Characterization of HLA-G and Related Immunosuppressive Effects in Human Umbilical Cord Stroma-Derived Stem Cells

Mesenchymal stem cells (MSCs) and especially those derived from fetal tissues exert a potent immunosuppressive effect that can be enhanced under inflammatory conditions. This study aimed to explore the immunosuppressive properties of human umbilical cord mesenchymal stem cells (HUCMSCs). We found that HLA-G, the nonclassical HLA allele with strong immune-inhibitory properties, was much more expressed on the HUCMSCs than on MSCs of other origins. Flow cytometry revealed that 90.8% of the HUCMSCs expressed HLA-G. RT-PCR revealed expression of HLA-G1, HLA-G5, and HLA-G7 in all of four HUCMSC lines. In a mixed lymphocyte reaction assay, the HUCMSCs inhibited the proliferation of lymphocytes by 35 ± 3% and could be reversed by treatment with an HLA-G blocking antibody. Upon coculture with the HUCMSCs, peripheral blood mononuclear cells expressed lower levels of proinflammatory mediators such as IL-6, TNF-α, and VEGF-α. This immunosuppressive effect was enhanced when the HUCMSCs were pretreated with IFN-γ, such that the expression of HLA-G was highly activated and HLA-DR diminished. The same phenomenon was not observed in MSCs derived from bone marrow or the placenta. In a xenograft rejection assay, the HUCMSCs survived in immunocompetent mice, whereas primary fibroblasts did not survive. This study confirms the HLA-G-related immunosuppressive property of HUCMSCs, which is more potent than MSCs of other origin. A good tolerance of this mesenchymal stem cell in allogeneic transplantation can thus be anticipated.

Human Infrapatellar Fat Pad-Derived Stromal Cells Have More Potent Differentiation Capacity Than Other Mesenchymal Cells and Can Be Enhanced by Hyaluronan

The microenvironment plays an important role in the homing in and differentiation of stem cells to repair injured tissue. Infrapatellar fat pad stromal cells (IFPSCs) are a promising source of such cells for the repair of articular injury-induced degeneration. This study investigated the chemotaxis of IFPSCs to chondrocytes and the effect of hyaluronan (HA) on the biological and regenerative properties of IFPSCs. The IFPSCs were obtained from patients undergoing arthroscopy and cultured via a standard 2-week culture protocol that yielded more than 10 million cells on passage 3. The results showed that the IFPSCs had a higher capacity for chondrogenic differentiation than mesenchymal cells from body fat, bone marrow, and Wharton's jelly of the umbilical cord. The IFPSCs cultured on 25% or 50% HA showed better osteogenic and adipogenic capabilities than those without HA or with 75% HA (p < 0.001). Cultures of the IFPSCs on 25% HA had a fourfold increase in chondrogenic differentiation compared to cultures without HA, which was better than with 50% and 75% HA (p < 0.05). Cell proliferation was not affected by the presence of HA. In conclusion, IFPSCs have a strong potential for chondrogenic regeneration, which can even be augmented in a 25% HA microenvironment.

Human adipose-derived stem cells cultured in keratinocyte serum free medium: Donor's age does not affect the proliferation and differentiation capacities

BACKGROUND

Although donor age-related effects of characteristics of mesenchymal stem cells (MSC), such as a decrease in the proliferation and differentiation capacity and an increase of senescence and apoptosis, are evident, such effects are generally less prominent in adipose-derived stem cells (ASC). Using a hormone and growth factor rich medium (KFSM), this study cultured ASC from abdominal subcutaneous fat of 27 adult females in three age groups: 30-39 y, 40-49 y and 50-60 y, and investigated the growth and differentiation characteristics.

RESULTS

The derived ASC had an immunophenotype similar to that of bone marrow derived MSC (BMSC). They could be stably expanded with an average population doubling time of 21.5 ± 2.3 h. Other than a higher pre-adipogenic commitment and a lower adipogenic differentiation capability in ASC derived from the old age group, other characteristics including proliferation rate, doubling time, telomere length, as well as the osteogenic and chondrogenic differentiation capacity were the same regardless of the donor's age.

CONCLUSIONS

The study demonstrates a promising proliferation and differentiation capabilities of ASC regardless of the donor's age. The compromised adipogenic potential in the older donors could be a benefit for their application in regeneration therapy.

Ultrastructural localization of matrix metalloproteinase-9 in eosinophils from the cerebrospinal fluid of mice with eosinophilic meningitis caused by Angiostrongylus cantonensis

Matrix metalloproteinase-9 (MMP-9) has been implicated in the pathogenesis of eosinophilic meningitis caused by Angiostrongylus cantonensis. In the present study, such meningitis in mice was found to be associated with elevated expression of MMP-9 mRNA, elevated MMP-9 concentrations and enhanced MMP-9 activity in the cerebrospinal fluid (CSF). Immunocytochemistry showed that an anti-MMP-9 antibody reacted with macrophages, neutrophils and eosinophils from the CSF. As eosinophils are generally considered to be effector cells in host defence against A. cantonensis infection, high-resolution immuno-electron microscopy was then used to confirm the localization of MMP-9 in the eosinophils from the CSF. The method used, which was based on immunogold, indicated that the eosinophilic MMP-9 was mostly localized in the 'small' granules in the cytoplasm and along the cell membrane, and not in the crystalloid-containing secretory granules observed. It therefore appears that MMP-9 is synthesised and/or stored in the small granules of the eosinophils, and is released into the subarachnoid space of the host's brain by secretion or cell rupture.

