Kohki Matsubara

Human dental pulp-derived stem cells promote locomotor recovery after complete transection of the rat spinal cord by multiple neuro-regenerative mechanisms

Spinal cord injury (SCI) often leads to persistent functional deficits due to loss of neurons and glia and to limited axonal regeneration after injury. Here we report that transplantation of human dental pulp stem cells into the completely transected adult rat spinal cord resulted in marked recovery of hind limb locomotor functions. Transplantation of human bone marrow stromal cells or skin-derived fibroblasts led to substantially less recovery of locomotor function. The human dental pulp stem cells exhibited three major neuroregenerative activities. First, they inhibited the SCI-induced apoptosis of neurons, astrocytes, and oligodendrocytes, which improved the preservation of neuronal filaments and myelin sheaths. Second, they promoted the regeneration of transected axons by directly inhibiting multiple axon growth inhibitors, including chondroitin sulfate proteoglycan and myelin-associated glycoprotein, via paracrine mechanisms. Last, they replaced lost cells by differentiating into mature oligodendrocytes under the extreme conditions of SCI. Our data demonstrate that tooth-derived stem cells may provide therapeutic benefits for treating SCI through both cell-autonomous and paracrine neuroregenerative activities.

Human Dental Pulp-Derived Stem Cells Protect Against Hypoxic-Ischemic Brain Injury in Neonatal Mice

Background and Purpose— Perinatal hypoxia-ischemia (HI) has high rates of neurological deficits and mortality. So far, no effective treatment for HI brain injury has been developed. In this study, we investigated the therapeutic effects of stem cells from human exfoliated deciduous teeth (SHED) for the treatment of neonatal HI brain injury. Methods— Unilateral HI was induced in postnatal day 5 (P5) mice. Twenty-four hours later, SHED, human skin fibroblasts, or serum-free conditioned medium derived from these cells was injected into the injured brain. The effects of cell transplantation or conditioned medium injection on the animals’ neurological and pathophysiological recovery were evaluated. Results— Transplanted SHED, but not fibroblasts, significantly reduced the HI-induced brain-tissue loss and improved neurological function. SHED also improved the survival of the HI mice. The engrafted SHED rarely differentiated into neural lineages; however, their transplantation inhibited the expression of proinflammatory cytokines, increased the expression of anti-inflammatory ones, and significantly reduced apoptosis. Notably, the intracerebral administration of SHED-conditioned medium also significantly improved the neurological outcome, inhibited apoptosis, and reduced tissue loss. Conclusions— SHED transplantation into the HI-injured brain resulted in remarkable neurological and pathophysiological recovery. Our findings indicate that paracrine factors derived from SHED support a neuroprotective microenvironment in the HI brain. SHED graft and SHED-conditioned medium may provide a novel neuroprotective therapy for HI.

Stem cell-conditioned medium accelerates distraction osteogenesis through multiple regenerative mechanisms

Distraction osteogenesis (DO) successfully induces large-scale skeletal tissue regeneration, but it involves an undesirably long treatment period. A high-speed DO mouse model (H-DO) with a distraction speed twice that of a control DO model failed to generate new bone callus in the distraction gap. Here we demonstrate that the local administration of serum-free conditioned medium from human mesenchymal stem cells (MSC-CM) accelerated callus formation in the mouse H-DO model. Secretomic analysis identified factors contained in MSC-CM that recruit murine bone marrow stromal cells (mBMSCs) and endothelial cells/endothelial progenitor cells (EC/EPCs), inhibit inflammation and apoptosis, and promote osteoblast differentiation, angiogenesis, and cell proliferation. Functional assays identified MCP-1/-3 and IL-3/-6 as essential factors in recruiting mBMSCs and EC/EPCs. IL-3/-6 also enhanced the osteogenic differentiation of mBMSCs. MSC-CM that had been depleted of MCP-1/-3 failed to recruit mBMSCs, and consequently failed to promote callus formation. Taken together, our data suggest that MSCs produce a broad repertoire of trophic factors with tissue-regenerative activities that accelerate healing in the DO process.

