That tissue factors extracted from various normal organs inhibit significantly the growth of animal cancers was reported by Chin and Kim1,2).
The following experiments were done to investigate further the effect of various tissue factors on hyperplasia of normal tissue.
Materials and Methods
Tissue factors were prepared, as in the previous report, from such organs as the liver, lung, kidney, muscle, skin and stomach from about 300 gms of albino rat, as follows. Homogenates of these six organs were centrifuged in a model PRI International centrifuge at 15,000 rpm. Ethyl alcohol was added to the supernatant fluid and the sediment was placed under electrophoresis in sodium barbital and barbital buffer. The slow-moving fraction was treated with trypsin and the material was dialyzed against distilled water in a cellophane tube. The substances in the cellophane tube were removed and precipitated by acetone. Well-dried precipitate was used this time in contrast to wet materials in the previous experiment. Experiments were done on two hyperplastic tissues: intraperitoneally on hyperplastic liver in partially hepatectomized albino rats and topically on the methylcholanthrene-induced epidermal hyperplasia of mice.
1) Mitosis count after partial hepatectomy
From 0.4 cc to 0.8 cc of 5 % tissue factors were injected intraperitoneally in the albino rats once daily for three successive days. This amount of tissue factors was comparable to : that which inhibits significantly the growth of Ehrlich ascites cancer and N-F sarcoma in mice, and to that which increases the amount of DNA in normal mice tissue in another experiment of ours.
Partial hepatectomy14.15.16.18) was performed on the third day under ether anesthesia, and careful asepsis was maintained throughout. A mid-line incision was begun at the level of the xyphoid and extended down about 3-4 cm. The median and left lateral lobe was securely ligated by silk and then excised. In this way, portions of the hepatic parenchyme ranging in extent from 65 to 75 percent of the total liver were removed. The abdomen was closed in two layers. In twenty-seven and half hours after the partial hepatectomy, the remaining liver tissue was removed as rapidly as possible under ether anesthesia, in most cases within one minute, cut in slices two mm thick and then fixed in Carnoy´s fluid for three hours. After dehydration and clearing, the tissues were embedded in paraffin, cut in sections six microns thick, and stained with hematoxylin and eosin. Mitoses were counted in twenty fields on each slide with the help of 0.65 mm objective lens and 15 x oculars.
Those counts were compared with the normal in each kind of organ and also with a control group in which 0.4 cc of 5 % dextrose was injected instead of tissue factors.
2) Cell counts in 3-methylcholanthrene-induced epidermal hyperplasia.
Epidermal cells were counted instead of mitoses. Methylcholanthrene was prepared As a ~0.2 % solution in distilled water. Materials were applied to the skin on the midline of the mouse´s back with a calibrated glass pipet, having carefully clipped its hair with scissors and avoiding scratches to the skin. MCA was applied only once, at the beginning of the study period, in those mice which were given a carcinogen. Tissue factors, when used in conjunction with MCA, were applied one day prior to the MCA and daily thereafter. The following treatment groups were used:
a) 0.05 cc of 0.2 % MCA preceded and followed by 0.05 cc of distilled water once daily for six
successive days.
b) 0.05 cc of 0.2 % MCA preceded and followed by 0.05 cc of 5 % tissue factor materials once -daily for six successive days.
c) 0.05 cc of 5 % tissue factor only applied once daily for seven successive days.
d) 0.05 cc of distilled water alone applied once daily for seven successive days.
Mice were sacrificed by cervical dislocation on the eighth day, and the skin was removed from the back where the materials had been applied. The fresh specimen was spread out on a piece of filter paper to prevent curling and then it was fixed in Carnoy"s fluid for three hours. Dehydration, clearing and embedding in paraffin was carried out and sections six microns thick were stained with hematoxylin and eosin. Cell counts were made for ten fields on each slide with the help of 1.25 mm oil immersion objective lens and 15 x oculars. Those counts were compared with those in each group and in each organ.
Results
:Increased mitosis with partial hepatectomy was well demonstrated in the control group. The number of mitoses in regenerating rat liver tissue after partial hepatectomy was decreased significantly with the intraperitoneal injection of the various tissue factors; more, significantly with the 0.4 cc of the _5 % . liver factor than with 0.B cc, and less significantly with the muscle factor .(Table 1).
A marked hyperplastic reaction was produced in the epidermis with the topical application of the MCA to the mouse skin. There was a significant decrease of cell counts with the repeated application of the various tissue factors to hyperplastic skin, and the inhibiting effect of the skin factors was most marked(Table 2). Mice treated daily with various tissue factors alone without MCA showed much different results from those with MCA (Table 3). The count of epidermal cells was increased significantly with the application of the liver factors, but was decreased with the muscle factor..
In summary, these experiments show that various tissue factors generally inhibit cellular mitosis and proliferation in hyperplastic tissue. The liver factor markedly inhibited liver tissue, and the skin factor markedly inhibited skin tissue. It is speculated from this that the tissue factor has tissue .specificity.
It is also assumed that tissue factors array have a different effect toward hyperplastic and normal . --tissues from the, fact that the application of the liver factor inhibits methylcholanthrene-induced epidermal hyperplasia but increases the epidermall cells of intact skin.
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