Preserving frozen stallion sperm on dry ice using polymers that modulate ice crystalization kinetics

Cryopreserved semen is routinely shipped in liquid nitrogen. Dry ice could serve as an alternative coolant, however, frozen storage above liquid nitrogen temperatures (LN2, -196 °C) may negatively affect shelf-life and cryosurvival. In this study, we determined critical temperatures for storage of cryopreserved stallion sperm. We evaluated: (i) effects of cooling samples to different subzero temperatures (-10 °C to -80 °C) prior to storing in LN2, (ii) stability at different storage temperatures (i.e., in LN2, dry ice, -80 °C and -20 °C freezers, 5 °C refrigerator), and (iii) sperm cryosurvival during storage on dry ice (i.e., when kept below -70 °C and during warming). Furthermore, (iv) we analyzed if addition of synthetic polymers (PVP-40, Ficoll-70) modulates ice crystallization kinetics and improves stability of cryopreserved specimens. Sperm motility and membrane intactness were taken as measures of cryosurvival, and an artificial insemination trial was performed to confirm fertilizing capacity. We found that adding PVP-40 or Ficoll-70 to formulations containing glycerol reduced ice crystal sizes and growth during annealing. Post-thaw sperm viability data indicated that samples need to be cooled below -40 °C before they can be safely plunged and stored in LN2. No negative effects of relocating specimens from dry ice to LN2 and vice versa became apparent. However, sample warming above -50 °C during transport in dry ice should be avoided to ensure preservation of viability and fertility. Moreover, addition of PVP-40 or Ficoll-70 was found to increase sperm cryosurvival, especially under non-ideal storage conditions where ice recrystallization may occur.

Easy and Rapid Methods for Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells and Human Umbilical Wharton's Jelly-Derived Mesenchymal Stem Cells

These protocols describe modified methods that use Ficoll-Paque density gradient for umbilical cord blood-derived mesenchymal stem cells and explant method for Wharton's jelly-derived mesenchymal stem cells. The Ficoll-Paque density gradient method allows to obtain mesenchymal stem cells while eliminating monocytic cells. In this method, precoating the cell culture flasks with fetal bovine serum helps remove the monocytic cells and instruct more pure mesenchymal stem cells. On the other hand, the explant method for Wharton's jelly-derived mesenchymal stem cell is user-friendly and cost-effective than enzymatic methods. In this chapter, we provide a collection of protocols to obtain mesenchymal stem cells from human umbilical cord blood and Wharton's jelly.

A Comparative Study of Different Protocols for Isolation of Murine Neutrophils from Bone Marrow and Spleen

Neutrophils are considered as the main player in innate immunity. In the last few years, it has been shown that they are involved in different physiological conditions and diseases. However, progress in the field of neutrophil biology is relatively slow due to existing difficulties in neutrophil isolation and maintenance in culture. Here we compare four protocols based on density-gradient and immunomagnetic methods for isolation of murine neutrophils from bone marrow and spleen. Neutrophil isolation was performed using Ficoll 1.077/1.119 g/mL density gradient, Ficoll 1.083/1.090/1.110 g/mL density gradient and immunomagnetic method of negative and positive selection. The different protocols were compared with respect to sample purity, cell viability, yield, and cost. The functionality of isolated neutrophils was checked by NETosis analysis and neutrophil oxidative burst test. Obtained data revealed that given purity/yield/viability/cost ratio the protocol based on cell centrifugation on Ficoll 1.077/1.119 g/mL density gradient is recommended for isolation of neutrophils from bone marrow, whereas immunomagnetic method of positive selection using Dynabeads is recommended for isolation of splenic neutrophils.

Manufacturing of CD34 + HPC-enriched, high-purity mononuclear cell products from umbilical cord blood

The purpose of this study was to explore methods of selectively enriching CD34 + haematopoietic progenitor cells (HPC) in mononuclear cell (MNC) preparations, and to outline a procedure for cryopreservation and thawing of manufactured material. Density gradient centrifugation of umbilical cord blood was achieved using Ficoll-Paque™ media at 1.077 g/mL and 1.065 g/mL densities and Leucosep preparation tubes. Post-process samples were analysed for CD34 + and MNC content. Finally, MNCs were frozen down at a concentration of 8.5 × 106 cells/mL in CryoStor CS10 using an Asymptote VIAFreeze controlled rate freezer at a rate of - 2 °C per minute, then thawed and analysed for viability and recovery. Processing with 1.065 g/mL media selectively depleted non-HPC cell types, producing an approximately fourfold increase in CD34 + frequency (M ± 1SD = 1.4 ± 1.3%, P < 0.01) relative to the pre-process sample (M ± 1SD = 0.4 ± 0.3%), whereas 1.077 g/mL media produced only a twofold enrichment (0.7 ± 0.6, P < 0.01). This was not accompanied by any significant forfeit of CD34 + recovery (79 ± 32% vs. 78 ± 32% respectively; P = 0.87). The MNCs generated by the 1.065 g/mL procedure were of greater purity (96 ± 2%) than in the 1.077 g/mL procedure (80 ± 7%, P < 0.01). Post-thaw, MNC viability was 95 ± 1% and CD34 + viability was 98 ± 1%. Ultra-pure MNCs rich in CD34 + HPCs can be generated with a simple, inexpensive modification to Ficoll-Paque™ media. These products can be easily cryopreserved using a simple controlled rate freezing procedure.

Comparison of Haemonetics Cell Saver 5+ and manual density separation for optimum depletion of red blood cells and preservation of CD34+ cells in major ABO-incompatible bone marrow grafts

BACKGROUND AIMS

The current approach for preventing hemolysis of red blood cells (RBCs) in major ABO-incompatible bone marrow (BM) grafts after infusion is to deplete RBCs from BM products before transplantation. Traditionally, manual density separation (MDS) using Ficoll-Hypaque (Cytiva Sweden AB, Uppsala, Sweden has been used to accomplish RBC depletion. This process yields good CD34+ cell recovery, but it requires open manipulation and is labor-intensive and time-consuming. We hypothesized that an alternative automated method using Haemonetics Cell Saver 5+ (Haemonetics Corporation, Boston, MA, USA) would offer equivalent RBC depletion and CD34+ cell recovery. Small marrow volumes from pediatric donors can be processed using Cell Saver (CS) without adding the third-party RBCs necessary for other automated methods.

METHODS

This retrospective analysis comprised data from 58 allogeneic BM grafts. RBC depletion and CD34+ cell recovery from BM using MDS (35 grafts) were compared with CS (14 grafts). Nine products underwent RBC depletion using CS with Ficoll (CS-F) when RBC volume was less than 125 mL.

RESULTS

Linear regression analysis of log transformation of CD34+ cell recovery adjusted for log transformation of both baseline CD34+ cell content and baseline total volume showed no significant difference between MDS and CS (estimated coefficient, -0.121, P = 0.096). All products contained an RBC volume of less than 0.25 mL/kg post-processing. CD34+ cell recovery with CS-F was comparable to MDS and CS and suitable for pediatric recipients of allogeneic hematopoietic cell transplantation.

CONCLUSIONS

We provide evidence that an automated method using Haemonetics Cell Saver 5+ achieves RBC depletion and CD34+ cell recovery comparable to MDS when adjusting for baseline factors.

Minimal Coarse-Grained Model for Immunoglobulin G: Diffusion and Binding under Crowding

Immunoglobulin G (IgG) is the most common type of antibody found in blood and extracellular fluids and plays an essential role in our immune response. However, studies of the dynamics and reaction kinetics of IgG-antigen binding under physiological crowding conditions are scarce. Herein, we develop a coarse-grained model of IgG consisting of only six beads that we find minimal for a coarse representation of IgG's shape and a decent reproduction of its flexibility and diffusion properties measured experimentally. Using this model in Brownian dynamics simulations, we find that macromolecular crowding affects only slightly the IgG's flexibility, as described by the distribution of angles between the IgG's arms and stem. Our simulations indicate that, contrary to expectations, crowders slow down the translational diffusion of an IgG less strongly than they do for a smaller Ficoll 70, which we relate to the IgG's conformational size changes induced by crowding. We also find that crowders affect the binding kinetics by decreasing the rate of the first binding step and enhancing the second binding step.

