Rung-Shu Chen

Long-term results of Taiwan Pediatric Oncology Group studies 1997 and 2002 for childhood acute lymphoblastic leukemia

The long-term outcome of 1390 children with acute lymphoblastic leukemia (ALL), treated in two successive clinical trials (Taiwan Pediatric Oncology Group (TPOG)-ALL-97 and TPOG-ALL-2002) between 1997 and 2007, is reported. The event-free survival improved significantly (P=0.0004) over this period, 69.3±1.9% in 1997–2001 to 77.4±1.7% in 2002–2007. A randomized trial in TPOG-97 testing L-asparaginase versus epidoxorubicin in combination with vincristine and prednisolone for remission induction in standard-risk (SR; low-risk) patients yielded similar outcomes. Another randomized trial, in TPOG-2002, showed that for SR patients, two reinduction courses did not improve long-term outcome over one course. Decreasing use of prophylactic cranial irradiation in the period 1997–2008 was not associated with increased rates of CNS relapse, prompting complete omission of prophylactic cranial irradiation from TPOG protocols, beginning in 2009. Decreased use of etoposide and cranial irradiation likely contributed to the low incidence of second cancers. High-risk B-lineage ALL, T-cell, CD10 negativity, t(9;22), infant, and higher leukocyte count were consistently adverse factors, whereas hyperdiploidy >50 was a consistently favorable factor. Higher leukocyte count and t(9;22) retained prognostic significance in both TPOG-97 and TPOG-2002 by multivariate analysis. Although long-term outcome in TPOG clinical trials is comparable with results being reported worldwide, the persistent strength of certain prognostic variables and the lower frequencies of favorable outcome predictors, such as ETV6-RUNX1 and hyperdiploidy >50, in Taiwanese children warrant renewed effort to cure a higher proportion of patients while preserving their quality of life.

Niemann-Pick disease type C (a cellular cholesterol lipidosis) treated by bone marrow transplantation.

Bone marrow transplantation (BMT) has been used for a wide variety of lysosomal storage diseases with encouraging results. We report a 3-year 5-month-old girl with Niemann–Pick type C disease (NPC) who received an allogeneic BMT. The patient presented with repeated lower respiratory tract infections, hepatosplenomegaly, failure to thrive, and developmental delay. Chest computed tomography (CT) revealed diffuse interstitial lung infiltration. Bone marrow and liver biopsies revealed abundant lipid-filled foamy macrophages. Skin fibroblast sphingomyelinase assay revealed partial deficiency. The ability of her skin fibroblasts to esterify cholesterol was very low, and the cells stained brightly for free cholesterol. She received BMT from a healthy HLA-identical male sibling donor at the age of 2 year 6 months. Full engraftment was evidenced by repeated bone marrow sex chromosome studies. Regression of the hepatosplenomegaly, markedly reduced foamy macrophage infiltration in bone marrow, and decreased interstitial lung infiltration was noted 6 months after BMT. Her neurological status, however, deteriorated. Follow-up magnetic resonance image (MRI) revealed progressive, diffuse brain atrophy. We conclude that resolution occurred in the liver, spleen, bone marrow and lung following successful engraftment. Such a response is remarkable since the underlying problem involves a membrane receptor for cholesterol. This positive response might be due to replacement of the monocyte–phagocytic system or it may imply the existence of cross-correction in the NPC membrane receptor defect by BMT approach. Since BMT did not halt the neurological deterioraton, it is unlikely to be an adequate treatment for NPC.

Improved treatment results for childhood acute myeloid leukemia in Taiwan

To improve treatment results for children with de novo acute myeloid leukemia (AML), we introduced a novel protocol, Taiwan Pediatric Oncology Group-AML-97A, for AML other than acute promyelocytic leukemia (APL), for which modified conventional protocols were used. From January 1, 1997, to December 31, 2002, 141 children younger than 17 years old with de novo AML were enrolled. In total, 117 patients with non-APL AML were treated with induction therapy of idarubicin and cytarabine (Ara-C), postremission therapy with high-dose Ara-C – containing regimens for four monthly courses, and moderate-dose therapy with idarubicin and Ara-C for four monthly courses. The first 19 patients with APL were treated with all-trans retinoic acid, idarubicin and Ara-C, with the remaining five patients receiving all-trans retinoic acid and idarubicin, followed by maintenance therapy for 2 years. Stem cell transplantation was performed in 29 patients in first remission with a similar outcome as chemotherapy alone. The remission rate in the AML-97A study was 90%, the 5-year survival 51±5.3% (s.e.) and the 5-year event-free survival 50±4.8%; for APL, these were 100%, 86±7.0, and 75±9.8%. For the whole group, the 5-year survival was 57±4.7% and the 5-year event-free survival 54±4.4%. The AML-97A regimen was well tolerated.

