Comparison between in vitro properties of washed platelet concentrates suspended in M-sol and those in BRS-A, both of which were prepared with an automated cell processor.

BACKGROUND: Washed platelet concentrate (WPC) is prepared manually in general, but automated preparation is desirable to minimize variation in the WPC quality and enhance WPC production. Recently, the software was improved for an automated cell processor (ACP) to control all processes of WPC preparation. M-sol and BRS-A, which are mixtures of medical solutions, are widely used for WPC preparation with a manual method in Japan. In this study, we prepared WPC suspended in M-sol (WPC-M) or BRS-A (WPC-B) with the ACP, and compared their in vitro properties during 7-day storage. STUDY DESIGN AND METHODS: PC was divided into two equal aliquots for WPC-M and WPC-B. A divided PC, medical solutions and disposable materials were set in the ACP, and it was started to prepare WPC-M or WPC-B on Day 0. Prepared WPC was stored on a flatbed shaker until Day 7. RESULTS: The pH of WPC-M and WPC-B was maintained above 6.8 during the 7-day storage. The differences in aggregation (%), HSR (%), P-selectin expression, GPIbα expression, and phosphatidylserine expression between WPC-M and WPC-B were minimal until Day 3. CONCLUSION: The in vitro properties of WPC-B are not markedly different from those of WPC-M until Day 3.

Pre-incubation with hyaluronan reduces cellular damage after cryopreservation in densely cultured cell monolayers.

Reduction of cellular damage in densely cultured cell monolayers after cryopreservation by pre-incubation with hyaluronan (HA) was investigated. Monolayers of human dermal fibroblasts were cultured for 24 h at a density of 0.5×104 or 5×104 cells/cm2. The following two experimental conditions were compared: cells incubated with or without 0.5% w/w HA solution for 6 h. Samples were frozen from 4 to -80°C at 0.3 or 3°C/min in a cryoprotectant solution containing 10% w/w dimethyl sulfoxide, cooled down below -185°C, and then thawed. Post-thaw cell viability was evaluated by the fluorescent double-staining technique using a fluorescence microscope, and cellular uptake of the fluorescein-isothiocyanate-labeled HA after pre-incubation was also observed. Cell viability decreased with increasing cell density at both cooling rates without preliminary HA incubation. However, cell viability did not decrease at either cooling rate with preliminary HA incubation. Cellular HA uptake was observed. Pre-incubation with HA reduces cellular damage in densely cultured cell monolayers.

Cryoprotective effect of low-molecular-weight hyaluronan on human dermal fibroblast monolayers.

The purpose of this study was to assess the availability of low-molecular-weight (low-MW) hyaluronan (HA) as a cryoprotectant for cellular cryopreservation. To clarify whether low-MW HA is cryoprotective, we evaluated the effect of HA concentration (0-5% w/w) in a cryoprotectant solution on cell membrane integrity after freeze-thaw. A test sample was created using human dermal fibroblast monolayers incubated in a culture dish for 24 h (37 degrees C, 5% CO2). Sodium hyaluronate (MW 3 x 10(4)-5 x 10(4)) dissolved in medium served as the cryoprotectant solution. Samples were immersed in the solution for 2 h at 0-4 degrees C. They were frozen at a cooling rate of 3 degrees C/min from 4 to -80 degrees C, cooled further to below -185 degrees C, and then thawed. Cell membrane integrity after thawing was evaluated using a trypan blue exclusion assay. The sample and freezing procedures were repeated in subsequent experiments, while the conditions of the solution immersion with respect to the sample varied. Next, to clarify whether the cryoprotective action of HA is intra- or extracellular, we performed three experiments. The first studied the dependence of membrane integrity after freeze-thaw on preliminary incubation time (0.75-24 h at 37 degrees C) with a sample immersed in the solution (5% w/w HA). In the second, membrane integrity of thawed samples that were initially frozen in a medium instead of solution, by removing extracellular HA following a preliminary 6-h incubation period, were evaluated. Thirdly, we investigated cellular uptake of fluorescein isothiocyanate-labeled HA (MW 10(5), 1% w/w) after a preliminary 6-h incubation period under fluorescent microscopy (without freeze-thaw). The results show that HA had a cryoprotective effect, and that this cryoprotective action was intracellular. Therefore, low- MW HA proves to be a promising cellular cryoprotectant.

Rotational stability based on displacements obtained by simulation and measurement when torsion loading is applied to hip stems.

BACKGROUND: The rotational stability of cementless hip prostheses corresponds to the design of the fixation parts. The appropriate design of a femoral stem is important for secure primary fixation. The relative displacement of the bone and stems in the rotational direction should be used to evaluate the initial fixability and stability of stems. This article addresses the issue of the fixation method of hip stems and their rotational stability. METHODS: Specimens comprised four kinds of hip prosthesis. Rotational displacement that reproduced a torsion moment was analyzed and measured. Various finite element models (FEMs) of the four femoral stems were constructed for computer simulation. The measurement models consisted of an artificial femur and real stems used clinically. Common conditions of analyses and measurements were as follows: (1) a torsion load of 18.9 Nm was applied to the proximal femur as the intrarotation; (2) a stepping load of 1800 N was applied to the proximal tip of the stem; and (3) rigid contact existed between the distal end of the model femur and the rigid base. RESULTS: It was found that the relative rotational displacement obtained by FEMs was 0.21 mm for the Intra-Medullary Cruciate stem, 0.10 mm for the VerSys stem, 0.67 mm for the PerFix SV stem, and 0.03 mm for the Duetto SI stem. The relative rotational displacement obtained by the laser sensor was 0.37 mm for the Intra-Medullary Cruciate stem, 0.25 mm for the VerSys stem, 1.87 mm for the PerFix SV stem, and 0.17 mm in the Duetto SI stem. CONCLUSIONS: Judging from rotational displacement values obtained by the two approaches, three types of stem (Intra-Medullary Cruciate stem, VerSys stem, Duetto SI stem) provided rotational stability.