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The serial cultivation of human diploid cell strains
Abstract
The isolation and characterization of 25 strains of human diploid fibroblasts derived from fetuses are described. Routine tissue culture techniques were employed. Other than maintenance of the diploid karyotype, ten other criteria serve to distinguish these strains from heteroploid cell lines. These include retention of sex chromatin, histotypical differentiation, inadaptability to suspended culture, non-malignant characteristics in vivo, finite limit of cultivation, similar virus spectrum to primary tissue, similar cell morphology to primary tissue, increased acid production compared to cell lines, retention of Coxsackie A9 receptor substance, and ease with which strains can be developed. Survival of cell strains at - 70 °C with retention of all characteristics insures an almost unlimited supply of any strain regardless of the fact that they degenerate after about 50 subcultivations and one year in culture. A consideration of the cause of the eventual degeneration of these strains leads to the hypothesis that non-cumulative external factors are excluded and that the phenomenon is attributable to intrinsic factors which are expressed as senescence at the cellular level. With these characteristics and their extremely broad virus spectrum, the use of diploid human cell strains for human virus vaccine production is suggested. In view of these observations a number of terms used by cell culturists are redefined.
... Challenging the "irreversible" dogma of cellular senescence Cellular senescence was described for the first time by Hayflick and Moorhead in 1961 (21), when they described and characterized the development of 25 strains of human cells from different fetal tissues, finding that normal cells can replicate only for a limited number of passages and then entered in an irreversible cell cycle arrest (6,21,22). This leads to the absence of Ki-67 protein, presence of senescence-associated b-galactosidase activity and expression of several tumor suppressors and cell cycle inhibitors. ...
Diabetes constitutes a world-wide pandemic that requires searching for new treatments to halt its progression. Cellular senescence of pancreatic beta cells has been described as a major contributor to development and worsening of diabetes. The concept of reversibility of cellular senescence is critical as is the timing to take actions against this “dormant” senescent state. The reversal of cellular senescence can be considered as rejuvenation of the specific cell if it returns to the original “healthy state” and doesn’t behave aberrantly as seen in some cancer cells. In rodents, treatment with senolytics and senomorphics blunted or prevented disease progression, however their use carry drawbacks. Modulators of cellular senescence is a new area of research that seeks to reverse the senescence. More research in each of these modalities should lead to new treatments to stop diabetes development and progression.
During aging and after traumatic injuries, cartilage and bone cells are exposed to various pathophysiologic mediators, including reactive oxygen species (ROS), damage-associated molecular patterns, and proinflammatory cytokines. This detrimental environment triggers cellular stress and subsequent dysfunction, which not only contributes to the development of associated diseases, that is, osteoporosis and osteoarthritis, but also impairs regenerative processes. To counter ROS-mediated stress and reduce the overall tissue damage, cells possess diverse defense mechanisms. However, cellular antioxidative capacities are limited and thus ROS accumulation can lead to aberrant cell fate decisions, which have adverse effects on cartilage and bone homeostasis. In this narrative review, we address oxidative stress as a major driver of pathophysiologic processes in cartilage and bone, including senescence, misdirected differentiation, cell death, mitochondrial dysfunction, and impaired mitophagy by illustrating the consequences on tissue homeostasis and regeneration. Moreover, we elaborate cellular defense mechanisms, with a particular focus on oxidative stress response and mitophagy, and briefly discuss respective therapeutic strategies to improve cell and tissue protection.
Cellular senescence, a state of permanent cell cycle arrest in response to endogenous and exogenous stimuli, triggers a series of gradual alterations in structure, metabolism, and function, as well as inflammatory gene expression that nurtures a low-grade proinflammatory milieu in human tissue. A growing body of evidence indicates an accumulation of senescent neurons and blood vessels in response to stress and aging in the retina. Prolonged accumulation of senescent cells and long-term activation of stress signaling responses may lead to multiple chronic diseases, tissue dysfunction, and age-related pathologies by exposing neighboring cells to the heightened pathological senescence-associated secretory phenotype (SASP). However, the ultimate impacts of cellular senescence on the retinal vasculopathies and retinal vascular development remain ill-defined. In this review, we first summarize the molecular players and fundamental mechanisms driving cellular senescence, as well as the beneficial implications of senescent cells in driving vital physiological processes such as embryogenesis, wound healing, and tissue regeneration. Then, the dual implications of senescent cells on the growth, hemostasis, and remodeling of retinal blood vessels are described to document how senescent cells contribute to both retinal vascular development and the severity of proliferative retinopathies. Finally, we discuss the two main senotherapeutic strategies—senolytics and senomorphics—that are being considered to safely interfere with the detrimental effects of cellular senescence.