Contrasting effect of ficoll on apo and holo forms of bacterial chemotaxis protein Y: Selective destabilization of the conformationally altered holo form

Chemotaxis Y (CheY), upon metal binding, displays a drastic alteration in its structure and stability. This premise prompted us to study the effect of crowding on the two conformationally distinct states of the same test protein. A comparative analysis on the structure and thermal stability in the presence and absence of the macromolecular crowder, ficoll, and its monomeric unit, sucrose, revealed a contrasting effect of ficoll on the apo and holo forms. In the presence of ficoll while the thermal stability (T_m) of the apo form is enhanced, the thermal stability of the holo form is reduced. The selective lowering of T_m for the holo form in the combined presence of ficoll and sucrose and not in sucrose alone suggests that the contrasting effect is due to the macromolecular nature of ficoll. Since metal-protein interaction remains unperturbed in the presence of ficoll and Mg²⁺ sequestration is ruled out in a systematic manner the alternative possibility for the exclusive reduction in the thermal stability of the holo form is the ficoll-induced modulation of the relative population of apo and holo forms of CheY.

E6020, a TLR4 Agonist Adjuvant, Enhances Both Antibody Titers and Isotype Switching in Response to Immunization with Hapten-Protein Antigens and Is Diminished in Mice with TLR4 Signaling Insufficiency

The mechanisms by which TLR4-based adjuvants enhance immunogenicity are not fully understood. We have taken advantage of a novel knock-in mouse strain that homozygously expresses two single-nucleotide polymorphisms (SNPs) that are homologous to human TLR4 (rs4986790 and rs4986791) and have been associated with LPS hyporesponsiveness in vivo and in vitro. TLR4-SNP (coexpressing mutations D298G/N397I in TLR4) mice that recapitulate the human phenotype were compared with wild-type (WT) mice for their hapten-specific Ab responses after immunization with hapten 4-hydroxy-3-nitrophenyl acetyl (NP) NP-Ficoll or NP-OVA in the absence or presence of a water-soluble TLR4 analog adjuvant, E6020. IgM and IgG anti-NP responses were comparable in WT and TLR4-SNP mice after immunization with either NP-Ficoll or NP-OVA only. E6020 significantly yet transiently improved the IgM and IgG anti-NP responses of both WT and TLR4-SNP mice to NP-Ficoll (T-independent), with modestly enhanced Ab production in WT mice. In contrast, T-dependent (NP-OVA), adjuvant-enhanced responses showed sustained elevation of NP-specific Ab titers in WT mice, intermediate responses in TLR4-SNP mice, and negligible enhancement in TLR4-/- mice. E6020-enhanced early humoral responses in WT and TLR4-SNP mice to NP-OVA favored an IgG1 response. After a second immunization, however, the immune responses of TLR4-SNP mice remained IgG1 dominant, whereas WT mice reimmunized with NP-OVA and E6020 exhibited increased anti-NP IgG2c titers and a sustained increase in the IgG1 and IgG2c production by splenocytes. These findings indicate that E6020 increases and sustains Ab titers and promotes isotype class switching, as evidenced by reduced titers and IgG1-dominant immune responses in mice with TLR4 insufficiency.

Determination of reference intervals for neutrophil granular enzymes is affected by cell isolation techniques

OBJECTIVES

Neutrophils and their granular enzymes such as neutrophil elastase (NE) and myeloperoxidase (MPO) play important roles in inflammatory diseases, and might be utilized as biomarkers for disease severity and progression. The aim of this study was to determine reference intervals for NE and MPO activity in healthy volunteers comparing two methods of neutrophil isolation.

METHODS

Neutrophils were isolated using ficoll density gradient centrifugation or immunomagnetic negative selection in two separate volunteers' cohorts. Subsequently, cells were lysed and incubated with chromogens for NE and MPO activity measurements, then measured with a microplate reader at 415 or 450 nm respectively.

RESULTS

The enzymatic activity of NE and MPO depended on the neutrophil isolation technique. Both enzymatic activities were significantly higher (P < 0.001) after isolating neutrophils with ficoll density gradient centrifugation than using the immunomagnetic negative selection.

CONCLUSIONS

We demonstrated that neutrophil isolation is an important factor that influences the outcome of enzymatic activity measurements. Techniques based on immunomagnetic negative selection are favorable, specifically for investigations related to NE and MPO activity. When using NE and MPO activity measurements in clinical practice, care must be taken to interpret the data depending on the applied cell isolation technique.

Cytokine Secretion Dynamics of Isolated PBMC after Cladribine Exposure in RRMS Patients

Cladribine (CLD) treats multiple sclerosis (MS) by selectively and transiently depleting B and T cells with a secondary long-term reconstruction of the immune system. This study provides evidence of CLD’s immunomodulatory role in peripheral blood mononuclear cells (PBMCs) harvested from 40 patients with untreated relapsing-remitting MS (RRMS) exposed to CLD. We quantified cytokine secretion from PBMCs isolated by density gradient centrifugation with Ficoll−Paque using xMAP technology on a FlexMap 3D analyzer with a highly sensitive multiplex immunoassay kit. The PBMC secretory profile was evaluated with and without CLD exposure. PBMCs isolated from patients with RRMS for ≤12 months had significantly higher IL-4 but significantly lower IFN-γ and TNF-α secretion after CLD exposure. PBMCs isolated from patients with RRMS for >12 months had altered inflammatory ratios toward an anti-inflammatory profile and increased IL-4 but decreased TNF-α secretion after CLD exposure. CLD induced nonsignificant changes in IL-17 secretion in both RRMS groups. Our findings reaffirm CLD’s immunomodulatory effect that induces an anti-inflammatory phenotype.

Characterization and optimization of polymer-polymer aqueous two-phase systems for the isolation and purification of CaCo2 cell-derived exosomes

Exosomes are cell-derived vesicles that present attractive characteristics such as nano size and unique structure for their use as drug delivery systems for drug therapy, biomarkers for prognostic, diagnostic and personalized treatments. So far, one of the major challenges for therapeutic applications of exosomes is the development of optimized isolation methods. In this context, aqueous two-phase systems (ATPS) have been used as an alternative method to isolate biological molecules and particles with promising expectations for exosomes. In this work, fractionation of exosomes obtained from CaCo2 cell line and culture media contaminants were individually performed in 20 polymer-polymer ATPS. The effect of design parameters such as polymer composition, molecular weight, and tie-line length (TLL) on polyethylene glycol (PEG)-Dextran, Dextran-Ficoll and PEG-Ficoll systems was studied. After partition analysis, 4 of the 20 systems presented the best exosome fractionation from contaminants under initial conditions, which were optimized via salt addition (NaCl) to a final concentration of 25 mM, to improve collection efficiency. The PEG 10,000 gmol-¹ –Dextran 10,000 gmol-¹ system at TLL 25% w/w with NaCl, showed the best potential isolation efficiency. Following this proposed strategy, an exosome purification factor of 2 in the top PEG-rich phase can be expected furtherly demonstrating that ATPS have the potential for the selective recovery of these promising nanovesicles.

How macromolecules softness affects diffusion under crowding

Diffusion in a macromolecularly crowded environment is essential for many intracellular processes, from metabolism and catalysis to gene transcription and translation. So far, theoretical and experimental work has focused on anomalous subdiffusion, and the effects of interactions, shapes, and composition, while the compactness or softness of macromolecules has received less attention. Herein, we use Brownian dynamics simulations to study how the softness of crowders affects macromolecular diffusion. We find that in most cases, soft crowders slow down the diffusion less effectively than hard crowders like Ficoll. For instance, at a 30% occupied volume fraction, the diffusion in Ficoll70 is about 20% slower than in soft crowders of the same size. However, our simulations indicate that elongated macromolecules, such as double-stranded DNA pieces, can diffuse comparably or even faster in hard crowders. We relate these effects to the volume excluded by soft and hard crowders to different tracers. Our results show that the softness and shape of macromolecules are crucial factors determining diffusion under crowding, relevant to diverse intracellular environments.

Delays during PBMC isolation have a moderate effect on yield, but severly compromise cell viability

OBJECTIVES

Peripheral blood mononuclear cells (PBMCs) are a versatile material for clinical routine as well as for research projects. However, their isolation via density gradient centrifugation is still time-consuming. When samples are taken beyond usual laboratory handling times, it may sometimes be necessary to pause the isolation process. Our aim was to evaluate the impact of delays up to 48 h after the density gradient centrifugation on PBMC yield, purity and viability.

