Tissue-engineered ribs for chest wall reconstruction: a case with 12-year follow-up.

We hereby report on a case in which a huge chest wall defect generated by resection of a massive aggressive tumor (desmoplastic fibroma) was repaired with osteogenic-induced mesenchymal stem cells embedded in a bone-derived biomaterial. In this case, there were three challenges to overcome: reconstruction of the soft tissue, repair of the skeletal defect of the thoracic wall and repair of the defect in the pleural cavity. The defects of soft tissue and pleural cavity were reconstructed, respectively, with an ipsilateral abdominal flap and a diaphragm muscular flap. The huge defect in the chest wall was successfully repaired with the tissue-engineered ribs, which was confirmed by long-term follow-up with computerized tomography and histological and immunohistochemical evaluations. In view of its effectiveness and safety, tissue-engineered bones may have a broad application for the repair of large skeletal defects and bone regeneration.

Tissue engineered esophagus scaffold constructed with porcine small intestinal submucosa and synthetic polymers.

Acellular porcine small intestinal submucosa (SIS) has been successfully used for reconstructing esophagus with half circumferential defects. However, repairing full circumferential esophageal defects with SIS has been restricted due to the latter's poor mechanical properties. In the present study, synthetic polyesters biomaterial poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(lactide-co-glycolide) (PLGA) have been used to improve the mechanical properties of SIS. Feasibility of SIS/PHBHHx-PLGA composite material scaffold for esophageal tissue engineering has been assessed through a series of testing. The appropriate mixing ratio of PHBHHx and PLGA polymers has been determined as 5:5 by mechanical testing and in vitro degradation experiment. The morphology of constructed membranous and tubular scaffolds was also characterized. As confirmed by enzyme-linked immunosorbent assay, the contents of VEGF and TGF-ß have respectively reached 657 ± 18 ng mL(-1) and 130 ± 4 pg mL(-1) within the SIS/PHBHHx-PLGA specimens. Biocompatibility of the SIS/PHBHHx-PLGA specimens with rat bone marrow mesenchymal stem cells (MSCs) was also evaluated by scanning electron microscopy and a live-dead cell viability assay. Actin filaments of MSCs on the composite materials were labeled. Biological safety of the extract from SIS/PHBHHx-PLGA specimens, measured as hemolysis rate, was all lower than 5%. Compared with SIS and SIS/PHBHHx-PLGA specimens, inflammatory reaction provoked by the PHBHHx-PLGA specimens in rats was however more severe. Our results have suggested that SIS/PHBHHx-PLGA composite material can offer a new approach for esophageal tissue engineering.

Tissue engineered esophagus by mesenchymal stem cell seeding for esophageal repair in a canine model.

PURPOSE: Acellular porcine small intestinal submucosa (SIS) has been successfully used for esophagoplasty in dogs. However, this has not led to complete epithelialization and muscular regeneration. We undertook the present study to assess the effect of tissue-engineered esophagus generated by seeding bone marrow mesenchymal stem cells (BMSCs) onto an SIS scaffold (BMSCs-SIS) in a canine model. METHODS: We cultured, passaged, and measured autologous BMSCs and myoblasts with cell proliferation and immunohistochemical assays. We labeled the third passage of BMSCs with PKH-26, a fluorescent dye, before seeded it onto the SIS. We resected canine cervical esophagus to generate a defect 5 cm in length and 50% in circumference, which we repaired with BMSCs-SIS or SIS alone. RESULTS: Four weeks later, barium esophagram demonstrated that esophageal lumen surface of the patch graft was smoother in the BMSCs-SIS group compared with the SIS group. Histological examination suggested a strong similarity between BMSCs and esophageal myoblasts in terms of morphology and function. Although both BMSCs-SIS and SIS repaired the esophageal defects, we noted complete re-epithelialization with almost no inflammation only in the former group. By 12 wk after the surgery, we observed long bundles of skeletal muscles only in the BMSCs-SIS group, where the microvessel density was also much greater. CONCLUSIONS: Bone marrow mesenchymal stem cells on an SIS scaffold can promote re-epithelialization, revascularization, and muscular regeneration. This approach may provide an attractive option for esophageal regeneration.

