We have not observed such a cluster in our fibroblast cultures. Is the flask coated with agar or else

be use checking in high magnification that it is not a micotic cluster.

Hi,

how did you get the cells? Are this primary cultures? Are they pure? Depending on the dissection procedure you might have harvested an additional cell type which can proliferate and form aggregates. It would be good to have more informations: how long did you culture, what culture medium did you use. did you perform any treatment?

Best wishes

KHS

In my opinion the cells are clearly way too overgrown and on the left side you can see that they are overlapping one over the other. on the right , on the contrary you have almost no cells.I t could be sufficient a simple mechanical stimulus (moving the flask) to detach the loosely attached overgrown cells and make them form such an aggregate. Unless you are interested in this,you should split the cells when they are 70-80% confluent..

This culture is overgrown. Fibroblasts secrete collagens and other ECM proteins to form an ECM layer. Then, when overgown they contract the layer and form these aggregates.

If you need to propagate them - you'd need to passage them long before they form these structures.

I experienced this kind of clusters using MEFs. According to our results you might consider three aspects to resolve the problem. Coat the surface with 0,2% gelatin (but make sure that it doesn’t have more than a month, otherwise cells are going to detach). Reduce the culture density and agitate the plaque after seeding fibroblast performing cross-like movements to avoid accumulation of cells in the middle of the plaque. This way you should achieve an homogeneous fibroblast monolayer.