Improvement of growth of Plasmodium falciparum fresh clinical isolates by using an established serum-free medium, GIT

In the present study, we have tried to establish continuous cultures of fresh clinical isolates of P. falciparum by using a serum-free medium, GIT. To examine the ability of GIT to support the parasite growth, the growth of various P. falciparum isolates including two laboratory strains of P. falciparum, FCR3 and K1 was compared in both of GIT and RPMI 1640 medium supplemented by 10% human serum (RPMI-HS). Growth rates of various P. falciparum expressed as fold increases were compared in GIT and RPMI-HS, and the maximum growth rates of P. falciparum were 72 in GIT and 35 in RPMI-HS during the culture for 8 days. Growth rate of the clinical isolates varied individually in both culture media, with average growth rates of parasites being 15.9 in GIT and 8.8 in RPMI-HS, respectively (not significant). Growth rates of FCR3 and K1 strains were 28.0 and 6.6 in GIT, and 10 and 7.5 in RPMI-HS. After 30 days culture of P. falciparum in GIT, 9 of 12 clinical isolates still continuously propagated but other three isolates disappeared. Despite variation of the P. falciparum isolates in their abilities to multiply in GIT, our experiments suggested that GIT is useful for culture of fresh clinical isolates of P. falciparum that are derived from geographically distinct areas as well as laboratory strains used commonly in laboratory research.     

The susceptibility of Plasmodium falciparum to sulfadoxine and pyrimethamine: correlation of in vivo and in vitro results

In 1982, 2 of 14 Plasmodium falciparum infections acquired in East Africa and diagnosed in Copenhagen were resistant to treatment with sulfadoxine plus pyrimethamine (Fansidar), while in 1983, 6 of 18 were so. The in vivo tests were supplemented by determinations of drug concentrations in serum, and 4 isolates from in vivo-sensitive cases and 6 from in vivo-resistant cases were selected for in vivo tests. These were performed in ordinary RPMI 1640 medium and in a medium with physiological p-aminobenzoic acid and folic acid concentrations. Pharmacokinetic aberrations were found to be of possible importance in only 2 of the in vivo-resistant cases. In vitro susceptibility to sulfadoxine was found to be uniformly low in all isolates. Testing with a combination of sulfadoxine and pyrimethamine in the medium with physiological concentrations of cofactors probably reflects the in vivo situation most accurately, but in all but 1 of the isolates studied in vitro the in vivo susceptibility to Fansidar would be predicted by in vitro susceptibility to pyrimethamine in either medium. The concentration of p-aminobenzoic acid in serum, quantitated by high performance liquid chromatography, was found to be subject to wide variation, and this may have implications for in vitro testing.     

A simplified method for cryopreservation of Plasmodium falciparum from continuous in vitro cultures

Human erythrocytes parasitized with Plasmodium falciparum, obtained from in vitro continuous cultures and stored at -185 degrees C and at -70 degrees C for several months, were successfully recovered. Ten per cent glycerol or 10% dimethyl sulphoxide in growth medium RPMI 1640 were used and found equally effective as cryopreservatives. This simplified method does not require centrifugation or special media before storage or after recovery of the parasites. The viability of the parasites is monitored in vitro by initiating new continuous cultures.     

Use of non-human plasma for in vitro cultivation and antimalarial drug susceptibility testing of Plasmodium falciparum

Viability, growth rate, and chemotherapeutic susceptibility of the CDC/Indochina III, CDC/Sierra Leone I, and FCR-3 (Subline F-86) isolates of Plasmodium falciparum grown continuously in RPMI 1640 medium supplemented with goat, horse, porcine, bovine, or ovine plasma were evaluated. Results were compared to those obtained from parallel cultures maintained in medium supplemented with non-immune human plasma. Only media supplemented with goat or horse plasma supported significant continuous multiplication of the isolates. Medium supplemented with either ovine or porcine plasma supported continuous multiplication of the CDC/Indochina III isolate, but not the FCR-3 isolate. Medium supplemented with bovine plasma did not support continuous growth of any of the isolates tested. The light microscopic appearance of the isolates during and after continuous culture in medium supplemented with either goat or horse plasma was identical to that of the control parasites maintained in medium supplemented with human plasma. There were no statistically significant differences in the susceptibility to antimalarial drugs of the culture lines maintained in medium supplemented with either human or goat plasma.     