The poor osteoinductive capability of human acellular bone matrix.

Demineralized bone matrix (DBM) has extensive clinical use for bone regeneration because of its osteoinductive and osteoconductive aptitude. It is suggested that the demineralization process in bone matrix preparation is influential in maintaining osteoinductivity; however, relevant investigations, especially into the osteoinductivity of acellular bone matrix, are not often performed. This study addressed the osteoinductive capability of human acellular cancellous bone matrix (ACBM) after subcutaneous implantation in a rat model. The growth and osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells (rBM-MSCs) seeded in this material were also studied. Without the demineralization process, the ACBM we obtained had an interconnected porous network and the micropores in the surface were clearly exposed. After the ACBM was subcutaneously implanted for 4 months, new osteoid formation was noted but not typical mature bone formation. rBM-MSCs grew well in the ACBM and kept a steady morphology after continuous culture for 28 days. However, no mineralized nodule formation was detected and the expression levels of genes encoding osteogenic markers were significantly decreased. These results demonstrated that human ACBM possess the structural features of native bone and poor osteoinductivity; nonetheless this material helped to preserve the undifferentiated phenotype of rBM-MSCs. Such insights may further broaden our understanding of the application of ACBM for bone regeneration and the creation of stem cell niches.

Placenta- versus bone-marrow-derived mesenchymal cells for the repair of segmental bone defects in a rabbit model.

Tissue-engineered bones (TEBs) constructed with bone-marrow-derived mesenchymal stem cells (BMSCs) seeded on biomaterial scaffolds have achieved good results for bone defect repair in both animal experiments and clinical trials. This has been limited, however, by the source and quantity of BMSCs. We here explored TEBs constructed by placenta-derived mesenchymal stem cells (PMSCs) and compared their effect for the repair of critical-sized segmental osteoperiosteal defects with TEBs constructed with BMSCs. PMSCs were isolated from rabbit placenta by gradient centrifugation and in vitro monolayer culturing, and BMSCs were isolated from the hindlimb bone marrow of newborn rabbit. Primary cultured PMSCs and BMSCs were uniformly in a spindle shape. Immunocytochemistry indicated that both types of cells are positive for CD44 and CD105, and negative for CD34 and CD40L, confirming that they are mesenchymal stem cells. BrdU-labeled PMSCs and BMSCs were respectively co-cultured with bio-derived bone materials to construct TEBs in vitro. Critical-sized segmental osteoperiosteal defects of radii were created in 24 rabbits by surgery. The defects were repaired with TEBs constructed with PMSCs and BMSCs. The results showed that TEBs constructed by both PMSCs and BMSCs could repair the osteoperiosteal defects in a 'multipoint' manner. Measurement of radiography, histology, immunohistochemistry, alkaline phosphatase activity, osteocalcin assaying and biomechanical properties have found no significant difference between the two groups at 2, 4, 8 and 12 weeks after the transplantation (P > 0.05). Taken together, our results indicate that PMSCs have similar biological characteristics and osteogenic capacity to BMSCs and can be used as a new source of seeding cells for TEBs.

Preparation and characterization of decellularized tendon slices for tendon tissue engineering.

To develop a naturally derived tendon tissue engineering scaffold with the preservation of the native ultrastructure, tensile strength, and biochemical composition of the tendon extracellular matrix (ECM), decellularized tendon slices (DTSs) were prepared using repetitive freeze/thaw of the intact Achilles tendons, frozen section, and nuclease treatment. The DTSs were characterized in the native ultrastructure, mechanical properties, biochemical composition, and cytocompatibility. Histological examination and DNA quantification analysis confirmed that cells were completely removed from tendon tissue by repetitive freeze/thaw in combination with nuclease treatment 12 h. The intrinsic ultrastructure of tendon tissue was well preserved based on scanning electron microscopy examination. The tensile strength of the DTSs was retained 85.62% of native tendon slice. More than 93% of proteoglycans (fibromodulin, biglycan) and growth factors (TGF-ß1, IGF-1, VEGF, and CTGF) inherent in tendon ECM were preserved in the DTSs according to ELISA analysis. Furthermore, the DTSs facilitated attachment and repopulation of NIH-3T3 fibroblasts in vitro. Overall, the DTSs are sheet scaffolds with a combination of elemental mechanical strength and tendon ECM bioactive factors that may have many potential applications in tendon tissue engineering.

