Giancarlo, 

The best method for you will depend on a couple things. Do you care what type of collagen the fibroblasts secrete (I, II, etc.)? Do you need to know how it's organized in space? Do you need to quantify it, or are you looking for qualitative or very rough numbers?

I used to do a Sirius Red/picric acid colorimetric assay to quantify total soluble collagen as an undergrad. This did not distinguish between types, but it didn't require much special equipment and wasn't very hard. You could buy a kit or run it homemade.

If you care about qualitative information, you may want some sort of microscopy. Immunofluorescence is a good start. If you have thick samples for some reason (3D culture or whole mount tissue samples), you could try confocal or multiphoton. All of these could be done with type-specific antibodies. To get a sense of the diameters of the collagen fibers, you could also do picrosirius red staining and view under polarized light.

Hope this helps!

Also, you may want to take a look at this paper. It discusses stimulating collagen production in fibroblasts using TGF-b1 to trigger transdifferentiation into myofibroblasts. There's lots of literature on TGF-b1 pathways you could dig into if you want to look more at molecular mechanisms.

Methods Find Exp Clin Pharmacol. 2002 Jul-Aug;24(6):333-44.

Hello 

agree with Chelsea Elizabeth Stowell  There are many ways and you can choose the better for your research

please , read the articles in attachment , Do not hesitate to ask for help

Good Luck

The Sirius Red/picric acid colorimetric assay seems like a good place to start for me, at least for an initial iteration of this study. I will certainly look into the literature you have both provided.

Thank you both very much!