Human granulopoiesis in vitro: An advantage in the use of Iscove's modified Dulbecco's medium

Summary With the aim of determining whether Iscove's modified Dulbecco's medium (IMDM) provides a growth advantage in the support of granulopoiesis from cultures of human bone marrow in agar, samples from 20 normal subjects were examined in triplicate after 7, 10 and 14 days in parallel cultures containing IMDM or Dulbecco's medium. From every sample, more granulocytemacrophage colonies were obtained at each culture interval with IMDM. In particular, the number of colonies with IMDM at 14 days (96±13 per 2×10⁵ bone marrow cells) was almost double that with Dulbecco's medium (50±10). This increment consisted almost entirely of pure granulocyte colonies (P<0.001). No significant change in the proportion of eosinophil colonies was observed. These data indicate that IMDM does provide a growth advantage over Dulbecco's medium in the generation of granulocyte (neutrophil and eosinophil) colonies from agar cultures of normal human bone marrow.Abbreviations CFUGM Cellular progenitor of granulocytes and macrophages - DEAE Diethylaminoethyl. - HEPES N-2-hydroxyethylpiperazine-N-ethanesulphonic acid - IMDM Iscove's modified Dulbecco's medium     

Liquid preservation of human neutrophils stored in synthetic media at 22 degrees C: controlled observations on storage variables

The purpose of this study was to use a chemically defined medium to identify essential substances and optimal conditions for the liquid storage of neutrophils at 22 degrees C. Several commercially available synthetic media were evaluated: L-15, McCoy's 5a, M199, minimum essential medium, Dulbecco's MEM, NCTC135, and RPMI 1640. Proteins, glucose, pH, and neutrophil concentration were systematically studied. Neutrophils were harvested by centrifugal cell separators or phlebotomy, and their maintenance was evaluated by monitoring cell counts, dye exclusion, phagocytosis, bacterial killing, and chemotaxis. Neutrophils stored equally well in all synthetic media except L-15; however, chemotaxis was poorly maintained in synthetic media as compared with autologous plasma. RPMI 1640 was arbitrarily selected as a basal medium to evaluate storage variables. RPMI 1640 supplemented with albumin to a concentration of 1% improved chemotaxis and was equivalent to plasma as a storage medium with regard to the in vitro functions tested. Cohn fractions IV-1, IV-4, and gamma globulin were not effective substitutes for albumin. Glucose is essential for neutrophil storage; its absence from the medium correlated with poor cell function. Optimal glucose requirements depend on the cell concentration. High glucose concentrations were toxic to neutrophils; at 1,000 mg/dL, chemotaxis was depressed by 58%. Glucose utilization was dependent on the initial pH of the medium and on the cell concentration. A wide range of hydrogen ion concentrations was tolerated, and the optimum pH range was 7.2 to 7.8. Cell concentration is an important variable because it affects the pH of the medium as well as glucose utilization.     