METHODS

PBMCs were isolated from samples of 20 donors, either with BD Vacutainer CPT tubes (CPT) or with the standard Ficoll method. Isolation was paused after initial density gradient centrifugation for 0, 24, or 48 h. PBMC yield (% output/input), purity (% PBMCs/total cells) and viability (% Annexin V-/propidium iodide-) were compared.

RESULTS

The yield did not change significantly over time when CPT were used (55%/52%/47%), but did after isolation with the standard method (62%/40%[p<0.0001]/53%[p<0.01]). Purity was marginally affected if CPT were used (95%/93%[p=n.s./92%[p<0.05] vs. 97% for all time points with standard method). Whereas viable PBMCs decreased steadily for CPT isolates (62%/51%[p<0.001]/36%[p<0.0001]), after standard Ficoll gradient isolation, cell apoptosis was more pronounced already after 24 h delay, and viability did not further decrease after 48 h (64%/44%[p<0.0001]/40%[p<0.0001]).

CONCLUSIONS

In conclusion, our findings suggest that while post-centrifugation delays ≥24 h might have only a minor effect on cell yield and purity, their impact on cell viability is substantial, even when CPT are used.

IFNγ-IL-17-IL-22+CD4+ subset and IL-22-producing cells in tumor draining lymph nodes of patients with breast cancer

BACKGROUND

A recently introduced CD4+ T subset that mainly secretes interleukin (IL-) 22 has been reported to be associated with a variety of tumors, including colon, gastric, hepatocellular, and small- and large-cell lung carcinoma. Both tumor-promoting and - suppressing roles have been suggested for these cells. In the present study, we aimed to investigate the frequency of IL-22-producing subsets in tumor-draining lymph nodes (TDLNs) of the patients with breast cancer and determine their association with the clinicopathological characterizations of the disease.

METHODS

Thirty untreated women diagnosed with breast cancer were enrolled and their axillary lymph nodes were dissected during surgery. Mononuclear cells were isolated using Ficoll density gradient, activated, permeabilized, and stained by fluorochrome-conjugated antibodies against CD4, IL-22, IL-17, and IFNγ. The cells were then acquired on the FACSCalibur flow cytometer, and raw data was analyzed by the FlowJo software package (V10).

RESULTS

Our results demonstrated that 2.39% ± 0.39 of CD4+ lymphocytes in TDLNs of patients with breast cancer produced IL-22. Among them, 0.64% ± 0.8 just produced IL-22 but were negative for IFNγ and IL-17. Statistical analysis indicated that the frequency of CD4+IL-22+ cells was significantly higher in the patients with stage III and the ones with 3-9 tumor involved lymph nodes (N2) compared to those with stage II and those having 1-3 tumor involved lymph nodes (N1) (P = 0.008 and P = 0.004, respectively).

CONCLUSION

The higher frequency of IL-22-producing cells in draining lymph nodes of patients with more advanced tumors (higher stage (stage III) and more involved lymph nodes) suggests a role for IL-22-producing cells in the tumor progression and invasion. However, further studies with larger sample size and more functional studies are needed to clarify the role of IL-22-producing cells in breast cancer pathogenesis.

Formation and properties of liposome-stabilized all-aqueous emulsions based on PEG/dextran, PEG/Ficoll, and PEG/sulfate aqueous biphasic systems

Vesicle-stabilized all-aqueous emulsion droplets are appealing as bioreactors because they provide uniform encapsulation via equilibrium partitioning without restricting diffusion in and out of the interior. These properties rely on the composition of the aqueous two-phase system (ATPS) chosen for the emulsion and the structure of the interfacial liposome layer, respectively. Here, we explore how changing the aqueous two-phase system from a standard poly(ethyleneglycol), PEG, 8 kDa/dextran 10 kDa ATPS to PEG 8 kDa/Ficoll 70 kDa or PEG 8 kDa/Na₂SO₄ systems impacts droplet uniformity and partitioning of a model solute (U15 oligoRNA). We also compare liposomes formed by two different methods, both of which begin with multilamellar, polydisperse vesicles formed by gentle hydration: (1) extrusion, which produced vesicles of 150 nm average diameter, and (2) vortexing, which produced vesicles of 270 nm average diameter. Our data illustrate that while droplet uniformity and stability are somewhat better for samples based on extruded vesicles, extrusion is not necessary to create functional microreactors, as emulsions stabilized with vortexed liposomes are just as effective at solute partitioning and allow diffusion across the droplet's liposome corona. This work expands the compositions possible for liposome-stabilized, all-aqueous emulsion droplet bioreactors, making them amenable to a wider range of potential reactions. Replacing the liposome extrusion step with vortexing can reduce time and cost of bioreactor production with only modest reductions in emulsion quality.

Isolation of Human Neutrophils from Venous Blood

Venous blood provides a ready source of large numbers of unstimulated granulocytes and mononuclear cells. Exploiting the differences in the relative densities of the leukocytes circulating in venous blood, one can separate leukocytes from erythrocytes as well as isolate the individual leukocyte populations in high purity for use in ex vivo studies. For selected functional studies, such as transcriptional analysis or cytokine quantitation, addition of an immunomagnetic negative selection step to the standard isolation protocol can yield highly purified human neutrophils.

Isolation of Human Peripheral Blood T-Lymphocytes

Peripheral blood is the most common source of T-lymphocytes for in vitro culture. Here, we present a simple and standardized method for small- or large-scale isolation of viable T-lymphocytes and other mononuclear cells from fresh peripheral blood or buffy coat blood samples using the density gradient centrifugation. T-cells obtained using the protocol described here can be used for a variety of downstream analysis, including cellular, molecular, and functional assays.

A Prospective Comparison of Discontinuous Euroficoll and Eurodextran Gradients for Islet Purification

Density gradient separation of islets from exocrine tissue is usually performed with Ficoll. However, this reagent adds significantly to the cost of the isolation. The aim of this study was to evaluate the performance of Dextran as a potential low-cost substitute for Ficoll and to evaluate the effects of cold storage of the pancreatic digest prior to purification. Pancreases were procured from mongrel dogs, loaded with collagenase and mechanically dissociated. Washed pancreatic digest was collected and divided into two fractions that were purified using discontinuous gradients on the Cobe 2991 processor using identically prepared EuroFicoll (EF) or EuroDextran (ED) gradients. Alternate groups were suspended in EC and stored on ice, while the other fraction were resuspended in the 1.108-g/mL gradient layer (either EF or ED) and loaded into the COBE. This tissue layer was overlaid with layers of densities 1.096 and 1.037 g/mL and a HBSS cap, and centrifuged for 5 min at 800 × g. Purified islets were collected from the interface between the 1.037 and 1.096 layers and islet recovery, purity, and function were assessed. From a series of eight isolations, 72.9 ± 8.2% (mean ± SEM) of the islets were recovered from the EF purified gradients compared with 62.6 ± 8.3% from ED gradients ( p = NS, paired t-test). Gradients of ED that were run following hypothermic storage of the digest in cold EC solution (stored ED) had reduced islet recovery when compared with islet recovery from gradients prepared in EF(stored EF) (51.6 ± 9.6% for ED stored vs. 72.9 ± 11.9 for EF stored, p < 0.05). Islet recovery from EF gradients was equivalent between the stored and nonstored groups. The purity of preparations from the stored ED gradients was also reduced (71.3 ± 4.3%) when compared with islets that were immediately purified after dissociation (82.5 ± 4.8%, p < 0.05). Static glucose stimulation assay showed equivalence between the islets from ED and EF gradients. The stimulation index (SI) was 9.3 ± 0.9 for EF islets compared with 7.9 ± 1.4 for ED islets for digest purified immediately. However, if the digest was hypothermically stored in EC solution, a decrease in functional viability was observed in both the EF and the ED groups (7.7 ± 1.4 and 5.9 ± 0.8, respectively). Out of five alloxan-induced diabetic nude mice transplanted under the kidney capsule with 2000 islets isolated from the nonstored groups, three remained euglycemic >50 days posttrans-plant with either EF or ED islets. These experiments demonstrate effective recovery of equivalent numbers of canine islets using discontinuous gradients of ED or EF immediately following enzymatic digestion. However, following storage of the digest in cold EC solution results in a reduction in both islet recovery and function when gradients of ED are utilized. © 1998 Elsevier Science Inc.

