Biomedical subjects

Kerong Dai

Publications and source records attributed to Kerong Dai.

At least 19 recordsLinked to original sources

PubMed2006

Proliferation and osteoblastic differentiation of human bone marrow-derived stromal cells on akermanite-bioactive ceramics.

In the present study, the effects of a calcium magnesium silicate bioactive ceramic (akermanite) on proliferation and osteoblastic differentiation of human bone marrow stromal cells (hBMSC) have been investigated and compared with the classical ceramic (beta-tricalcium phosphate, beta-TCP). Akermanite and beta-TCP disks were seeded with hBMSC and kept in growth medium or osteogenic medium for 10 days. Proliferation and osteoblastic differentiation were evaluated on day 1, 4, 7 and 10. The data from the Alamar Blue assay and lactic acid production assay showed that hBMSC proliferated more significantly on akermanite than on beta-TCP. The analysis of osteoblast-related genes, including alkaline phosphatase (ALP), osteopontin (OPN), bone sialoprotein (BSP) and osteocalcin (OC), indicated that akermanite ceramics enhanced the expression of osteoblast-related genes, but type I collagen (COL I) showed no noticeable difference among akermanite and beta-TCP ceramics. Furthermore, this stimulatory effect was observed not only in osteogenic medium, but also in normal growth medium without osteogenic reagents such as l-ascorbic acid, glycerophosphate and dexamethasone. This result suggests that akermanite can promote osteoblastic differentiation of hBMSC in vitro even without osteogenic reagents, and may be used as a bioactive material for bone regeneration and tissue engineering applications.

Adult↗

PubMed2006

Direct chitosan-mediated gene delivery to the rabbit knee joints in vitro and in vivo.

Chitosan vector system is expected to be useful for direct gene therapy for joint disease. This study first sought to confirm that foreign genes can be transferred to articular chondrocytes in primary culture. Next, chitosan-DNA nanoparticles containing IL-1Ra or IL-10 gene were injected directly into the knee joint cavities of osteoarthritis rabbits to clarify the in vivo transfer availability of the chitosan vectors. Clear expression of IL-1Ra was detected in the knee joint synovial fluid of the chitosan IL-1Ra-injected group. While no expression was detected in the chitosan IL-10-injected group, this demonstrates that the transfection efficiency of chitosan-DNA nanoparticles was closely related to the type of the gene product. A significant reduction was also noted in the severity of histologic cartilage lesions in the group that received the chitosan IL-1Ra injection. This avenue may therefore represent a promising future treatment for osteoarthritis.

Animals↗

PubMed2006

[Study on the differentiation of marrow mesenchymal stem cells of the rats mediated by bone morphogenetic protein 2].

OBJECTIVE: To explore the effect of age and gene therapy on the differentiation of marrow mesenchymal stem cells (MSCs) of the rats. METHODS: MSCs from the young (1-month-old), adult (9-month-old), and the aged (24-month-old) rats were expanded in culture and infected with adenovirus mediated human bone morphogenetic protein 2 gene (Ad-BMP-2). The expression of BMP-2 and osteoblastic markers such as alkaline phosphatase (ALP), collagen I (Col I), bone sialoprotein (BSP) and osteopontin (OPN) were assayed during the process of differentiation. Their abilities to induce ectopic bone formation in nude mice were also tested. RESULTS: There was no significant difference in the expression of BMP-2 among the 3 groups. ALP activity assay and semi-quantitative reverse transcription polymerase chain reaction(RT-PCR) demonstrated that there were no significant differences in the expression of osteoblastic markers ALP, Col- I, OPN and BSP among the 3 groups. Histomorphometric analysis indicated that there were no significant differences in the volume of the newly formed ectopic bones in nude mice among the 3 groups. CONCLUSION: MSCs obtained from the aged rats can restore their osteogenic activity following human BMP-2 gene transduction,therefore provides an alternative to treating the aged bone disease.

