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ABSTRACT: Stem cells of fetal origin lie between embryonic and adult stem cells in terms of potentiality. Because of the ethical controversy surrounding embryonic stem cells and the relatively inferior quality of adult stem cells, the use of fetal stem cells would be an attractive option in future therapeutic applications. Here, we have investigated primitive characteristics of human umbilical-cord-derived fetal mesenchymal stem cells (UC fMSCs) during extensive expansion. We have successfully isolated and cultured UC fMSCs from all UC samples, but with two early fungal contaminations. UC fMSCs proliferated without significant evidence of morphological changes, and the average cumulative population-doubling level was over 25 for about 3 months. UC fMSCs showed the positive expression of several CD markers, known to be related to MSCs, including CD73 (SH-3, 4), CD90 (Thy-1), CD105 (SH-2), CD117 (c-kit), and CD166 (ALCAM). They demonstrated primitive properties throughout the expansion period: multilineage differentiation potentials examined by functional assays, a variety of pluripotent stem cell markers including Nanog, Oct-4, Sox-2, Rex-1, SSEA-3, SSEA-4, Tra-1-60, and Tra-1-81, minimal evidence of senescence as shown by beta-galactosidase staining, and the consistent expression of telomerase activity. These results suggest that UC fMSCs have more primitive properties than adult MSCs, which might make them a useful source of MSCs for clinical applications.
Cell and Tissue Research 11/2008; 334(3):423-33. · 3.11 Impact Factor
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ABSTRACT: The purpose of this biomechanical study was to determine optimized configuration of additional half-hitches placed after various arthroscopic sliding knots. Four commonly used arthroscopic sliding knots, namely, the Duncan loop, the SMC, Weston, and SP knot, were included in this study. All knots were tied with a single-hole knot pusher using a knot-tying simulator. After tying a sliding knot, it was backed up with zero to four additional reverse half-hitches on alternating posts (RHAPs). The first half-hitch was either placed on the same post (conventional RHAP; c-RHAP) or on the loop limb of the sliding knot (switched RHAP; s-RHAP). Ten knots were tied in each configuration using No. 2 Ethibond or No. 1 PDSII sutures. Loop security (loop circumference at 5 N) and knot security (highest load to failure at a cross-head displacement of 3 mm) were measured. Knot configurations, number of RHAPs, or mode of placement of the first half-hitch did not make clinically significant effects on loop security for either suture type. Using No. 2 Ethibond sutures, SMC, SP, and Weston knots required at least three additional half-hitches before knot security plateaued. However, when the first half-hitch was switched to the loop limb of the sliding knot, only two additional half-hitches (2 s-RHAPs) were required to reach maximum knot security. Using No. 1 PDSII sutures, SMC knots needed one additional half-hitch to reach maximum knot security, whereas SP and Weston knots required two half-hitches. However, SMC, SP and Weston knots with switched first half-hitch only required one additional half-hitch (1 s-RHAP) to achieve maximum knot security. This study demonstrated that switching the post just after the sliding knot could save one half-hitch without compromising knot security. That means that sliding knots with 2 s-RHAPs for No. 2 Ethibond and 1 s-RHAPs for No. 1 PDSII achieved knot security comparable to that of sliding knots with 3 c-RHAPs and with 2 c-RHAPs, respectively. The results suggested that the optimized configuration for arthroscopic sliding knots required a secure sliding knot, such as, the SMC, SP, or Weston knots and 2 s-RHAPs when No. 2 Ethibond or No. 1 PDSII suture materials were used considering the unraveling tendency of No. 1 PDSII. Results of the current study may be helpful for establishing arthroscopic sliding knot-tying routines for best results in clinical practice.
Knee Surgery Sports Traumatology Arthroscopy 04/2008; 16(8):787-93. · 2.21 Impact Factor
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ABSTRACT: We control the hydrophobicity of submicrometer silica spheres by modifying their surface with -CH3, -CH=CH2, -(CH2)(2)CH3, -CH2(CH2)(4)CH2-, -C(6)H(5), -(CH2)(7)CH3, and -(CH2)(11)CH3 groups through a modified one-step process. The scanning electron microscopy (SEM), quasi-elastic light scattering (QELS), UV-visible spectra, nitrogen sorption, and water vapor adsorption methods are used to characterize the particles. The SEM micrographs of the particles demonstrate that the modified particles are uniformly spherical, monodisperse, and well-shaped with the particle size ranging from 130 to 149 nm depending on the modified organic groups. In aqueous solution, the particles modified with phenyl groups have an obvious UV absorption peak at around 210 nm, whereas the other modified particles and unmodified particles do not have any UV-visible absorption peaks. There exist obvious differences in the amount of water vapor adsorbed depending on the type of surface functional groups of the modified particles. Compared with the unmodified particles, the modified particles have a lower water vapor adsorption because of the improved hydrophobicity of the particle surface. As a potential application, we prepared polystyrene/SiO2 nanocomposites by blending polystyrene with the synthesized particles. Water contact angle measurements show that the surface of the composite prepared with the modified particles are more hydrophobic. Confocal microscopy demonstrates that the particles are less agglomerated in the nanocomposite as the particles become more hydrophobic. These comprehensive experimental results demonstrate that the hydrophobicity of the particles can be easily controlled by surface modification with different organosilanes through a modified one-step process.
Langmuir 08/2007; 23(14):7799-803. · 4.19 Impact Factor