Introducing a New Experimental Islet Transplantation Model using Biomimetic Hydrogel and a Simple High Yield Islet Isolation Technique

BACKGROUND

Islet transplantation could be an ideal alternative treatment to insulin therapy for type 1 diabetes Mellitus (T1DM). This clinical and experimental field requires a model that covers problems such as requiring a large number of functional and viable islets, the optimal transplantation site, and the prevention of islet dispersion. Hence, the methods of choice for isolation of functional islets and transplantation are crucial.

METHODS

The present study has introduced an experimental model that overcomes some critical issues in islet transplantation, including in situ pancreas perfusion by digestive enzymes through common bile duct. In comparison with conventional methods, we inflated the pancreas in Petri dishes with only 1 ml collagenase type XI solution, which was followed by hand-picking isolation or Ficoll gradient separation to purify the islets. Then we used a hydrogel composite in which the islets were embedded and transplanted into the peritoneal cavity of the streptozotocin-induced diabetic C57BL/6 mice.

RESULTS

As compared to the yield of the classical methods, in our modified technique, the mean yield of isolation was about 130-200 viable islets/mouse pancreas. In vitro glucose-mediated insulin secretion assay indicated an appropriate response in isolated islets. In addition, data from in vivo experiments revealed that the allograft remarkably maintained blood glucose levels under 400 mg/dl and hydrogel composite prevents the passage of immune cells.

CONCLUSION

In the model presented here, the rapid islet isolation technique and the application of biomimetic hydrogel wrapping of islets could facilitate islet transplantation procedures.

A Modified Combination of Two Methods for Isolation of Polymorphonuclear Granulocytes from Human Blood for Polymerase Chain Reaction (PCR)

BACKGROUND

The aim of the study was to determine a rapid and simple method for isolation of polymorphonuclear (PMN) granulocytes from human blood appropriate for PCR of extracted DNA.

METHODS

A modification of the combined dextran plus Ficoll-Hypaque methods was the final method used in 41 samples of normal white cells from humans. The changes encompassed a lower dextran-blood ratio (2:1), a shorter centrifugation time of leukocytes, a small volume of Ficoll-Hypaque suspension, and a decreased speed in the last centrifugation. The final key point was skipping the lysis of erythrocytes to avoid interference by salt solutions.

RESULTS

These modifications rendered a mean PMN granulocyte recovery and purity of over 95% with a very narrow 2 - 8% coefficient of variation and did not alter the purity of DNA extraction.

CONCLUSIONS

The combined dextran plus Ficoll-Hypaque method changes offer a fast and simple method to obtain an adequate purity of granulocytes for PCR.

Gelatin Density Gradient for Isolation of Islets of Langerhans

Isolation of islets of Langerhans (islets) has been performed by means of collagenase digestion of the pancreatic tissue combined with density gradient separation of islets from unwanted exocrine tissues. An enormous number of islets are necessary for clinical islet transplantation. The density gradient used for isolation of a large number of islets should satisfy several requirements in addition to those for the conventional density gradients, such as high viscosity for creating fine interfaces with a large area, easy sterilization, and low cost. This study is concerned with the development of a new density gradient made of low-molecular-weight gelatin. We isolated islets from the hamster pancreatic tissue using the gelatin density gradients. The yield and purity of islet and its insulin release function were compared with those of islets isolated using Ficoll and Ficoll-Conray density gradients that have been conventionally used. The new gelatin density gradient can separate islets from the unwanted exocrine tissue as effectively as the Ficoll density gradient and more effectively than the Ficoll-Conray density gradients. The islets collected using the gelatin gradient retain ability of insulin release increase in response to glucose stimulation, similar to those isolated by the Ficoll-Conray gradient and more than those collected by the Ficoll gradient. In addition, the gelatin effectively inhibited enzyme activities, that is, collagenase and proteolytic enzymes released from the exocrine tissue, and thus it can inhibit overdigestion of islets during their density gradient isolation. The gelatin gradient satisfies most of the additional requirements for islet isolation from the pancreatic tissue of large animals mentioned above. Although several factors, such as molecular weight of gelatin, osmolality of the gradient, and centrifugal conditions, still remain to be optimized, our results suggest that the gelatin gradient has potentiality to isolate islets from the pancreatic tissue of a large animal.

Fluorescence Analysis of Vitamin D Receptor Status of Circulating Tumor Cells (CTCS) in Breast Cancer: From Cell Models to Metastatic Patients

The Vitamin D receptor (VDR) expressed in normal breast tissue and breast tumors has been suggested as a new prognostic biomarker in breast cancer (BC). Besides, increasing evidence supports the view that the detection of circulating tumor cells (CTCs) predicts outcome in early and metastatic BC. Consequently, an evaluation of VDR expression in the CTCs of BC patients may allow optimization of their treatment. As an attempt to profile and subtype the CTCs of metastatic patients, we established an innovative fluorescence technique using nine BC cell lines to visualize, define, and compare their individual VDR status. Afterwards, we tested the CTC presence and VDR expression in blood samples (cytospins) collected from 23 metastatic BC patients. The results demonstrated major differences in the VDR levels among the nine cell lines, and VDR positive CTCs were detected in 46% of CTC-positive patients, with a total of 42 CTCs individually analyzed. Due to the limited number of patients in this study, no correlation between VDR expression and BC subtype classification (according to estrogen receptor (ER), progesterone receptor (PR) and HER2) could be determined, but our data support the view that VDR evaluation is a potential new prognostic biomarker to help in the optimization of therapy management for BC patients.

Isolation and Functional Analysis of Human Neutrophils

This unit describes the isolation of human polymorphonuclear neutrophils (PMN) from blood using dextran sedimentation and Percoll or Ficoll-Paque density gradients. Assays of neutrophil functions including respiratory burst activation, phagocytosis, and microbial killing are also described.

Simple separation of chicken gonadal primordial germ cells with and without foreign genes

Simplicity is the key element of an inexpensive technique described that is superior in performance to previous methods. It can make it the rapid method of choice to obtain reasonable yields of purified primordial germ cells (PGCs) for immediate production of germline chimeric chickens with integrated foreign genes. After Ficoll centrifugation, the purity of PGCs from gonads was 80.9+/-0.08% (mechanical) compared with 86.1+/-0.19% (enzymatic). GFP gene and lacZ-transduced chicken gonadal primordial germ cells (gPGCs) examined 72h after transduction had a transfection efficiency of approximately 61% and approximately 64%, respectively. After 10 days of G418 selection, approximately 90 and 92% of pure gPGCs did not contain other cells following this Ficoll gradient centrifugation method of preparation.

Rapid screening of granulocyte antibodies with a novel assay: flow cytometric granulocyte immunofluorescence test

BACKGROUND

White blood cell (WBC)-associated antibodies can lead to severe pulmonary transfusion reactions (transfusion-related acute lung injury [TRALI]). Investigation of a large number of blood donor samples using the standard granulocyte immunofluorescence test (GIFT) and granulocyte agglutination test (GAT) proved to be difficult to perform due to the time-consuming process and the large quantity of test cells required. This study describes the novel flow cytometric GIFT (Flow-GIFT) method for a rapid detection of granulocyte antibodies by flow cytometric analysis.

STUDY DESIGN AND METHODS

A total of 141 sera were analyzed for the presence of granulocyte antibodies that were previously associated with suspected TRALI. As test cells whole blood samples from human neutrophil antigen (HNA)-typed donors were isolated using cell sedimentation in a ficoll density gradient. WBCs were incubated with the respective serum and binding of antibodies to the test cells was detected using fluorescein isothiocyanate-conjugated anti-human antibody. Standard GIFT and GAT were performed as reference methods.

RESULTS

Seven sera containing anti-HNA-3a, CD16, and HLA Class I were negative in the standard GIFT and eight sera containing anti-HNA-2a, anti-CD16, and anti-HLA Class I were not detected in the GAT. The novel Flow-GIFT was able to detect all granulocyte antibodies, which were only detectable in a combination of standard GIFT and GAT. In serial dilution tests, the Flow-GIFT detected the antibodies at higher dilutions than the reference methods GIFT and GAT.

CONCLUSION

The Flow-GIFT method permits rapid detection of granulocyte antibodies requiring fewer donor test cells. This method is ideal for automation and will potentially open the way for screening of granulocyte antibodies in a large donor population.

