Human disc cells in monolayer vs 3D culture: cell shape, division and matrix formation

Three experimental studies showed that cells respond specifically to culture microenvironments by changes in cell shape, mitosis and ECM production: 1) Cell passages showed extensive immunohistochemical evidence of Type I and II collagens only in 3D culture. Chondroitin sulfate and keratan sulfate were abundant in both monolayer and 3D cultures. 2) Cells showed significantly greater proliferation in monolayer in the presence of platelet-derived growth factor compared to cells in 3D. 3) Cells on Matrigel？-coated monolayer substrates became rounded and formed nodular colonies, a finding absent during monolayer growth.The cell's in vivo interactions with the ECM can regulate shape, gene expression and other cell functions. The shape of the annulus cell changes markedly during life: the young, healthy disc contains spindle shaped cells and abundant collagen. With aging and degeneration, many cells assume a strikingly different appearance, become rounded and are surrounded by unusual accumulations of ECM products. In vitro manipulation of disc cells provides an experimental window for testing how disc cells from given individuals respond when they are grown in environments which direct cells to have either spindle- or rounded-shapes. In vitro assessment of the response of such cells to platelet-derived growth factor and to Matrigel？ showed a continued influence of cell shape even in the presence of a growth factor stimulus. These findings contribute new information to the important issue of the influence of cell shape on cell behavior.Information on the in vitro behavior of human intervertebral disc cells is still relatively scarce in spite of the large health care expenditures associated with degenerative disc disease. Chelberg et al have studied human disc cells cultured in alginate beads [1], and several other laboratories have recently studied disc cells from a variety of animals [2,3,4,5,6,7,8,9]. Although these cells are most easily established initially in monolay