Hypoxia inhibits the spontaneous calcification of bone marrow-derived mesenchymal stem cells.

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are the popular seed cells for regenerative medicine, and there has been a rapid increase in the number of BM-MSC-based clinical trials. However, the safety of these cells should also be closely studied. In this study, spontaneous calcification of BM-MSCs from rats was evaluated in normoxia (20% O(2)) without osteogenic medium after continuous culture for 21 days; obvious mineralized nodules were observed, which were positive for Alizarin Red, collagen-I (Col-I), osteocalcin (OC) and alkaline phosphatase (ALP), and mainly consisted of C, O and Ca elements. Interestingly, hypoxia (2% O(2)) significantly inhibited this spontaneous calcification. In addition, the ALP and calcium content of rBM-MSCs were sharply reduced. Based on RT-PCR results, the expression of osteogenic genes (Cbfa1/Runx2, Col-I, ALP, and OC) was reduced compared to that in normoxia. These results demonstrate a natural and unique characterization of rat BM-MSCs in normoxia after continuous culture and highlight the inhibiting effects of hypoxia. Finally, this study contributes to the information regarding the application of BM-MSCs in the regeneration of various tissues.

A multi-step method for preparation of porcine small intestinal submucosa (SIS).

Porcine small intestinal submucosa (SIS) has been widely used in repairing various tissues and organs. Despite this, some SIS products have the capacity to cause variable inflammatory responses after implantation resulting in severe adverse effects due to porcine cell existence. In this study, we described a multi-step method including mechanical disassociation, degrease, enzyme digestion, detergent treatment, freeze-drying and sterilization by irradiation for preparation of SIS. The efficacy of acellularization was evaluated by histological observation and the content of porcine immunoreceptor DAP12 gene. The change of growth factors contents within SIS accompanying with decellularization was quantitatively assessed by ELISA. Inflammatory reaction of SIS implanted subcutaneously in a rat was investigated. The histological examination revealed no remaining cells after enzyme digestion. Moreover, qPCR analysis demonstrated that the content of a porcine immunoreceptor gene DAP12 DNA in final SIS product (SISv) was only 1.05% of that in SIS samples (SISi) prepared by mechanical disassociation. Degrease with methanol/chloroform dramatically reduced the contents of VEGF, b-FGF, TGF-ß, and TNF-α within SISii, but further treatment could not significantly reduced the contents of growth factors. SIS implanted into rats showed that inflammatory cells was more accumulated surrounded to SISi at 1, and 2 weeks, but reduced in SISv samples. The degree of inflammatory reaction for SISv was significantly less than that of SISi.

[Experiment of oral mucosa epithelial cells cultured on small intestinal submucosa in vitro].

OBJECTIVE: To explore an effective method to culture oral mucosa epithelial cells (OMECs) of canine in vitro, and to observe the biological characteristics of OMECs growing on small intestinal submucosa (SIS) in order to provide the experimental basis for epithelium tissue engineering. METHODS: The primary OMECs were cultivated with DKSFM (defined keratinocyte serum free medium) containing 6% fetal bovine serum (FBS). The morphological characteristics and the growth curve of OMECs were observed. The expressions of OMECs marker (CK19) were examined by immunocytochemistry. The 2nd passage of OMECs were seeded on SIS, OMECs co-cultured with SIS were observed by hematoxylin-eosin staining, immunohistochemical staining, and scanning electron microscope (SEM). RESULTS: OMECs were grown well in DKSFM. Immunohistochemical staining of the 2nd passage cultured canine OMECs with broadly reacting anti-cytokeratin anyibodies (CK19) was positive. OMECs formed a single layer on the surface of SIS, and eight days later the cells were polygong and arranged like slabstone. CONCLUSION: Culture of canine OMECs in DKSFM containing 6% FBS is a simple and feasible method. SIS has good biocompatibility, it is a kind of good bioscafold in the tissue-engineered epithelium.