Animals↗

PubMed2006

[Effects of impaction on tissue engineered bone modified by BMP-2 gene].

OBJECTIVE: To observe effects of the direct impaction on the cell survival and the bone formation of the tissue engineered bone modified by the adenovirus mediated human bone morphogenetic protein 2 (Adv-hBMP2) gene and to verify the feasibility of the impacted grafting with it. METHODS: The marrow stromal cells (MSCs) were separated from the canine bone marrow and were cultured. MSCs were transfected with the Adv-hBMP2 gene and combined with the freeze-dried cancellous bone (FDB) to form the tissue engineered bone. Four days after the combination, the tissue engineered bone was impacted in a simulated impactor in vitro and implanted in the mouse. The cell survivals were evaluated with SEM 1 and 4 days after the combination, immediately after the impaction, and 1 and 4 days after the impaction, respectively. The bone formation and the allograft absorption were histologically evaluated respectively. RESULTS: There were multiple layers of the cells and much collagen on FDB before the impaction. Immediately after the impaction, most of the cells on the direct contact area disappeared and there was much debris on the section. Some of the cells died and separated from the surface of FDB at 1 day, the number of the cells decreased but the collagen increased on the surface at 4 days. Histologically, only the fibrous tissue was found in FDB without the cells, the bone formation on FDB was even in distribution and mass in appearance before the impaction, but declined and was mainly on the periphery after the impaction in the Adv-hBMP-2 modified tissue-engineered bone. CONCLUSION: The simulated impaction can decrease the cells survival and the bone formation of the Adv-hBMP-2 modified tissue-engineered bone. The survival cells still function well. It is feasible to use the tissue engineered bone in the impaction graft.

Adenoviridae↗

PubMed2006

[Micro-particles of bioceramics could cause cell and tissue damage].

We conducted studies to confirm the hypothesis that the cellular damage occurring around implanted biphasic bioceramics could be related to a micro-particles release because of an insufficient sintering. An in vitro cytotoxicity study was performed on four biphasic ceramic (BCP) samples. Without the treatment of extraction medium, a cytotoxicity was observed, although after centrifugation this cytotoxicity disappeared in all samples. (2) Micro-particles of HA, beta-TCP and 40%beta-TCP/60%HA mixture were used for a cell inhibition study. A decrease of cell viability was observed with the increase in particles concentration. At 10000 particles/ cell, the viability and proliferation were completely inhibited. (3) HA, beta-TCP and BCP ceramic granules were implanted in rabbit femoral cavities for 12 weeks. No degradation of HA granules was observed. The degradation was higher for beta-TCP (40%) than for BCP (5%). On the other hand, new bone formation was significantly higher for beta-TCP (21%) and HA (18%) than for BCP (12%). Much more micro-particles were formed around BCP granules than around beta-TCP, and were phagocytosed by macrophages. The release of ceramic micro-particles could be related to the sintering process. BCP ceramics have to be sintered at only 1160 degrees C. Consequently, HA microparticles of BCP ceramic are incompletely sintered and easily released after immersion or implantation. The microparticles could be at the origin of local inflammation and cell damage and could perhaps modify osteogenesis. Particular attention must be paid to this problem with regard to BCP ceramics because of the sintering difficulties of this bioceramic.

Biocompatible Materials↗

PubMed2006

[Expression of nerve growth factor and its receptor during osteoinduction of recombined human bone morphogenetic protein 2].

