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PubMed1999

Effects of genetic engineering on the pharmacokinetics of antibodies.

Monoclonal antibodies (MAbs) may be considered 'magic bullets' due to their ability to recognize and eradicate malignant cells. MAbs, however, have practical limitations for their rapid application in the clinics. The structure of antibody molecules can be engineered to modify functional domains such as antigen-binding sites and/or effector functions. Advances in genetic engineering have provided rapid progress in the development of new immunoglobulin constructs of MAbs with defined research and therapeutic application. Recombinant antibody constructs are being engineered, such as human-mouse chimeric, domain-dispositioned, domain-deleted, humanized and single-chain Fv fragments. Genetically-engineered antibodies differ in size and rate of catabolism. Pharmacokinetic studies show that the intact IgG (150 kD), enzymatically derived fragments Fab' (50 kD) and single chain Fv (28 kD) have different clearance rates. These antibody forms clear 50% from the blood pool in 2.1 days, 30 minutes and 10 minutes, respectively. Genetically-engineered antibodies make a new class of immunotherapeutic tracers for cancer treatment.

Adenocarcinoma↗
PubMed2001

[The influence of tissue engineered tendon on subgroup of T lymphocytes and its receptor in roman chickens].

OBJECTIVE: To investigate the influence of tissue engineered tendon on subgroup of T lymphocytes and its receptor in Roman chickens. METHODS: The flexor digitorum profundus of the third toes of right feet in 75 Roman chickens were resected and made 2.5 cm defects as experimental model. They were randomly divided into five groups according to five repair methods: no operation (group A), autograft (group B), fresh allograft (group C), polymer combined with allogenous tendon cells (group D), derived tendon materials combined with allogenous tendon cells (group E). The proliferation and transformation of lymphocytes and contribution of CD4+, CD8+, CD28 and T cell receptor (TCR) were detected to study the immune response. RESULTS: The CD4+, CD8+ and TCR of group D and E were increased slightly than that of group B after 7 days, while after 14 days, those data decreased gradually and no significant difference between tissue engineered tendon and autografts (P > 0.05), and there was significant difference between fresh allograft and tissue engineered tendon (P < 0.05). Lymphocytes transformation induced by conA also showed no significant difference between tissue engineered tendon and autografts (P > 0.05). CONCLUSION: Tendon cells are hypoantigen cells, there are less secretion of soluble antigen or antigen chips dropped out from cells. Tissue engineered tendon has excellent biocompatibility.

Animals↗
PubMed2001

An introduction to biodegradable materials for tissue engineering applications.

Tissue generation by autogenous cell transplantation is one of the most promising treatment concepts being developed as it eliminates problems of donor site scarcity, immune rejection and pathogen transfer. Cultured cells are seeded onto a three-dimensional biocompatible scaffold that will slowly degrade and resorb as the soft and hard structures grow and assimilate in vitro and/or in vivo. The 3-D scaffold provides the necessary template for cells to proliferate and maintain their differentiated state. Ultimately, it defines the overall shape of the tissue-engineered transplant. The aim of this review is to describe and discuss the scaffold materials of natural and synthetic origin that are of specific interest to tissue engineers. This review is based on previous publications and our own experience in the use of biomaterials of natural and synthetic origin for tissue engineering applications. Biodegradable polymers which have been used for tissue engineering applications are mainly based on clinically established medical devices and implants. In the group of macromolecules of natural origin collagen, alginate, agarose, hyaluronic acid derivatives, chitosan, and fibrin glue have been used as scaffolds. Man-made polymers such as polyglycolide (PGA), polylactides (PLLA, PDLA), poly(caprolactone) (PCL), and poly(dioxanone) (PDS) have been studied as matrix material to guide the differentiation and proliferation of cells into the targeted functional premature and/or mature tissue. Appropriate selection of scaffold material with respect to the targeted tissue is essential. Today, biomaterials of choice remain to be those approved by the US Food and Drug Administration. In spite of that, novel biomaterials should be developed specifically designed for tissue engineering applications.

Absorbable Implants↗
PubMed2001

Functional tissue engineering: the role of biomechanics in articular cartilage repair.

