Biomedical subjects

C S Potten

Publications and source records attributed to C S Potten.

292 records · Page 17Linked to original sources

PubMedDate not supplied

Progressive morphogenesis in vivo after transplantation of cultured small bowel epithelium.

An experimental model for the primary culture and transplantation of late foetal rat small intestinal epithelium is described. Multicellular aggregates of mucosal epithelium containing pre-crypt proliferative cells were isolated from 20-day foetal rat intestine by enzymatic disaggregation. Cellular aggregates, which we refer to as "epithelial organoids," attached readily in culture, proliferated, and spread to produce coalescing colonies within 10 days. Enterocytes were maintained in culture for 3 days, removed as cell sheets, and incubated overnight with foetal mesenchyme. Fourteen recombinant preparations were then grafted to the renal subcapsular space of adult nude mice. Four of six grafts retrieved after 1 wk had developed. Histology demonstrated the formation of simple tubular structures lined by a polarized columnar epithelium. At 14 days, two of eight grafts had developed and demonstrated temporal progression of morphogenesis. Histology showed rudimentary crypts and villi lined by different epithelial cell types, including enterocytes and goblet cells. Small bowel proliferative cells within "epithelial organoids" from 20-day foetal intestine, may be maintained in primary culture for up to four days. After short term primary culture, these proliferative cells retain the capacity for progressive organotypic morphogenesis and pluripotent cytodifferentiation, after transplantation to adult recipients.

Animals↗

PubMedDate not supplied

Kinetics and possible regulation of crypt cell populations under normal and stress conditions.

The proliferative organisation of the crypts of the small intestine is considered with special reference to the existence, location and numbers of stem cells. It is concluded that the crypt contains a minority population of cells at its base that are the true stem cells. These cells provide an input of cells for the larger proliferative compartment higher up the crypt. The presumptive stem cells may be pluripotent and produce Paneth, goblet and columnar cells. They are probably also the cells which are capable of regenerating the crypt after X-ray depopulation. Radiobiological experiments indicate that the number of cryptogenic cells is less than 80, while the results of several experiments on the kinetics of the cell populations indicate that the number of stem cells is about 20. The stem cells are located in the Paneth cell zone of the crypt, and are apparently passing through the cell cycle at about half the speed of the proliferative cells. It is these vital stem cells that will determine the response of the mucosa to therapeutic agents, probably play a role in carcinogenesis and play a dominant role in mechanisms controlling cell proliferation.

Cell Differentiation↗

PubMedDate not supplied

3H-thymidine labelling index (TLI) as a marker of tumour growth heterogeneity: evaluation in human solid carcinomas.

Many studies deal with the analysis of cell kinetic, cytogenetic, biochemical and molecular cell biology parameters to identify prognostic factors relating to tumour growth but all methods use only a small part of the total tumour mass. This study is devoted to the analysis of the heterogeneity of the growth of human solid tumours assaying proliferative activity by means of 3H-thymidine labelling index (TLI) in a fixed number of samples collected in different areas of the lesion (larynx and colon cancers), or in different lesions of the same subject (breast and bladder cancers). Each sample (at the macroscopic level) was divided into small fragments (at the microscopic level) and proliferative activity was determined. The analysis of variance for hierarchical designs demonstrated that in all cases a high component of the variance is attributable to the subjects and to the fragments whereas the variance attributable to the different areas is very low. The heterogeneity of proliferative activity displays a higher focal variability among the fragments (microscopic level) compared with that among areas (macroscopic level) within subjects, provided an adequate number of fragments and cells are counted. In multiple synchronous carcinoma of the bladder the wide variability of proliferation among the single lesions demonstrated that it is necessary to analyse all the tumours in a subject because each one is characterized by a different cell growth potential.

Adult↗

PubMedDate not supplied

The effects of irradiation at different times of the day on rat intestinal goblet cells.

Quantitative changes in jejunal goblet cells were studied in control and whole body irradiated rats using PAS-Alcian blue staining of crypt sections. A circadian dependence was observed when control animals were killed at different times during the light/dark cycle. Irradiation with 3 Gy produced a 2-3-fold increase within 36 h in goblet cells relative to controls, followed by a reduction to very low levels. There was a return to pre-treatment levels later than was observed for the columnar cells. The present results on the pattern of response of goblet cells and those of brush border enzyme activity are consistent with the hypothesis that ionizing radiation can influence differentiation. In fact during the first hours after irradiation an early induction of differentiation is evident while during the early repopulation phase columnar cells prevailed relative to the goblet cells. Only at later times were normal differentiation patterns seen. Groups of animals exposed to the same dose of radiation at different times of the day showed similar general patterns of behaviour even if the group irradiated at midnight showed a more marked and longer lasting injury.

Animals↗