Colony growth of mouse bone marrow cells in agar contained in glass capillaries

Clonogenic growth patterns correlate with chemotherapy response in acute myeloid leukaemia

Cytosine arabinoside and anthracycline-containing regimens induce remission in upwards of 60% of previously untreated patients with adult acute myeloid leukaemia (AML). Despite this, in addition to primary drug resistance, the majority of these patients relapse. Reliable methods for uniformly recognising these two subgroups at presentation do not exist and therefore a further attempt has been made to relate in vitro toxicity, using a clonogenic assay, to clinical outcome. In 10 normal controls and 12 chemotherapy naïve cases, mononuclear cells harvested by density gradient separation were re-suspended at a concentration of 2 x 10(5)/ml and quadruplicates of 250 microl per well cultured in methycellulose containing foetal calf serum and phytohaemagglutinin stimulated leucocyte conditioned medium. Cell kill was determined for cytosine arabinoside, daunorubicin and etoposide either singly or in combination using both a pulsed and continuous exposure. Aggregates were scored after seven days and three distinct patterns recognised. The patients all received the same drugs in a standard protocol and achievement of complete remission correlated with growth pattern. The survival of normal marrow colony-forming cells or GM-CFUc and the leukemic equivalent designated L-CFUc were assessed and a sensitivity index (SI) determined as a ratio of these two values in which more reproducible results were found when the drug was continuously present. It is concluded that the microculture technique is feasible and clearly demonstrates chemotherapy effect but no correlation was demonstrated with clinical outcome. This is a negative pilot study and, as a means of recognising drug sensitivity or resistance, should be discarded in favour of currently available molecular techniques.

Selectivity of hemoregulatory peptide (HP5b) action in culture

A synthetic analog of a hemoregulatory peptide associated with mature human granulocytes (HP5b) has been investigated for inhibitory effects on various cell types in culture as compared to inhibitory action on mouse and human myelopoietic colonies (CFU-gm), which occurs from 1 X 10(-13) to 1 X 10(-6) M in vitro. This includes colony formation by lymphoid T and B cells in capillary cultures, as well as mitogen activation of T, B and NK cells. At higher concentrations, i.e., above 1 X 10(-7) M, an inhibitory effect was found on colony formation. Neither the production of interleukin (IL) 3 by mitogen-activated T cells, nor the proliferation of the IL-3-dependent L/B cell line were affected by the peptide up to 1 X 10(-5) M. A slight inhibitory effect was found above 1 X 10(-9) M on mouse 3T3 fibroblasts. A series of malignant cell lines was also tested. No effect was seen between 1 X 10(-11) and 1 X 10(-7) M on human mammary carcinoma cells in culture. On Ehrlich ascites mouse mammary carcinoma cells a 30% inhibition was seen at 10(-6) M. On a human glioblastoma cell line (GaMg) no effect was seen, and on a rat glioma cell line (BT5C) an inhibitory effect was seen at 1 X 10(-7) M and above. No significant inhibition of cell growth was seen on SC1 mouse lymphoma cells from 1 X 10(-9) to 1 X 10(-5) M during 7 days of culture. The investigated normal and malignant cell types in culture were thus not inhibited in very low concentrations which act on CFU-gm. However, a variable inhibitory effect was found at higher concentrations where the inhibition of myelopoiesis was maximal and at concentrations where the inhibition is released. The hemoregulatory peptide thus seems to be a concentration-dependent selective inhibitor of myelopoiesis. The finding that various malignant cells do not respond at lower concentrations supports the possibility of using the peptide as a protector of normal cells during cancer chemotherapy.

Isolation of a specific granulopoiesis inhibitor from calf spleen and identification as glutathione

A small peptide was isolated from calf spleen, specifically inhibiting murine granulopoiesis in vitro. Purification involved ultrafiltration, anion-exchange chromatography with a FPLC system and reversed-phase chromatography on HPLC. Determination of the amino acid composition, following acid hydrolysis and phenyl isothiocyanate and dabsyl chloride derivatization, revealed the amino acids glutamic acid, cysteine and glycine. Although the N-terminal amino group was not blocked, peptide sequencing with common techniques was not possible. Comparison of the isolated peptide with the well-known tripeptide glutathione by HPLC and fast atom bombardment (FAB)/tandem mass spectrometry showed the identity of both substances. Moreover, glutathione was found to be a specific granulopoiesis inhibitor in vitro at 10-100 nM, a so far unknown property of this well-known peptide.