Iodixanol-controlled density gradient during islet purification improves recovery rate in human islet isolation

BACKGROUND

For pancreatic islet transplantation, islet purification minimizes the risks associated with islet infusion through the portal vein by reducing the amount of transplanted tissue. However, the purification step may result in decreased numbers of islets recovered from digested tissue and be traumatic to the islets. In this study, we evaluated the effectiveness of iodixanol-controlled density gradients on the islet purification step.

METHODS

For 14.3% of the isolations, the density was 1.085 g/cm3, 32.1% were 1.090 g/cm3, 46.4% were 1.095 g/cm3, 3.6% were 1.100 g/cm3, and 3.6% were 1.105 g/cm3, indicating that the density varies with each isolation. This has profound implications for the difficulty of islet purification. According to the density of digested tissue before purification, the density of the purification solutions was controlled by changing the volumetric ratio of iodixanol and the purification solutions (iodixanol-Kyoto [IK] solutions).

RESULTS

Islet yield after purification and rate of postpurification recovery were significantly higher in the IK group than with standard continuous gradient purification by Ficoll solutions (islet yield=Ficoll group: 377,230+/-50,207 islet equivalents, IK group: 594,136+/-50,570 islet equivalents, P less than 0.01; percentage of recovery=Ficoll group: 55.6%+/-5.8%, IK group: 84.9%+/-4.2%, P less than 0.01). In vitro and in vivo assays suggest that the quality of islets was similar between the two groups.

CONCLUSION

Our data suggest that using an iodixanol-controlled density gradient improves the islet recovery rate in human islet isolation. On the basis of these data, we now use this purification method for clinical islet transplantation.

The efficiency of Percoll and Ficoll density gradient media in the isolation of marrow derived human mesenchymal stem cells with osteogenic potential

BACKGROUND

Percoll and Ficoll density gradient media are widely used in the isolation of human mesenchymal stem cells (hMSCs) for research. However, the efficacy of the two methods in the isolation of hMSCs and their differentiation potentiality have not been evaluated. In this study, the ability of the two methods to isolate MSCs from human bone marrow was compared.

METHODS

Colony forming unit-fibroblasts (CFU-Fs) are considered colonies of stem and progenitor cells. Thus it was proposed that MSCs be represented by CFU-Fs. Therefore, we compared the relative efficiencies of the two media, Ficoll and Percoll, in isolating colony forming unit-fibroblasts with alkaline phosphatase activity (CFU-F/ALP(+)) and the percentages of CD166(+)/CD34(-), CD90(+)/CD34(-), SH3(+)/CD34(-) and CD105(+)/CD34(-) cells in all nucleated cells from bone marrow (BM).

RESULTS

A significantly higher number of nucleated cells could be isolated with Ficollthan with Percoll. The percentages of cells which were CD166(+)/CD34(-), CD90(+)/CD34(-), SH3(+)/CD34(-) and CD105(+)/CD34(-) were significantly higher for the Ficoll group. The colony-forming efficiency from Ficoll isolates (119 +/- 69 CFU-F/ALP(+) per dish) was also higher than that from Percoll isolates (46 +/- 35 CFU-F/ALP(+) per dish) (p < 0.01). However, the average colony size, percentage of CFU-Fs with ALP(+) and the differentiation abilities of CFU-Fs were not significantly different between groups.

CONCLUSIONS

Ficoll and Percoll are both suitable but the Ficoll methodology is superior to that of Percoll in the preparation of hMSCs.

NMR observation of Tau in Xenopus oocytes

The observation by NMR spectroscopy of microinjected 15N-labelled proteins into Xenopus laevis oocytes might open the way to link structural and cellular biology. We show here that embedding the oocytes into a 20% Ficoll solution maintains their structural integrity over extended periods of time, allowing for the detection of nearly physiological protein concentrations. We use these novel conditions to study the neuronal Tau protein inside the oocytes. Spectral reproducibility and careful comparison of the spectra of Tau before and after cell homogenization is presented. When injecting Tau protein into immature oocytes, we show that both its microtubule association and different phosphorylation events can be detected.

Tissue stabilizer methods in histochemistry

Quantitative studies in the 1960s established that the tissue disruption and enzyme loss which occurs when unfixed cryostat sections are incubated could be prevented with high concentrations of polyvinyl alcohol without inhibition of enzyme activity. This use of polymeric stabilizers has been largely confined to studies of 'soluble' dehydrogenases in tissue sections. However, optimum conditions for 'soluble' enzymes in cut sections may not be ideal for membrane-bound enzymes or for whole cells, where an over-stabilization of membranes can lead to restricted entry of reagents and thereby low activities. Lower concentrations, or other stabilizers such as Ficoll (a synthetic polysucrose) and collagen polypeptides, have been used in such cases. Suggested criteria for a tissue stabilizer are: (i) The stabilizer should be chemically inert, of defined and constant composition, and generally available; (ii) The tissue must remain structurally intact during the incubation, and the final preparation should look 'clean' and have the proper morphology; (iii) The component being assayed must remain inside the section, and not diffuse into the incubation medium. Ideally, it and any reaction product should remain at their original loci, although it may not always be possible to verify this; (iv) Recorded activities should be comparable to those found in biochemical systems under similar conditions.

The impact of drying method and formulation on the physical properties and stability of methionyl human growth hormone in the amorphous solid state

The objective of this work was to investigate the impact of drying method and formulation on the physical stability (aggregation) and selected important physical properties of dried methionyl human growth hormone (Met-hGH) formulations. Solutions of Met-hGH with different stabilizers were dried by different methods (freeze drying, spray drying, and film drying), with and without surfactant. Properties of the dried powders included powder morphology, specific surface area (SSA), protein surface coverage, thermal analysis, and protein secondary structure. Storage stability of Met-hGH in different formulations was also studied at 50 degrees C and at 60 degrees C for 3 months. The dried powders displayed different morphologies, depending mainly on the method of drying and on the presence or absence of surfactant. Film dried powders had the lowest SSA (approximately 0.03 m(2)/g) and the lowest total protein surface accumulation (approximately 0.003%). Surfactant caused a reduction in the SSA of both spray dried and freeze dried powders. Spray dried powders showed greater protein surface coverage and SSA relative to the same formulations dried by other means. Greater in-process perturbations of protein secondary structure were observed with polymer excipients. Formulation impacted physical stability. In general, low molecular weight stabilizers provided better stability. For example, the aggregation rate at 50 degrees C of Met-hGH in a freeze dried trehalose-based formulation was approximately four times smaller than the corresponding Ficoll-70-based formulation. Drying method also influenced physical stability. In general, the film dried preparations studied showed superior stability to preparations dried by other methods, especially those formulations employing low molecular weight stabilizers.

Conventional freezing, straw, and open-pulled straw vitrification of mouse two pronuclear (2-PN) stage embryos

Little is known on the cryopreservation of mouse pronuclear (PN) stage embryos. In the present experiment the mouse 2-PN stage embryos were cryopreserved by conventional freezing, straw, or open-pulled straw (OPS) vitrificaiton methods. The conventional freezing solution was 1.5 mol/L ethylene glycol (EG), and vitrification solutions were EFS30 (30% EG, Ficoll, and sucrose), EFS40 (40% EG, Ficoll, and sucrose), EDFS30 (15% EG, 15%dimethyl sulfoxide [DMSO], Ficoll, and sucrose), or EDFS40 (20% EG, 20%DMSO, Ficoll, and sucrose). The blastocyst rate of 2-PN stage embryos cryopreserved by conventional method (30.4%) was lower than those vitrified by straw method with EDFS (56.9% to 69.1%), by OPS method (66.0% to 85.7%), and that of control (80.8%) (P < 0.05). With a given vitrificaiton solution EFS30, EFS40, EDFS30, or EDFS40, the blastocyst rate of embryos vitrified by the OPS method (66.7%, 66.0%, 85.7%, or 76.9%) was higher than that of those vitrified by the straw method (46.8%, 43.8%, 69.1%, or 56.9%) (P < 0.05). When mouse 2-PN-stage embryos were vitrified with EDFS30 by straw or OPS method, the highest blastocyst rate was achieved (69.1% or 85.7%) and was similar to that of the control, respectively. The embryos transfer results revealed that the full-term development of blastocysts derived from 2-PN stage embryos vitrified by OPS method with EDFS30 (19.9%) was similar to that of the control (23.5%), and higher than that of those cryopreserved by conventional freezing (9.3%) (P < 0.05). The present research demonstrates that the OPS method, especially with EDFS30, is more effective in cryopreserving mouse 2-PN embryos.