OBJECTIVE: To identify the expression of nerve growth factor (NGF) and its high affinity receptor (tyrosine kinase receptor A, TrkA) during bone induction by recombined human bone morphogenetic protein 2 (rhBMP-2) by immunohistochemistry and reverse transcriptase-polymerase chain reaction (RT-PCR) and to discuss the role of NGF on the bone induction of the BMP. METHODS: Thirty-six ICR mice were divided into the experimental group and the control group at random. rhBMP-2 /collagen sponge and collagen sponge were implanted into the right thigh muscle pouches of the mice in the experimental group and the control group, respectively. The tissues in the implanted site of the two groups were removed on the 7th, 14th and 21st day after the implantation. Histological, immunohistochemical and RT-PCR analyses were performed to detect osteoinductive effects of rhBMP-2 and the expression of NGF and TrkA. RESULTS: Gross observation showed that a solid lump was found in the right thigh in the experimental group on the 7th day and became harder on the 14th and 21st day, which was not found in the control group. rhBMP-2 /collagen sponge displayed a potent ability to induce bone formation, while immunostaining for NGF and TrkA was observed in the course of osteoinduction by rhBMP-2. On the 7th day in the experimental group, NGF positive immunostaining reached the peak in the stage of chondrogenesis and there were a large number of cells expressing NGF, including fibroblasts, chondroblasts, chondrocytes, and osteoblasts; then, there was a decrease in the number of the positive cells and in the intensity of immunostaining on the 14th and 21st day. Staining of TrkA was similar to that of NGF. The expression level of the mRNA of NGF during the course of bone induction peaked 7 days rhBMP-2/collagen is a kind of satisfactory osteoinductive after the implantation and then decreased. CONCLUSION: material, and many different kinds of cells induced by rhBMP-2 can express NGF and TrkA, which suggests that NGF may play an important role in the osteogenesis initiated by exogenous BMP through direct and indirect pathways.

Animals↗

PubMed2005

Evaluation of different scaffolds for BMP-2 genetic orthopedic tissue engineering.

To better understand the effects of scaffold materials for bone morphogenetic protein 2 (BMP-2) genetic tissue engineering in vivo, several gels, including alginate, collagen, agarose, hyaluronate, fibrin, or Pluronic, were mixed with adenovirus-mediated human BMP-2 gene (Adv-hBMP-2) transduced bone marrow stromal cells (BMSCs) and injected into the muscles of athymic mice to evaluate the resulting osteogenesis and chondrogenesis. These gel and gene-transduced BMSC mixtures were also loaded onto beta-TCP/HAP biphasic calcined bone (BCB) and observed under scanning electron microscopy (SEM). In addition, these composite scaffolds were implanted into the subcutaneous site of athymic mice to construct tissue-engineered bone. After injection, collagen, hyaluronate, or alginate gel mixed with gene-transduced BMSCs induced more bone formation than a cell suspension in alpha-MEM. The agarose-gene-transduced BMSC gel was found to contain much more hyaline cartilage. SEM showed the BMSCs could survive in alginate, agarose, and collagen gel in vitro for up to 8 d. After implantation of tissue-engineered bone, the alginate, collagen, and agarose gel could promote new bone formation within a BCB in vivo. Little or no bone formed after injection of fibrin or Pluronic gel mixed with BMSCs or implantation with BCB. These findings help to elucidate the effects of various scaffold materials for future research in orthopedic tissue engineering using BMP-2 transduced cells.

Adenoviridae↗

PubMed2005

Immune response and effect of adenovirus-mediated human BMP-2 gene transfer on the repair of segmental tibial bone defects in goats.

BACKGROUND: Tissue-engineered bone may be used for filling bone defects. There are, however, no reports on this technique used in large animals. METHODS: We evaluated the effectiveness of, and immune response in repairing diaphyseal bone defects by gene transfer using bone morphogenetic proteins (BMPs). We used adenovirus-mediated human BMP-2 (Adv-hBMP-2) gene-transduced bone marrow stromal cells (BMSCs) to repair 2.1-cm segmental tibial bone defects in goats (group I, n = 7). An Adv-ssgal-transduced BMSC group (group II, n = 5), a non-transduced BMSC group (group III, n = 5), and an untreated group (group IV, n = 2) were used as controls. Self-secreted extracellular matrix was used as cellular carrier. RESULTS: Radiographic and histomorphometric examination demonstrated more callus in the bone defects of group I compared to other groups. Week 24 after implantation, the defect healing rates of groups I, II, III, and IV were 6/7, 1/5, 2/5, and 0/2, respectively. The maximum compressive strength of new tissue in the bone defects of group I was higher than those of groups II and III. Temporary cellular and persistent humoral immune responses against adenovirus were detected after hBMP-2 gene transfer. INTERPRETATION: We found that Adv-hBMP-2 genetransduced BMSCs had superior osteoinductivity in the repair of tibial bone defects in goats, but it could cause temporary cellular and persistent humoral immune responses against adenovirus.