Establishment,growth properties,and morphological characteristics of permanent human small cell lung cancer cell lines

Summary Cell lines from SCLC were established with a success rate of 43% from different metastatic sites of treated and untreated patients. All 6 SCLC cell lines grew as floating cell aggregates without substrate adherence. The degree of aggregation ranged from very tight spheroids to very loose sheets and chains. This gross morphological property showed a striking correlation to the PDT, with short PDTs in loose growing cell lines and long PDTs in tight growing cell lines. Cell size and nuclear features, i.e., chromatin pattern and nucleolar prominence, also seemed to correlate with the PDT and gross morphology. All SCLC cell lines had dense core granules by electron microscopical examination. Several different serum-free and serum-supplemented growth media were tested for their feasibility in estabilishing and permanently growing SCLC. Serum-free SIT medium and SIT 2.5 medium provided the best results in liquid culture. For semisolid SCLC cultivation, R10 medium was suprior to all other media tested. These cell lines are currently under intensive biochemical, molecular biological, and cytogenetical investigation in different laboratories and thus provide a tool for studying the biology of lung cancer.Abbreviations SCLC small cell lung cancer - FBS fetal bovine serum - R 10 Roswell Park Memorial Institute (RPMI) 1640 medium supplemented with 10% FBS - D 10 Dulbecco's modified Eagle's medium supplemented with 10% FBS - SIT RPMI 1640 medium supplemented with selenium, insulin, transferrin - HITES RPMI 1640 medium supplemented with hydrocortisone, insulin, transferrin, estradiol, selenium - SIT 2.5 SIT medium supplemented with 2.5% FBS - PBS phosphate buffered saline - PDT population doubling time This work was supported by the SFB 215 of the German Research Society. The authors Thank Dr. Adi F. Gazdar for reviewing the morphology     

一种便于现场测定恶性疟原虫抗药性的培养基

为了各地开展体外微量测定法调查恶性疟原虫的抗药性,研制了便于现场调查使用的培养基。将连续培养恶性疟原虫用的RPMI1640完全液体培养基用安瓿封装,冰瓶贮存.可供现场50d内使用。该培养基的效果与冰冻干燥培养基相似,明显优于WHO培养基。     

An in vitro system for assessing the sensitivity of Plasmodium vivax to chloroquine

Following earlier observations on short-term culture of Plasmodium vivax, an in vitro test system has been developed for assessing the parasite's sensitivity to chloroquine. Fresh isolates with predominantly young trophozoites are diluted 1:19 with a (v/v=1/1) mixture of RPMI 1640 and Waymouth medium. The blood-medium mixture (BMM) is inoculated into the predosed microtitre plates before incubation in a candle jar. Incubation for 30 or 42 h yielded the best results. Incubation for 18 or 24 h was generally insufficient for an adequate development of the parasites. The reading of the test is based on stage-specific differential counts in the Giemsa-stained pre-incubation and post-incubation thick films, the evaluation on log-probit analysis of drug-related inhibition of parasite development. The test system has been evaluated on 200 fresh P. vivax isolates in an area with satisfactory clinical-parasitological response to chloroquine. At 30 or 42 h incubation 121 isolates (61.5%) showed adequate control growth and yielded valid sensitivity tests. Complete inhibition of parasite development occurred within the concentration range of 40-1280 nM. The mean EC50 for 30 h of incubation was 50.3 nM, as compared to 49.7 nM with 42 h of incubation. The geometric mean cut-off concentration of parasite development was 488 nM with 30 h of incubation as against 470 nM with 42 h of incubation.     

Molecular epidemiology of malaria in Cameroon. XV. Experimental studies on serum substitutes and supplements and alternative culture media for in vitro drug sensitivity assays using fresh isolates of Plasmodium falciparum

In vitro drug sensitivity assay is an important tool for various on-going studies aiming to establish the correlation between candidate molecular markers for drug resistance and drug response in laboratory-adapted strains and field isolates of Plasmodium falciparum. A widespread use of this technique in the field would require a suitable substitute that can replace human serum. In this study, several alternative sources of serum substitutes and supplements were evaluated for their capacity to sustain parasite growth for a single life cycle and their compatibility with in vitro assays for clinical isolates that have not been adapted to in vitro culture. Albumax, a commercial preparation of lipid-enriched bovine albumin, did not support parasite growth as much as human serum and fetal calf serum in several isolates. Other serum supplements (AmnioMax and Ultroser) supported parasite growth relatively well. The 50% inhibitory concentrations (IC50s) of chloroquine and antifolates determined with 0.05% Albumax were generally two or three times higher than with human serum. With 10% fetal calf serum, IC50s for chloroquine and antifolates were approximately two times higher and three times lower than with human serum, respectively. The use of AmnioMax and OptiMAb resulted in a greater than two-fold increase in IC50s and several uninterpretable assays. Despite possible batch-to-batch differences, fetal calf serum may be a suitable substitute for in vitro drug assays while awaiting the results of further studies on other serum substitutes and supplements.     