Cell cycle dependent phosphorylation and subnuclear organization of the histone gene regulator p220(NPAT) in human embryonic stem cells

Human embryonic stem (ES) cells have an expedited cell cycle ( approximately 15 h) due to an abbreviated G1 phase ( approximately 2.5 h) relative to somatic cells. One principal regulatory event during cell cycle progression is the G1/S phase induction of histone biosynthesis to package newly replicated DNA. In somatic cells, histone H4 gene expression is controlled by CDK2 phosphorylation of p220(NPAT) and localization of HiNF-P/p220(NPAT) complexes with histone genes at Cajal body related subnuclear foci. Here we show that this 'S point' pathway is operative in situ in human ES cells (H9 cells; NIH-designated WA09). Immunofluorescence microscopy shows an increase in p220(NPAT) foci in G1 reflecting the assembly of histone gene regulatory complexes in situ. In contrast to somatic cells where duplication of p220(NPAT) foci is evident in S phase, the increase in the number of p220(NPAT) foci in ES cells appears to precede the onset of DNA synthesis as measured by BrdU incorporation. Phosphorylation of p220(NPAT) at CDK dependent epitopes is most pronounced in S phase when cells exhibit elevated levels of cyclins E and A. Our data indicate that subnuclear organization of the HiNF-P/p220(NPAT) pathway is rapidly established as ES cells emerge from mitosis and that p220(NPAT) is subsequently phosphorylated in situ. Our findings establish that the HiNF-P/p220(NPAT) gene regulatory pathway operates in a cell cycle dependent microenvironment that supports expression of DNA replication-linked histone genes and chromatin assembly to accommodate human stem cell self-renewal.

A clinical-scale selective allodepletion approach for the treatment of HLA-mismatched and matched donor-recipient pairs using expanded T lymphocytes as antigen-presenting cells and a TH9402-based photodepletion technique

Selective allodepletion is a strategy to eliminate host-reactive donor T cells from hematopoietic stem cell allografts to prevent graft-versus-host disease while conserving useful donor immune functions. To overcome fluctuations in activation-based surface marker expression and achieve a more consistent and effective allodepletion, we investigated a photodepletion process targeting activation-based changes in p-glycoprotein that result in an altered efflux of the photosensitizer TH9402. Expanded lymphocytes, generated using anti-CD3 and IL-2, were cocultured with responder cells from HLA-matched or -mismatched donors. Optimal results were achieved when cocultured cells were incubated with 7.5 muM TH9402, followed by dye extrusion and exposure to 5 Joule/cm(2) light energy at 5 x 10(6) cells/mL. In mismatched stimulator-responder pairs, the median reduction of alloreactivity was 474-fold (range, 43-fold to 864-fold) compared with the unmanipulated responder. Third-party responses were maintained with a median 1.4-fold (range, 0.9-fold to 3.3-fold) reduction. In matched pairs, alloreactive helper T-lymphocyte precursors were reduced to lower than 1:100 000, while third-party responses remained higher than 1:10 000. This establishes a clinical-scale process capable of highly efficient, reproducible, selective removal of alloreactive lymphocytes from lymphocyte transplant products performed under current Good Manufacturing Practice. This procedure is currently being investigated in a clinical trial of allotransplantation.

High detection rate of circulating tumor cells in blood of patients with prostate cancer using telomerase activity

BACKGROUND

Circulating tumor cells (CTCs) cannot be readily detected with currently available methods in the majority of patients with prostate cancer. Telomerase activation, one of the major immortalization events, is found in most cases of prostate cancer. We attempted to develop a method using telomerase activity to isolate CTCs in patients with prostate cancer.

PATIENTS AND METHODS

Peripheral blood mononuclear cells (PBMCs) were isolated from whole blood using Ficoll-Hypaque. Immunomagnetic beads coated with an epithelial cell-specific antigen antibody (BerEP4) were used to harvest epithelial cells from PBMCs. Telomerase activity was detected in harvested epithelial cells using the telomerase-PCR-enzyme-linked immunosorbent assay method.

RESULTS

Blood samples from 107 patients with prostate cancer were studied. CTCs were detected in 19 of 24 (79%) patients with advanced prostate cancer. In contrast, CTCs were not detected in blood samples from 22 healthy male volunteers. CTCs were even identified in patients with an undetectable (<0.1 ng/ml) serum prostate-specific antigen (PSA). CTCs were detected in 55 of 70 (79%) patients with localized prostate cancer before radical prostatectomy (n = 30) or brachytherapy (n = 40). CTCs were also detected in 3 of 13 patients (23%) with an undetectable serum PSA measured at least 1 year after radical prostatectomy, which is consistent with the expected relapse rate in this setting.

CONCLUSION

CTCs can be detected using telomerase activity in a large majority and a wide variety of patients with prostate cancer, including those with localized disease.

Effect of macromolecules in solutions for vitrification of mature bovine oocytes

This study was designed to evaluate vitrification procedures for in vitro matured bovine oocytes for efficient blastocyst production after warming, IVF and culture. A second goal was to replace serum as the macromolecular component of the vitrification solution, without compromising efficacy. The first experiment compared two containers, open pulled straws (OPS) versus cryoloops, and two vitrification protocols: short equilibration (H-TCM-199+10% EG+10% DMSO+20% FCS for 30s, followed by H-TCM-199+20% EG+20% DMSO+20% FCS+0.48M galactose for 20s) versus long equilibration (H-TCM-199+3% EG+20% FCS for 10min, followed by H-TCM-199+31% EG+20% FCS+1M galactose for 20s). Subsequent experiments used only cryoloops and the short equilibration protocol to evaluate the effect of replacing FCS with defined macromolecules (BSA, Ficoll, PVP, and PVA) in vitrification solutions. Cryoloops were superior to OPS for vitrification of oocytes as determined by blastocyst production (P<0.05). The short and long vitrification protocols gave similar results. The presence of macromolecules in vitrification solutions for bovine oocytes was necessary for acceptable post-warming developmental capacity; 20% FCS, 1% and 2% BSA, 6% and 18% Ficoll, 6% and 20% PVP, 1% PVA, and the combinations of 18% Ficoll+1% BSA, and 6% PVP+1% BSA provided similar protection during vitrification of oocytes; development ranged from 14.8% to 23.0% blastocysts/oocyte, which was not different (P>0.05) from non-vitrified controls (26.9-34.0% blastocysts/oocyte). Too much (6%) and too little (0.3%) BSA, and 0.3% PVA for vitrification resulted in lower blastocyst production (P<0.05) relative to unvitrified oocytes.

Effect of In-Straw Thawing on In Vitro- and In Vivo-Development of Vitrified Mouse Morulae

For the purpose of ascertaining parameters to embryo transfer on some domestic animals, mouse morulae were used as a model to investigate the effect of in-straw thawing on in vitro and in vivo-development of vitrified embryos. Embryos were vitrified in 0.25 ml straws preloaded with dilution solution (0.5 M Sucrose) and thawed in the straw by mixing the vitrification solution (Ethylene glycol + Ficoll 70 + Sucrose) and the dilution solution at 25 degrees C. The embryos were randomly divided into six groups and expelled from the straws after they had been suspended in the in-straw mixture for 3 min, 5 min, 8 min, 12 min, 16 min, and 20 min, respectively, and then they were collected under a microscope for in vitro culture or direct transfer. The in vitro developmental rates of the embryos were 92.3% to 98.4% and hatching rates were 64.1% to 75.6% for the groups of 3 min to 16 min, showing no significant differences with those of nonfrozen controls (100%, 76.2%; P > 0.05). While embryos were suspended in the straw for 20 min, the developmental rate (86.6%) and hatching rate (52.4%) were significant lower than those of the control (100%, 76.2%; P < 0.01). When the 168 frozen-thawed embryos (in-straw thawing for 5 min) and 168 fresh embryos were transferred, respectively, the proportion of live fetuses in the pregnant recipients between them (58.7% vs. 54.5%) showed no significant difference (P > 0.05). The data indicate that vitrification with EFS30 and suspension in the in-straw mixture for 3 min to 16 min, when thawing, did not affect the in vitro developmental rate and hatching rate. Moreover, the in vivo developmental rate between vitrified embryos and fresh embryos did not differ significantly. It can be concluded that this method is fit for nonsurgical embryo transfer in some domestic animals with a suggestion that the operation of embryo transfer should be accomplished within 16 min.