Characterization of MSCs from human placental decidua basalis in hypoxia and serum deprivation.

Recently, we reported that human PDB (placental decidua basalis) is an excellent source of MSCs (mesenchymal stem cells), meanwhile, PDB-MSCs could survive under hypoxia and serum deprivation. Herein, we investigated the proliferation, clonogentic efficiency, phenotypes, metabolic activity and cytokines secretion of PDB-MSCs in hypoxia and serum deprivation. PDB-MSCs were cultured in four groups: normoxia (20% O2) and complete medium [10% FBS (foetal bovine serum)+DMEM-HG (Dulbecco's modified Eagle's medium-high glucose)], hypoxia and complete medium, normoxia and serum deprivation (0% FBS), and hypoxia and serum deprivation. After 96 h of culture in the above groups, PDB-MSCs maintain the phenotypes stably. Interestingly, hypoxia notably enhanced the proliferation, colony-forming potential and lactate/glucose ratio in complete medium, but suppressed the secretion of BMP-2 (bone morphogenetic protein-2) and bFGF (basic fibroblast growth factor), while it did not change the quantity of VEGF (vascular endothelial growth factor) and bFGF in serum deprivation. Although PDB-MSCs grew slowly and seldom formed a colony unit in hypoxia and serum deprivation, they possessed a moderate metabolism. In conclusion, our results indicate that PDB-MSCs appear to be promising seed cells for ischaemia-related tissue engineering.

Mesenchymal stem cells transplantation mildly ameliorates experimental diabetic nephropathy in rats.

BACKGROUND: Diabetic nephropathy is a common complication of diabetes mellitus. This study aimed to explore whether mesenchymal stem cells (MSCs) transplantation could attenuate diabetic nephropathy in experimental diabetic rats. METHODS: Sprague-Dawley rats received a single intraperitoneal injection of streptozotocin (STZ) (60 mg/kg). Diabetic rats were randomized to four groups: diabetes control group (DC), ciclosporin A group (CsA), MSC group, and MSC + CsA group (MSCA). Bone marrow mesenchymal stem cells were cultured, identified and labeled by 5-bromo-2'-deoxyuridine (BrdU) in vitro. Then they were transplanted to diabetic rats via introcardiac infusion. Ciclosporin A was administered daily at 5 mg/kg. At 1, 2, 4, 8 weeks after transplantation, random blood glucose, urine albumin/creatinine ratio (Alb/Cr), endogenous creatinine clearance rate and renal mass index were tested. Renal morphology and labeled cells were examined. RESULTS: Cultured MSCs expressed mesenchymal cell phenotype, and could be multidifferentiated to osteogenic and adipogenic cells. Labeled MSCs could be detected in the kidney of nephropathic rats, mainly in renal interstitium, but they did not propagate after engrafting in kidney. Over the course of the experiment, MSCA group showed a significant decrease in blood glucose compared with MSC group, CsA group and DC group (P < 0.05, respectively). The Alb/Cr in MSCA group and MSC group were significantly lower than CsA group and DC group (P < 0.05). And the Alb/Cr in MSCA group showed a significant decrease compared with MSC group (0.74 vs 0.84, P < 0.05). There was a significant difference in renal mass index between the MSCA group and DC group (5.66 vs 6.37, P < 0.05). No significant difference was found in creatinine clearance rate among 4 groups (P > 0.05). Treatment with MSC + CsA significantly ameliorated the morphology of diabetic kidney. CONCLUSION: MSC could mildly ameliorate diabetic nephropathy by decreasing blood glucose, Alb/Cr ratio and renal mass index.

The possible role of myosin light chain in myoblast proliferation.