The deoxyribonucleic acid (DNA) content of Feulgen-stained interphase nuclei from human amnion epithelium and liver parenchyma as well as the DNA content of their sex chromatin or heterochromatic bodies was determined histophotometrically. In female nuclei the ratio between the nuclear DNA content and that of their sex chromatin or heterochromatic bodies remains constant irrespective of the polyploid state of the nucleus. Thus, in polyploid nuclei the heterochromatic bodies double their DNA content with each duplication of the diploid nuclear DNA content. Therefore, it is assumed that the large or multiple heterochromatic bodies of female polyploid nuclei are conjugated or multiple sex chromatin bodies. Some male diploid nuclei show a distinct heterochromatic body whose DNA content is about one-half that of a sex chromatin. About one-half of the polyploid male nuclei have heterochromatic bodies whose DNA content is approximately one-half of those of female nuclei of the corresponding polyploid class. This would indicate that in male diploid nuclei the single X chromosome sometimes leaves a heterochromatic rest one-half the size of a sex chromatin and in polyploid male nuclei the two or more X's may leave larger heterochromatic bodies. However, many male nuclei, even when polyploid, do not have distinct heterochromatic bodies. Possibly the heterochromatic portions of the X's have failed to join and form a sex chromatin-like body; or the Y inhibits the X from leaving a heterochromatic rest. The proposal of other authors that the sex chromatin is derived from but one of the X chromosomes of the female nucleus, the X in the male leaving no heterochromatic rest, is also considered. The DNA content does not vary significantly between nuclei with and without sex chromatin or heterochromatic bodies. It remains clear that female nuclei with abnormally large or multiple sex chromatin bodies and male nuclei with large distinct heterochromatic bodies are always polyploid.
In 1951 Gey (7) succeeded in developing for the first time & strain of human cells (HeLa) that could be cultivated indefinitely in vitro. This strain has since been used widely as a laboratory tool. In the few years following Gey's achieve ment, other investigators have applied themselves to establishing lines of human cells from normal and cancer tissue. Many of these efforts have been successful. In the fall of 1955, twenty different strains of human cells were reported in answer to a questionnaire circulated by the Tissue Culture Association. Established strains of human cells are being used in a variety of areas in experimental
A strain of rabies fixed virus has been successfully cultivated in tissue cultures of hamster kidney cells. This confirms an earlier report by Kissling. In the experiments here recorded a special culture tube incorporating a dialyzing membrane made it possible to maintain the cells in continuous culture for many weeks. By using this technique it was possible to obtain culture fluids of high infectivity.
Zusammenfassung Der Verfasser gibt eine kurze Übersicht über die neueren Methoden derin vitro-Kultur von Säugerzellen. Eingehend wird die Entwicklung von stabilen Kulturen diploider Zellen und Untersuchungen über die spezifischen Wachstumsfaktoren isolierter menschlicher Zellen besprochen. Auch die Wirkung der Ultraviolettstrahlung auf solche Zellen wird diskutiert.
THE contamination of tissue culture cell lines by pleuropneumortia-like organisms has become an increasingly important problem1-4. The contamination itself is insidious and cannot be detected ordinarily by gross changes in the appearance of the media macroscopically or microscopically. The tissue culture cells themselves, when observed microscopically, may or may not exhibit slight cytopathology as evidenced by intracytoplasmic granularity. Properly stained preparations may reveal intracytoplasmic particles, presumably the contaminating pleuropneumonia-like organisms5-7.