Density separation of quiescent yeast using iodixanol.

As yeast are starved of nutrients, they enter G0, a quiescent state. Quiescent yeast (Q) cells retain viability for extended periods of time and resume growth following supplementation of missing nutrients. As such, Q cells have become a valuable model for studying longevity and self-renewal of chronologically aged cells. Traditional isolation of Q cells involves a relatively long centrifugation time through a continuous density gradient. Here, we describe a rapid and cost-effective Q-cell isolation technique that uses a single-density, one-step gradient prepared from media containing iodixanol.

Rapid separation of Arabidopsis male gametophyte developmental stages using a Percoll gradient.

Research investigating the dynamics of male gametophyte (MG) development has proven to be challenging for the plant science community. Here we describe our protocol for separating Arabidopsis MG developmental stages, which is based on the centrifugation of pollen through a discontinuous Percoll concentration gradient. This Percoll gradient can be formed using a pipette, and it does not require a gradient maker. The purity of the isolated developing spores is as high as 70%, and in most separations it is well above 80%. Using this protocol, we can separate four different stages of pollen development-uninucleate microspore (UNM), bicellular pollen (BCP), tricellular immature pollen (TCP) and mature pollen grain (MPG). The duration of the separation procedure, excluding the cutting of flower inflorescences, is 6 h. This is reduced to 4 h when using a vacuum cleaning method to remove the MPGs before the Percoll density separation.

Rapid visual identification of PCR amplified nucleic acids by centrifugal gel separation: Potential use for molecular point-of-care tests.

Recently, nucleic acid amplification and detection techniques have progressed based on advances in in microfluidics, microelectronics, and optical systems. Nucleic acids amplification based point-of-care test (POCT) in resource-limited settings requires simple visual detection methods. Several biosensing methods including lateral flow immunoassays (LFIA) were previously used to visually detect nucleic acids. However, prolonged assay time, several washing steps, and a need for specific antibodies limited their use. Here we developed a novel, rapid method to visualize amplified nucleic acids with naked eyes in clinical samples. First, we optimized conditions based on separation using very low centrifugal force and a density medium to detect human papillomavirus (HPV)-16 DNA in cervical specimens. After DNA extraction, HPV16 PCR was performed with biotin-labeled forward primer and Cy3-labeled reverse primer. PCR amplicon was mixed with streptavidin-magnetic beads, introduced into the density medium. After two-minute centrifugation, the result was visually identified. This system showed identical results with commercial HPV real-time PCR for 30 clinical samples and could detect up to 10(2)copies/mL of HPV DNA without any optical instruments. This robust and sensitive visual detection system is suitable for non-specialist personnel and point-of-care diagnosis in low-resource settings.

Red blood cell depletion from bone marrow and peripheral blood buffy coat: a comparison of two new and three established technologies.

BACKGROUND: Red blood cell (RBC) depletion is a standard technique for preparation of ABO-incompatible bone marrow transplants (BMTs). Density centrifugation or apheresis are used successfully at clinical scale. The advent of a bone marrow (BM) processing module for the Spectra Optia (Terumo BCT) provided the initiative to formally compare our standard technology, the COBE2991 (Ficoll, manual, "C") with the Spectra Optia BMP (apheresis, semiautomatic, "O"), the Sepax II NeatCell (Ficoll, automatic, "S"), the Miltenyi CliniMACS Prodigy density gradient separation system (Ficoll, automatic, "P"), and manual Ficoll ("M"). C and O handle larger product volumes than S, P, and M. STUDY DESIGN AND METHODS: Technologies were assessed for RBC depletion, target cell (mononuclear cells [MNCs] for buffy coats [BCs], CD34+ cells for BM) recovery, and cost/labor. BC pools were simultaneously purged with C, O, S, and P; five to 18 BM samples were sequentially processed with C, O, S, and M. RESULTS: Mean RBC removal with C was 97% (BCs) or 92% (BM). From both products, O removed 97%, and P, S, and M removed 99% of RBCs. MNC recovery from BC (98% C, 97% O, 65% P, 74% S) or CD34+ cell recovery from BM (92% C, 90% O, 67% S, 70% M) were best with C and O. Polymorphonuclear cells (PMNs) were depleted from BCs by P, S, and C, while O recovered 50% of PMNs. Time savings compared to C or M for all tested technologies are considerable. CONCLUSION: All methods are in principle suitable and can be selected based on sample volume, available technology, and desired product specifications beyond RBC depletion and MNC and/or CD34+ cell recovery.

