Objective To investigate the possibility of creation of tissue engineered heart valve leaflets in vitro . Methods Aorta were obtained from 9 hybrid young pigs. The endothelial cell, fibroblast and smooth muscle cells were isolated and cultured to get enough cell. The expanded fibroblast, smooth muscle cell,and endothelial cells were seeded on the polymers sequentially. The cell polymer constructs were sent for scanning electron microscopy(SEM) examination after cultured for 7, 14, and 28 days. Histological examination were performed after the cell polymer constructs cultured for 28 days. Results SEM showed that the number of cells on the polymers increased as the culture time prolonged, with the formation of matrix. After 28 days, there were a great number of cells and large amount of matrix on the scaffolds. The confluent cell had covered a large area of the polymers. Hematoxylin and eosin(HE) stain showed large amount of cells attached to the polymers. Conclusion With the viability of the cultured cellular scaffolds,it is possible to create tissue engineered heart valve leaflets in vitro.
ObjectiveTo review the research progress of constructing injectable tissue engineered adipose tissue by adipose-derived stem cells (ADSCs). MethodsRecent literature about ADSCs composite three-dimensional scaffold to construct injectable tissue engineered adipose tissue is summarized, mainly on the characteristics of ADSCs, innovation of injectable scaffold, and methods to promote blood supply. ResultsADSCs have a sufficient amount and powerful ability such as secretion, excellent compatibility with injectable scaffold, plus with methods of promoting blood supply, which can build forms of injectable tissue engineered adipose tissue. ConclusionIn despite of many problems to be dealt with, ADSCs constructing injectable tissue engineered adipose tissue may provide a promising source for soft-tissue defect repair and plastic surgery.
ObjectiveTo evaluate the effect of using Schwann-like cells derived from human umbilical cord blood mesenchymal stem cells (hUCBMSCs) as the seed cells to repair large sciatic nerve defect in rats so as to provide the experimental evidence for clinical application of hUCBMSCs. MethodsFourty-five male Sprague Dawley (SD) rats in SPF grade, weighing 200-250 g, were selected. The hUCBMSCs were harvested and cultured from umbilical cord blood using lymphocyte separating and high molecular weight hydroxyethyl starch, and then was identified. The hUCBMSCs of 3rd generation were induced to Schwann-like cells, and then was identified by chemical derivatization combined with cytokine. The acellular nerve basal membrane conduit was prepared as scaffold material by the sciatic nerve of SD rats through repeated freezing, thawing, and washing. The tissue engineered nerve was prepared after 7 days of culturing Schwann-like cells (1×107 cells/mL) on the acellular nerve basal membrane conduit using the multi-point injection. The 15 mm sciatic nerve defect model was established in 30 male SD rats, which were randomly divided into 3 groups (10 rats each group). Defect was repaired with tissue engineered nerve in group A, with acellular nerve basal membrane conduit in group B, and with autologous sciatic nerve in group C. The nerve repair was evaluated through general observation, sciatic function index (SFI), nerve electrophysiology, weight of gastrocnemius muscle, and Masson staining after operation. ResultsThe hUCBMSCs showed higher expression of surface markers of mesenchymal stem cells, and Schwann-like cells showed positive expression of glia cell specific markers such as S100b, glial fibrillary acidic protein, and P75. At 8 weeks after operation, the acellular nerve basal membrane conduit had no necrosis and liquefaction, with mild adhesion, soft texture, and good continuity at nerve anastomosis site in group A; group B had similar appearance to group A; adhesion of group C was milder than that of groups A and B, with smooth anastomotic stoma and no enlargement, and the color was similar to that of normal nerve. SFI were gradually decreased, group C was significantly greater than groups A and B, group A was significantly greater than group B (P<0.05). The compound action potential could be detected in anastomotic site of 3 groups, group C was significantly greater than groups A and B, and group A was significantly greater than group B in amplitude and conduction velocity (P<0.05). Atrophy was observed in the gastrocnemius of 3 groups; wet weight's recovery rate of the gastrocnemius of group C was significantly greater than that of groups A and B, and group A was significantly greater than group B (P<0.05). Masson staining showed that large nerve fibers regeneration was found in group A, which had dense and neat arrangement with similar fiber diameter. The density and diameter of medullated fibers, thickness of myelinated axon, and axon diameter of group C were significantly greater than those of groups A and B, and group A was significantly greater than group B (P<0.05). ConclusionTissue engineered nerves from hUCBMSCs-derived Schwann-like cells can effectively repair large defects of the sciatic nerve. hUCBMSCs-derived Schwann-like cells can be used as a source of seed cells in nerve tissue engineering.