In vitro development of Haplorchis taichui (Trematoda: Heterophyidae)

Newly excysted metacercariae of Haplorchis taichui were cultured in a candle jar set at 37 degrees C. Both monophasic culture media [0.85% NaCl, RPMI 1640, RPMI 1640+10% fetal calf serum (FCS)] and diphasic culture media [RPMI 1640 + egg yolk agar, RPMI 1640 + 5%, 10% or 15% blood in blood agar (BA), RMPI 1640 + 5%, 10% and 15% FCS with 5% blood in BA] were used in vitro. Parasites survived for only 1 day in 0.85% NaCl without any development. In RPMI 1640 with egg yolk agar and RMPI 1640 + 5%, 10% FCS, the parasite survived for 3-5 days. In contrast, worms survived for 12-14 days in RPMI 1640 with blood agar without any change in result in a different concentration of blood in BA. The ovary and testes were observed after 3 days incubation in this media. Nevertheless, only 1 parasite in RPMI 1640 with 15% blood in BA had vitellaria and eggs at day 6. RPMI 1640 with blood agar can be used as short-term maintenance for the in vitro culture of H. taichui. However, further studies are needed.     

In vitro cultivation of third stage larvae of Wuchereria bancrofti to the fourth stage

Third stage larvae of Wuchereria bancrofti obtained from laboratory-infected mosquitoes grew and molted to the fourth stage in vitro. The culture medium which supported the best growth and development consisted of a 1:1 mixture (v/v) of two commercially available cell culture media, NCTC 135 and Iscove's modified Dulbecco's medium supplemented with 10% human serum or plasma and an antibacterial/antimycotic mixture. Cultures were incubated at 37 degrees C in an atmosphere of either 5% or 8% CO2 in air. After 35 days of culture, 65% to 100% of the larvae were fourth stage. They were motile and in excellent morphological condition with development of the reproductive system in males and females. This culture system will provide an important tool for biochemical and immunological studies.     

Effect of tissue culture media on multiplication of Plasmodium falciparum in vitro.

To date RPMI-1640 has been the best medium for cultivation of Plasmodium falciparum in vitro. In addition to this medium, several alternative media, essentially the ones used in animal and plant tissue culture, were employed for the cultivation of P. falciparum. Only the media rich in glucose content, viz. Nitsch medium and White's medium S-3, supported the parasite multiplication.     

Molecular epidemiology of malaria in Cameroon. XXV. In vitro activity of fosmidomycin and its derivatives against fresh clinical isolates of Plasmodium falciparum and sequence analysis of 1-deoxy-D-xylulose 5-phosphate reductoisomerase

The in vitro activities of fosmidomycin derivatives, chloroquine, and pyrimethamine were assessed by the radioisotopic assay in clinical isolates of Plasmodium falciparum. In a series of experiments with RPMI 1640 medium-10% fetal bovine serum, the geometric mean 50% inhibitory concentrations (IC(50)s) (n = 34) for fosmidomycin and FR900098 were 301 nM and 118 nM, respectively. In another series of experiments, the geometric mean IC(50)s (n = 33) for fosmidomycin and TH II46 were 413 nM and 249 nM, respectively. The IC(50)s were 2-3 times lower with RPMI-10% fetal bovine serum than the IC(50)s obtained with RPMI-10% human serum. FR900098 and TH II46 were 2.6 and 1.7 times more potent, respectively, than fosmidomycin. There was no correlation between chloroquine or pyrimethamine and fosmidomycin, which suggested the absence of in vitro cross-resistance. Sequence analysis showed five amino acid substitutions, but their possible relationship with the response to fosmidomycin is not clear. Fosmidomycin derivatives are promising candidates for further development.     