Skeletal muscles have the potential to regenerate by activation of quiescent satellite cells, however, the molecular signature that governs satellite cells during muscle regeneration is not well defined. Myosin light chains (Myls) are sarcomere-related proteins as traditional regulator of muscle contraction. In this report, we studied the possible role of Myl in the proliferation of skeletal muscle-derived myoblasts. Compared to diaphragm-derived myoblasts, the extraocular muscle-derived myoblasts with lower levels of Myl proliferated faster, maintained a longer proliferation phase, and formed more final myotubes. It was found that blockading Myl with anti-Myl antibody or knockdown of Myll by siRNA targeted against Myll could enhance the myoblast proliferation and delay the differentiation of myoblasts. Our results suggested that Myl, likely Myll, can negatively affect myoblast proliferation by facilitating myoblast withdrawal from cell cycle and differentiation.

Isolation of mesenchymal stem cells from human placental decidua basalis and resistance to hypoxia and serum deprivation.

Mesenchymal stem cells (MSCs) are the most promising seed cells for cell therapy and tissue engineering, which can be isolated from various sources of human adult tissues such as bone marrow and adipose tissue. However, cells from these tissues must be obtained through invasive procedures and sometimes the individual difference is hard to control. Hence, the search continues for an ethically conducive, easily accessible and controllable source of stem cells. We herein report the isolation of a population of stem cells from the human placental decidua basalis (termed as PDB-MSCs), a maternal portion of placenta. PDB-MSCs were further shown to express markers common to MSCs and positive for SSEA-1, SSEA-3, SSEA-4, TRA-1-60, TRA-1-81 and Oct-4. In order to facilitate the further utility in ischemic diseases, we tested the apoptosis of PDB-MSCs in hypoxia and serum deprivation, two components of ischemia in vivo. Taken together, our findings indicate that PDB-MSCs are resistant to hypoxia and serum deprivation, which may relate to Bcl-2.

Repair of infarcted myocardium using mesenchymal stem cell seeded small intestinal submucosa in rabbits.

Myocardial infarction (MI) remains a common and deadly disease. Using tissue-engineered cardiac grafts to repair infarcted myocrdium is considered to be a therapeutic approach. This study tested the feasibility of using MSCs-seeded SIS to repair chronic myocardial infarction in a rabbit model. MI in rabbits was created by ligation of the left anterior descending artery. BrdU-labeled mesenchymal stem cells (MSCs) were seeded on the small intestinal submucosa and cultured for 5-7 days prior to implantation. Four weeks after myocardial infarction, cardiac grafts were implanted onto the epicardial surface of infarcted myocardium. Four weeks after implantation of the membranes, a serial of tests including echocardiography, hemodynamics, histology and immunohistochemistry were undertaken to evaluate the effect of the implanted grafts on recovery of the infarcted myocardium. It was shown that left ventricular contractile function and dimension, the capillary density of the infarcted region, and myocardial pathological changes were significantly improved in rabbits implanted either SIS or MSCs-seeded SIS. But the MSCs-seeded SIS was more effective. Immunofluorescence staining demonstrated the migration of Brdu-labeled MSCs from the membrane into the infarcted area and their differentiation to cardiomyocytes and smooth muscle cells. Taken together, these results suggest that MSCs-seeded SIS can be used to repair chronic myocardial infarction, which enhances myocardial regeneration.

Grafts of porcine small intestinal submucosa with cultured autologous oral mucosal epithelial cells for esophageal repair in a canine model.

The acellular porcine small intestinal submucosa (SIS) has been successfully used for esophagoplasty. However, it does not lead to a complete epithelialization in a canine model. A cellular component may be required for better reconstruction. The present study was undertaken to investigate the feasibility and effectiveness of the combination of SIS and autologous oral mucosal epithelial cells (OMECs) for esophageal reconstruction. The OMECs harvested from beagle dogs were cultured and propagated, and the 3rd passage cells were seeded on a single-layer SIS. Male beagle dogs were subjected to surgical resection to produce cervical esophageal defects (5 cm in length, 180 degrees in range). SIS with or without OMECs was patched on the esophageal defects. Barium esophagram, immunohistochemistry, and histology were performed to evaluate the therapeutic effectiveness. Four weeks after surgery, the histological examination showed a complete re-epithelialization and almost no inflammation in the SIS with OMECs group. But in the SIS group, only a partial epithelialization was observed along with inflammation. Eight weeks after surgery, the squamous epithelium was found to cover the entire graft surface in both groups; however, the muscular regeneration was observed in the SIS with OMECs, but not in the SIS group. The graft of SIS combined with autologous OMECs promotes re-epithelialization and muscular regeneration. It is an effective alternative method for esophageal repair.