A novel polyurethane/cellulose fibrous scaffold for cardiac tissue engineering

The present work demonstrates a biomimetic electrospun scaffold based on polyurethane (PU) and ethyl cellulose (EC), featuring uniform fibrous nanostructures and three dimensional porous networks. The relationship between processing conditions and fibrous nanostructures is established which guides the rational processing with tunable fiber diameters. Additionally, the developed scaffold template reveals biocompatibility in retention and proliferation of cardiac myoblast H9C2 cells. The high mechanical strength of the PU/EC scaffolds enables the processing and handling of an ultrathin patch. Their elastomeric characteristics revealed the compatibility between the patch and contractile tissues. Furthermore, anisotropic PU/EC scaffolds with aligned nanofibers were successfully fabricated, exhibiting higher mechanical strength and essential characteristics for the survival and function of cardiac cells with native anisotropy. This work demonstrates a bioengineered PU/EC fibrous scaffold with uniform nanostructural webs and provides insight into the relationships between processing control, nanostructures and associated properties, with promising potential in cardiac tissue engineering.

Biphenyl liquid crystalline epoxy resin as a low-shrinkage resin-based dental restorative nanocomposite

Low-shrinkage resin-based photocurable liquid crystalline epoxy nanocomposite has been investigated with regard to its application as a dental restoration material. The nanocomposite consists of an organic matrix and an inorganic reinforcing filler. The organic matrix is made of liquid crystalline biphenyl epoxy resin (BP), an epoxy resin consisting of cyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (ECH), the photoinitiator 4-octylphenyl phenyliodonium hexafluoroantimonate and the photosensitizer champhorquinone. The inorganic filler is silica nanoparticles (∼70-100 nm). The nanoparticles were modified by an epoxy silane of γ-glycidoxypropyltrimethoxysilane to be compatible with the organic matrix and to chemically bond with the organic matrix after photo curing. By incorporating the BP liquid crystalline (LC) epoxy resin into conventional ECH epoxy resin, the nanocomposite has improved hardness, flexural modulus, water absorption and coefficient of thermal expansion. Although the incorporation of silica filler may dilute the reinforcing effect of crystalline BP, a high silica filler content (∼42 vol.%) was found to increase the physical and chemical properties of the nanocomposite due to the formation of unique microstructures. The microstructure of nanoparticle embedded layers was observed in the nanocomposite using scanning and transmission electron microscopy. This unique microstructure indicates that the crystalline BP and nanoparticles support each other and result in outstanding mechanical properties. The crystalline BP in the LC epoxy resin-based nanocomposite was partially melted during exothermic photopolymerization, and the resin expanded via an order-to-disorder transition. Thus, the post-gelation shrinkage of the LC epoxy resin-based nanocomposite is greatly reduced, ∼50.6% less than in commercialized methacrylate resin-based composites. This LC epoxy nanocomposite demonstrates good physical and chemical properties and good biocompatibility, comparable to commercialized composites. The results indicate that this novel LC nanocomposite is worthy of development and has potential for further applications in clinical dentistry.

Formation of salivary acinar cell spheroids in vitro above a polyvinyl alcohol-coated surface

Tissue engineering of salivary glands offers the potential for future use in the treatment of patients with salivary hypofunction. Biocompatible materials that promote acinar cell aggregation and function in vitro are an essential part of salivary gland tissue engineering. In this study, rat parotid acinar cells assembled into three-dimensional aggregates above the polyvinyl alcohol (PVA)-coated surface. These aggregates developed compact acinar cell spheroids resembling in vivo physiological condition, which were different from the traditional monolayered morphology in vitro. Cells remained viable and with better functional activity in response to acetylcholine in the spheroids and could form monolayered acinar cells when they were reinoculated on tissue culture polystyrene wells. To interpret the phenomenon further, we proposed that the formation of acinar cell spheroids on the PVA is mediated by a balance between two competing forces: the interactions of cell-PVA and cell-cell. This study demonstrated the formation of functional cell spheroids above a PVA-coated surface may provide an in vitro system for investigating cell behaviors for tissue engineering of artificial salivary gland.

