Explant organ culture of hamster alimentary tract epithelium

Explant organ culture: a review

Organ explant culture models offer several significant advantages for studies of patho-physiologic mechanisms like cell injury, secretion, differentiation and structure development. Organs or small explants/slices can be removed in vivo and maintained in vitro for extended periods of time if careful attention is paid to the media composition, substrate selection, and atmosphere. In the case of human tissues obtained from autopsy or surgery, additional attention must be paid to the postmortem interval, temperature, hydration, and cause of death. Explant organ culture has been effectively utilized to establish outgrowth cell cultures and characterize the histiotypic relationships between the various cell types within an organ or tissue.

Long-term culture of human esophageal explants and cells

Human esophageal epithelium obtained from intermediate autopsies (less than 12 h) was maintained as cell and explant cultures. In order to develop a serum-free, defined media culture model, several medias and additives were evaluated. The viability and differentiation of the epithelial cells cultured with serum-free, Keratinocyte Growth Media (KGM, Clonetics Co., San Diego, CA) was improved over that of esophageal cells and explants cultured in either serum-supplemented CMRL 1066 (OCM), serum-free additive-supplemented CMRL 1066, or cimetidine-supplemented CMRL 1066. The KGM component EGF was determined to be trophic for esophagus cells on the basis of findings of increased 3H-TdR labelling in KGM cultures when compared to control cells grown in KGM without EGF (KBM). The morphologic pattern of the cytoskeletal proteins actin, keratin, and vimentin were characterized in isolated cell populations. The intermediate filaments, keratin, and vimentin were co-expressed in these epithelial cells. Esophageal explant viability, differentiation, and outgrowth from 15 cases were also evaluated in dishes coated with basement membrane associated proteins. Explants cultured in these dishes were equally well-preserved and differentiated. There were no significant differences in the explant histology when there was protein coating of the culture dishes, although one case showed improved outgrowth with laminin coating. A main advantage for using this culture system is that the same medium (KGM) can be used for both the culture of explants and isolated epithelial cells. Future applications of this model include determining: (1) the effect different concentrations of EGF and calcium in the media will have on esophageal proliferation and differentiation, and (2) the role of different basement membrane associated proteins on the plating efficiency of either isolated or outgrowth epithelial esophageal cells.

Cell injury and regeneration of human epithelium in organ culture

Human esophageal, tracheal, and pancreatic ductal fragments were collected at autopsy after a postmortem interval of 12 hours or less and maintained in explant organ culture for 30 days. The viability and growth of the explants was assessed by morphology, LDH enzyme release, and cellular outgrowth. The viability and growth of the bronchial explant epithelium was directly related to the postmortem interval. Esophageal epithelial regeneration followed the desquamation of the superficial cell layers. Pancreatic epithelia appeared to grow more slowly and with less outgrowth than the other tissues. Epithelial cell growth along the explant surface and onto the culture dish appeared to proceed through the well-characterized process that follows cell injury, i.e., flattening, migration, replication, and differentiation. Thus, sufficient numbers of viable epithelial cells capable of regeneration were present in routine autopsy epithelium, but there was considerable variation from tissue to tissue and case to case. The most effective and accurate approach to follow when evaluating and predicting the growth and viability of these explants is by using a combination of morphologic, enzymatic and biologic assays. Errors in the interpretation of viability are possible when only one assay method is utilized. These tissues grown in explant organ culture are suitable for studies on the mechanism and response of epithelia to cell injury, recovery and wound healing.

Intestinal tissue and cell cultures

The culture of animal cells and tissues is a widely used technique in the field of cellular and molecular biology; one of the most interesting aspect being linked to the study of the mechanisms of cell differentiation. In the specific case of intestinal epithelial cells, various tissue culture technologies have proved to be important tools for the study of precise facets related to intestinal function, pathology and differentiation. Concerning this latter aspect, organ culture experiments have brought about interesting data on the hormonal or nutritional control of intestinal maturation. Nevertheless, the study of the precise mechanisms underlying epithelial proliferation and/or differentiation at the cellular level needs more adequate cell culture model systems. One of them has been described for two cell lines derived from human colonic adenocarcinomas, in which the cells can be induced to achieve enterocytic-like differentiation. Up to date, none of the continuous cell lines starting from normal undifferentiated cells have allowed generation of morphological or functional enterocytic polarity. In contrast, primary cell cultures which allow maintenance of a more physiological environment for the epithelial cells like contacts with their in vivo counterparts, mesenchymal cells or extracellular matrix molecules, have proved to be promising approaches.