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Objective To study the stress distribution and biomechanical stability of the long-type composite locking plate already used in clinic practice and the novel short-type composite locking plate for treating Sanders type IIa, IIb and IIIab calcaneal fractures. Methods The three-dimensional (3D) models of Sanders type IIa, IIb and IIIab calcaneal fractures were established, and the force conditions of calcaneus in neutral standing position and under 20°dorsal extension were simulated. By referring to the physical form of human specimens, 500 N vertical axial load was applied, so as to study the displacement and relative displacement of the fracture block under the force, and the force conditions of bone tissues and internal fixation were analyzed. Results For Sanders type IIa, IIb calcaneal fractures treated with long-type and short-type composite locking plates, the stress concentration positions of the plates and calcaneal fractures were basically the same. The maximum stress difference of the two plates for fixing calcaneal fractures with the same type was smaller than 5 MPa, and there was no significant difference in the maximum displacement of the fracture models. For Sanders type IIIab calcaneal fractures treated with long-type and short-type composite locking plates, the maximum stress concentration occurred in the forearm of plate screws, indicating the risk of metal fatigue. The maximum stress difference was up to 12 MPa, and the maximum calcaneal displacement was up to 9 μm. Conclusions The long-type and short-type composite locking plates showed no significant differences in treating Sanders type IIa, IIb calcaneal fractures. For fixing Sanders type IIIab calcaneal fractures, the long-type composite locking plate was superior to the short-type composite locking plate.
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The present study was undertaken to investigate the effect of human PMNs on the production of TNF-α by the human peripheral blood mononuclear cells (PBMCs) and to elucidate its tentative mechanism. Human PMNs and PBMCs were isolated from the venous blood of healthy donors by dextran sedimentation and density gradient centrifugation. In the presence of lipopolysaccharide (LPS), PMNs and PBMCs were cocultured at the ratio of 2:1 for 20 h and the concentration of TNF-α in the supernatant was measured by enzyme-linked immunosorbent assay. The binding rate of monocytes with the fluorescein isothiocyanate-labeled LPS (FITC-LPS) and the mean surface fluorescence intensity of monocytes were analyzed by flow cytometry. Results showed that PMNs were capable of inhibiting the TNF-α release from PBMCs (P＜0.05). PMNs suppressed the TNF-α release from PBMCs by 45% on average when PMNs and PBMCs cocultured at the ratio of 2:1. Paraformaldehyde-fixed PMNs still demonstrated the same inhibition (P＜0.05)，which proved that the inhibition was dependent on cell-to-cell contact and suggested that effector molecules responsible for this effect existed on the cell surface of PMNs. In the presence of PMNs, the binding rate of monocytes with the FITC-LPS and the mean surface fluorescence intensity of monocytes were not affected compared with PBMCs alone (P＞0.05). As incubation time was prolonged, the binding of FITC-LPS to monocytes increased (P＜0.05). Thus PMNs did not block the binding of LPS with monocytes. It was concluded that PMNs suppressed the TNF-α release from PBMCs via cell-to-cell interaction. In a cell-contact dependent manner, PMNs might interfere with the signal transduction pathway through which LPS activated PBMCs, thus attenuating the response of PBMCs to LPS and downregulating the TNF-α release.
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AIM: To investigate the differentiation from adult rat and human bone marrow mesenchymal stem cells (BMMSCs) into neuron with musk polypeptide (Mu-P).METHODS: Adult rat and human BMMSCs were induced with Mu-P.Neuron-specific enolase (NSE),neurofilament (NF),Nestin,glial fibrillary acidic protein (GFAP) were detected by immunohistochemistry.RESULTS: Simple methods with Mu-P induced adult rat and human BMMSCs exhibiting a neuronal phenotype,expressing Nestin at 3 hours to 5 hours,and expressing NE and NF at 5 hours to 7 days.But the neuron-like cells didn't express the glial astrocyte marker GFAP.CONCLUSION: Adult rat and human BMMSCs can be induced to differentiate into neurons with Mu-P.
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AIM: To investigate the effect of human polymorphonuclear leukocytes (PMNs) on the release of TNF-? by the human peripheral blood mononuclear cells (PBMCs) and to elucidate its mechanism. METHODS: Human PMNs and PBMCs were isolated from the venous blood of healthy donors by dextran sedimentation and density gradient centrifugation. After the cells were cocultured at the ratio of 2:1 in the presence of lipopolysaccharide (LPS), the concentration of TNF-? in the supernatant was measured by enzyme-linked immunosorbent assay. The binding rate of monocytes with the fluorescein isothiocyanate-labeled LPS (FITC-LPS) and the mean surface fluorescence intensity of monocytes were analyzed by flow cytometry. RESULTS: PMNs do not produce detectable TNF-? in the presence of LPS. PMNs were capable of inhibiting the TNF-? release from PBMCs ( P
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AIM: To investigate multi-potential of rat bo ne marrow mesenchymal stem cells (rBMMSC) and mutation inclination, the rBMMSC w ere long passaged in vitro. METHODS: Cellular cycles of diff erent passages were assayed by FA CSan flow cytometry and karyotypes of passage 6, passage 25 and passage 45 were compared by G-binding analysis. RESULTS: The early passages and long-term passages all showed st rong proliferation; passage 6, passage 25 and passage 45 all showed normal karyo type. CONCLUSION: Long-term culture and passage of rBMMSC still remain s strong proliferation. With this capability, the mutation inclination is not enhanced.