Secreted Ectodomain of Sialic Acid-Binding Ig-Like Lectin-9 and Monocyte Chemoattractant Protein-1 Promote Recovery after Rat Spinal Cord Injury by Altering Macrophage Polarity

Engrafted mesenchymal stem cells from human deciduous dental pulp (SHEDs) support recovery from neural insults via paracrine mechanisms that are poorly understood. Here we show that the conditioned serum-free medium (CM) from SHEDs, administered intrathecally into rat injured spinal cord during the acute postinjury period, caused remarkable functional recovery. The ability of SHED-CM to induce recovery was associated with an immunoregulatory activity that induced anti-inflammatory M2-like macrophages. Secretome analysis of the SHED-CM revealed a previously unrecognized set of inducers for anti-inflammatory M2-like macrophages: monocyte chemoattractant protein-1 (MCP-1) and the secreted ectodomain of sialic acid-binding Ig-like lectin-9 (ED-Siglec-9). Depleting MCP-1 and ED-Siglec-9 from the SHED-CM prominently reduced its ability to induce M2-like macrophages and to promote functional recovery after spinal cord injury (SCI). The combination of MCP-1 and ED-Siglec-9 synergistically promoted the M2-like differentiation of bone marrow-derived macrophages in vitro, and this effect was abolished by a selective antagonist for CC chemokine receptor 2 (CCR2) or by the genetic knock-out of CCR2. Furthermore, MCP-1 and ED-Siglec-9 administration into the injured spinal cord induced M2-like macrophages and led to a marked recovery of hindlimb locomotor function after SCI. The inhibition of this M2 induction through the inactivation of CCR2 function abolished the therapeutic effects of both SHED-CM and MCP-1/ED-Siglec-9. Macrophages activated by MCP-1 and ED-Siglec-9 extended neurite and suppressed apoptosis of primary cerebellar granule neurons against the neurotoxic effects of chondroitin sulfate proteoglycans. Our data suggest that the unique combination of MCP-1 and ED-Siglec-9 repairs the SCI through anti-inflammatory M2-like macrophage induction.

Multifaceted Neuro-Regenerative Activities of Human Dental Pulp Stem Cells for Functional Recovery after Spinal Cord Injury

Spinal cord injury (SCI) often leads to persistent functional deficits due to the loss of neurons and glia and to limited axonal regeneration after such injury. Recently, three independent groups have reported marked recovery of hindlimb locomotor function after the transplantation of human adult dental pulp stem cells (DPSCs) and stem cells from human exfoliated deciduous teeth (SHEDs) into rats or mice with acute, sub-acute or chronic SCI. This review summarizes the primary characteristics of human dental pulp stem cells and their therapeutic benefits for treating SCI. Experimental data from multiple preclinical studies suggest that pulp stem cells may promote functional recovery after SCI through multifaceted neuro-regenerative activities.

Factors secreted from dental pulp stem cells show multifaceted benefits for treating acute lung injury in mice.

BACKGROUND AIMS Acute respiratory distress syndrome (ARDS) is a severe inflammatory disorder characterized by acute respiratory failure, resulting from severe, destructive lung inflammation and irreversible lung fibrosis. We evaluated the use of stem cells derived from human exfoliated deciduous teeth (SHEDs) or SHED-derived serum-free conditioned medium (SHED-CM) as treatments for bleomycin (BLM)-induced mice acute lung injury (ALI), exhibiting several pathogenic features associated with the human disease ARDS. METHODS Mice with BLM-induced ALI with or without SHED or SHED-CM treatment were examined for weight loss and survival. The lung tissue was characterized by histological and real-time quantitative polymerase chain reaction analysis. The effects of SHED-CM on macrophage differentiation in vitro were also assessed. RESULTS A single intravenous administration of either SHEDs or SHED-CM attenuated the lung injury and weight loss in BLM-treated mice and improved their survival rate. Similar recovery levels were seen in the SHEDs and SHED-CM treatment groups, suggesting that SHED improves ALI by paracrine mechanisms. SHED-CM contained multiple therapeutic factors involved in lung-regenerative mechanisms. Importantly, SHED-CM attenuated the BLM-induced pro-inflammatory response and generated an anti-inflammatory/tissue-regenerating environment, accompanied by the induction of anti-inflammatory M2-like lung macrophages. Furthermore, SHED-CM promoted the in vitro differentiation of bone marrow-derived macrophages into M2-like cells, which expressed high levels of Arginase1, CD206 and Ym-1. DISCUSSION Our results suggest that SHED-secreted factors provide multifaceted therapeutic effects, including a strong M2-inducing activity, for treating BLM-induced ALI. This work may open new avenues for research on stem cell-based ARDS therapies.

Dopaminergic differentiation of stem cells from human deciduous teeth and their therapeutic benefits for Parkinsonian rats.