Effects of chlorhexidine on stem cells from exfoliated deciduous teeth

BACKGROUND/PURPOSE Chlorhexidine (CHX) is a type of chemical antiseptic that is widely used in dental practice. Stem cells from human exfoliated deciduous teeth (SHED) are multipotent cells. However, there is little knowledge about the effects of chlorhexidine on SHED cells. The purpose of this study is to investigate the effects of CHX on SHED. METHODS SHED cells were treated with 0.1%, 0.01%, 0.001%, and 0.0001% CHX for 10 seconds to test the effects of different concentrations of CHX on SHED cells. The cells were also treated with 0.01% CHX for 10 seconds, 1 minute, and 5 minutes to test the time effects of CHX on SHED cells. Cell proliferation was investigated by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and an autonomously replicating sequence (ARS) assay was used for the evaluation of the mineralization potential. RESULTS This study demonstrated that different concentrations of CHX had cytotoxic effects on SHED cells in a dose- and time-dependent manner. The proliferation of SHED cells was inhibited by approximately 50% by the use of 0.01% CHX. It was also found that the cell proliferation and mineralization potential of SHED cells were inhibited to some degree by different concentrations of CHX. CONCLUSION Different concentrations of CHX can inhibit SHED cell proliferation in a dose- and time-dependent manner. In addition, the mineralization potential of SHED cells is inhibited to some degree by different concentrations of CHX.

Induction of differentiation and mineralization in rat tooth germ cells on PVA through inhibition of ERK1/2.

Poly(vinyl alcohol) (PVA) has been widely used in the field of biomedical applications because of its hydrophilic properties for desired functions. Nonetheless, the role of PVA in tooth germ (TG) cell differentiation and mineralization has seldom been explored. To test the capacity of PVA in regulating TG cell differentiation and mineralization, TG cells obtained from 4-day-old Wistar rats were cultured on the PVA substrate. It was found that PVA was able to promote TG cell exhibiting high levels of alkaline phosphatase (ALP) activity, mineralization, and mRNA expression of osteocalcin (OCN), osteopontin (OPN), dentin matrix protein 1 (DMP1) and enamelin. Even when the additives routinely administrated in the differentiation medium such as dexamethasone, beta-glycerophosphate and ascorbic acid were removed from the culture system, PVA itself still stimulated TG cells with the differentiation and mineralization ability. By showing the direct suppression of extracellular signaling-regulated kinase1/2 (ERK1/2) of TG cells treated with U0126, known to suppress the activation of ERK1/2, and significant synergistic effects between PVA and U0126, we demonstrated the suppression of ERK1/2 pathway is one of the effects of PVA-promoted TG cell differentiation and mineralization. Taken together, this study demonstrated a novel role of PVA in promoting the differentiation and mineralization of TG cells through ERK1/2 acting as a negative regulator.

Liquid crystalline epoxy nanocomposite material for dental application

BACKGROUND/PURPOSE Novel liquid crystalline epoxy nanocomposites, which exhibit reduced polymerization shrinkage and effectively bond to tooth structures, can be applied in esthetic dentistry, including core and post systems, direct and indirect restorations, and dental brackets. The purposes of this study were to investigate the properties of liquid crystalline epoxy nanocomposites including biocompatibility, microhardness, and frictional forces of bracket-like blocks with different filler contents for further clinical applications. METHODS In this study, we evaluated liquid crystalline epoxy nanocomposite materials that exhibited various filler contents, by assessing their cell activity performance using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and their microhardness with or without thermocycling. We also evaluated the frictional force between bracket-like duplicates and commercially available esthetic bracket systems using Instron 5566. RESULTS The liquid crystalline epoxy nanocomposite materials showed good biocompatibility. The materials having high filler content demonstrated greater microhardness compared with commercially available bracket materials, before and after the thermocycling treatment. Thus, manufacturing processes are important to reduce frictional force experienced by orthodontic brackets. CONCLUSION The microhardness of the bracket-like blocks made by our new material is superior to the commercially available brackets, even after thermocycling. Our results indicate that the evaluated liquid crystalline epoxy nanocomposite materials are of an appropriate quality for application in dental core and post systems and in various restorations. By applying technology to refine manufacturing processes, these new materials could also be used to fabricate esthetic brackets for orthodontic treatment.

The behavior of rat tooth germ cells on poly(vinyl alcohol)

The purpose of this study was to evaluate the behaviors of rat tooth germ (TG) cells cultured on poly(vinyl alcohol) (PVA). It was found that TG cells suspended and aggregated to form three-dimensional spheroids on PVA. Compared with traditional monolayered cells on tissue culture polystyrene, TG cell spheroids on PVA obviously increased the alkaline phosphatase activity, the degree of mineralization, and upregulated both osteopontin and dentin matrix protein 1 genes, regardless of the seeding density. Surprisingly, PVA appears to activate the alkaline phosphatase activity and mineralization effects on TG cell spheroids in the absence of a differentiation medium. Furthermore, the present study indicates that integrins may play an important role in the mineralization on TG cell spheroids by adding Arg-Gly-Asp (RGD) peptides. Therefore, the information presented here should help to clarify the role of PVA in the regulation of the mineralization, differentiation and integrin-mediation of TG cells.