Locally Applied Stem Cell Exosome-Scaffold Attenuates Nerve Injury-Induced Pain in Rats

Abstract

Purpose

Nerve injury-induced pain is difficult to treat. In this study, we developed an alginate scaffold with human umbilical cord mesenchymal stem cell exosomes (EX-SC) to treat nerve injury-induced pain.

Materials and Methods

The scaffold was prepared and characterized for its physical traits and biocompatibility. In vitro studies of PC12 and HEK293 cells were used to evaluate the neuroprotective and neurotrophic effects of exosomes. Right L5/6 spinal nerve ligation (SNL) was performed in Sprague-Dawley rats to induce mechanical allodynia and thermal hyperalgesia, evaluated by von Frey hair and radiant heat tests. The EX-SC was wrapped around ligated L5/6 spinal nerves for treatment. Western blotting and immunofluorescence staining were used to evaluate neuron/glial activation, cytokines and neurotrophic factor of affected dorsal root ganglion (DRG).

Results

In cell culture assay, the exosomes induce neurite outgrowth of PC12 cells and protect PC12 and HEK293 cells against formaldehyde acid treatment. On post-ligation day 21, rats receiving EX-SC had significantly higher median (interquartile range) withdrawal threshold and latency [14.1 (13.7–15.5) g, 14.2 (13.7–15.3) s] than saline-SC-treated rats [2.1 (1.7–3.0) g, 2.0 (1.8–2.4) s, P=0.02 and 0.002]. The EX-SC also attenuated SNL-induced up-regulation of c-Fos, GFAP, Iba1, TNF-α and IL-1β, while enhancing the level of IL-10 and GDNF, in the ipsilateral L5/6 DRG. After implantation for 21 days, the EX-SC enhanced the expression of myelin basic protein and IL-10 in injured L5/6 axons.

Conclusion

We demonstrate the EX-SC possesses antinociceptive, anti-inflammation and pro-neurotrophic effects in the SNL pain model. It could be a promising therapeutic alternative for nerve injury-induced pain.

Keywords:

• exosome
• nerve injury
• neuropathic pain
• scaffold
• spinal nerve ligation
• stem cell

Acknowledgments

We thank Han-Yu Shen, Jia-Shun Hong and Zi-Hao Liu in Prof. Hsin-Yi Lin’s lab for scaffold preparation and characterization; Zhi-Xiang Li in Prof. Kuender D. Yang’s Lab for exosome preparation.

Presentation: Part of this work has been presented as poster at the annual meeting of Society for Neuroscience (Oct. 19-23, 2019), Chicago, USA.

Author Contributions

All authors made substantial contributions to conception and design, acquisition of data, or analysis and interpretation of data; took part in drafting the article or revising it critically for important intellectual content; agreed to submit to the current journal; gave final approval of the version to be published; and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest for this work.

Additional information

Funding

This work was supported by grants from Ministry of Science and Technology, Taiwan [MOST 105-2314-B-195-003-MY3 and 108-2314-B-195-006-MY3 (to J.K.C.); 106-2811-B-195-001 and 107-2811-B-195-500 (to S.J.S.); 108-2811-B-195-500 (to P.P.)]; Mackay Memorial Hospital, Taipei, Taiwan [MMH-E-108-15, MMH-E-109-15, MMH 10723, 10799, 107105, TT-10705, 10801 (to J.K.C.); MMH-E-107-05 (to K.D.Y.)]; and National Taipei University of Technology [NTUT-MMH Joint Research Program, NTUT-MMH-107-05, NTUT-MMH-108-01 and 108DMH0100032 (to H.Y.L.)].