ObjectiveTo review the research progress of the role of seed cells and related cytokines in angiogenesis of the vascularized tissue engineered bone. MethodsThe latest literature of tissue engineered bone angiogenesis was reviewed, including the common source of seed cells, biological characteristics, transformation mechanism, related cytokines, and signaling pathways in re-vascularization. ResultsMicrosurgery technique, genetic technique, and co-culture system of vascularized tissue engineered bone have developed to a new level. Moreover, both the induction of introduced pluripotent stem cells and vascular endothelial growth factor-angiopoietins 1 transfected mesenchymal stem cells and endothelial progenitor cells have some advantages for bone regeneration and vascularization. However, all the techniques were not used in clinical practice. ConclusionUsing techniques of genetically modified seed cells, related cytokines, and scaffolds may have bright prospects for building vascularized tissue engineered bone.
Objective To observe the impact of collagen patches using 1-ethyl-3- （3-dimethylaminopropyl) carbod-iimide hydrochloride chemistry （EDC） to conjugate vascular endothelial growth factor （VEGF） ＋ basic fibroblast growth factor （bFGF） or VEGF alone on the survival rate of transplanted human bone morrow mesenchymal stem cells （hBM-MSCs）in vitro and in vivo. Methods Collagen patches which were activated by EDC were used as the control group，and EDC activated collagen patches that were conjugated with VEGF or VEGF ＋ bFGF were used as the experiment groups（VEGF group and VEGF ＋ bFGF group）. hBM-MSCs （0.5×106/patch） were used as seeding cells to construct engineered heart tissue （EHT）. MTT assay was performed to assess in vitro proliferation of hBM-MSCs on 3 different collagen patches. Ventricular aneurysm model after myocardial infarction was created by left anterior descending artery （LAD） ligation in male SD rats，and EHT which were constructed with 3 different patches were used for ventricular plasty. Four weeks later，immunofluorescence staining was used to examine arteriole density （anti-α-SMA staining） and transplanted cell survival （anti-h-mitochondria staining）. Results （1） hMSCs proliferation in VEGF group and VEGF ＋ bFGF group was significantly better than that in the control group on the 2nd and 4th day after cell transplantation （P＜0.05）； （2） Four weeks afterEHT implantation，immunofluorescence staining for α-SMA revealed that arteriole density of VEGF group and VEGF ＋ bFGF group was significantly higher than that of the control group （P＜0.05）； （3） Immunofluorescence staining forh-mitochondria showed that survival rates of transplanted hBM-MSCs of VEGF group and VEGF ＋ bFGF group were significantly higher than that of the control group （P＜0.05）； （4） There was a significantly positive correlation between survival rate of hBM-MSCs and arteriole density （r 2=0.99，P=0.02）. Conclusion VEGF or VEGF ＋ bFGF conjugated collagen patch can significantly improve hBM-MSCs proliferation in vitro and enhance survival rate of transplanted hBM-MSCs by accelerating revascularization of EHT in vivo.
Decellularized tissue engineering scaffolds appear to have the properties of similar structure and mechanical characteristics to native tissues，good biocompatibility，suitability for cell adhesion，growth and angiogenesis induction，and non-immunogenicity. Genipin has anti-inflammatory，antithrombotic and antioxidative features which can considerably suppress vascular and endothelial inflammatory activation，increase mechanical strength of biological scaffolds，inhibit inflammatory response and decrease degradation rate of biological scaffolds. By cross-linking with decellularized matrices，Genipin can further improve corresponding performance of tissue engineering matrices，which is very helpful to promote the application of tissue engineering into clinical practice of cardiothoracic surgery. This review focuses on recent research process and possible prospects of Genipin cross-linking in tissue engineering in the field of cardiothoracic surgery.
The establishing of myocardial tissue engineering techniques not only solve a series of issues that generate in cell and tissue transplantation after myocardial infarction, but also create a platform for selecting better materials and transplantation techniques. However, both experimental animal studies and recent clinical trials indicate that current transplantation techniques still have many defects, mainly including lack of suitable seed cells, low survival rate and low differentiation rate after transplantation. In this context, extracellular matrix （ECM）, as myocardial tissue engineering scaffold materials, has gained increasing attention and become a frontier and focus of medical research in recent years. ECM is no longer merely regarded as a scaffold or a tissue, but plays an important role in providing essential signals to influence major intracellular pathways such as cell proliferation, differentiation and metabolism. The involved models of ECM can be classified into following types：natural biological scaffold materials, synthetic polymer scaffold materials and composite scaffold materials with more balanced physical and biological properties. This review mainly introduces research progress of ECM in myocardial tissue engineering and ECM materials.