Parkinsons disease (PD) is a progressive neurodegenerative disorder caused by the loss of nigrostriatal dopaminergic (DAergic) neurons and the depletion of striatal dopamine. Here we show that DAergic-neuron-like cells could be efficiently induced from stem cells derived from human exfoliated deciduous teeth (SHEDs), and that these induced cells had therapeutic benefits in a 6-OHDA-induced Parkinsonian rat model. In our protocol, EGF and bFGF signaling activated the SHEDs expression of proneural genes, Ngn2 and Mash1, and subsequent treatment with brain-derived neurotrophic factor (BDNF) promoted their maturation into DAergic neuron-like SHEDs (dSHEDs). A hypoxic DAergic differentiation protocol improved cell viability and enhanced the expression of multiple neurotrophic factors, including BDNF, GDNF, NT-3, and HGF. Engrafted dSHEDs survived in the striatum of Parkinsonian rats, improved the DA level more efficiently than engrafted undifferentiated SHEDs, and promoted the recovery from neurological deficits. Our findings further suggested that paracrine effects of dSHEDs contributed to neuroprotection against 6-OHDA-induced neurodegeneration and to nigrostriatal tract restoration. In addition, we found that the conditioned medium derived from dSHEDs protected primary neurons against 6-OHDA toxicity and accelerated neurite outgrowth in vitro. Thus, our data suggest that stem cells derived from dental pulp may have therapeutic benefits for PD.

Multifaceted therapeutic benefits of factors derived from stem cells from human exfoliated deciduous teeth for acute liver failure in rats

In acute liver failure (ALF), a poorly controlled innate immune response causes massive hepatic destruction, which elicits a systemic inflammatory response, progressive multiple organ failure and ultimate sudden death. Although the liver has inherent tissue‐repairing activities, its regeneration during ALF fails, and orthotopic liver transplantation is the only curative approach. Here we show that a single intravenous administration of stem cells derived from human exfoliated deciduous teeth (SHEDs) or of SHED‐derived serum‐free conditioned medium (SHED–CM) into the d‐galactosamine‐induced rat model of ALF markedly improved the condition of the injured liver and the animals’ survival rate. The engraftment of infused SHEDs was very low, and both SHEDs and SHED–CM exerted similar levels of therapeutic effect, suggesting that the SHEDs reversed ALF by paracrine mechanisms. Importantly, SHED–CM attenuated the ALF‐induced pro‐inflammatory response and generated an anti‐inflammatory/tissue‐regenerating environment, which was accompanied by the induction of anti‐inflammatory M2‐like hepatic macrophages. Secretome analysis by cytokine antibody array revealed that the SHED–CM contained multiple tissue‐regenerating factors with known roles in anti‐apoptosis/hepatocyte protection, angiogenesis, macrophage differentiation and the proliferation/differentiation of liver progenitor cells. Taken together, our findings suggest that SHEDs produce factors that provide multifaceted therapeutic benefits for AFL. Copyright

Secreted Ectodomain of SIGLEC-9 and MCP-1 Synergistically Improve Acute Liver Failure in Rats by Altering Macrophage Polarity

Effective treatments for acute liver failure (ALF) are still lacking. We recently reported that a single intravenous administration of serum-free conditioned medium from stem cells derived from human exfoliated deciduous teeth (SHED-CM) into the D-galactosamine (D-Gal)-induced rat ALF model improves the liver injury. However, the specific factors in SHED-CM that are responsible for resolving ALF remain unclear. Here we found that depleting SHED-CM of two 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)—abolished its ability to resolve rat ALF. Furthermore, treatment with MCP-1/sSiglec-9 alone dramatically improved the survival of ALF rats. This treatment induced anti-inflammatory M2, suppressed hepatocyte apoptosis, and promoted hepatocyte proliferation. Treatment with an M2-depletion reagent (mannosylated clodronate liposomes) suppressed the recovery. In addition, MCP-1 and sSiglec-9 synergistically promoted the M2 differentiation of bone marrow-derived macrophages via CCR2, accompanied by the production of multiple liver-regenerating factors. The conditioned medium from MCP-1/sSiglec-9-activated M2 macrophages, but not from interleukin-4-induced ones, suppressed the D-Gal- and LPS-induced apoptosis of primary hepatocytes and promoted their proliferation in vitro. The unique combination of MCP-1/sSiglec-9 ameliorates rat ALF by inhibiting hepatocellular apoptosis and promoting liver regeneration through the induction of anti-inflammatory/tissue-repairing M2 macrophages.

Analysis of the Neuroregenerative Activities of Mesenchymal Stem Cells in Functional Recovery after Rat Spinal Cord Injury

Spinal cord injury (SCI) involves concurrent, interacting pathological processes, and requires a multifaceted therapeutic strategy. Stem cell-based transplantation holds great promise as such an approach. We have reported that stem cells derived from human dental pulp have remarkable neuroregenerative activity, and that when transplanted into animal models of SCI, these cells promote functional recovery by inhibiting massive SCI-induced apoptosis, preserving neural fibers and myelin, regenerating transected axons, and replacing damaged cells by differentiating into oligodendrocytes. Here, we introduce some details of our experimental procedures, which may serve as a guide for designing experiments to evaluate the therapeutic benefits of various types of stem cells.