Effect of platelet-derived growth factor (PDGF-BB) and bone morphogenic protein 2 (BMP-2) transfection of rBMSCs compounded with platelet-rich plasma on adipogenic differentiation

The aim of this study was to inhibit adipogenic differentiation by transfecting two growth factors, platelet-derived growth factor (PDGF-BB) and bone morphogenic protein 2 (BMP-2), into modified rat bone marrow mesenchymal stem cells (rBMSCs) and then compounded with platelet-rich plasma (PRP). To achieve rBMSCs, the osteoporosis model of rats was established, and then the rBMSCs from the rats were isolated and identified. Co-transfection of rBMSCs with PDGF-BB-GFP and BMP-2 and detection of PDGF-BB/BMP-2 expression in transfected BMSCs was assessed by qRT-PCR and western blot, respectively. Moreover, the effect of the two growth factors transfection of rBMSCs on adipogenic differentiation was evaluated by oil red O staining and western blot, respectively. Finally, construction of the two growth factors transfection of rBMSCs compounded with PRP and detection of adipogenic differentiation were assessed by oil red O staining, CCK-8, and western blot, respectively. In vitro studies revealed that the two growth factors transfection of rBMSCs compounded with PRP promoted cell viability and inhibited adipogenic differentiation and could be promising for inhibiting adipogenic differentiation.

Effect of platelet-derived growth factor (PDGF-BB) and bone morphogenic protein 2 (BMP-2) transfection of rBMSCs compounded with platelet-rich plasma on adipogenic differentiation.

The aim of this study was to inhibit adipogenic differentiation by transfecting two growth factors, platelet-derived growth factor (PDGF-BB) and bone morphogenic protein 2 (BMP-2), into modified rat bone marrow mesenchymal stem cells (rBMSCs) and then compounded with platelet-rich plasma (PRP). To achieve rBMSCs, the osteoporosis model of rats was established, and then the rBMSCs from the rats were isolated and identified. Co-transfection of rBMSCs with PDGF-BB-GFP and BMP-2 and detection of PDGF-BB/BMP-2 expression in transfected BMSCs was assessed by qRT-PCR and western blot, respectively. Moreover, the effect of the two growth factors transfection of rBMSCs on adipogenic differentiation was evaluated by oil red O staining and western blot, respectively. Finally, construction of the two growth factors transfection of rBMSCs compounded with PRP and detection of adipogenic differentiation were assessed by oil red O staining, CCK-8, and western blot, respectively. In vitro studies revealed that the two growth factors transfection of rBMSCs compounded with PRP promoted cell viability and inhibited adipogenic differentiation and could be promising for inhibiting adipogenic differentiation.

Strained Si0.2Ge0.8/Ge multilayer Stacks Epitaxially Grown on a Low-/high-Temperature Ge Buffer Layer and Selective Wet-Etching of Germanium.

With the development of new designs and materials for nano-scale transistors, vertical Gate-All-Around Field Effect Transistors (vGAAFETs) with germanium as channel materials have emerged as excellent choices. The driving forces for this choice are the full control of the short channel effect and the high carrier mobility in the channel region. In this work, a novel process to form the structure for a VGAA transistor with a Ge channel is presented. The structure consists of multilayers of Si0.2Ge0.8/Ge grown on a Ge buffer layer grown by the reduced pressure chemical vapor deposition technique. The Ge buffer layer growth consists of low-temperature growth at 400 °C and high-temperature growth at 650 °C. The impact of the epitaxial quality of the Ge buffer on the defect density in the Si0.2Ge0.8/Ge stack has been studied. In this part, different thicknesses (0.6, 1.2 and 2.0 µm) of the Ge buffer on the quality of the Si0.2Ge0.8/Ge stack structure have been investigated. The thicker Ge buffer layer can improve surface roughness. A high-quality and atomically smooth surface with RMS 0.73 nm of the Si0.2Ge0.8/Ge stack structure can be successfully realized on the 1.2 µm Ge buffer layer. After the epitaxy step, the multilayer is vertically dry-etched to form a fin where the Ge channel is selectively released to SiGe by using wet-etching in HNO3 and H2O2 solution at room temperature. It has been found that the solution concentration has a great effect on the etch rate. The relative etching depth of Ge is linearly dependent on the etching time in H2O2 solution. The results of this study emphasize the selective etching of germanium and provide the experimental basis for the release of germanium channels in the future.