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AIM: To study the effects of cotransplantation of donor-derived bone marrow mesenchymal stem cells on graft versus host disease in a rat allogeneic bone marrow transplantation model. METHODS: Fisher 344 rat bone marrow MSCs were isolated and cultured to the fifth passage (P5) in vitro . The recipient Wistar rats were conditioned with lethal total body irradiation and transplanted with F344 rat bone marrow cells and spleen cells in the presence or absence of (P5) MSCs. The onset time of graft versus host disease (GVHD), incidence of GVHD and survival time were monitored. RESULTS: Cotransplantation of MSCs deferred the onset time of GVHD[(19.1?1.7) d vs (15.6?1.5) d, P
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AIM: To investigate the differentiation potential of human bone marrow mesenchymal stem cells (hBMMSCs) into hematopoietic cells in vivo. METHODS: hBMMSCs prepared from the bone marrow-aspirate sample obtained from healthy human donors were culture-expanded in vitro with 5-8 passages. hBMMSCs(P5-8, 4.8?10 5 cells/mouse) were injected into the severe combined immuodeficiency (SCID) mice treated by cyclophosphamide(CPA) and various tissues were analyzed at 35 days post-transplant for the presence of differentiated human cells. RESULTS: hBMMSCs(P5-8) viability, which was determined by typan blue staining at the end of the harvest and before infusion, was greater than 95% in every infusate at both time points. Cells characterized by flow cytometry using human MSC-specific monoclonal antibodies were uniformly positive for CD29, CD44, CD90, CD105, CD106, CD166 and negative for CD11a, CD14, CD34, CD38, CD45, CD80, CD86 which are common on cells of the hematopoietic lineages. Analysis of PB demonstrated that 5 of 6 hBMMSCs transplanted SCID mice had low level of circulating human CD45 +/ H-2D d- cells(range from 0.17% to 0.36%)and CD34 +/ H-2D d- cells(range from 0.10% to 0.50%). Analysis of BM for the presence of hematopoietic chimerism demonstrated human CD45 +/ H-2D d- cells and CD34 +/ H-2D d- cells in the marrow of 4 out of 6 hBMMSCs transplanted SCID mice (0.10%-0.19% and 0.03%-0.52%, respectively). Human hematopoietic cells with these same phenotype were also detected in the spleen 4 of the hBMMSCs transplanted SCID mice (range from 0.19% to 1.65% ,from 0.20% to 0.26%, respectively). No human hematopoietic cell was seen either in the PB, BM or spleen of all control animals. CONCLUSION: hBMMSCs have the ability to differentiate into blood cells of multiple lineages, including CD34 + hematopoietic stem cells/progenitor cells (HSC/HPC).
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AIM: To explore the potential of human bone marrow mesenchymal stem cells (hMSCs) differentiating into hematopoietic cells with murine fetal liver stromal cell-conditioned medium (FLSC-CM) in vitro. METHODS: 12.5-14.5 days post coitus (dpc ) of KM mice were used for the preparation of fetal liver stromal cell-conditioned medium (FLSC-CM) and embryonic fibroblast feeder layer (FD). Culture-expanded hMSCs were directly contacted with FLSC-CM, FD, and the combination of human interleukin-6 (IL-6) or stem cell factor (SCF), respectively. Seven days later, the non-adherent cells were collected and characterized by morphology, immunophenotypes, and colony forming unit-granulocyte/macrophage culture assay. RESULTS: The number of nonadherent cells derived from hMSCs cultured with FLSC-CM was increased remarkably than those with either FD or cytokines. The non-adhered cells with the morphology of monocyte-or small lymphocyte-like cells were positive for human CD34, CD45 and had the capacity to form the hematopoietic progenitor colonies in methylcellulose cultures containing recombined human granulocyte/macrophage-colony stimulating factor (rhGM-CSF). CONCLUSION: hMSCs were successfully induced toward their differentiation into CD34+CD45+ hematopoietic progenitors after being cultivated with FLSC-CM. This study suggests that hMSCs have the hematopoietic differentiation potential in vitro. [
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AIM: To construct recombinant adenovirus vector containing brain derived neurotrophic factor, (BDNF) gene using bacterial homogenous recombination, and investigate the expression in expanded rat mesenchymal stem cells (rMSC) in vitro. METHODS: BDNF gene and proBDNF gene were subcloned into adenovirus shuttle plasmid pAdTrack-CMV containing enhanced green fluorescent protein gene (EGFP) expression cassette, forming shuttle vector of pAdTrack-BDNF, and pAdTrack-proBDNF, and co-transformed into BJ5183 bacterial cells with adenovirus backbone vector pAdEasy-1 using chemical transformation. After the recombinant adenovirus vector was obtained, the identified recombinant adenovirus plasmid DNA was digested with Pac I and transfected to 293 cells to package recombinant adenovirus particles. rMSC were infected by recombinant adenovirus and EGFP expression was detected using fluorescent microscope. Infection efficiency was assessed by flow cytometrics. Western blotting identified expression of Ad -proBDNF and Ad-BDNF in rMSC. rMSC infected with Ad -proBDNF and Ad-BDNF were induced to differentiate into neuron-like cells. rMSC infected with Ad -proBDNF and Ad-BDNF were injected into nude mice and assessd in vivo. RESULTS: We successfully constructed the recombinant adenovirus Ad -proBDNF and Ad-BDNF that expressed in expanded rMSC in vitro.CONCLUSION: Recombinant adenovirus high-effectively mediates Ad -proBDNF and Ad-BDNF expression in expanded rMSC in vitro and in vivo.