In vitro sensitivity of Plasmodium falciparum to sulfadoxine and pyrimethamine

An in vitro microtechnique of Rieckmann et al., (1978) modified by Yisunsri and Rieckmann (1980) using 3 media; Waymouth, Waymouth plus 10% human serum, and RPMI was assessed to determine the sensitivity of P. falciparum to sulfadoxine, pyrimethamine and its combination. The study confirmed the synergism between sulfadoxine and pyrimethamine. There was no interaction between media and drug tested. MIC1 and MIC2 of sulfadoxine in different media showed significant difference (p less than 0.001). No significant difference was observed in MIC1 and MIC2 of pyrimethamine in the three media used (p greater than 0.05). For sulfadoxine-pyrimethamine combination, MIC1 and MIC2 in Waymouth alone and plus 10% human serum showed no significance (p greater than 0.05) while in RPMI showed positive correlation (p less than 0.001). MIC1 might be more applicable for clinical evaluation than MIC2. At present Waymouth medium with 5% patient serum, is considered to be the most suitable for testing sensitivity of malarial parasites.     

Non-immune human sera at higher concentrations inhibit Plasmodium falciparum growth in vitro

Plasmodium falciparum growth in vitro related to the concentration of inactivated, non-immune human serum supplement to the RPMI medium. This study investigated the concentration of non-immune serum required to support adequate in vitro parasite growth without saturating the medium. Parasitaemia was highest with 7.5% serum concentration in suspension cultures. However, peak parasitaemia obtained under static cultures with 12.5% serum concentration did not significantly differ from the level attained with suspension cultures at the same serum concentration. Ten per cent serum-supplemented medium supported parasite growth in static and suspension cultures, and levels of parasitaemia declined with further increases in serum concentration.     

In vitro antimalarial activity of tetrahydrofolate dehydrogenase inhibitors

Three tetrahydrofolate dehydrogenase (dihydrofolate reductase = EC 1.5.1.3) inhibitors were tested for antimalarial activity against Plasmodium falciparum, using an in vitro radioisotopic technique. Activity of each drug was tested in both normal RPMI medium 1640 and in modified medium (containing no p-aminobenzoic acid and 2.27 X 10(-8) M folic acid) after a 24- or 48-hour exposure. Activity was increased 20- to 85-fold using the modified medium and the longer exposure time. Under all conditions, pyrimethamine and cycloguanil were of equal or greater potency than an experimental pyrimethamine analogue, M&B 35769, against pyrimethamine-sensitive strains, but M&B 35769 was more active than either pyrimethamine or cycloguanil against pyrimethamine-resistant strains.     

Isolated mouse pancreatic islets in culture: Effects of serum and different culture media on the insulin production of the islets

Summary Various conditions for tissue culture of collagenase-isolated mouse pancreatic islets were studied in an attempt to optimize the maintenance of glucose stimulated insulin biosynthesis and release in the cultured specimens. Islets which had been cultured at a physiological glucose concentration (5.5 mmol/l) in the absence of serum had an impaired glucose-stimulated insulin biosynthesis and release as well as a reduced insulin content. Thus, insulin biosynthesis was three times higher after culture in a serum supplemented medium. Further, the insulin secretion of islets cultured in the presence of serum was markedly enhanced in acute incubations with high concentrations of glucose. This response was most pronounced in islets which had been cultured free-floating. A comparison between different culture media showed that islets cultured in RPMI 1640 had the highest insulin production. The present data suggest that the most favourable conditions for long-term storage of isolated islets in culture may be obtained when the islets are maintained as free-floating explants in a culture medium consisting of RPMI 1640 supplemented with serum.     