Variations in the ratios of co-cultured mesenchymal stem cells and chondrocytes regulate the expression of cartilaginous and osseous phenotype in alginate constructs.

As mesenchymal stem cells (MSCs) are capable of self-renewal and multilineage differentiation, the feasibility and efficacy of co-culturing human MSCs (hMSCs) with rabbit articular chondrocytes (rACs) to promote chondrogenic and osteogenic differentiation of hMSCs for clinical osteoarthritic therapy were investigated in the present study. The two distinct cell types were encapsulated in alginate hydrogels singly or in one of three ratios (2:1, 1:1, 1:2 of hMSCs to rACs) and cultured under chondrogenic conditions for 28 days. The results demonstrated that newly synthesized cartilaginous extracellular matrix (ECM) and type II collagen (col-2) gene signal were upregulated with greater hMSC ratios and longer culture periods. However, a specific col-2 gene probe for human was found only in single hMSC group but absent in all co-culture groups, which indicate that the enhanced cartilaginous phenotype originated from the co-cultured rACs. Osseous phenotype was histologically detected only in the 2:1 group on day 28; and xenogenic osteocalcin assay showed that it originated from hMSCs. This suggests that variations in the ratios of co-cultured hMSC and rAC regulated the cartilaginous and osseous phenotype as well as the differentiation of hMSCs in alginate constructs. The study provides new insights into the role of cell-cell interactions in regulating both cell differentiation and cell function and highlights the importance of developing appropriate differentiation protocols for tissue engineering therapies.

[Effects of hypoxia on human placental decidua basalis-mesenchymal stem cells proliferation, apoptosis and VEGF expression.].

Human placental decidua basalis-mesenchymal stem cells (PDB-MSCs) are multipotent cells from the human term placenta, which are ethically conducive, easily accessible and high-yielding source. PDB-MSCs can differentiate into adipogenic, osteogenic and neurogenic cells under appropriate conditions, which may be an attractive and alternative source of seed cells for tissue engineering. To investigate the effect of hypoxia (1% O2) on human PDB-MSCs and the expression of cytokine, PDB-MSCs were isolated from human placenta by density gradient centrifugation and cultured in the Dulbecco's modified Eagle's medium-high glucose (DMEM-HG) containing 10% fetal bovine serum (FBS), and the fifth passage of PDB-MSCs were taken. PDB-MSCs were divided into 4 groups according to the concentrations of O2 and FBS: 20% O2, 10% FBS; 20% O2, 0% FBS; 1% O2, 10% FBS; 1% O2, 0% FBS. The proliferation and apoptosis of PDB-MSCs were detected by MTT and flow cytometric analysis at the time points of 6 h, 12 h, 24 h, 48 h, 72 h, and 96 h, respectively. Vascular endothelial growth factor (VEGF) released from PDB-MSCs was detected by enzyme-linked immunosorbent assay (ELISA) at the same time points. The results showed that hypoxia enhanced the proliferation of PDB-MSCs at 12 h under the condition of 10% FBS, while at 24 h under the condition of 0% FBS (P<0.01, n=3). In normoxia, the cells cultured in 10% FBS displayed a significant proliferation compared to those cultured in 0% FBS. However, in hypoxia, the number of cells cultured in 0% FBS (serum deprivation) increased significantly compared to that cultured in 10% FBS at 24 h and 96 h respectively (P<0.05, P<0.01, n=3). With the flow cytometric analysis of cell apoptosis under the condition of hypoxia and serum deprivation, we found that hypoxia and serum deprivation did not induce PDB-MSCs apoptosis (P>0.05, n=3). This conclusion may relate to the expression of VEGF which needs further research. In conclusion, the results obtained indicate that PDB-MSCs are able to bear hypoxia and serum deprivation, suggesting that PDB-MSCs can be used as seed cells for ischemia related tissue engineering.