Articular cartilage shows little or no intrinsic capacity for repair in response to injury or disease, and even minor lesions or injuries may lead to progressive damage and joint degeneration. Tissue engineering is a relatively new but rapidly growing field that has sought to use combinations of implanted cells, biomaterials, and biologically active molecules to repair or regenerate injured or diseased tissues. Despite many advances, tissue engineers have faced significant challenges in repairing or replacing tissues that serve a predominantly biomechanical function, such as articular cartilage. An evolving discipline termed functional tissue engineering seeks to address these challenges by emphasizing and evaluating the role of biomechanical factors in the intrinsic and engineered repair of tissues and organs. In the current study, the authors describe some of the fundamental issues involving the interaction of biomechanical stresses in vivo and in vitro with native and repair articular cartilage and with other biomechanically functional tissues. A more thorough and formal investigation of these issues may provide a basis for developing rational design principles for tissue engineered replacement or repair of load-bearing structures in the body.

Animals↗
PubMed2001

A tissue engineered cell-occlusive device for hard tissue regeneration--a preliminary report.

Tissue engineering is an emerging discipline that applies engineering principles to create devices for the study, restoration, modification, and assembly of functional tissues and organs from native or synthetic sources. In the field of guided bone regeneration (GBR), cellular matter engineering has been applied, more or less successfully, to the development of biodegradable and bioresorbable devices with chemical, physical, or mechanical properties, structure, or form that permit active tissue integration with desirable cell types and tissue components. The employment of synthetic and naturally occurring polymers as well as sophisticated manufacturing technologies allow the tissue engineering of matrix configurations so that the biophysical limitations of mass transfer can be satisfied. The configuration of such a hybrid matrix can also be manipulated to vary the surface area available for cell attachment, as well as to optimize the exposure of the attached cells to nutrients. A biodegradable and bioresorbable device made of synthetic and natural polymers was engineered specifically for GBR procedures. The degradation and resorption kinetics as well as the mechanical properties give the device the potential to function as a carrier for bone growth factors. This innovative device was applied as a GBR membrane in a clinical investigation in seven patients.

Absorbable Implants↗
PubMed2001

[Human GDNF cDNA-engineered SH-SY5Y cells' neurotrophic and protective effect on primary dopaminergic neurons of rat].

OBJECTIVE: To construct a kind of engineered cell secreting human GDNF and study its possible effects on gene therapy of Parkinson's disease. METHOD: Human GDNF cDNA with Kozak sequence was cloned by RT-PCR, and then was transfected into SH-SY5Y cell line of human neuroblastoma. These engineered cells were co-cultured with primary mesencephalic cells of rats. Dopaminergic neurons were examined by immunohistochemistry. RESULTS: The number of dopaminergic neurons protected by engineered cells increased at least by 95.4% in comparison with the control cells (P < 0.01). The number of dopaminergic neurons protected by engineered cells against MPP+ toxicity increased 9.5-10.8 times (P < 0.01). CONCLUSION: A kind of engineered SH-SY5Y cells secreting human GDNF has been constructed successfully. These cells obviously protect dopaminergic neurons against degeneration and MPP+ toxication and may play an important role in gene therapy of Parkinson's disease.

1-Methyl-4-phenylpyridinium↗
PubMed2000

[Short tandem repeat loci examination after repair of coracoclavicular ligament injury by tissue engineered tendon].

OBJECTIVE: To evaluate the result of clinical application in the repair of coracoclavicular ligament injury by tissue engineered tendon using the technique of short tandem repeat loci examination. METHODS: In september 1999, human embryonic tendon cells and artificial materials were co-cultured in vitro to construct tissue engineered tendon, which repaired coracoclavicular ligament injury. After 6 months of operation, micro-tissue were sampled during the operation of removal of internal fixation, and morphological characteristics were examined by HE staining, DNA of tissues were extracted to examine D3S1754 and Cyar04 gene loci. RESULTS: The shoulder function of the patient was recovered well after operation, and no local or systemic immunological rejection were occurred. The electrophoresis typing showed 13/14 at D3S1754 and 8/9 at Cyar04 in the tissue of tissue engineered tendon, while the autogenous ligament were 13/13 and 8/8 at D3S1754 and Cyar04 loci respectively, which suggested that the tissue engineered tendon was survived in vivo. CONCLUSION: The examination of short tandem repeat loci is a better index to evaluate the survival situation of tissue engineered tissue after transplantation in clinical application.

Acromioclavicular Joint↗
PubMed2002

[Repair of tibial defect with tissue-engineered bone graft and radionuclide bone imaging in goats].