Defined, serum-free culture conditions for the GM-micro-clonogenic assay using agar-capillaries

Culture conditions were determined and optimised for the serum-free growth of granulocyte-macrophage (GM) colonies, derived from mouse bone marrow cells, in agar-containing glass capillaries. The standard medium is DMEM/F-12 (1:1) mixture containing per ml: 10 mg BSA, 35 micrograms transferrin, 20 micrograms soybean lipids and 5 micrograms insulin. In contrast to previous attempts by others, GM-colony yield in serum-free medium was found to be equal to that in serum-containing medium (around 25 colonies/capillary) and to correlate satisfactorily with the cell density at seeding.--The role of polyamine oxidases in cell-proliferation experiments could be studied by this microclonogenic assay without interference from any type of serum.

Two different types of granulocyte colony-stimulating factor produced by bovine lung tissue

Bovine lung tissue produces two different types of granulocyte colony-stimulating factor (CSF). The high molecular weight (MW) type (CSF-F) of 70,000 d by Sephadex G-100 gel filtration is only found in conditioned medium of homogenized tissue incubated in sealed glass bottles. The species of CSF exclusively stimulates CFU-C of mouse bone marrow, human bone marrow only hardly. The low MW type CSF (CSF-M) of approximately 29,000 d by gel filtration is found mainly in conditioned medium of slightly minced tissue incubated in Petri dishes. It stimulates both human and mouse CFU-C. Methods to prepare both types of CSF are described. By propagating a fibroblast cell line from bovine lung tissue it was found that fibroblasts are the source of the 70,000 d CSF. Indirect evidence suggests that macrophages produce the 29,000 d CSF species.

Biological properties of partially purified granulocyte extract (chalone) assayed in soft agar culture

The inhibitory effects of partly purified low molecular weight granulocyte extracts (GE) from human peripheral blood were investigated on mouse myelopoietic cells in agar cultures. By repeated freezing and thawing the inhibitory effect of the extract was lost, and instead a stimulatory effect was seen. The stimulation was seen mainly as an increase of colonies and clusters from the sixth day of culture. The degree of inhibition depended on the length of the preincubation time. After half an hour a stable and lasting inhibition was found. The biological effects of the extracts were temperature dependent. Inhibition or stimulation was seen when the target cells were exposed to GE at 37 degrees C and not at 4 degrees C. Colony formation in agar showed circannual variation with maxima in spring and autumn and minima in summer and winter. The data indicated that the inhibitory effect of GE did not show circannual variations.

Control of CFUc proliferation by selective endogenous inhibitors

The susceptibility of mouse bone marrow colony forming cells (CFUc) to three different types of proliferation inhibitors in capillary semisolid agar gel was studied. GI-3, a target specific peptide containing granulocyte fraction, T4-1, an oligospecific thymic factor of proteid nature, and the alkylating cytostatics dianhydrogalactitol (DAD) inhibit myeloid colony formation as a function of concentration. The respective MED values amount to 8, 10, and 0.002 microgram/ml. When compared with this same parameter 3H-TdR incorporation into DNA of liquid bone marrow cultures showed a single fold charge for the endogenous inhibitors (GI-3, T4-1) for the cytostatic (DAD) a 3 to 4 fold lower difference. It was demonstrated, that in competitive antagonism of GI-3 and colony stimulating factor the inhibitor prevails over CSF.

[The influence of cytostatic and immunosuppressive methyl hydrazones on myelo- and lymphopoiesis in vitro (author's transl)]

The cytostatic and immunosuppressive N'-methyl-N'-beta-chloroethylbenzaldehyde hydrazones B1 and B2 inhibit the colony growth of mouse bone marrow cells and PHA-stimulated human lymphocytes in vitro in a dose-dependent manner. In the presence of B1, however, in contrast to B2, the inhibition of 3H-thymidine (3H-Tdr) uptake by the bone marrow cells and lymphocytes is insignificant. Two further benzaldehydrazones CyB4 and EB4 show little or no influence both on clony growth and nucleoside uptake. On the other hand, CyB4 inhibits the 3H-Tdr uptake by ConA- or LPS-stimulated mouse spleen cells to a gretaer degree than does B1 or B2, although CyB4 unlike B1 or B2 does not display any immunosuppressive effects in the mouse. These findings demonstrate that the 3H-Tdr method is less sensitive than the colony assays and is hence only of limited value as a measure of the vitro proliferation of mammalian cells treated with cytostatics.

