در رفتار اجتماعی از سلول ها

Polystyrene Petri dishes are in use in hundreds of thousands of laboratories world wide. Cell culture experiments performed in them provide fundamental information in a wide range of applications, including but not limited to testing novel biomaterials and pharmaceuticals, and stem cell research. These experiments cost billions of dollars per year. In this study we report on a potential deficiency of polystyrene Petri dishes, possibly caused by an increase in interfacial pH under relevant culture conditions and affecting cell performance. We conclude that cell performance on Petri dishes could be improved by improving the Petri dishes. As a spin-off of our study we postulate the concept that cancer cells and stem cells are social. It is impossible to validate this concept on the basis of the model established in this paper. However, the coherence of our insights may encourage further study and lead to the development of a qualitative improvement of cell culture devices, including Petri dishes and culture flasks, to the identification of potential strategies for chemotherapy and chemoprevention that could suppress progression of metastasis, and to the establishment of improved settings for tissue engineering and stem cell research. An immediate recommendation of our study is to use chemically and biologically inert substrates for important cell culture experiments, for example, nanocrystalline diamond.

We wish to draw the attention to a potential deficiency in the biocompatibility of polystyrene Petri dishes: a possible increase in the interfacial pH, probably accompanied by a softening of the material surface under relevant culture conditions. This potential deficiency is of considerable biological interest. In a biomimetic approach, which attempts to mimic the native environment of a cell, the biocompatibility of a material is expressed in terms of a set of eight quantifiable determinants, including surface charge and hardness[1]. Changes in interfacial pH are manifestations of surface charge.Because surface hardness is usually a long-term determinant,its temporal and spatial constancy is normally presumed and precondition for a clear quantification of the parameter. Exceptions are biodegradable materials.Spatial gradients in surface hardness can affect the behaviour of cells, which register even minimal spatial gradients. Reportedly, 3T3-fibroblasts tended to migrate towards increasing substrate hardness[2]. Cellular locomotion induced by a spatial variation in surface hardness is called durotaxis, and reveals the existence of hardness sensing receptors. The susceptibility of cells to mechanical variations in their microenvironment (extracellular matrix – ECM) is not surprising: For instance,variations in the compliance of the ECM are interpreted by surface receptors called integrins, which connect to the cytoskeleton and translate the external mechanical information into modification of cell contractility[3].Derailment of the mechanical properties of the ECM has consequences not only for the shape, but also for the proliferative activity of normal cells, thereby indicating that alterations of stromal compliance could prelude oncogenic conversion[4]. The ECM-cell interplay determines changes from normal to cancerous tissues.According to a recent atomic force microscopy study,cancer cells isolated from patients were about 70% less stiff than normal cells[5]. Mechanical microenvironment properties play further a key role in directing stem cell lineage specification[6]. Notably, 3T3-fibroblast durotaxis was observed only at very low cell densities[2]. It is assumed that durotaxis contributes to directing motile cells into stiff, fibrotic regions of tissue[7].