Matrix metalloproteinase-2 and -9 in the granulomatous fibrosis of rats infected with Angiostrongylus cantonensis

The histomorphology of granuloma formation and gelatinase production were investigated in the brains, hearts, lungs and livers of Sprague-Dawley rats infected with Angiostrongylus cantonensis. The relationships between two gelatinases and granulomatous fibrosis were explored, following infection of each rat with 60 infective larvae of the nematode. Worm recovery from the brain was maximal on day 15 post-inoculation whereas peak recovery from the lungs was maximal 75 days later, on day 90. The granulomatous reactions and fibrosis were marked in the lungs but only mild, if present at all, in the brain, heart and liver. Gelatin zymography revealed that matrix metalloproteinase2 (MMP-2) was present, at all time-points, in the heart and lungs, although only in the lungs was there partial conversion of the 72-kDa pro-enzyme to the 64-kDa active form during granulomatous fibrosis. The activity of the MMP-9 pro-enzyme was significantly higher at the time-points when granuloma formation was observed than at other times. Immuno-histochemistry revealed MMP-2 and MMP-9 within the lung granulomas, around infiltrating leucocytes and the epithelial cells of the alveoli. As the granulomatous fibrosis appeared to be strongly associated with MMP-2 and MMP-9, these enzymes may be useful markers in the lungs of rats infected with A. cantonensis.

Association of matrix metalloproteinase-9 in eosinophilic meningitis of BALB/c mice caused by Angiostrongylus cantonensis

Induction of gelatinase in eosinophilic meningitis of BALB/c-strain mice was caused by Angiostrongylus cantonensis. Time-course studies showed that the molecular weight of 94-kDa gelatinase was detected at day 10 post-inoculation (PI), and reached a high intensity from days 15 to 25 PI. The 94-kDa gelatinase activity was clearly inhibited by EDTA and 1,10-phenanthroline, but not by leupeptin and phenylmethanesulphonyl fluoride. When immunoblots were performed using specific antiserums against the 94-kDa gelatinase B (matrix metalloproteinase-9; MMP-9) with cerebrospinal fluid (CSF), the 94-kDa immunopositive band was MMP-9. Immunohistochemistry studies demonstrated MMP-9 localisation within eosinophils and macrophages. The increased MMP-9 activity was closely associated with the rapid rise of CSF eosinophils, and the inflammatory reaction of the subarachnoid space. In contrast to changes in MMP-9, MMP-2 activity was constitutive and unaffected in this parasitic meningitis. These results show that MMP-9 was associated with eosinophilic meningitis, and that the enzyme may be a useful marker for angiostrongyliasis meningitis.

The protective effect of hypervolemic hemodilution in experimental heatstroke

The authors tested the hypothesis in a rat model that hypervolemic hemodilution during heatstroke affected the mean arterial pressure (MAP), striatal dopamine (DA) release, and local cerebral blood flow and neuronal damage score in different brain structures. The heatstroke was induced by exposing the urethane-anesthetized rats to an ambient temperature of 42 degrees C. Hypervolemic hemodilution was produced by intravenous administration of 10% human albumin. Relative and absolute blood flow in the corpus striatum were determined using the laser Doppler flowmetry and the autoradiography diffusible tracer technique, respectively. The DA release in the striatum was estimated using the in vivo microdialysis technique. After onset of heatstroke, animals with hypervolemic state alone, produced by saline or heparinized blood injection, displayed higher values of DA release, as well as neuronal damage score in the striatum, hypothalamus, or cortex, but lower values of MAP and blood flow in the striatum, hypothalamus, or cortex compared to normothermic controls. However, the heatstroke-induced arterial hypotension, cerebral ischemia, increased striatal DA overload, and increased neuronal damage score were attenuated by induction of both hypervolemic and hemodilution state with 10% albumin either before or after the onset of heatstroke. In addition, constant infusions of a vasopressor agent phenylephrine (2 microg kg(-1) min(-1)) after the onset of heatstroke failed to maintain appropriate levels of MAP and resulted in no protection against heatstroke. Thus, it appears that the observed benefit of the 10% albumin is secondary to hemodilution and/or maintenance of MAP.

The study of lipid-protein interactions: effect of melittin on phase transition of phosphatidylethanolamine and sensitivity of phospholipases to phase state

The effects of melittin on the bilayer-to-inverted hexagonal (HII) phase transition of egg phosphatidylethanolamine (EPE) and the influence of the phase state of membrane matrix on hydrolysis of EPE by phospholipases have been studied. The phase transitions were measured using the fluorescent probe N-(7-nitro-2,1,3-benzoxadiazol-4-yl)phosphatidylethanolamine (N-NBD-PE) and differential scanning calorimetry. In the presence of melittin at a lipid-to-melittin molar ratio (R1) of 200, 100, and 20, the phase transition of EPE disappeared, indicating that melittin stabilizes the bilayer structure. In the presence of 10 mol% of cholesterol, the phase transition temperature (TH) decreased and TH was observed even in the presence of melittin at R1 of 200 and 100. The fluorescence intensity of the tryptophan residue of melittin is sensitive to the phase transition and the wavelength of emission maxima shift from 352 to 337 nm upon addition of EPE and EPE-cholesterol (10 mol%) at R1 of 200. Kinetic parameters for phospholipase-catalyzed hydrolysis of EPE in bilayer and HII phases showed that HII phase of EPE is a poorer substrate for phospholipases and that cholesterol decreases the susceptibility of EPE to phospholipases.