Intrathecal bone marrow stromal cells inhibit neuropathic pain via TGF-β secretion
Gang Chen, … , Rou-Gang Xie, Ru-Rong Ji
Gang Chen, … , Rou-Gang Xie, Ru-Rong Ji
Published July 13, 2015
Citation Information: J Clin Invest. 2015;125(8):3226-3240. https://doi.org/10.1172/JCI80883.
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Research Article Neuroscience

Intrathecal bone marrow stromal cells inhibit neuropathic pain via TGF-β secretion

Abstract

Neuropathic pain remains a pressing clinical problem. Here, we demonstrate that a local, intrathecal (i.t.) injection of bone marrow stromal cells (BMSCs) following lumbar puncture alleviates early- and late-phase neuropathic pain symptoms, such as allodynia and hyperalgesia, for several weeks in murine chronic constriction injury (CCI) and spared nerve injury models. Moreover, i.t. BMSCs reduced CCI-induced spontaneous pain and axonal injury of dorsal root ganglion (DRG) neurons and inhibited CCI-evoked neuroinflammation in DRGs and spinal cord tissues. BMSCs secreted TGF-β1 into the cerebrospinal fluid, and neutralization of TGF-β1, but not IL-10, reversed the analgesic effect of BMSCs. Conversely, i.t. administration of TGF-β1 potently inhibited neuropathic pain. TGF-β1 acted as a powerful neuromodulator and rapidly (within minutes) suppressed CCI-evoked spinal synaptic plasticity and DRG neuronal hyperexcitability via TGF-β receptor 1–mediated noncanonical signaling. Finally, nerve injury upregulated CXCL12 in lumbar L4–L6 DRGs, and this upregulation caused migration of i.t.-injected BMSCs to DRGs through the CXCL12 receptor CXCR4, which was expressed on BMSCs. BMSCs that migrated from the injection site survived at the border of DRGs for more than 2 months. Our findings support a paracrine mechanism by which i.t. BMSCs target CXCL12-producing DRGs to elicit neuroprotection and sustained neuropathic pain relief via TGF-β1 secretion.

Authors

Gang Chen, Chul-Kyu Park, Rou-Gang Xie, Ru-Rong Ji

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Figure 5

BMSCs release TGF-β1 to inhibit neuropathic pain in CCI mice.

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BMSCs release TGF-β1 to inhibit neuropathic pain in CCI mice. (A) ELISA ...
(A) ELISA analysis showing TGF-β1 and IL-10 release in BMSC culture medium and the effects of TNF (10 ng/ml, 60 min) and LPS (100 ng/ml, 60 min) on the release. *P < 0.05, compared with the respective control group; n = 8 separate cultures from different mice. (B) ELISA analysis showing increased TGF-β1 release in CSF 8 days after CCI and 4 days after i.t. delivery of 2.5 × 105 BMSCs. *P < 0.05, compared with naive and vehicle-treated cells; #P < 0.05; n = 4 mice/group. (C) Reversal of BMSC-induced inhibition of mechanical allodynia by TGF-β1–neutralizing Abs (4 μg, i.t.), but not by IL-10–neutralizing Abs (4 μg, i.t.) or control IgG (4 μg, i.t.). *P < 0.05, compared with the control IgG group; n = 5 mice/group. (D) Reduction of TGF-β1 release and expression in BMSCs following Tgfb1 siRNA treatment (1 μg/ml for 18 h). Both baseline release and evoked release by TNF (10 ng/ml, 1 h) were measured. *P < 0.05, compared with nontargeting siRNA; #P < 0.05; n = 4 separate cultures from different mice. (E) Antiallodynic effect of BMSCs (2.5 × 105 cells) was compromised by pretreatment of BMSCs with Tgfb1 siRNA (1 μg/ml for 18 h), but not with nontargeting control siRNA. Arrow indicates the time of the BMSC injection. *P < 0.05, compared with nontargeting siRNA control. n = 5 mice/group. (F and G) Dose-dependent reversal of mechanical allodynia by i.t. TGF-β1 at 5 and 21 days after CCI. Arrows in F and G indicate the time of the BMSC injection. *P < 0.05, compared with the vehicle group; #P < 0.05; n = 5 mice/group. (H) TGF-βR1 inhibitor SB431542 (100 pmol, i.t.) completely blocked the antiallodynic effect of TGF-β1 (10 ng, i.t.). Arrow indicates the time of i.t. injection given 19 days after CCI. *P < 0.05; n = 4–5 mice/group. Statistical significance was determined by 1-way ANOVA (A, B, and D), 2-way ANOVA, followed by Bonferroni’s post-hoc test (C, E, and F–H), or Student’s t test (E and H). All data are expressed as the mean ± SEM. NT, nontargeting.