Regulation of cell proliferation by fast Myosin light chain 1 in myoblasts derived from extraocular muscle, diaphragm and gastrocnemius.

The extraocular muscle (EOM) suffers much less injury from Duchenne muscular dystrophy (DMD) than other skeletal muscles such as diaphragm and gastrocnemius. The present study was undertaken to test the hypothesis that differential expression of regulatory proteins between the EOM and other skeletal muscles is responsible for the observed difference in the sensitivity to DMD-associated damage. Protein expression in the tissue samples obtained from EOM, diaphragm or gastrocnemius of C57BL/6 mice was analyzed by two-dimensional gel electrophoresis and mass spectrometry. There were 35 proteins that were identified to be differentially expressed among different skeletal muscle tissues. Among the 35 proteins, a fast skeletal muscle isoform myosin light chain 1 (MLC1f) protein was further studied in relation to muscle cell proliferation. The EOM-derived myoblasts had much lower levels of MLC1f and higher rate of cell proliferation in contrast to the myoblasts derived from diaphragm or gastrocnemius, which displayed a higher expression of MLC1f along with a slow proliferation. Deletion of MLC1f using siRNA targeting MLC1f resulted in an increased rate of cell proliferation in the myoblasts. Cell cycle analysis revealed that MLC1f inhibited the transition of the cell cycle from the G1 to the S phase. Therefore, the present study demonstrates that MLC1f may negatively regulate proliferation of myoblasts through inhibition of the transition from the G1 to the S phase of the cell cycle. Low levels of MLC1f in myoblasts of EOM may ensure cell proliferation and enhance the repair process for EOM under the DMD disease condition, thus making EOM suffer less injury from DMD.

[Constructing tissue-engineered urothelial structures in vitro and in vivo].

OBJECTIVE: To develop a method for reconstructing urothelial structures using tissue engineering techniques. METHODS: The bladder mucosa of a puppy dog was mechanically separated, cutted into pieces, and digested with trypsin. The obtained bladder transitional epithelia were cultured with DKSFM and then transplanted to the surface of the small intestinal submucosa (SIS) framework. The compound of the epithelia and small intestinal submucosa (SIS) materials were planted under the back skin of the nude rats. The rats were sacrificed at week 1, 2, 4 and 8 after the transplant. Histological and immunohistochemical examinations were performed to the implanted samples. RESULTS: The bladder transitional epithelia adhered to, and grew and proliferated on the surface of the SIS framework. The bladder transitional epithelia covered the entire surface of the framework after nine days of culture in vitro, showing a single-layer cellular structure. The bladder transitional epithelia planted on the SIS framework formed a multi-layer structure after four weeks or eight weeks of transplant to the nude rats. The brown cellular plasma staining was observed, indicating a positive reaction to the immunohistochemical staining with cytokeratin. CONCLUSION: Urothelial structures can be reconstructed in vitro and in vivo with tissue engineering technologies, which lays a technical foundation for further urinary tract reconstructing experiments.

[The experiment of porcine keratinocytes cultured on porcine small intestinal submucosa in vitro].

OBJECTIVE: To investigate the feasibility of acellular porcine small intestinal submucosa (SIS as bioscaffold of tissue engineering skin. METHODS: The second passage keratinocytes were seeded on SIS, after seeded for 11, 13, 15, 17 days, the keratinocytes/SIS composites were observed by dye directly, histopathology, immunohistochemical studies with monoclonal antibodies against laminin and transmission electron microscope (TEM). RESULTS: At eleventh day, keratinocytes were growth very well on the surface of SIS, there are 2-3 cell layers on partial of the SIS surface, the continued expression of laminin can be detected between the keratinocytes and the surface of SIS. After 13, 15, 17 days this stratified structure increased, cells contact more closely, the tonofibrils in cells, desmosome between cells and the basal membrane between the keratinocytes and the surface of SIS can be seen with TEM. CONCLUSIONS: SIS is a kind of good bioscaffold in the culture of porcine keratinocytes in vitro.