OBJECTIVE: To observe the effect of tissue-engineered bone grafts in repairing large tibial defect in goats, and assess the value of radionuclide bone imaging in monitoring the therapeutic effect of this approach. METHODS: Tibial defects measuring 2 cm was artificially made in the left tibia of 27 normal goats that were subsequently divided into 3 groups (9 each) to undergo treatment with tissue-engineered bone grafts, artificial bone grafts or without any grafts (as control group) respectively. The tissue-engineered bone grafts contained bone marrow stroma cells (BMSCs) of the goats and coral hydroxyapatite (CHAP), while the artificial bone grafts were from CHAP only. After the operations, radionuclide bone imaging was used to monitor the therapeutic effects at 2, 4 and 8 postoperative weeks. RESULTS: The 99mTc-MDP uptake of the region of interest (ROI) and the target to non-target ratios (T/NT) of the control group did not indicate any process of revascularization or bone regeneration. An increasing tendency of the revascularization and bone regeneration, in contrast, was observed in goats receiving the artificial bone grafts, a tendency that was far more obvious in the goats with tissue-engineered bone grafts. CONCLUSION: Tissue-engineered bone graft is eligible in repairing large defect in the caprine tibia, and radionuclide bone imaging may accurately monitor the revascularization and bone regeneration after the bone graft implantation.

Animals↗
PubMed2003

[Expression of basic fibroblast growth factor and fibronectin in tissue engineering skin allograft during healing process].

OBJECTIVE: The aim of this study was to explore the expression of basic fibroblast growth factor (bFGF) and fibronectin during the healing process of allograft tissue engineering skin. METHODS: The tissue engineering skin that was obtained from neonatal SD rats was cultured in the lab. Afterwards, the skin was grafted into adult SD rats, and the expressions of bFGF and fibronectin were detected on the 7th, 10th, 14th, 20th and 30th day after the allograft of the tissue engineering skin. The autografted skin in 15 adult Wistar rats and the normal skin in 15 Wistar were treated as the control. HE staining and immunohistochemical staining were used to examine the healing of grafted skin. RESULTS: The expression of bFGF and fibronectin was the strongest on the 10th day after graft, and was weaker before the 10th day and after the 14th day. The expression changes of bFGF and fibronectin were similar as they were in the autograft group. CONCLUSION: The expression changes of bFGF and fibronectin in the tissue engineering skin during the process of wound healing were similar to those of autografted skin, and these can promote the repair of tissue engineering skin allograft.

Animals↗
PubMed2003

[Repair of segmental bone defects in rhesus monkeys' radius with allogeneic tissue engineered bones].

OBJECTIVE: To construct tissue engineering bone with bio-derived materials and bone marrow stromal cells (MSCs), and to investigate the effect of allogeneic engineering bone implants on healing of segmental bone defects. METHODS: MSCs being aspirated aseptically from tibial tuberosities of young rhesus monkeys were induced into osteoblasts in vitro and then were cultured and marked with 5-bromo-2-deoxyuridine (BrdU). Tissue engineering bones were constructed with these labeled osteoblasts being seeded onto bio-derived materials made from fresh human bones which were treated physically and chemically, Then the constructs were implanted in 15 allogeneic monkeys to bridge 2.5 cm segmental bone defects of left radius as experimental groups, bio-derived materials only were implanted to bridge same size defects of right radius as control group. and, 2.5 cm segmental bone defects of both sides of radius were left empty in two rhesus monkeys as blank group. Every 3 monkeys were sacrificed in the 1st, 2nd, 3rd, 6th and 12th weeks postoperatively and both sides of the implants samples were examined macroscopically, histologicaly, and immunohistochemicaly. The two monkeys in blank group were sacrificed in the 12th week postoperatively. RESULTS: Apparent inflammatory reactions were seen around both sides of the implants samples in the 1st, 2nd, 3rd weeks, but it weakened in the 6th week and disappeared at the 12th week. The labeled osteoblasts existed at the 6th week but disappeared at the 12th week. The bone defects in experimental group were repaired and the new bone formed in multipoint way, and osteoid tissue, cartilage, woven bone and lamellar bone occurred earlier when compared with control group in which the bone defects were repaired in 'creep substitution' way. The bone defects in blank group remained same size at the 12th week. CONCLUSIONS: Engineering bones constructed with bio-derived materials and MSCs were capable of repairing segmental bone defects in allogeneic monkeys beyond 'creep substitution' way and making it healed earlier. Bio-derived materials being constituted with allogeneic MSCs may be a good option in construction of bone tissue engineering.

