[Ca2+]i independent mitogenesis in cultured human fibroblasts revealed by single cell microfluorimetry.

A transient rise in intracellular free Ca2+ concentration ([Ca2+]i) has been implicated in mitogenic induction of cell division. Individual human foreskin fibroblasts in confluent cultures examined with the Ca2+ indicator Fura-2 and a fluorescence microscope-imaging system had a basal [Ca2+]i which varied markedly from cell-to-cell. A transient serum-induced rise in [Ca2+]i was demonstrated the magnitude of which was directly correlated with the basal [Ca2+]i level.

Calcium, lanthanum, pyrophosphate, and hydroxyapatite: a comparative study in fibroblast mitogenicity.

Calcium-containing crystals and elevated levels of calcium chloride (CaCl2) and lanthanum chloride (LaCl3) have been previously reported to enhance the proliferative activity of cultured fibroblasts. We have investigated the relative mitogenicity of these agents, whether they function via precipitation on the cell surface and whether they interact with one another. Confluent cultures of newborn foreskin fibroblasts provided with fresh medium containing 10% fetal bovine serum (FBS) in the presence of hydroxyapatite (HA), pyrophosphate (PPi), LaCl3 (La), or additional CaCl2 (Ca) were all stimulated more than control cultures provided with fresh medium and 10% FBS alone as assessed by cell counts 5 days later.

Use of strontium to separate calcium-dependent pathways for proliferation and differentiation in human keratinocytes.

The role of extracellular calcium (Caex) in modulating keratinocyte differentiation has been well documented, but its role in proliferation has been harder to define due to the confounding effect of terminal differentiation. Because strontium (Sr) does not induce terminal differentiation in murine keratinocytes but does mimic the stimulatory effect of Caex on DNA synthesis in chick fibroblasts, experiments were undertaken to determine if Sr could be used to separate the presumably opposing effects of Caex on the proliferation and differentiation of cultured human keratinocytes. In response to additions of SrCl2, keratinocytes in a serum-free hormone-supplemented basal medium containing 0.

Modulation of WI-38 cell proliferation by elevated levels of CaCl2.

Elevating the level of extracellular calcium (CaEx2+) increases the saturation density achieved by the normal human diploid cell line, WI-38, but does not change the growth rate. Day 7 cell yields remain unchanged when [CaEx2+] is between 0.5 mM and 3.

Influence of increased extracellular calcium concentration and donor age on density-dependent growth inhibition of human fibroblasts.

Elevated calcium chloride concentration [( CaCl2]) has been shown to increase saturation density for an established mouse fibroblast line and for human fetal lung fibroblasts (WI-38). In order to examine the effect of increased [CaCl2] on human fibroblasts from donors of varying age, fibroblasts were grown in medium (basal level of 1.8 mM CaCl2) supplemented with fetal bovine serum (FBS) until confluent.