Open-pulled Straw (OPS) Vitrification of Mouse Hatched Blastocysts

This study was first employed to investigate the developmental potential of mouse hatched blastocyts (HBs) vitrified by a two-step open-pulled straw (OPS) method. HBs were obtained by culture of morulae in vitro. First, the embryos were placed in four cryprotectant solutions - that is, 10% ethylene glycol (EG), 10%E + 10%D (10% EG and 10% dimethyl sulphoxide (DMSO) in mPBS), EFS30 (30% EG, Ficoll, and sucrose) and EDFS30 (15% EG, 15% DMSO, Ficoll, and sucrose)--at 25 degrees C for 0.5 to 10 min, respectively, to determine their optimal survival after rapid dilution in 0.5 M sucrose. Secondly, based on the above best survival, the embryos were plunged into liquid nitrogen after first pretreatment in 10%E for 0.5 min and then 0.5 min equilibration in EFS30 (Group 1), or 10%E + 10%D and EDFS30 for 0.5 min, respectively (Group 2). When warming, three methods were used to dilute the cryoprotectants from the vitrified embryos. The embryos were assessed by the re-expansion of the blastocoel or development to term. The result showed that all the vitrified-warmed HBs got high in vitro survival rates (83.7% to 98.9%). The highest in vitro survival rates (87.8% in Group 1, 98.9% in Group 2) were obtained when the vitrified embryos were diluted first in 0.3 M sucrose for 5 min, then in 0.15 M sucrose for 2 min (method C). When the vitrified embryos diluted with method C were transferred, their survival rate in vivo (35.5% to 42.2% of the total) were similar to (P > 0.05) that of control (45.7%). These results demonstrate OPS method was highly efficient for the cryopreservation of mouse HBs.

VACUTAINER CPT and Ficoll density gradient separation perform equivalently in maintaining the quality and function of PBMC from HIV seropositive blood samples

Background

For immune monitoring studies during HIV vaccine clinical trials, whole blood specimens from HIV seropositive (HIV⁺) patients may be collected at multiple sites and sent to a central location for peripheral blood mononuclear cell (PBMC) isolation, cryopreservation and functional evaluation. In this study we show a comparison of two PBMC preparation options, Ficoll density gradient separation (Ficoll) and Cell Preparation Tubes (CPT) using shipped whole blood specimens from 19 HIV⁺ patients (CD4 > 350, viral load < 50). The pre- and post- cryopreservation performance of samples collected by these two methods were compared by assessment of antigen-specific IFNγ expression in CD8⁺ and CD8^- T cells, cellular viability, and cellular recovery.

Results

The results indicate that cryopreserved PBMC samples tested for CMV- and HIV- specific interferon-gamma (IFNγ) expression performed equivalent to the respective fresh PBMC processed under both collection conditions. Compared to fresh PBMC, the viability was significantly lower for cryopreserved PBMC derived using Ficoll, although it was never less than 90%. There were no significant differences in the IFNγ response, viability, or recovery between cryopreserved PBMC derived by Ficoll and by CPT.

Conclusion

These data suggest that CPT is an efficient system for the collection and cryopreservation of functionally active HIV⁺ PBMC, as well as a viable alternative to Ficoll gradient separation.

Optimization in osmolality and range of density of a continuous ficoll-sodium-diatrizoate gradient for isopycnic purification of isolated human islets

INTRODUCTION

According to previous estimates from large animals and man, a minimum of approximately 5000 to 6000 engrafted islet equivalents (IEQ)/kg recipient weight is critical to establish insulin independence. Utilizing a single donor, this threshold yield of purified islets can be retrieved from approximately one third of all isolations. The aim of this study was to improve human islet purification by optimization of the osmolality and the density range of the continuous Ficoll-sodium-diatrizoate (FSD) gradient to facilitate consistent purities >80% of human islet preparations without considerable loss of islet yield.

METHODS

Aliquots of human pancreatic digests were placed on continuous density gradients. After centrifugation, sequential aliquots were extracted for amylase and insulin to determine the relative and cumulative density distribution of endocrine and exocrine tissue. We addressed the impact of two factors: (1) osmolalities (300 to 600 mosm/kg) in the gradient of FSD covering a density range of 1.070 to 1.100 g/cm(3); and (2) density (FSD 500/1.070 to 1.100) versus density-osmolarity gradient (DO-FSD 400-530/1.080 to 1.113).

RESULTS

The density of exocrine and endocrine tissue increased with rising osmolality. Differences in density of both tissues were highest at 450 and lowest at 300 and 600 mOsmol/kg. Purity and recovery were highest at 450 versus 400 or 500 mOsm/kg (NS). Exocrine but not endocrine tissue was more dense in DO-FSD than in FSD gradient (P < .05). The differences in density were 0.004 versus 0.013 g/cm(3) (P < .01), resulting in an increased islet purity and recovery.

CONCLUSION

The best osmolality for the FSD 1.070 to 1.100 g/cm(3) is at 450 mOsm/kg. Using the DO-FSD may improve human islet purification allowing successful clinical islet transplantation.

Bi-specific immunomagnetic enrichment of micrometastatic tumour cell clusters from bone marrow of cancer patients

Metastasis-the spread of tumour cells from a primary lesion to distant organs-is the main cause of cancer-related death, and bone marrow (BM) is a frequent site for the settlement of disseminated tumour cells. Many BM samples harbour isolated tumour cells, whereas tumour cell clusters, as the potential precursors of solid distant metastases, are rarely detected after current enrichment procedures. We have analysed BM samples from 43 patients with carcinomas of the breast, colon and ovaries; 41 of these patients had no clinical signs of overt metastases (stage M0). Tumour cells in BM were enriched with immunomagnetic beads coupled to monoclonal antibodies against both EpCAM and HER2/neu. After enrichment, tumour cells were identified by immunostaining with the anti-cytokeratin antibody A45-B/B3. In total, 886 CK-positive cells were detected in 16 (35%) samples after immunomagnetic enrichment as compared to 34 cells in 9 (21%) samples using Ficoll density centrifugation previously used as the standard enrichment technique. Most remarkably, clusters of 2 to 10 CK-positive cells were found in 75% of CK-positive samples enriched by immunobeads, whereas no CK-positive cell clusters were detected after Ficoll enrichment. The method described offers an excellent tool for the enrichment of micrometastatic tumour cell clusters; these clusters may represent the initial stage of development from a single disseminated tumour cell towards an overt metastasis.

A simple method to optimize peripheral blood mononuclear cell preparation from cynomolgus monkeys and improve mixed lymphocyte reactions

INTRODUCTION

The standard Ficoll-Hypaque method used to isolate peripheral blood mononuclear cells (PBMC) gives very variable results when used with cynomolgus monkey blood. We have improved the method by using special cell processing tubes (CP-tubes), originally developed for clinical use.

METHODS

Blood samples were collected from cynomolgus monkeys and processed for PBMC preparation using either the classical Ficoll-Hypaque method or CP-tubes following various centrifugation protocols. The preparations were compared according to their cellular content as well as their response in the mixed lymphocyte reaction (MLR).

RESULTS

Good PBMC separation was achieved in >90% of samples by centrifugation of blood samples in CP-tubes for 40-45 min at 1650 x g and 20 degrees C. For the remaining samples, poor PBMC separation was probably due to low corpuscular hemoglobin concentrations (< 28 g/dl), but this could be rectified by using one to two additional centrifugations. The PBMC preparations thus obtained showed lower red blood cell (RBC) and polymorphonuclear (PMN) cell contamination, reacted well to mitogen and showed improved MLR stimulation indices vs. standard Ficoll-Hypaque-PBMC-derived preparations. The inhibitory effect of Cyclosporine-A (CsA) was within the low nanomolar range with both methods.

DISCUSSION

These results demonstrate that the use of CP-tubes is a practical way of improving PBMC separation and MLR responses with cynomolgus monkey blood.