Dialyzable factor in human serum of platelet origin stimulates endothelial cell replication and growth

Porcine aortic endothelial cells were isolated and maintained in Dulbecco's modified Eagle's medium (DME medium)/10% citrate-treated human plasma. They were stimulated by DME medium/10% human serum to grow from a density of 10,100 ± 500 per well to a final density of 83,000 ± 1,800 per well over a 9-day period. On the other hand these cells grew poorly (11% increase) in DME medium/10% human platelet-poor plasma prepared without chelating agents and containing platelet factor 4 at 18 ng/ml by radioimmunoassay. Dialysis of the human serum (M_r cutoff, 3,500) eliminated all the stimulatory activity. The activity recovered from the dialysate stimulated growth when added to endothelial cultures in conjunction with either dialyzed serum or platelet-poor plasma alone. The dialyzable factor could be obtained directly from platelets; both acetic acid extracts and boiled NaCl extracts stimulated porcine aortic endothelial cell replication. Gel filtration chromatography on Sephadex G-15 showed that the endothelial growth factor had a molecular weight of 700. Partially purified material induced a concentration-dependent stimulation of porcine aortic endothelial cell replication in the presence of DME medium alone; however, simultaneous incubation with platelet-poor plasma resulted in a much greater response. Fibroblast growth factor isolated from bovine brain was found to be mitogenic only in the presence of nondialyzed serum or of the dialyzable factor together with plasma. In the absence of this serum factor, fibroblast growth factor had no effect. We conclude that human serum contains a potent endothelial cell mitogen of platelet origin. Human plasma that is devoid of platelet content does not stimulate endothelial cell growth. This growth factor may be an important stimulant of the endothelial cell response to vascular wall injury.     

不同血清浓度及介质对体外培养小鼠成纤维细胞L929细胞系生长曲线和细胞形态的影响

目的：通过探讨不同血清浓度及介质对体外培养小鼠成纤维细胞L929细胞系生长曲线和细胞形态的影响，了解它们对成纤维细胞体外生存和生长的情况。方法：采用体外细胞培养技术进行小鼠成纤维细胞L929细胞，并采用磺基罗丹明B（sulforhodamineB，SRB）酶标仪法（A490nm波长下）测量各孔的吸光值（A值）并转换为小鼠成纤维细胞L929细胞系生长曲线；同时，分别采用HE（苏木精-伊红）染色法、、吖啶橙荧光染色和Hoechst33342荧光染色法进行小鼠成纤维细胞L929细胞系形态学观察。结果：小鼠成纤维细胞L929细胞系不同浓度的血清分别在3种不同的介质（RPMI1640培养基、0．9％生理盐水和5％葡萄糖生理盐水）中表现出不同的生长和生存情况及细胞形态学改变。其中，在不同血清浓度（0％、10％、20％、30％、40％、50％、60％、70％、80％、90％、100％）的同一介质中，血清浓度为0％和100％浓度组的小鼠成纤维细胞L929细胞生长明显抑制及吸光度（A）值呈逐步减少的趋势，而除此之外的其它血清浓度组对小鼠成纤维细胞L929细胞的影响，基本表现为随着血清浓度的升高，吸光度（A）值呈逐步增加及促进细胞生长的趋势。而某些相同血清浓度在不同介质中对小鼠成纤维细胞L929细胞系生长和生存及形态学的有利影响，则基本表现为RP—M11640培养基作为介质的细胞培养效果优于0．9％生理盐水，而0．9％生理盐水作为介质的细胞培养效果又优于5％葡萄糖生理盐水。结论：不同血清浓度及介质对体外培养小鼠成纤维细胞L929细胞系生长和生存及细胞学形态均有明显影响。提示在进行体外细胞培养时应充分考虑细胞培养介质及所添加血清的浓度。