can stimulate OEC proliferation without changing the phenotype of the cells are therefore highly sought after. Additionally, compounds which can stimulate favourable cell behaviours such as migration and phagocytic activity are desirable. We conducted a medium-throughput screen testing the Davis open access natural product-based library (472 compounds) and subsequently identified the known plant natural product 2-methoxy-1,4naphthoquinone as a stimulant of OEC viability. We showed that 2-methoxy-1,4-naphthoquinone: (i) strongly stimulates proliferation over several weeks in culture whilst maintaining the OEC phenotype; (ii) stimulates the phagocytic activity of OECs, and (iii) modulates the cell cycle. We also identified the transcription factor Nrf2 as the compound's potential molecular target. From these extensive investigations we conclude that 2-methoxy-1,4-naphthoquinone may enhance the therapeutic potential of OECs by stimulating proliferation prior to transplantation.

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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The plant natural product 2-methoxy-1,4-naphthoquinone stimulates therapeutic neural repair properties of olfactory ensheathing cells

Chen

Vial

Gee

et al. 2020

“…Recent studies began to adopt the standard wound healing assay for screening multi-phenotypic responses of compounds with polypharmacologic effects 13 . Other studies tried to investigate the effect of compounds or natural extract by integrating results from two independent phenotypic assays including both cell viability assay and wound healing assay 7,8,14,15 . However, such previous studies still required the primary screening to eliminate false positive compound with cytotoxic effect.…”

Section: Discussionmentioning

confidence: 99%

Novel Analytical Platform For Robust Identification of Cell Migration Inhibitors

Somchai

Phongkitkarun

Kueanjinda

et al. 2020

Wound healing assay is a simple and cost-effective in vitro assay for assessing therapeutic impacts on cell migration. its key limitation is the possible confoundment by other cellular phenotypes, causing misinterpretation of the experimental outcome. in this study, we attempted to address this problem by developing a simple analytical approach for scoring therapeutic influences on both cell migration and cell death, while normalizing the influence of cell growth using Mitomycin C pre-treatment. By carefully mapping the relationship between cell death and wound closure rate, contribution of cell death and cell migration on the observed wound closure delay can be quantitatively separated at all drug dosing. We showed that both intrinsic cell motility difference and extrinsic factors such as cell seeding density can significantly affect final interpretation of therapeutic impacts on cellular phenotypes. Such discrepancy can be rectified by using the actual wound closure time of each treatment condition for the calculation of phenotypic scores. finally, we demonstrated a screen for strong pharmaceutical inhibitors of cell migration in cholangiocarcinoma cell lines. our approach enables accurate scoring of both migrastatic and cytotoxic effects, and can be easily implemented for high-throughput drug screening.

“…The transplanted cells are thought to promote regeneration by secreting growth factors and guidance factors, by providing physical support, and by clearing debris arising from dead cells 13,15 . It has also been suggested that stimulation of the phagocytic activity to more rapidly clear the injury site of cell debris will further promote regeneration 13,[17][18][19][20][21] . To date, it remains unknown how peripheral glia recognize, internalize and process necrotic targets.…”

mentioning

confidence: 99%

Key differences between olfactory ensheathing cells and Schwann cells regarding phagocytosis of necrotic cells: implications for transplantation therapies

Nazareth

Shelper

Chacko

et al. 2020

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Transplantation of peripheral nervous system glia is being explored for treating neural injuries, in particular central nervous system injuries. These glia, olfactory ensheathing cells (OECs) and Schwann cells (SCs), are thought to aid regeneration by clearing necrotic cells, (necrotic bodies, NBs), as well as myelin debris. The mechanism by which the glia phagocytose and traffic NBs are not understood. Here, we show that OECs and SCs recognize phosphatidylserine on NBs, followed by engulfment and trafficking to endosomes and lysosomes. We also showed that both glia can phagocytose and process myelin debris. We compared the time-course of glial phagocytosis (of both NBs and myelin) to that of macrophages. Internalization and trafficking were considerably slower in glia than in macrophages, and OECs were more efficient phagocytes than SCs. The two glial types also differed regarding their cytokine responses after NB challenge. SCs produced low amounts of the pro-inflammatory cytokine TNF-α while OECs did not produce detectable TNF-α. Thus, OECs have a higher capacity than SCs for phagocytosis and trafficking, whilst producing lower amounts of pro-inflammatory cytokines. These findings suggest that OEC transplantation into the injured nervous system may lead to better outcomes than SC transplantation.