Isolation of porcine monocyte population: a simple and efficient method.

Monocytes are important mediators of inflammatory processes and are in the focus of immunological studies. While the preparation of human monocytes is widely established, little is published on the isolation of porcine monocytes for experimental studies. The aim of this study is to establish a cost efficient method of preparing and culturing porcine monocytes of considerable purity and reasonable yield. In our method, we combined and modified different protocols of human monocyte preparation. The blood of a single pig is harvested and treated with EDTA to prevent coagulation. Peripheral blood mononuclear cells are obtained by a density gradient centrifugation using a Bicoll gradient and monocytes are harvested by culturing on serum-treated culture flasks, rinsing and tapping. A high yield is obtained by constant cooling of flasks and tubes. The purity of the culture is evaluated by the expression of CD14, using flow cytometry. Using this method, we reached a purity of 92.6 % (± 3.06 %). With this procedure, we established a reliable method to prepare and cultivate porcine monocytes which can be performed cost effectively and does not require special equipment.

Optimization of culture conditions for bone marrow stromal cells in RPMI-1640 medium.

UNLABELLED: Bone marrow mesenchymal stem cells are important for both research and clinical purpose. A number of culture methods for these cells are available on the market, many of them consisting of specialized growing media in combination with growth factors. Our goal was to optimize a less expensive culture method for bone marrow mesenchymal cells. MATERIAL AND METHODS: Eight samples of bone marrow aspirates from patients were used. Out these 8 samples 2 were from healthy people, 3 from chronic granulocytic leukemia patients, 2 from multiple myeloma patients and 2 from patients with myelodysplastic syndrome. Bone aspirates from healthy people were used to optimize the culture method and the rest were used for testing the optimized method. Two methods were tried: 1. Cell culture starting from whole bone marrow, 2) cell culture after bone marrow separation in density gradient with Histopaque. RESULTS: Cell culture starting from whole bone marrow gives better yields for mesenchymal stem cells than methods which include gradient density separation of mononuclear cells with Ficoll-Histopaque. CONCLUSIONS: We have optimised a less expensive cell culture method for bone marrow mesenchymal cells.

Fast and cost-effective purification of gold nanoparticles in the 20-250 nm size range by continuous density gradient centrifugation.

A multilayer quasi-continuous density gradient centrifugation method for separating 20-250 nm metal colloids with high size resolution while maintaining particle stability is presented. Colloidal mixtures containing monodisperse gold nanospheres and clusters thereof, in particular, gold dimers, are purified with yields up to 94%. The rapid method uses standard laboratory equipment.

Histopaque provides optimal mouse islet purification kinetics: comparison study with Ficoll, iodixanol and dextran.

Islet transplantation has become a very promising treatment for type 1 diabetes. To facilitate further clinical improvements in this exciting field, rodent islets are used to evaluate new strategies and modifications. One method to purify islets is on a density gradient, although the optimal gradient component can be debated. N=6 separate mouse islet isolations were used and the resulting islets were separated and purified on either a Ficoll, Histopaque, Dextran or Iodixanol gradient. Islets were assessed for recovery, viability, purity and in vitro functionality. Aliquots were transplanted into diabetic mice to assess in vivo functionality and survival. There was no difference in the number of islets recovered across groups nor in the size of recovered islets. Use of a Ficoll or Histopaque gradient led to the most pure and viable islets in comparison to Dextran and Iodixanol. Functionally, islets isolated on a Ficoll gradient had the highest glucose-stimulated insulin release in vitro while performing equally to Histopaque and Dextran gradients in vivo. Using a Ficoll gradient, however, comes at a higher monetary cost. We recommend using a Histopaque gradient, which led to the isolation of viable and functional islets with a reduced cost as compared to a Ficoll gradient.

A homemade device for linear sucrose gradients.

We have developed a simple and inexpensive device to obtain linear sucrose gradients with commonly used laboratory materials--a syringe, a flask, a plastic tube, and a piece of Pongo (Play-Doh). Refractive index values measured on sucrose fractions collected using our system demonstrate both the linearity and reliability of the gradients obtained.