Animals↗
PubMed2003

[Gene-enhanced tissue engineering: applications in osteoinduction using cultured mesenchymal stem cells transduced with the bFGF gene].

To investigate the effect of basic fibroblast growth factor(bFGF) gene transfection on the proliferation and differentiation of mesenchymal stem cells (MSCs) and to provide basis for accelerating bone defect repairing using gene-enhanced tissue engineering technology, Rabbit periosteum-derived MSCs were transfected with the full-length rat bFGF cDNA in vitro. The transient and stable gene expression of bFGF were determined by immunohistochemistry. The proliferation and the synthesis alkaline phosphatase (ALP) and osteocalcin(OC) of the transfected MSCs were also examined. The results showed that bFGF cDNA could be transferred into osteoblasts and expressed stably at least 4 weeks. The proliferation and OC content of genetically modified MSCs were increased significantly, whereas the ALP activity remained no change. In conclusion, transfer of gene encoding bFGF to MSCs increases its proliferation and osteogenesis property. Based on the successful conjunction of the existing techniques of tissue engineering with the novel possibilities offered by modern gene transfer technology, an innovative concept, molecular tissue engineering, was put forward for the first time. As a new branch of tissue engineering, it represents both a new area and an important trend in tissue engineering research.

Alkaline Phosphatase↗
PubMed2003

[Construction of tissue engineering skin containing melanocytes].

OBJECTIVE: To construct a tissue engineering skin containing melanocytes by employing tissue engineering method. METHODS: The keratinocytes, dermal fibroblasts and melanocytes were isolated and purified. Then the cells were used to construct a tissue engineering skin containing melanocytes. The location of melanocytes in the tissue engineering skin were detected by Dopa staining, transmission electron microscope (TEM) and S-100 immunohistochemical staining. RESULTS: Melanocytes can be detected in the basal layer of the constructed tissue engineering skin. The results of TEM showed that the melanocytes were in good conditions. CONCLUSION: The artificial skin containing melanocytes was successfully constructed in vitro and can be used to repair the full-thickness skin defects.

Adolescent↗
PubMed2003

[Functional reconstruction with tissue engineered myoblast in facial muscle of rat].

OBJECTIVE: The purpose of this article is to discuss the reconstruction of facial muscle defects with tissue engineered myoblast in SD rats. METHODS: Using purified, subcultured myoblast of neonatal rats and type I collagen gels as extracellular matrix (ECM) and scaffold, tissue engineered muscle was transplanted in the face of syngeneic nutured rats. RESULTS: Tissue engineered myoblast generated and differentiated in vitro were observed with microscope. Myoblast fused each other and formed myofibers in the face of rats, nerve fibers and vessels regeneration could also be found in some samples. Postoperative electromiographs showed the myofibers were active when stimulating the nerve trunk that innervates the engineered facial muscle. CONCLUSION: Tissue engineered method is hopeful to be used as a new technique to reconstruct defects of facial muscle.

Animals↗
PubMed2004

The ACCEND program: a combined BS and MS program in environmental engineering that includes co-operative work experience.

Environmental engineering education has rapidly expanded in recent years and new teaching methods are needed. Many professionals and educators believe that a MS degree in environmental engineering should be the minimum in order to practice the profession, along with practical training. This paper describes an innovative program being offered at the University of Cincinnati that combines an integrated BS in civil engineering and an MS in environmental engineering with extensive practical co-operative education (co-op) experience, all within a five-year period. The program includes distance learning opportunities during the co-op periods. The result is a well-trained graduate who will receive higher pay and more challenging career opportunities, and who will have developed professionalism and maturity beyond that from traditional engineering programs.

Cooperative Behavior↗
PubMed2004

[The cryopreservation technology in research and development of tissue engineered products].

In this brief review, some key issues related to cryopreservation of seeding cells, scaffolds, and engineered tissues are outlined. The importance of cryopreservation technology to the research and development of tissue engineered products is demonstrated. The biological or biochemical reaction rate must be reduced or completely shut off in order to preserve the tissue engineered products for a long period of time. Cryopreservation may be one of the possible approaches to the fulfillment of this requirement. Seeding cells are stored at low temperature. Tissue engineered scaffold products are usually lyophilized. Engineered tissues are preserved by vitreous cryopreservation technology.

