K G Brand's research while affiliated with Saint Catherine University and other places

Of the 98 foreign-body or scar-related cancers reported in the literature, over 25 percent have developed within 15 years, and over 50 percent within 25 years. Substantial numbers of various implants have now been in place for 10 to 20 years. Since at least 25 percent of cancer cases should already have occurred, the low number actually observed permits the prediction that the incidence of cancers at implantation sites will remain low. This conclusion is supported by studies on 27 specimens of chronic foreign-body reactions against a variety of implants that had been in situ for 1 to 19 years. Employing a cell-culture technique previously developed for experimental mice, an attempt was made to identify specific precancer cells in the tissues. None were detected, in contrast to foreign-body reactions of mice, in which the incidence of foreign-body tumors is high.

Cell types (I-IV), isolated and expanded in vitro from mouse foreign-body (FB)-reactive capsule tissue or from surfaces of FB segments, were sectioned en face and studied ultrastructurally. The macrophage-like and fibroblast-like nature of respectively, the euploid types I and II cells were substantiated by this ultrastructural study and thus confirmed earlier conclusions that were based on light microscopic morphology and in vitro growth characteristics. Particular emphasis was placed on the characterization and identification of type IV cells in that these aneuploid cells are sarcomagenic when implanted or injected sc into histocompatible recipient mice. The submicroscopic features of the aneuploid type IV cells included: 1) numerous microfilaments (diameter, 6-9 nm); 2) many plasma lemmal (pinocytotic) vesicles; 3) many surface microvilli, ruffles, or blebs; 4) formation of intercellular gap junctions; and 5) relatively extensive smooth-surfaced endoplasmic reticulum. The much smaller bipolar type III cells had several features in common with type IV cells: 1) an abundance of 6- to 9-nm (diameter) microfilaments, 2) moderate numbers of plasmalemmal vesicles, and 3) many evaginations of the plasma membrane to form microvilli or blebs. A relationship between types III and IV cells was considered likely on the basis of these morphologic similarities and other observations. The submicroscopic feature of both types III and IV cells correlated closely with those present in FB-induced sarcoma cells. The specific in vitro characteristics of aneuploid type IV cells most closely resembled those of endothellal cells. The results of this study supported the hypothesis that the progenitor cells of FB-induced sarcomas were derived from primitive cells associated with the local microvasculature.

Sarcomas were induced by sc implantation of unplasticized polyvinylchloride-vinylacetate films in gonadectomized and normal male and female CBA/H mice. Gonadectomy did not demonstrably influence tumor incidence and tumor latencies in males but significantly prolonged tumor latencies in females. The results suggest that estrogen influences the pace of foreign-body tumorigenesis in CBA/H mice.

(CBA/H X CBA/H-T6)F1 mice were given sc implants of unplasticized vinyl chloride acetate 15 X 22-mm copolymer films. The animals were pulsed with [3H]thymidine at various times during the 15 months following implantation. DNA synthesis occurred in the film-attached cell population, predominantly macrophages, throughout the preneoplastic phase in both females and males. Giant cells with fewer than 10 nuclei were labeled synchronously and asynchronously. No DNA synthesis was detected in giant cells with more than 10 nuclei. Previous studies have shown that phagocytic inactivity and ultrastructural signs of functional dormancy are characteristic for the foreign-body-reactive macrophage. However, this investigation demonstrated that the macrophage was not dormant with respect to DNA synthesis.

Cells isolated in vitro from preneoplastic foreign body (FB)-reactive capsule tissue or surfaces of FB segments from mice were studied and found to conform to 1 of 4 cell-type categories on the basis of light-microscopic morphology, pattern of in vitro appearance, in vitro topographical relations, and certain karyotype similarities. Euploid type 1 (macrophage-like) and II (fibroblast-like) cells predominated in primary cultures and early passages (passages 1 and 2) of cells derived from FB-reactive capsule tissue. The observation of small numbers of type III cells (unidentified cell type with unknown karyotype characteristics) in passages 1 and 2 of cells from FB-reactive capsule origin coincided with the deterioration of euploid type II cell populations and preceded the observation of type IV (endothelial-like) cells. Type IV cells had a pronounced growth advantage over cell types 1, II, and III, resulting in cultures composed only of IV cells after 3 passages. Cultures derived from cells attached to the surfaces of FB segments also conformed to the criteria established for type IV cells. Of the 4 cell types identified in this study, type IV cells were determined to have special importance regarding the nature of the progenitor cell in FB tumorigenesis, in that they were aneuploid and eventually produced homologous sarcomas when injected as a suspension into compatible hybrid recipient mice. These findings are consistent with an earlier reported hypothesis implicating certain cells of the microvasculature as the likely progenitor cells from which FB sarcomas are derived.