Selective Digital Etching of Silicon-Germanium Using Nitric and Hydrofluoric Acids.

A digital etching method was proposed to achieve excellent control of etching depth. The digital etching characteristics of p+-Si and Si0.7Ge0.3 using a combination of HNO3 oxidation and buffered oxide etching oxide removal processes were investigated. Experimental results showed that oxidation saturates as time goes on because of low activation energy and its diffusion-limited characteristic. An oxidation model was developed to describe the wet oxidation process with nitric acid. The model was calibrated with experimental data, and the oxidation saturation time, final oxide thickness, and selectivity between Si0.7Ge0.3 and p+-Si were obtained. In Si0.7Ge0.3/p+-Si stacks, the saturated relative etched depth per cycle was 0.5 nm (four monolayers), and variation between experiments was about 4% after saturation. A corrected selectivity calculation formula was also proposed, and the calculated selectivity was 3.7-7.7 for different oxidation times, which was the same as the selectivity obtained from our oxidation model. The proposed model can be used to analyze process variations and repeatability, and it can provide credible guidance for the design of other wet digital etching experiments.

The Radiated Deep-frozen Xenogenic Meniscal Tissue Regenerated the Total Meniscus with Chondroprotection.

Meniscal allograft transplantation yields good and excellent results but is limited by donor availability. The purpose of the study was to evaluate the effectiveness of radiated deep-frozen xenogenic meniscal tissue (RDF-X) as an alternative graft choice in meniscal transplantation. The xenogenic meniscal tissues were harvested from the inner 1/3 part of the porcine meniscus and then irradiated and deeply frozen. The medial menisci of rabbits were replaced by the RDF-X. Meniscal allograft transplantation, meniscectomy and sham operation served as controls. Only a particular kind of rabbit-anti-pig antibody (molecular ranging 60-80 kD) was detected in the blood serum at week 2. The menisci of the group RDF-X grossly resembled the native tissue and the allograft meniscus with fibrocartilage regeneration at postoperative 1 year. Cell incorporation and the extracellular matrix were mostly observed at the surface and the inner 1/3 part of the newly regenerated RDF-X, which was different from the allograft. The biomechanical properties of the group RDF-X were also approximate to those of the native meniscus except for the compressive creep. In addition, chondroprotection was achieved after the RDF-X transplantation although the joint degeneration was not completely prevented. To conclude, the RDF-X could be a promising alternative for meniscal transplantation with similar tissue regeneration capacity to allograft transplantation and superior chondroprotection. The potential minor immunological rejection should be further studied before its clinical application.

Meniscus transplantation using treated xenogeneic meniscal tissue: viability and chondroprotection study in rabbits.

PURPOSE: This was a preliminary study performed in vivo to evaluate the viability and the chondroprotective effects of irradiated deep-frozen xenogeneic meniscal tissue as a novel substitute for meniscus transplantation. METHODS: Medial meniscectomies were performed on the right knees of 48 New Zealand white rabbits. The inner one-third of pig meniscus was harvested and then irradiated and deeply frozen. The treated xenogeneic meniscal tissues were then transplanted to 24 right knees (Xeno group), whereas 24 other knees received meniscus allograft transplantations (Allo group). The left knees of the Xeno group and Allo group received meniscectomies (Meni group) and sham operations (Sham group), respectively. The rabbits were killed at weeks 6, 12, and 24 postoperatively. The newly formed structure of the implanted tissue and cartilage of the medial compartment of each group was assessed by gross and semiquantitative histologic analysis. RESULTS: After 24 weeks, the implanted xenogeneic meniscal tissue completely healed to the synovium and formed meniscus-like tissue. The chondrocyte-like cell infiltrated into the tissue with extracellular matrix including type II collagen and proteoglycans. The Xeno group showed significantly less cartilage degeneration than that of the Meni group in the medial tibial plateau at week 24 (P < .05). No significant difference was found between the Xeno group and the Allo group except for the meniscus-covered regions at week 24. From week 12 to week 24, almost no advanced cartilage degeneration was found in weight-bearing regions of the medial tibial plateau of the Xeno group. CONCLUSIONS: The treated xenogeneic meniscal tissue healed to the synovium with tissue regeneration and slowed down articular cartilage degeneration in the short-term. The chondroprotection of xenograft transplantation was similar to that of allograft transplantation. CLINICAL RELEVANCE: The treated xenogeneic meniscal tissue showed the potential for viability and slowed cartilage degeneration, but more studies are required for application in humans in the future.