Cell Count↗
PubMed2004

[Construction of a tissue engineering skin containing capillary-like network].

OBJECTIVE: To construct a tissue engineering skin containing capillary-like network by employing tissue engineering method. METHODS: The numan umbilical vein endothelial cells(HUVECs) were isolated from a new-born umbilical cord. The keratinocytes and dermal fibroblasts were isolated from a new-born foreskin biopsy. After the collagen gel was prepared, the fibroblasts and the vascular endothelial cells were added in a ratio of 1 to 1 to construct a skin substitute containing capillary-like network. The skin substitute was observed by HE staining and immuno histochemical staining (VIII factor). The reconstructed skin containing capillary-like network was used to repair the nude mice skin defects in the experimental group. The tissue engineering skin containing no vascular endothelial cells was used in control group. RESULTS: Capillary-like network could be observed in the dermal layer of the tissue engineering skin, and the nude mice skin defects were repaired by the skin substitutes in the experimental group. In control group, no capillary-like network was found. CONCLUSION: The tissue engineering skin containing capillary-like network is successfully constructed in vitro and can be used to repair the full-thickness skin defects.

Animals↗
PubMed2005

[Expression of interleukin 2 and IL-2 receptor after implanted tissue engineered bones constructed with allogeneic marrow stromal stem cells and bio-derived materials in rhesus monkeys].

OBJECTIVE: To explore the feasibility of allogeneic marrow stromal stem cells (MSCs) as seed cells to construct tissue engineered bone by detecting the expressions of interleukin 2 (IL-2) and IL-2 receptor in rhesus monkeys after implanting these tissue engineered bones. METHODS: Engineered bones were constructed with osteoblasts which derived from allogeneic MSCs and bio-derived materials in vitro, and then were implanted to bridge 2.5 cm segmental bone defects of left radius in 15 rhesus monkeys as experimental group, bio-derived materials only were implanted to bridge same size defects of right radius as control group. Every 3 monkeys were sacrificed in the 1st, the 2nd, the 3rd, the 6th and the 12th weeks postoperatively and the expressions of IL-2 and IL-2 receptor in blood and graft samples were detected quantitatively by enzyme-linked immunosorbent assay (ELISA). RESULTS: There was no significant difference in the contents of IL-2 and its receptor between 2 groups (P>0.05). The contents of IL-2 and its receptor increased from the 2nd week and maintained high level from the 2nd to the 6th week, but decreased after 6 weeks. CONCLUSION: Tissue engineered bones constructed with allogeneic MSCs and bio-derived materials show low immunogenicity. Allogeneic MSCs may be used as seed cells to construct tissue engineered bone.

Animals↗
PubMed2005

[Experimental study on constructing muscle tissue in rabbits with tissue engineering methods].

OBJECTIVE: To explore the possibility of constructing tissue engineering muscles by combining allogeneic myoblasts with small intestinal submucosa (SIS) in rabbits. METHODS: A large number of purified myoblasts were obtained with multi-procedure digestion and repeated attachment method from skeletal muscles taken from extremities of immature rabbits which were born 7 days ago. The myoblasts were labeled with BrdU, and then combined with SIS to construct tissue engineering muscles. This kind of tissue engineering muscles were grafted into the gastrocnemius muscle defect (1.5 cm in length, 1.0 cm in width) of fifteen rabbits as the experimental group. The SIS was grafted into the same position in the control group. The rabbits were sacrificed 4, 6, 8 weeks after operation. The tissue engineering muscles were evaluated by macroscopic, histological and immunohistochemical observations, and by quantitative analysis of local immunocyte in the grafting site. RESULTS: Allogeneic myoblasts with SIS were combined perfectly in vitro. The SIS was connected tightly to surrounding skeletal muscles and inflammation response was obvious 4 weeks after grafting. The SIS began to break down and inflammation response became slight 6 and 8 weeks after operation. Compared with that of 8th week, the quantitative analysis of local immunocyte in 4th and 6th week in both experimental and control group has significance (P<0.05). Newly formed muscle tissues were found around SIS in the experimental group in 4th, 6th, and 8th week. Expression of BrdU and myosin immunohistochemical staining were positive in the experimental group and negative in the control group. CONCLUSION: Tissue engineering muscles of rabbits which are constructed by combining allogeneic myoblasts with SIS can survive and proliferate.

Animals↗