Adenoviridae↗

PubMed2005

[Experimental study of immunological tolerance induced by cytotoxic T lymphocyte-associated antigen 4 immunoglobulin in fresh bone allografts].

OBJECTIVE: To study the immunological tolerance induced by blocking the second signal of T cell with extrinsic cytotoxic T lymphocyte-associated antigen 4 immuno globulin (CTLA4-Ig). METHODS: Fifty-four BALB/C mice, inbred strains, were employed as recipients of bone allografts, using a model of heterotopic muscle pouch. The 54 mice were divided into 3 groups and 18 for each group. The first group, in which the donor was C57BL/6 with intraperitoneal injection of L6 (as a control), was named AL group. The second group, also C57BL/6 with injection CTLA4-Ig, was named AC group. The third group, homologous BALB/C with injection of PBS buffer solution, was named AB group. The serum antibody, lymphocyte proliferation of the second stimulation by splenic cell and bone supernatant of donor, the analysis of lymphocyte subsets, a regraft experiment and histology were determined 2, 4 and 6 weeks after transplantation. The second transplantation was to regraft C57BL/6 (BC group) and C3H (BH group) mice respectively after first 12 mice being transplanted with C57BL/6 and injected with CTLA4-Ig as to detect donor-specificity of immunological tolerance. RESULTS: Compared with AB group, AL group created more intensive immune rejection: CD4 T cell subsets (P<0.05), the serum antibody (P<0.05) and lymphocyte proliferation of the second stimulation by splenic cell and bone supernatant of donor (P<0.01 and 0.05) were significantly increased. However, the results of AC group showed that CTLA4-Ig significantly inhibited the immune rejection: CD4 T cell subsets (P>0.05), the serum antibody (P>0.05), and lymphocyte proliferation of the second stimulation (P>0.05) were similar to those of AB group. Histological observation of AC group showed that lymphocyte infiltration disappeared, cartilage and new bone formed, and bone marrow cavities emerged. A regraft experiment showed that CD4 T cell subsets (P<0.05) and lymphocyte proliferation of the second stimulation by splenic cell and bone supernatant of donor (P<0.05), BC group was significantly lower than those of BH group. So the immunological tolerance induced by CTLA4-Ig was of donor-specificity. CONCLUSION: The immunological tolerance induced by CTLA4-Ig was prolonged for 6 weeks. This study provides a brand-new path for bone transplantation, which can be helpful to other organ transplantation.

Animals↗

PubMed2005

[An immunological study on adenovirus mediated human bone morphogenetic protein 2 gene therapy].