Effect of bone morphogenetic protein-12 gene transfer on posterior cruciate ligament healing in a rabbit model.

BACKGROUND: The posterior cruciate ligament heals to some extent after injury. However, results after conservative treatment may diminish with long-term follow-up. Bone morphogenetic protein-12 can induce formation of ligament tissues. HYPOTHESIS: Bone morphogenetic protein-12 gene transfer can improve the histologic and biomechanical properties of healing posterior cruciate ligaments. STUDY DESIGN: Controlled laboratory study. METHODS: Bilateral posterior cruciate ligaments of 32 rabbits were injured. The cut ends in 1 limb received an injection containing 3 x 10(7) pfu recombinant bone morphogenetic protein-12 adenovirus, and the posterior cruciate ligament in the contralateral limb served as an untreated control. Eight rabbits were sacrificed at each time point of 3, 6, 12, and 26 weeks after the operation. In addition, 6 rabbits receiving a sham operation were used to obtain normal control data. The posterior cruciate ligament specimens were evaluated biomechanically and histologically. RESULTS: The repair tissue of the treatment group at 26 weeks was similar to the normal posterior cruciate ligament in collagen arrangement, collagen formation, and mechanical properties. At weeks 6, 12, and 26, the ultimate load, stiffness, and energy absorbed at failure of the treatment group were significantly greater than those of the untreated group. CONCLUSION: Adenovirus-mediated bone morphogenetic protein-12 gene transfer in a partial posterior cruciate ligament laceration rabbit model resulted in an obvious improvement of histologic properties, tensile strength, and stiffness of the repaired ligaments, indicating improved posterior cruciate ligament healing. CLINICAL RELEVANCE: Bone morphogenetic protein-12 gene transfer is a potential future strategy to improve the repair of injured posterior cruciate ligaments.

Articular cartilage repair using dedifferentiated articular chondrocytes and bone morphogenetic protein 4 in a rabbit model of articular cartilage defects.

OBJECTIVE: To observe redifferentiation of dedifferentiated chondrocytes after transplantation into the joint, and to evaluate the ability of dedifferentiated chondrocytes transduced with adenovirus containing bone morphogenetic protein 4 (BMP-4) to redifferentiate in vitro and in vivo in a rabbit model of articular cartilage defects. METHODS: Monolayer and pellet culture systems were used to evaluate the redifferentiation of dedifferentiated chondrocytes transduced with BMP-4. A rabbit model of partial-thickness articular cartilage defects was used to evaluate cartilage repair macroscopically and histologically, 6 and 12 weeks after transplantation with first-passage, fifth-passage, or transduced fifth-passage chondrocytes. Histologic grading of the repaired tissue was performed. Expression of BMP-4 and the ability of transplanted cells to recover a chondrocytic phenotype were also assessed. RESULTS: BMP-4--expressing dedifferentiated chondrocytes recovered a chondrocytic phenotype in vitro. After transplantation into the joint, some of the dedifferentiated chondrocytes in the defect sites could undergo redifferentiation and formed matrix that displayed positive toluidine blue staining for glycosaminoglycans. Histologic scores of the regenerative tissue revealed significantly better cartilage repair in rabbits transplanted with BMP-4--expressing cells than in the other treatment groups. Staining with toluidine blue revealed expression of BMP-4 in the cells and in the matrix surrounding the cells. CONCLUSION: Some dedifferentiated chondrocytes can redifferentiate after transplantation into the load-bearing joint. BMP-4 can be used to induce redifferentiation of dedifferentiated chondrocytes in vitro and in vivo, which could help enhance articular cartilage repair.