Distribution Of Proliferating Cells Research Articles

Retrograde movements determine effective stem cell numbers in the intestine.

The morphology and functionality of the epithelial lining differ along the intestinal tract, but tissue renewal at all sites is driven by stem cells at the base of crypts1-3. Whether stem cell numbers and behaviour vary at different sites is unknown. Here we show using intravital microscopy that, despite similarities in the number and distribution of proliferative cells with an Lgr5 signature in mice, small intestinal crypts contain twice as many effective stem cells as large intestinal crypts. We find that, although passively displaced by a conveyor-belt-like upward movement, small intestinal cells positioned away from the crypt base can function as long-term effective stem cells owing to Wnt-dependent retrograde cellular movement. By contrast, the near absence of retrograde movement in the large intestine restricts cell repositioning, leading to a reduction in effective stem cell number. Moreover, after suppression of the retrograde movement in the small intestine, the number of effective stem cells is reduced, and the rate of monoclonal conversion of crypts is accelerated. Together, these results show that the number of effective stem cells is determined by active retrograde movement, revealing a new channel of stem cell regulation that can be experimentally and pharmacologically manipulated.

Identification and culture of proliferative cells in abnormal Taenia solium larvae: Role in the development of racemose neurocysticercosis.

Racemose neurocysticercosis is an aggressive disease caused by the aberrant expansion of the cyst form of Taenia solium within the subarachnoid spaces of the human brain and spinal cord resulting in a mass effect and chronic inflammation. Although expansion is likely caused by the proliferation and growth of the parasite bladder wall, there is little direct evidence of the mechanisms that underlie these processes. Since the development and growth of cysts in related cestodes involves totipotential germinative cells, we hypothesized that the expansive growth of the racemose larvae is organized and maintained by germinative cells. Here, we identified proliferative cells expressing the serine/threonine-protein kinase plk1 by in situ hybridization. Proliferative cells were present within the bladder wall of racemose form and absent from the homologous tissue surrounding the vesicular form. Cyst proliferation in the related model species Taenia crassiceps (ORF strain) occurs normally by budding from the cyst bladder wall and proliferative cells were concentrated within the growth buds. Cells isolated from bladder wall of racemose larvae were established in primary cell culture and insulin stimulated their proliferation in a dose-dependent manner. These findings indicate that the growth of racemose larvae is likely due to abnormal cell proliferation. The different distribution of proliferative cells in the racemose larvae and their sensitivity to insulin may reflect significant changes at the cellular and molecular levels involved in their tumor-like growth. Parasite cell cultures offer a powerful tool to characterize the nature and formation of the racemose form, understand the developmental biology of T. solium, and to identify new effective drugs for treatment.

Morphogenesis of the saccus vasculosus of turbot Scophthalmus maximus: assessment of cell proliferation and distribution of parvalbumin and calretinin during ontogeny.

The ontogenesis of the saccus vasculosus (SV) of turbot Scophthalmus maximus is described using histological and immunohistochemical methods to assess the general morphology, as well as the distribution of proliferative cells and several calcium-binding proteins (CaBP). The results reveal that the SV begins to differentiate on hatching, when immature coronet cells are morphologically distinguishable. Further morphogenesis involves the formation of a tubular avascular SV, which remains until premetamorphic larval stages. Folding and vascularization of the SV occurs mostly during metamorphosis, when S. maximus settle down on the bottom. Proliferative cells were placed within the SV itself and in the neighbouring infundibular hypothalamus. Their putative relationship with the growth of the SV is discussed. The CaBPs analysed are expressed in coronet cells. Parvalbumin is expressed in these cells from the beginning of their differentiation, while calretinin expression arises in the tubular SV and becomes more widespread over time. These data emphasize the importance of calcium buffering in the function of coronet cells.