Abstract: Objective To investigate the feasibility of the bone marrow mesenchymal stem cells (BMSCs) as the seed cells for construction of small diameter blood vessels and its induced mechanisms. Methods The bone marrow cells were obtained from hind femur and tibia of male Sprague-Dawley（SD） rats with a body weight of 100 g. The cells were purified by whole bone marrow primary culture before repeated passage in vitro amplification. Cell morphology was observed, and expressions of CD34, CD90, and CD105 cell factors were examined by flow cytometry to identify whether they were the BMSCs. Then, the BMSCs obtained were divided into the experiment group and the control group. The cells in the experiment group were induced to differentiate into the vascular smooth musclelike cells by the Dulbecco’s modified Eagle’s mediumlow glucose(DMEM-LG) plus alltrans retinoic acid and dbcAMP, while the cells in the control group were cultured by the normal DMEM-LG. We observed the morphological characteristics of the BMSCs and detected the expressions of smooth muscle-α actin (SM-α-actin), calponin, and vascular smooth muscle myosin heavy chain(SMMHC) by immunofluorescence and flow cytometry with the fifth generations cells after induction. Results The cells obtained through primary culture appeared spindleshaped and showed characteristic swirling growth. The surface marker CD34 was negative, while CD90 and CD105 were positive. After induction, the cells in the experiment group grew slowly and were slightly ovalshaped. The expression of SM-α-actin, calponin, and SMMHC was significant in the experiment group. In the control group, cell morphology and cell growth were similar to the those of BMSCs in the experiment group, but the expression of SM-α-actin, calponin, and SMMHC was negative. Conclusion The BMSCs can be induced to differentiate into the phenotype of vascular smooth musclelike cells by alltrans retinoic acid，the induced cells which can act as seed cells for tissue engineering construction of small diameter blood vessels.
Objective Choose polylactide-co-glycolide/hydroxyapatite (PLGA/HA) and porous phosphate calcium (PPC) as the object that we will study, compare their degradabality and choose one as a suitable scaffold for rib reconstruction. Methods All the experiments were divided into PLGA/HA group and CPC group. Degradabality experiment in exvivo: put the two scaffold which have the same size into 0.9% NaCl, keep sterile, then put the container into warm cage，get out and weigh them in 2, 4, 8, 12 and 24 weeks, compare the different speed of the two scaffold. Degradability experiment in vivo: put the two scaffold which have the same size under the skin of the rabbit, and weigh them in 2, 4, 8, 12 and 24 weeks, the tissue around the scaffold was examinzed by HE and the scaffold was examined by electron scanning microscope. Results Micro-CT and Scanning electron microscopy shows that CPC group had better structure （1101.2228±0.6184 mg/ccm vs. 1072.5523±0.7442 mg/ccm）and porosity（70.26％±0.45％ vs.72.82％±0.51％）than PLGA/HA group; The result of degradabality experiment in vitro shows that the speed of the two scaffolds was slow. It is at 24 weeks that the degradability is obvious,and the PLGA/HA group degraded a lot which was 60%. The result of degradabality experiment in vivo shows that the speed of degradabality of PLGA/HA group was faster than that is in the 0.9% Nacl, also was faster than that of CPC group which was 96%.The reponse of tissue around the PLGA/HA was more sever than that of CPC group which is in favour of the growth of cells. Conclusion As for the reconstruction of large defect of rib, CPC is more suitable than PLGA/HA.
Abstract: Objective Using Amplex red fluorometric assay to detect the lysyl oxidase (LOX) enzyme activity in tissue engineered heart valve (TEHV). Methods Porcine aortic valves were decellularized with trypsin+ethylene diaminetetraacetic acid(EDTA), TritonX-100, and RNaseⅠ＋DNaseⅠ, then they were seeded by myo-fibroblasts that harvested from rats. Then they were fed with Dulbecco’s modified Eagle medium (DMEM) which contained high glucose for 27 days, they were fed with phenol red-free and serumfree DMEM for 24 hours, and the medium was harvested and used for LOX enzyme activity assays with the Amplex red fluorometric assay. And reverse transcription-polymerase chain reaction (RT-PCR) technique was used to analyze the expression of LOXmRNA in TEHV. Results All the samples produced measurable amounts of active LOX enzyme. The fluorescence units were 45.60±1.66, and the corresponding concentration of LOX enzyme were 0.123±0.003μg/ml. At the same time, all the samples expressed LOXmRNA. The expression of LOXmRNA was corresponding to the results of the Amplex red fluorometric assay. Conclusion It is feasible to detect the LOX enzyme activity in TEHV with the Amplex red fluorometric assay. And this assay gives a way to reflect that LOX plays an important role in collagen cross-linking of extracellar matrix in TEHV.