The unresponsiveness of aged mice to polysaccharide antigens is a result of a defect in macrophage function

A reduction in macrophage (MPhi) function with aging makes mice less responsive to bacterial capsular polysaccharides, such as those present in the pneumococcal polysaccharide vaccine, a model of thymus independent (TI) antigen (Ag). Using trinitrophenol (TNP)-lipopolysaccharide (LPS) and TNP-Ficoll, two other well-studied TI Ag, we studied the mechanistic basis of reduced MPhi function in the aged. We show that aged mice are profoundly hyporesponsive to these TI Ag. As a result of a requirement for MPhi, highly purified B cells from young-adult mice do not respond to TI Ag. When purified, young B cells were immunized with TNP-Ficoll, the antibody production from those cultures reconstituted with MPhi from aged mice was significantly lower than that seen with young MPhi. Consequently, this unresponsiveness can be overcome by a mixture of interleukin (IL)-1beta and IL-6. Upon stimulation with LPS, in comparison with young MPhi, aged MPhi secreted reduced amounts of IL-6, tumor necrosis factor alpha, IL-1beta, and IL-12, cytokines necessary for B cells to respond to TI Ag. LPS also induced aged MPhi to produce an excess of IL-10. Neutralization of IL-10 enhanced the production of proinflamatory cytokines by MPhi upon LPS stimulation and also induced Ab production by aged splenocytes. Thus, the inability of aged MPhi to help the B cell response appears to be caused by an excess of IL-10. As aged MPhi have a reduced number of cells expressing Toll-like receptor 4 and CD14, the imbalance in cytokine production might be partly a result of fewer cells expressing key components of the LPS receptor complex.

Ficoll density gradient method for recovery of isolated human ovarian primordial follicles

OBJECTIVE

To develop a simple and efficient technique to allow rapid recovery of a maximum number of good quality isolated follicles.

DESIGN

Prospective experimental study.

SETTING

Academic research unit of the department of gynecology in a university hospital.

PATIENT(S)

Biopsies were obtained from five women (between 26 and 31 years of age).

INTERVENTION(S)

Biopsies were cut with a tissue sectioner. Enzymatic digestion was performed in a collagenase solution for 90 min at 37 degrees C. The follicles were recovered using a discontinuous Ficoll density gradient method.

MAIN OUTCOME MEASURE(S)

The number of follicles present in the interface layers of Ficoll gradient was quantified. Follicular viability of these recovered follicles was assessed with live-dead stains, using calcein-AM and ethidium homodimer-I.

RESULT(S)

Out of a total of 6,811 recovered follicles, we found 63% (n = 4,201) at the medium-1.06 Ficoll interface and 36.9% (n = 2,590) at the 1.06-1.09 Ficoll interface, which represents 99.9% of total recovered follicles. Analysis by vital fluorescent staining showed that 95.8% of the follicles treated with Ficoll were totally viable.

CONCLUSION(S)

The Ficoll density gradient method allows us to maximize the recovery of isolated human ovarian follicles and minimize the manipulation time while maintaining high follicular viability.

Development of an Oral Exposure Mouse Model to Predict Drug-Induced Hypersensitivity Reactions by Using Reporter Antigens

The capability of certain drugs to cause immune-mediated drug hypersensitivity reactions in susceptible individuals has initiated a search for pre-clinical screening tools to identify immunosensitizing drugs. Since most drugs are taken orally, hazard assessment of their immunosensitizing potential should include oral exposure models. In this study, the predictive value of the reporter antigen (RA) approach was investigated in combination with oral or intraperitoneal (ip) exposure to a selection of allergenic drugs, i.e., D-penicillamine (D-Pen), Diclofenac (DF), or Nevirapine (Nevi). The RA trinitrophenyl-Ovalbumin (TNP-OVA) was used to assess the capacity of the drugs to stimulate systemic immune responses to a bystander antigen, whereas the RA TNP-Ficoll was used to indicate whether the drugs were able to induce specific anamnestic T-cell responses. TNP-OVA was injected (ip) in C3H/HeOuJ mice that were subsequently exposed (orally or ip) to one of the drugs via different exposure protocols. All three model drugs used resulted in delayed type hypersensitivity reactions to TNP-OVA after ip and oral exposure. In addition, TNP-specific serum antibody levels were increased after ip exposure to Nevi, and after both oral and ip exposure to D-Pen and DF. These data indicate that the present drugs are able to stimulate immune responses to bystander antigens. Responses to TNP-Ficoll were measured in the popliteal lymph node of BALB/c mice three weeks after they received a single oral dose of D-Pen or DF. Results of this approach show that orally pre-treated mice responded with enhanced responses (TNP-specific IgG1 and IFN-gamma production) to sub-optimal doses of D-Pen or DF in a drug-specific manner. Data with TNP-Ficoll indicate that these drugs stimulate systemic formation of specific T cells. Together, the RA-approach allows assessment of systemic sensitization upon oral and/or ip exposure to the selected drugs. To further evaluate the utility of these models, more drugs, including non-allergenic drugs and those that require metabolic conversion to become allergenic need to be studied in the present models.

A fast centrifuge method for nematocyst isolation from Pelagia noctiluca Forskal (Cnidaria: Scyphozoa)

Nematocyst isolation from surrounding tissue is an important step to characterize Cnidarian venom. Although several protocols have been used to extract venoms from cnidarian tissues, the complete isolation of nematocysts from tissue is still difficult. The goal of the present work was to evaluate the effectiveness of three different media, Percoll, Ficoll and Methylcellulose in isolating nematocysts from Pelagia noctiluca tentacles by centrifugation. The complete sedimentation of nematocysts and tissue fragments to the bottom of the test tubes was observed in Ficoll and Methylcellulose suspensions. The best result was obtained using a discontinuous density gradient of Percoll: three types of nematocysts were concentrated in three different fractions along the density gradient. Protein assay and preliminary chromatographic analyses confirmed these results.

Respiratory burst activity of polymorphonuclear cells is dependent on the cell preparation technique

BACKGROUND

Controversial results have been reported regarding the effect of anaesthetics on superoxide anion production during the respiratory burst (RB) of polymorphonuclear cells (PMN). The differences could be caused by the cell preparation methods and the aim of this study was to compare two techniques.

METHODS

RB activity was measured in cell suspensions isolated with the single-step Ficoll procedure and in unfractionated whole blood. Two concentrations of propofol (therapeutic and 10-fold of this, 6 microg ml-1 or 60 microg ml-1) were investigated after cell preparation with both methods. RB was stimulated with Escherichia coli (E. coli), phorbol 12-myristate 13-acetate (PMA) or N-formyl-methionyl-leucyl-phenylalanine (fMLP) and measured by means of fluorescence intensity in a flow cytometer.

RESULTS

The percentage of PMNs in whole blood which generate superoxide anions in response to fMLP was significantly lower (2.5 +/- 0.7%; mean +/- SEM) than that in Ficoll isolated cell suspensions (15.1 +/- 1.7%). Incubation with propofol led to a concentration-related decrease of RB activity in Ficoll separated PMNs after both PMA and fMLP stimulation. No significant effect of propofol was observed on the RB in PMA stimulated whole blood samples.

CONCLUSION

The results suggest that the influence of cell preparation methods should be considered when the in vitro effects of anaesthetics on PMN functions are studied with flow cytometric methods.

Simple and cost-effective isolation of monocytes from buffy coats

We have optimized the procedure of monocyte isolation on a Percoll density gradient. The new procedure consists of three steps: (1) the isolation of MNC on a Ficoll density gradient; (2) the separation of monocytes from lymphocytes on a high-density hyper-osmotic Percoll density gradient; and (3) the separation of monocytes from platelets and dead cells on a low-density iso-osmotic Percoll density gradient. The procedure is simple and cost-effective. Monocyte purity and recovery are both about 75% and platelet contamination is low. The isolated monocytes retain their capacity to differentiate into dendritic cells in vitro.

[A method for measuring the strength of adhesion of Candida albicans on epithelial cells]

A method on estimation of Candida albicans adhesion to epitheliocytes is proposed. The principle consists in the fact that while centrifuging epitheliocytes (1000 cycles/min, 10 min) with adhered Candida albicans through phycoll-verografin (1.077 g/cm3 density), Candida albicans cells having poor adhesion are separated from epitheliocytes trying to rise to the surface of phycoll-verografin. Candida albicans strongly adhered to epitheliocytes settle down to the bottom of test tube. In experiments with buccal epitheliocytes of healthy donors the number of strongly adhered Candida albicans ranged from 13% to 50% and they amounted to 37.0 +/- 7.8% on an average.