OBJECTIVE: To evaluate the host immune reaction against adenovirus mediated human bone morphogenetic protein 2 (Adv-hBMP-2) gene therapy in repair of tibial defects. METHODS: Twelve goats were made 2.1 cm segmental defects in the tibial diaphysis and divided into 2 groups. Adv-hBMP-2 transfected marrow mesenchymal stem cells (MSCs) and untransfected MSCs were implanted into the defect sites of transfected group(n = 7) and untransfected group (n = 5), respectively. The defect repair was observed by X-ray films after 4, 8, 16 and 24 weeks of transplantation and cellular and humoral immune reactions to adenovirus were assayed before implantation and after implantation. RESULTS: More bony callus was found in the bone defects of transfected group. The healing rates were 6/7 in transfected group and 2/5 in untransfected group, respectively at 24 weeks after implantation. The mixed culture of lymphocytes and MSCs showed that the lymphocytes stimulation indexes (SI) increased 14 days after implantation, and there was significant difference between the transfected group (4.213 +/- 1.278) and the untransfected group(- 0.310 +/- 0.147, P < 0.05); SI decreased after 28 days, but there was no significant difference between the transfected group (2.544 +/- 0.957) and the untransfected group (3.104 +/- 0.644, P > 0.05). After 14, 28, 49, and 120 days of treatment, the titer values of neutralizing antibody against Adv-hBMP-2 (log0.1) were 2.359 +/- 0.226, 2.297 +/- 0.200, 2.214 +/- 0.215 and 2.297 +/- 0.210 in transfected group, and - 0.175 +/- 0.335, - 0.419 +/- 0.171, 0 +/- 0.171 and 0.874 +/- 0.524 in untransfected group, being significant differences between two groups (P < 0.05). CONCLUSION: Adenovirus mediated BMP-2 gene therapy can cause cellular and humoral immune reactions against adenovirus, which can eliminate the influence of adenoviral genes and proteins within a certain period.

Adenoviridae↗

PubMed2005

[Preliminary observation of biological characters of chondrocytes in articular loose body].

OBJECTIVE: To observe the biological characters of chondrocytes in articular loose body and to find out seeding cells for cartilage tissue engineering. METHODS: Samples from 5 loose body cartilages, 2 normal articular cartilages and 6 osteoarthritis articular cartilages were collected. Part of each sample's cartilage was histologically studied to observe the chondrocytes distribution the morphologic changes by toluidine-blue staining, chondrocytes' apoptosis by terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate-biotin nick end-labeling (TUNEL). The rest of each cartilage was digested and isolated by 0.25% trypsin and 0. 2% collagenase II, and then were cultivated in 10%DMEM. Their morphologic changes were observed 24h later. Comparison was made between three cartilages. RESULTS: Compared with normal cartilage and osteoarthritis articular cartilage, the cells density was higher, their lacunary were larger, cells distribution was irregular, and apoptosis was more apparent in loose body cartilage. CONCLUSION: The characters of chondrocytes from loose body is more like fibroblasts so they can not serve as seeding cells directly for cartilage tissue engineering.

Adult↗

PubMed2005

[A method for automatic selection of optimal standard hip stems].

In a hip replacement case when a standard hip stem is chosen, it is rough to select hip stems before operation, thus some stand-up standard hip stems should be prepared. The operation time is usually prolonged. In order to solve this problem, this paper presents a method to automatically select optimal standard hip stems by computers. Femoral anatomical data of a patient are acquired from X-ray films. Based on these anatomical data and a database of average cross-sections in proximal femurs, proximal femur of the patient can be reconstructed. This proximal femur model makes it possible to optimally select a standard hip stem. Theory analyses indicate that the method, presented in this paper, is practicable.

Arthroplasty, Replacement, Hip↗

PubMed2004

[Custom design of hip joint prostheses based on X-ray films].

A novel method for the design of hip joint prostheses based on X-ray films is introduced. Only arcs and straight-lines form figures of hip joint prostheses. Because geometrical tolerances of manufacturing hip joint prostheses matching section are usually not strict, hip joint prostheses can be manufactured without CNC machine tool. Three hip joint prostheses for three different femurs were designed through a program which was developed by the present authors. Approximate marrow cavities of these femurs were simulated according to a standard database about femur. These models of femur marrow cavities were used to verify the hip joint prostheses designed. These hip joint prostheses designed were manufactured and implanted into femurs respectively. Experimental results indicate that the novel method for the design of hip joint prostheses is practicable.

Computer-Aided Design↗

PubMed2004

[Morphological analysis of acetabulum bony curved surface].