Sarcomas were induced by sc implantation of unplasticized polyvinylchloride acetate films in female and male mice of strains AKR/J, BALB/cJ, BALB/cWat, CBA/H and CBA/H-T6, C3H/HeJ, C57BL/10ScSn, C57BL/6J-bgj, C57BL/cdJ, DBA/-1J l/LnJ, LP/J, SJL/J, X/Gf, 129/J, and hybrids (CBA/H-T6 X AKR/J)F1, (C57BL/10ScSn x CBA/H or CBA/H-T6)F1, (C57BL/6J-bgj x C57BL/6J)F1. The strains and sexes showed marked differences in incidence and mean latency of resulting tumors. Crucial information was provided for the selection of appropriate mouse strains for the study of interrelationships between genotypes, defined somatic properties, and the multifactorial process of foreign-body tumorigenesis.

Sarcomas were induced in CBA/H mice by sc implantation of 15 X 22 X 0.2-mm polyvinyl chloride vinyl acetate copolymer films. The animals were immunosuppressed with azathoprine, antilymphocyte globulin, or thymectomy. Sarcoma development was not accelerated in comparison to nonimmunosuppressed demonstrated in sarcomas of immunosuppressed mice. It was concluded that foreign body tumorigenesis in mice in neither associated with nor dependent on the emergence of tumor-specific transplantation antigens.

The model of foreign body (FB) tumorigenesis appears particularly suited for studying the multifactorial in vivo process of carcinogenesis. While the natural preneoplastic events and developments run their course in the animal, cell samples can be periodically taken for culture, cloning, and expansion. Analytic results obtained on such cell preparations at different preneoplastic maturation stages can be related retrospectively, in the case of homology, to specific tumor characteristics. In addition, 2 fundamental assumptions derived from studies on FB tumorigenesis may be of significance in cancer research: The primary carcinogenic event does not seem to occur uniformly at one specific locus but may do so at various sensitive points within the cellular growth control system. Diversity of carcinogenic key events should be at least expected in FB tumorigenesis, since the agent introduced lacks cell invasiveness and biologic activity and actually does not even physically interact with target cells at the time of the key event. All the more it seems plausible that chemical and viral carcinogens, radiation, and similar cell invasive agents would affect still other target points. And secondly: ultimate expression of specific tumor characteristics, as predetermined by the initiating key event, and arrival at the stage of neoplastic autonomy require the cells to pass through preneoplastic maturation phases. This intracellular developmental process depends on a stringent sequence of extracellular environmental conditions reminiscent of induction phenomena described for normal cell and tissue differentiation. Some factors involved are effective only in vivo and have not been simulated in a simple tissue culture environment. In general, several theoretical and practical consequences ensue.

This review deals with factors and mechanisms involved in sarcoma development upon implantation of chemically inert foreign bodies. The topic is of importance regarding cancer in asbestosis or schistosomiasis, and also in view of increasing ise of artificial implants. After detailing morphological and biological characteristics of foreign body-induced sarcomas in man and animals, the review focuses on specific properties of implants and experimental animals which determine or influence tumor incidence and latency. Included are surface properties, size and shape of implants, and species characteristics, sex, and genetic background of animals. It follows a description of recent etiologic research which has evealed foreign body tumorigenesis as a multistage developmental process. Some of the salient features are monoclonal forigin from mesenchymal stem cells of the micro-vasculature; origination of neoplastic destination and specific tumor leterminants in cells distant from the implant during the earliest stage of the tumorigenic process; the regular finding of aried aneuploidies; the importance of fibrosis and macrophage inactivity during the preneoplastic maturation process; and lirect contact with the foreign body surface as the terminal requirement for preneoplastic cells to attain neoplastic utonomy. The findings open new theoretical perspectives and experimental avenues in cancerology.