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Biomedical subjects

Swee-Hin Teoh

Publications and source records attributed to Swee-Hin Teoh.

7 recordsLinked to original sources
PubMed2006

Co-culture of umbilical cord blood CD34+ cells with human mesenchymal stem cells.

Insufficient numbers of hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) sometimes limit allogenic transplantation of umbilical cord blood (UCB). Ex vivo expansion may overcome this limitation. Mesenchymal stem cells (MSCs), as non-hematopoietic, well-characterized skeletal and connective-tissue progenitor cells within the bone marrow stroma, have been investigated as support cells for the culture of HSCs/HPCs. MSCs are attractive for the rich environmental signals that they provide and for immunological compatibility in transplantation. Thus far, HSC/MSC co-cultures have mainly been performed in 2-dimensional (2D) configuration. We postulate that a 3-dimensional (3D) culture environment that resembles the natural in vivo hematopoietic compartment might be more conducive for regulating HSC expansion. In this study, we compared the co-culture of HSCs and MSCs in 2D and 3D configurations. The results demonstrated the benefit of MSC inclusion in HSC expansion ex vivo. Direct contact between MSCs and HSCs in 3D cultures led to statistically significantly higher expansion of cord blood CD34+ cells than in 2D cultures (891- versus 545-fold increase in total cells, 96- versus 48-fold increase of CD34+ cells, and 230- versus 150-fold increase in colony-forming cell assay [CFC]). Engraftment assays in non-obese diabetic/severe combined immunodeficiency mice also indicated a high success rate of hematopoiesis reconstruction with these expanded cells.

Animals↗
PubMed2006

Integrative haptic and visual interaction for simulation of PMMA injection during vertebroplasty.

In vertebroplasty, physician relies on both sight and feel to properly place the bone needle through various tissue types and densities, and to help monitor the injection of PMMA or cement into the vertebra. Incorrect injecting and reflux of the PMMA into areas where it should not go can result in detrimental clinical complication. This paper focuses on the human-computer interaction for simulating PMMA injection in our virtual spine workstation. Fluoroscopic images are generated from the CT patient volume data and simulated volumetric flow using a time varying 4D volume rendering algorithm. The user's finger movement is captured by a data glove. Immersion CyberGrasp is used to provide the variable resistance felt during injection by constraining the user's thumb. Based on our preliminary experiments with our interfacing system comprising simulated fluoroscopic imaging and haptic interaction, we found that the former has a larger impact on the user's control during injection.

Computer Simulation↗
PubMed2006

Flow visualization for interactive simulation of drugs injection during chemoembolization.

Chemoembolization is an important therapeutic procedure. A catheter was navigated to the artery that feeds the tumor, and chemotherapy drugs and embolus are injected directly into the tumor. There is a risk that embolus may lodge incorrectly and deprive normal tissue of its blood supply. This paper focuses on visualization of the flow particles in simulation of chemotherapy drugs injection for training of hand-eye coordination skills. We assume that the flow follows a defined path in the hepatic vascular system from the catheter tip. The vascular model is constructed using sweeping and blending operations. Quadrilaterals which are aligned to face the viewer are drawn for the trail of each particle. The quadrilateral in the trail is determined using bilinear interpolation. On simulated fluoroscopic image, the flow is rendered as overlaying and semitransparent quadrilaterals representing the particles' trails. This visualization model achieves a good visual approximation of the flow of particles inside the vessels under fluoroscopic imaging.

Antineoplastic Agents↗
PubMed2004

Surface modification of ultra thin poly (epsilon-caprolactone) films using acrylic acid and collagen.

Poly (epsilon-caprolactone) (PCL) has been used as a bioresorbable polymer in numerous medical devices as well as for tissue engineering applications. Its main advantage is its biocompatibility and slow degradation rate. PCL surface, however, is hydrophobic and cell-biomaterial interaction is not the best. We attempt for the first time to modify an ultra thin PCL surface with collagen. The PCL film was prepared using solvent casting and biaxial stretching technique developed in our laboratory. This biaxial stretching produced an ultra thin PCL 3-7 microm thick, ideal for membrane tissue engineering applications. The PCL film was pretreated using Argon plasma, and then UV polymerized with acrylic acid (AAc). Collagen immobilization was then carried out. The modified film surface was characterized by Fourier Transform Infrared (FT-IR) and X-ray Photoelectron Spectroscopy (XPS). Water contact angles were also measured to evaluate the hydrophilicity of the modified surface. Results showed that the hydrophilicity of the surface has improved significantly after surface modification. The water contact angle dropped from 66 degrees to 32 degrees. Atomic Force Microscopy (AFM) showed an increase in roughness of the film. A change from 46 to 60 nm in the surface morphology was also observed. The effect of cells attachment on the PCL film was studied. Human dermal fibroblasts and myoblasts attachment and proliferation were improved remarkably on the modified surface. The films showed excellent cell attachment and proliferation rate.

Acrylates↗
PubMed2003

Scaffold design and in vitro study of osteochondral coculture in a three-dimensional porous polycaprolactone scaffold fabricated by fused deposition modeling.

Tissue engineering offers an alternative method that can overcome some of the existing drawbacks of current articular defect repair methods because articular cartilage has a limited capacity to respond to injury. The solution may lie in the design of a three-dimensional load-bearing scaffold. Here we describe the tissue engineering of an osteochondral construct by coculturing osteogenic cells and chondrogenic cells on a three-dimensional load-bearing bioresorbable polymer scaffold. Porous polycaprolactone scaffolds were designed and fabricated via fused deposition modeling. Osteogenic cells were seeded and precultured in one-half of the partitioned scaffolds. Chondrogenic cells were later seeded into the other half. The cell-seeded scaffolds were cultured in a coculture medium. Both cell types proliferated, migrated, linked in their scaffold compartments, and integrated at the interface. Osteoblasts and chondrocytes produced different extracellular matrices in each scaffold compartment. Mineralized nodules deposited in the osteogenic cell seeded compartment. High osteocalcin was detected in precultured osteogenic cell supernatant and high alkaline phosphatase was detected in the coculture supernatant of osteochondral constructs. This study suggests that a tissue-engineered osteochondral construct with a three-dimensional polycaprolactone scaffold has the potential for osteochondral defect repair.

Alkaline Phosphatase↗