Physiologic Parameter Estimation Using Inverse Problems

The estimation of in vivo physiologic parameters is an important, but difficult, issue in bio-medicine. Therefore the development of mathematical techniques predicting these parameter values is very relevant. In a previous work we have proposed a convection-diffusion-shape model, which correlates colonic crypt patterns with the cellular kinetics occurring inside the crypts (this correlation is significant in the context of colorectal cancer). This model involves several physiologic parameters, for which only qualitative information is available in the literature, such as the birth rate of proliferative cells. In this paper we present a framework for estimating this birth rate parameter, in a colonic crypt, assuming that the distribution of proliferative cells is known in that crypt. More precisely, we resolve an inverse problem, where the unknown coefficient field, the birth rate, is connected to the observed measurements, the proliferative cell density, through a partial differential equation. This inverse problem is a PDE-constrained optimization problem, highly nonlinear and time-dependent, which is solved by an inexact Newton method. Some test simulations illustrate the efficacy of the proposed parameter inversion and forecast its application with real patient data.

Distribution and characterization of proliferative cells in the rat mandibular condyle during growth.

Distribution of proliferative cells and localization of types I and II collagen were examined in the rat mandibular condylar cartilage of 36 long-Evans/Turku strain rats during normal postnatal growth using an immunohistochemical method combined with histomorphometry. There were considerable differences in the thickness of the proliferative cell layer in the condylar head, with most mitoses occurring in the postero-superior area. It was found that the extracellular matrix of the proliferative cells does not stain for type II collagen in 20-day-old and older rats, and that besides the subchondral bone, the strongest intensity for type I collagen stain was always localized in the articular surface of the condylar head. Statistically significant overlapping of the proliferative cell layer and the one secreting type II collagen occurred during the earlier stages of development, particularly in the postero-superior area of the condylar head. As type II collagen is considered to be a marker for identification of typical cartilage cells, the findings indicate that, in addition to undifferentiated cells, a portion of the proliferative cells can be characterized as chondroblasts during the early postnatal period in rats, but not in the later stages of development. The developmental phase of the condylar cartilage should therefore be taken into consideration when the effect of various biomechanical and humoral/hormonal factors on growth of the condylar cartilage is examined.

In vivo administration of genistein has no effect on small intestinal epithelial proliferation and apoptosis, but a modest effect on clonogen survival

The soya metabolite genistein possesses anti-proliferative, pro-apoptotic activities in intestinal epithelial cells in vitro and may reduce epithelial cancer incidence. This could involve cell cycle arrest/apoptosis in the proliferative or clonogenic cells. We investigated the effects of genistein on the small intestinal epithelium in vivo. No effect on the number or distribution of proliferative cells in the crypts was detected. Similarly, no change in spontaneous apoptotic cell incidence or the characteristic stem cell apoptotic response following low dose irradiation was observed. Genistein afforded a modest decrease in clonogen radiosensitivity. Hence, using a range of dosing protocols, sub-cutaneous administration of genistein for periods of up to 1 week did not alter intestinal epithelial homeostasis.

Cell proliferation and cell death (apoptosis) in epithelial tumors of the stomach--analysis of tumor tissues by the endoscopic mucosal resection

To answer the question why some gastric cancers make elevation while others make depression in their early stage, and why polypoid cancers grow larger than their benign counterpart adenomas, the distribution of proliferating cells and apoptotic cells was compared between these lesions. Proliferating cells and apoptotic cells were detected with anti Ki-67 antibody (MIB-1) and with the in situ nick end labeling (ISNEL), respectively. A total of 62 gastric tumors, taken by the endoscopic mucosal resection method, was assessed. They consisted of 14 adenomas and 48 mucosal carcinomas (27 polypoid and 21 depressed type). Overall positive rates of Ki-67 were 27.5 +/- 9.0% in adenoma, 40.1 +/- 11.1% in polypoid cancer and 47.5 +/- 9.7% in depressed cancer. Proliferating cells were preferentially found in the cripts of metaplastic mucosa, in the middle to upper layer of adenomas, and in the whole layer including their surface of adenocarcinomas. Within cancers the polypoid type had more positive cells in the upper layer, so did the depressed type in the lower layer. ISNEL positive nuclei showed sphere, fragmented, ringed forms, or the same form as neighboring tumor nuclei. Apoptotic cells lay scattered throughout tumor glands. Apoptotic cell counts per 1000 tumor cells were 26.0 +/- 9.7 in adenoma, 36.3 +/- 32.1 in polypoid cancer, and 52.5 +/- 19.3 in depressed cancer. Depressed type cancers and a few polypoid cancers rich in non-tumor tissues showed higher numbers of apoptotic cells than adenomas and usual polypoid cancers. (ABSTRACT TRUNCATED AT 250 WORDS)