[The agar culture of the leucopoietic stem cell (CFU-C) and its stimulation (author's transl)]

This review summarizes the different in vitro culture techniques of the leukopoietic stem cell. Mainly the results obtained by the system of Pluznik and Sachs and Bradley and Metcalf are described apply with semisolid agar and its modification by Iscove using methylcellulose. Furthermore, recently published modifications of culture technique are listed. The principal results obtained with mouse and human bone marrow cells are summarized with respect to the origin of the colony-stimulating factor acting in different species, its biochemical characteristics, as well as with regard to the colony forming cell and its different subclasses.

Chalone inhibition of granulocyte colony growth in agar: kinetic quantitation by capillary tube scanning

Mouse bone marrow cells were seeded into capillary tubes containing agar with colony stimulating factor. The development of myelomonocytic clusters and colonies was followed by daily tube scanning using their light scattering properties. Three kinetic scanning parameters were determined and the significance of different threshold settings was evaluated; viz. the number of signals, the mean signal height and the signal integrals. The inhibitory effect of two extracts with known granulocyte chalone activity which had been prepared from human peripheral leukocytes and rat bone marrow cells, was followed with the scanning method. A continuous reduction of clusters and colony formation and their growth throughout the incubation period was observed which suggested a sustained retardation of proliferation of both the stem cells committed for myelomonopoiesis and their progeny.

In vitro culture of lymphocyte colonies in agar capillary tubes after PHA-stimulation

Human peripheral lymphocytes were stimulated with phytohemagglutinin (PHA) in liquid culture, suspended in agar and incubated in glass capillary tubes. Compact colonies of lymphocytes were found growing along the tube bottom in a buffer film, while compact clusters and rare diffuse colonies were observed inside the agar. Several parameters affecting the clonal growth were studied and optimized: PHA-dose, agar concentration, gel length (volume), quantity and density of seeded cells per capillary and gel length. Colony yield mainly depends on the seeded-cell density with a sharp optimum at 2 X 10(5) cells/ml irrespective of gel length; higher cell densities reduce the colony yield, suggesting that colony growth is the result of both stimulatory and inhibitory factors produced by cooperating cells. Following the daily clonal growth was only possible with undisturbed tubes; the number of colonies steadily increased from day 2 until day 7. Densitometric colony scanning is possible, yet problematic. Colony yield (plating efficiency is 10--50-fold higher in agar capillaries than in the usual Petri dishes. An additional advantage is that the capillaries provide a basis for a simple and reliable assay system for determining regulatory factors of lymphocyte proliferation (including chalones).

A lymphocyte chalone assay using lymphocyte colony growth in agar capillaries

Using a recently developed method of culturing T-lymphocyte colonies in agar-containing capillary tubes, the capacity of three different lymphoid extracts with lymphocyte chalone (LC) activity to inhibit colony growth was demonstrated. Sephadex fractions from a calf spleen extract were tested on the colony growth of granulocytic cells and PHA-stimulated T-lymphocytes as well as on the in vitro uptake of 3H-thymidine by bone marrow and ConA- and LPS-stimulated mouse spleen cells. The data strongly suggest that it is only the combination of several different assay systems applied to the same fractions that permits a clear-cut determination of a specific lymphocyte proliferation inhibitor like LC.

Growth kinetics by scanning of granulocytic cell colonies in glass capillaries

Pure granulocytic colonies were cultivated from mouse bone marrow cells in agar contained in glass capillary tubes using mouse embryo conditioned medium as colony stimulating activity. A random distribution of colonies along the agar gels was achieved under controlled conditions. Only 3 capillaries were needed for a coefficient of variation around 5% provided at least 104 cells were seeded per capillary. The daily growth of single colonies within an agar capillary was followed, using the light scattering properties of the colonies for automatic scanning. The position of the colonies in the capillary greatly affected the scan signal; the consequences of positional changes were studied in detail. Using the mean peak height as growth parameter, the onset of measureable granulocytic colony growth was found between day 2 and 3, the maximum colony size was reached between day 7 and 9, after which the colonies decayed. Other parameters such as colony count and total peak are were determined and their sinificance discussed.