Biomedical subjects

Yng Jiin Wang

Publications and source records attributed to Yng Jiin Wang.

6 recordsLinked to original sources

PubMed2006

Growth of mesenchymal stem cells on electrospun type I collagen nanofibers.

We reconstituted type I collagen nanofibers prepared by electrospin technology and examined the morphology, growth, adhesion, cell motility, and osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (MSCs) on three nano-sized diameters (50-200, 200-500, and 500-1,000 nm). Results from scanning electron microscopy showed that cells on the nanofibers had a more polygonal and flattened cell morphology. MTS (3-[4,5-dimethythiazol-2-yl]-5-[3-carboxy-methoxyphenyl]-2-[4-sul-fophenyl]-2H-tetrazolium compound) assay demonstrated that the MSCs grown on 500-1,000-nm nanofibers had significantly higher cell viability than the tissue culture polystyrene control. A decreased amount of focal adhesion formation was apparent in which quantifiable staining area of the cytoplasmic protein vinculin for the 200-500-nm nanofibers was 39% less compared with control, whereas the area of quantifiable vinculin staining was 45% less for both the 200-500-nm and 500-1,000-nm nanofibers. The distances of cell migration were quantified on green fluorescent protein-nucleofected cells and was 56.7%, 37.3%, and 46.3% for 50-200, 200-500, and 500-1,000 nm, respectively, compared with those on the control. Alkaline phosphatase activity demonstrated no differences after 12 days of osteogenic differentiation, and reverse transcription-polymerase chain reaction (RT-PCR) analysis showed comparable osteogenic gene expression of osteocalcin, osteonectin, and ostepontin between cells differentiated on polystyrene and nanofiber surfaces. Moreover, single-cell RT-PCR of type I collagen gene expression demonstrated higher expression on cells seeded on the nanofibers. Therefore, type I collagen nanofibers support the growth of MSCs without compromising their osteogenic differentiation capability and can be used as a scaffold for bone tissue engineering to facilitate intramembranous bone formation. Further efforts are necessary to enhance their biomimetic properties.

Alkaline Phosphatase↗

PubMed2005

Influence of alginate on type II collagen fibrillogenesis.

Collagen II is the majority of extracellular matrix components in articular cartilage, which with the major functions of preventing expansion of the tissue and distributing the load of body weight. To obtain man-made ECM, the reconstitution of collagen could be conducted in the presence of negatively charged polysaccharide, such as alginate. Alginate is an anionic polysaccharide capable of eversible gelated in calcium ion solution to prepare different shapes of biomaterials. Its well-known biocompatibility makes it an ideal material in biomedical applications. Thus, the aim of this study was to evaluate the effects of alginate on the fibrillogenesis of type II collagen. The preliminary results revealed that inclusion of alginate into soluble type II collagen solution could inhibit the development of turbidity of collagen solution, and the apparent rate constants in lag and growth phases decreased during collagen formation period, both rate constants decreased to about one-third of the original constants, respectively. From TEM observations, the collagen fibrils were significantly thicker in 0.05% and 0.1% alginate as compared with pure collagen solution. Furthermore, the D-periods of collagen fibers kept unchanged significantly under all reconstituted conditions, which meant the packing of collagen monomer was probably not affected by adding these amounts of alginate.

Alginates↗

PubMed2004

Microencapsulation of parathyroid tissue with photosensitive poly(L-lysine) and short chain alginate-co-MPEG.

Human parathyroid glands were encapsulated using the alginate-PLL system in this study. In order to improve the mechanical strength and the biocompatibility, the microcapsules were fabricated with a three-layer structure that consisted of alginate/photosensitive poly(L-lysine)/short chain alginate-co-MPEG. These modified microcapsules were used for encapsulating human parathyroid tissue. In vitro experiments revealed that microencapsulated parathyroid glands maintained differentiative properties in culture, and the capsular membrane was freely permeable to the human parathyroid hormone. For in vivo experiments, these capsules were transplanted into parathyroidectomized SD-rats. After parathyroidectomy, serum calcium decreased from 2.25 to 1.68 mmol/L and remained in a constantly low concentration until transplantation. Parathyroidectomized SD-rats were normocalcemic after transplant of encapsulated parathyroid tissue. The microcapsules were then explanted at 12 weeks for examination. Histological evaluations of excised transplants revealed that the microcapsules remained intact structurally and were free of cell adhesions. The results demonstrated that human parathyroid tissue microencapsulated by this system retains stability and is functional both in vitro and in vivo. This encapsulating system will have valuable application for endocrine surgery in the future.

Alginates↗

PubMed2003

Osteogenic enrichment of bone-marrow stromal cells with the use of flow chamber and type I collagen-coated surface.

The stromal cells of the bone marrow are able to attach to the surface and differentiate into cells with bone-forming capability when stimulated with osteogenic supplements. In this study, we have employed a flow-chamber device containing a collagen-coated surface to enrich the potential osteoprogenitor cells from bone marrow stromal cells (BMSCs). The population of the cells attached to the collagen-coated substratum is about twice that attached to the uncoated surface. In the flow chamber, almost all marrow cells attached on the untreated glass were flushed out at the shear stress of 1.10 dyne/cm(2). On the other hand, 25% of the marrow cells remained attached to the collagen-coated glass, even under the shear stress of 1.30 dyne/cm(2). The collagen-attached marrow cells exhibited similar, specific alkaline phosphatase activity compared with that of the cells attached to the uncoated dish in the early stage of culturing. Nevertheless, only the collagen-attached marrow cells later expressed significant amounts of osteocalcin, which is a specific marker for osteoblast cells. Thus, we have successfully developed a protocol that uses a collagen-coated surface efficiently in a flow chamber to enrich the osteogenic cells from the BMSCs. This provides a useful tool to obtain osteogenic cells from bone marrow for biologic and clinical applications.

Alkaline Phosphatase↗

PubMed2003

Collagen as an immobilization vehicle for bone marrow stromal cells enriched with osteogenic potential.

The bone marrow contains mesenchymal cells that can be divided into two categories: cells of hemopoietic lineage and stromal cells. The stromal cells are adhesive to the surface of culture dish, and could be differentiated into cells with bone-forming capability when stimulated with osteogenic supplements. In this study, we have employed collagen to immobilize cells with osteogenic potential from bone marrow. A more than two-fold increase in cell density was obtained on the collagen-coated substratum as compared to the uncoated ones. The selected marrow cells exhibited elevated alkaline phosphatase activity in parallel with the proliferation of the cells attached to the collagen surface. The osteoblastic expression of the selected cells was further confirmed by the histological stains of alkaline phosphatase and mineral deposit. This method provides a simple and fast screening technique to isolate osteoprogenitor-enriched population from the bone marrow stromal cells. It has a great potential for future biological and clinical applications.

Animals↗

PubMed2002

Biocompatible microcapsules with enhanced mechanical strength.

A block copolymer, (short-chain alginate)-co-MPEG, was synthesized and used for coating the capsular membranes of the photosensitive microcapsules. The resulted microcapsules exhibited an excellent mechanical strength. The permeability test results revealed that the capsular membrane was freely permeable to cytochrome C and myoglobin, less permeable to serum albumin, and almost impermeable to IgG. In the cell attachment test, the results showed that the surface formed by (short-chain alginate)-co-MPEG copolymer could effectively reduce cell adhesion as compared to poly(L-lysine) and alginate. The microcapsules were evaluated by intraperitoneal implantation experiment of mice. The results demonstrated that microcapsules coated with (short-chain alginate)-co-MPEG were more biocompatible than the conventional alginate/PLL/alginate microcapsules.

3T3 Cells↗