The effect of dietary omega-3 fatty acids (fish oil) on azoxymethanol-induced focal areas of dysplasia and colon tumor incidence

MaxEPA (MA), a fish oil high in omega-3 fatty acids, was combined with various levels of corn oil (CO), rich in omega-6 fatty acids, and fed to female CF1 mice. The three fish oil blends with CO and the two CO levels of the diets studied were as follows: 16.0% CO + 4.4% MA (Diet 1); 10.2% CO + 10.2% MA (Diet 2); 4.4% CO + 16.0% MA (Diet 3); 20.4% CO (Diet 4); and 4.4% CO (Diet 5). The diets were provided 2 weeks before weekly subcutaneous injection of saline or azoxymethanol (AOM). Studies of epithelial cell proliferation and the incidence of focal areas of dysplasia (FAD) involved six weekly AOM injections. One week after the last AOM injection and 1 hour before killing, mice were injected with tritiated thymidine (3HTdR). No differences in any proliferative parameters were found among the five groups of saline-treated mice. Among the AOM-treated animals, those fed Diet 3 showed significantly fewer cells per crypt and significantly fewer labeled cells/gland than CO Diets 4 and 5. Additionally, the distribution of S-phase cells in crypts of AOM-treated mice fed Diet 3 most closely resembled that of the saline controls. The greatest alteration in the distribution of proliferative cells was observed in the high-CO diet (Diet 4) and the lowest MA level (Diet 1). Mice fed Diets 2 and 3 had significantly fewer FAD/500 microns of distal colonic serial sections than those fed the high CO diet (Diet 4). Mice involved in chronic tumor incidence studies received only three weekly injections of the same dose of AOM. Regardless of diet, approximately 88% of all tumors arose in the distal colon. A significantly larger tumor-bearing population was observed in both the high-CO Diet 4 and the lowest MaxEPA (MA) diet (Diet 1) compared with the incidence in MA Diets 2 and 3 and the low-CO Diet 5. A diet with a ratio of omega-6 to omega-3 fatty acids of approximately 1.0 apparently prevented the development of an adenoma-type proliferative pattern thereby reducing FAD numbers and subsequent tumor incidence.

Histogenesis of the mouse pyloric mucosa with special reference to the development of surface mucous cells and pylorocytes, and the formation of the generative zone.

The distribution of proliferative cells and maturation of epithelial cells were studied in the pyloric mucosa of developing mice by 3H-thymidine autoradiography, carbohydrate histochemistry and electron microscopy. The formation of the gastric foveola and pyloric gland were seen to begin as an invagination in the epithelial surface and/or the formation of intraepithelial cavity on day 13 of gestation (day E13). Surface mucous cells and pylorocytes were first identified on day E16 by carbohydrate staining as well as by their fine structure. Both types of cells rapidly acquired abundant membranous organelles and secretory granules within the first postnatal day, maturing in fine structure by day 28. Proliferative cells were distributed over the epithelium by day E15, while they were rarely found at the mucosal surface after day E16. Concomitantly with the elongation of foveolae and glands during postnatal development, the proliferative capability of surface mucous cells diminished from the foveolae and that of pylorocytes from the glands, respectively; the generative zone was restricted to the isthmus by day 21, as in the adult animal. These results reveal that the histogenesis of the mouse pyloric mucosa is accomplished by the end of the weaning period.