By using the reverse engineering (RE) technology, the mesh surface model of acetabulum was reconstructed by triangulation. Based on this kind of model, the local morphological analysis (LMA) and global morphological analysis (GMA) could be processed. The fitting minimal quadric surface method was applied to calculate the curvature of any point on the acetabulum bony surface, the local morphological character of its surface could be acquired, and its global surface character could be determined by GMA. The results showed that the acetabulum bony surface is elliptical surface, and its three eigenvalues (lambda1, lambda2, lambda3) relations on the three axes (x, y, z) are as follows: lambda1 is short than lambda2 and lambda3, lambda2 is close to lambda3.

Acetabulum↗

PubMed2004

[A study on new computer-aided modeling method of hip joint].

The main reason of invalidation of prosthetic hip joint is the prostheses flexibility and shift, dislocation and disjunction. Promoting the long time stability of the prostheses is the key of improving the long term hip joint replacement effect. Former research work was focused on the upper segment of femur, and assumed the acetabulum cup to be a spheric concave, and the external form of acetabulum prostheses was basically semi spheric. This paper presents a method of acquiring the point data on the surface of the hip bone using the reverse engineering technology. By analyzing the acetabulum surface fitting error we use rotating elliptical surface to fit the acetabulum surface, together with the optimal technique to build up the CAD model of acetabulum surface. We compare the fitting error between the sphere fitting and rotating elliptical surface fitting and get the result that the rotating elliptical surface fitting error is smaller than the sphere fitting error, and the rotating elliptical surface can describe the shape of the acetabulum better.

Acetabulum↗

PubMed2003

Trauma care systems in China.

The prehospital emergency service is an integral and important part of the Emergency Medical Service System. In China, emergency service centres (stations) have been set up at the levels of province, prefecture and county. With the vast territory of China and the marked differences in economic power and size of cities, five different models of prehospital emergency service have been adopted: (1) independent emergency service centres, (2) mainly prehospital emergency services, without sickbeds, (3) prehospital emergency services, supported by a general hospital, (4) unified communications command centres with prehospital emergency-care to be handled by different hospitals, and (5) three-level emergency service networks in small cities.

Ambulances↗

PubMed2003

[Research development of hydroxyapatite-based composites used as hard tissue replacement].

Hydroxyapatite has been considered as the most promising materials for hard tissue replacements, due to its similar chemical composition and crystallographic structure to that of bone mineral. But the brittleness is one of the most serious obstacles for its wider applications as load-bearing implants. Therefore, various HA composites get much attention. In the present paper, HA composites were introduced according to the kind of reinforcement. Although bioactive ceramics, bioactive glass or glass-ceramic, bio-inactive ceramics, polymers and metals all have been used to fabricate HA composites, no one can well satisfy the requirements for hard tissue replacement. The vital problem of the existing HA composites is that the biological properties cannot match with the mechanical properties well.

Aluminum Oxide↗

PubMed2003

[Morphologic features of the acetabulum bone joint area].

The research on the morphology features of the acetabulum bone joint surface area would be helpful to establishing the acetabulum 3D model for the purpose of the biomechanical analysis of hip joint, and therefore might have its important clinical significance. However, in former studies, the acetabulum was simply considered as a semi sphere. In this study, based on the acetabulum 3D-point data acquired by the 3D laser surface scanner and the reverse engineering technology together with the optimal fit algorithm, two kinds of best-fit model were achieved by a sphere surface and a rotating elliptical surface respectively approaching to the acetabulum bone joint surface. Both fitting errors were then compared and analyzed. The results showed that the fitting error of the rotating elliptical surface was significantly less than that of the sphere surface (P < 0.001). The average radius of fitting sphere was 24.37 +/- 2.22 mm and the average long axis of fitting rotating elliptical surface was 26.02 +/- 2.76 mm while its short axis was 24.17 +/- 2.16 mm. These findings would be helpful to our new recognition of the acetabulum since they were results of the first quantitative analyses for the acetabulum bone surface and also might serve as an important reference base in its further studies and application.

Acetabulum↗