Secreted Ectodomain of Sialic Acid-Binding Ig-Like Lectin-9 and Monocyte Chemoattractant Protein-1 Synergistically Regenerate Transected Rat Peripheral Nerves by Altering Macrophage Polarity

Abstract

Peripheral nerves (PNs) exhibit remarkable self-repairing reparative activity after a simple crush or cut injury. However, the neuronal transection involving a nerve gap overwhelms their repairing activity and causes persistent paralysis. Here, we show that an implantation of the serum-free conditioned medium from stem cells from human exfoliated deciduous teeth (SHED-CM) immersed in a collagen sponge into the nerve gap formed by rat facial nerves transection restored the neurological function. In contrast, SHED-CM specifically depleted of a set of anti-inflammatory M2 macrophage inducers, monocyte chemoattractant protein-1 (MCP-1) and the secreted ectodomain of sialic acid-binding Ig-like lectin-9 (sSiglec-9) lost the ability to restore neurological function in this model. Notably, the combination of MCP-1 and sSiglec-9 induced the polarization of M2 macrophages in vitro, resulting in the expression of multiple trophic factors that enhanced proliferation, migration, and differentiation of Schwann cells, blood vessel formation, and nerve fiber extension. Furthermore, the implantation of a collagen graft containing MCP-1/sSiglec-9 into the nerve gap induced anti-inflammatory M2 macrophage polarization, generated a Schwann-cell bridge instead of fibrotic scar, induced axonal regrowth, and restored nerve function. The specific elimination of M2 macrophages by Mannosylated-Clodrosome suppressed the MCP-1/sSiglec-9-mediated neurological recovery. Taken together, our data suggest that MCP-1/sSiglec-9 regenerates PNs by inducing tissue-repairing M2 macrophages and may provide therapeutic benefits for severe peripheral nerve injuries. Stem Cells 2017;35:641-653.

Dental Stem Cell-Derived Secretome/Conditioned Medium: The Future for Regenerative Therapeutic Applications

“…These in vitro results were confirmed in vivo [110,111]. SHED-CM administration in a rat nerve gap model induced axon regeneration and remyelination [110,111]. Notably, MCP-1/sSiglec-9 prompted the polarization of M2 macrophages, which antagonized the proinflammatory M1 conditions associated with neural insult [111,112], thereby increasing the expression of anti-inflammatory markers IL-10 and Arginine-1 and markedly suppressing inflammatory mediators IL-1β, tumor necrosis factor (TNF-α), IL-6, and inducible nitric-oxide synthase (iNOS) [111].…”

“…The unique combination of neurotrophic factors, MCP-1 and secreted ectodomain of sialic acid-binding Ig-like lectin-9 (sSiglec-9), were described as crucial for SHED-CM mediated functional recovery, following severe peripheral nerve injury. This neuroprotective effect was evident through the promotion of migration, proliferation, and differentiation of Schwann cells; blood vessel formation; and nerve fiber extension [111]. These in vitro results were confirmed in vivo [110,111].…”

“…This neuroprotective effect was evident through the promotion of migration, proliferation, and differentiation of Schwann cells; blood vessel formation; and nerve fiber extension [111]. These in vitro results were confirmed in vivo [110,111]. SHED-CM administration in a rat nerve gap model induced axon regeneration and remyelination [110,111].…”

“…SHED-CM administration in a rat nerve gap model induced axon regeneration and remyelination [110,111]. Notably, MCP-1/sSiglec-9 prompted the polarization of M2 macrophages, which antagonized the proinflammatory M1 conditions associated with neural insult [111,112], thereby increasing the expression of anti-inflammatory markers IL-10 and Arginine-1 and markedly suppressing inflammatory mediators IL-1β, tumor necrosis factor (TNF-α), IL-6, and inducible nitric-oxide synthase (iNOS) [111]. In a perinatal hypoxia-ischemia-induced brain injury mouse model, intracerebral administration of SHED-CM resulted in significant recovery in neurological function, survival rate, and neuropathological score [113].…”

“…It is well known that the immunomodulatory and antiinflammatory effects of MSC-CM are mediated through soluble immune-regulatory molecules. Dental MSC-CM induce an immunoregulatory activity by converting the proinflammatory conditions and induced anti-inflammatory M2-like macrophage differentiation, thereby treating neural diseases [111,112,115,117,118,122], lung injury [126], and liver failure [125]. Dental MSC-CM promoted anti-inflammatory cytokines (IL-10 and TGF-β1) as well as M2 cell markers (CD206 and Arginase-1) [125].…”