scholarly journals Low Magnitude of Compression Enhances Biosynthesis of Mesenchymal Stem Cells towards Nucleus Pulposus Cells via the TRPV4-Dependent Pathway

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Yibo Gan ◽  
Bing Tu ◽  
Pei Li ◽  
Jixing Ye ◽  
Chen Zhao ◽  
...  
Keyword(s):  
Nucleus Pulposus ◽  
Transient Receptor Potential ◽  
Compressive Loading ◽  
3D Culture ◽  
Receptor Potential ◽  
Immunohistochemical Analysis ◽  
Transient Receptor Potential Vanilloid ◽  
Nucleus Pulposus Cells ◽  
Anabolic Response ◽  
Low Magnitude

Mesenchymal stem cell- (MSC-) based therapy is regarded as a promising tissue engineering strategy to achieve nucleus pulposus (NP) regeneration for the treatment of intervertebral disc degeneration (IDD). However, it is still a challenge to promote the biosynthesis of MSC to meet the requirement of NP regeneration. The purpose of this study was to optimize the compressive magnitude to enhance the extracellular matrix (ECM) deposition towards discogenesis of MSCs. Thus, we constructed a 3D culture model for MSCs to bear different magnitudes of compression for 7 days (5%, 10%, and 20% at the frequency of 1.0 Hz for 8 hours/day) using an intelligent and mechanically active bioreactor. Then, the underlying mechanotransduction mechanism of transient receptor potential vanilloid 4 (TRPV4) was further explored. The MSC-encapsulated hybrids were evaluated by Live/Dead staining, biochemical content assay, real-time PCR, Western blot, histological, and immunohistochemical analysis. The results showed that low-magnitude compression promoted anabolic response where high-magnitude compression induced the catabolic response for the 3D-cultured MSCs. The anabolic effect of low-magnitude compression could be inhibited by inhibiting TRPV4. Meanwhile, the activation of TRPV4 enhanced the biosynthesis analogous to low-magnitude compression. These findings demonstrate that low-magnitude compression promoted the anabolic response of ECM deposition towards discogenesis for the 3D-cultured MSCs and the TRPV4 channel plays a key role on mechanical signal transduction for low-magnitude compressive loading. Further understanding of this mechanism may provide insights into the development of new therapies for MSC-based NP regeneration.

scholarly journals Osmotic adaptation of nucleus pulposus cells: the role of aquaporin 1, aquaporin 4 and transient receptor potential vanilloid 4

2021 ◽  
Vol 41 ◽  
pp. 121-141
Author(s):  
JW Snuggs ◽  
◽  
RAD Bunning ◽  
CL Le Maitre
Keyword(s):  
Nucleus Pulposus ◽  
Disc Degeneration ◽  
Primary Cilia ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Aquaporin 4 ◽  
Transient Receptor Potential Vanilloid ◽  
Nucleus Pulposus Cells ◽  
Aquaporin 1 ◽  
Transient Receptor

The microenvironment of the nucleus pulposus is hyperosmotic and fluctuates diurnally due to mechanical loading. Changes in extracellular osmolality result in cell volume alterations, responsiveness to such changes is essential for cellular homeostasis. Aquaporins allow movement of water across cell membranes and control water permeability in response to osmotic gradients. Furthermore, transient receptor potential vanilloid 4 has been shown to sense osmotic and mechanical stimuli resulting in changes to intracellular Ca2+. It has been shown previously that aquaporin 1 and 4 expression decreases during disc degeneration. Here, the expression of transient receptor potential vanilloid 4 by human nucleus pulposus cells during disc degeneration, and the roles of aquaporin 1, 4 and transient receptor potential vanilloid 4 in regulating responses to osmotic gradients was investigated. Transient receptor potential vanilloid 4 was expressed by the majority of human nucleus pulposus cells and not affected by disc degeneration. Aquaporin 4 staining co-localised with primary cilia. Nucleus pulposus cells modulated their rate of volume change, water permeability and Ca2+ influx in response to extracellular osmolality. These responses were inhibited by chemical inhibition of aquaporin 4, transient receptor potential vanilloid 4, and to a lesser extent aquaporin 1; suggesting that both aquaporins and transient receptor potential vanilloid 4 play important roles in the fundamental adaptation of nucleus pulposus cells to their osmotic environment. Co-localisation with primary cilia indicates these proteins may function synergistically to achieve adaptation, which may be lost during disc degeneration, when aquaporin 1 and 4 expression is reduced.

Stretch-activated cation channel TRPV4 mediates hyposmotically induced prolactin release from prolactin cells of mozambique tilapia Oreochromis mossambicus

2012 ◽  
Vol 302 (8) ◽  
pp. R1004-R1011 ◽  
Author(s):  
Soichi Watanabe ◽  
Andre P. Seale ◽  
E. Gordon Grau ◽  
Toyoji Kaneko
Keyword(s):  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Immunohistochemical Analysis ◽  
Ruthenium Red ◽  
Cation Channel ◽  
Transient Receptor Potential Vanilloid ◽  
Functional Assay ◽  
Mozambique Tilapia ◽  
Transient Receptor ◽  
Rostral Pars Distalis

In teleost fish, prolactin (PRL) is an important hormone for hyperosmoregulation. The release of PRL from the pituitary of Mozambique tilapia is stimulated by a decrease in extracellular osmolality. Previous studies have shown that hyposmotically induced PRL release is linked with cell volume changes, and that stretch-activated Ca2+ channels are likely responsible for the initiation of the signal transduction for PRL release. In this study, we identified the stretch-activated Ca2+ channel transient receptor potential vanilloid 4 (TRPV4) from the rostral pars distalis (RPD) of tilapia acclimated to freshwater (FW). TRPV4 transcripts were ubiquitously expressed in tilapia; the level of expression in RPDs of FW-acclimated fish was lower than that found in RPDs of seawater (SW)-acclimated fish. Immunohistochemical analysis of the pituitary revealed that TRPV4 is localized in the cell membrane of PRL cells of both FW and SW tilapia. A functional assay with CHO-K1 cells showed that tilapia TRPV4 responded to a decrease in extracellular osmolality, and that its function was suppressed by ruthenium red (RR) and activated by 4α-phorbol 12,13-didecanoate (4aPDD). Exposure of dissociated PRL cells from FW-acclimated tilapia to RR blocked hyposmolality induced PRL release. PRL release, on the other hand, was stimulated by 4aPDD. These results indicate that PRL release in response to physiologically relevant changes in extracellular osmolality is mediated by the osmotically sensitive TRPV4 cation channel.

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