I work in the field of cell encapsulation technology and our in vivo assays comprise the SC implantation of microcapsules. At the end of the study, microcapsules are retrieved from the SC space and my final aim is to analyse it histologically and in terms of released protein production (to see whether the encapsulated cells still keep alive).

I have tried a tissue digestion method to get rid of all the tissue formed around microcapsules, for the protein production assay, but I don't get quite good results.

I was told to use collagenase H (2mg/mL) and hialuronidase (1mg/mL) and to keep the tissue embedded in this solution in a water bath 37C, for three hours... (this was a protocol somebody used in the past here) but I don't think the results are too good and I would like to find alternatives.

Hope somebody can help me. Thank you very much in advance,

Ainhoa PhD student, Spain

Try using your protocol with Collagenase XI, (aliquot and store this frozen, as the enzyme can be fairly labile with freeze thaws) instead of Collagenase H - esp if your enzyme is old. This can be done in a buffer such as HBSS, at 37dC for ~ 2h and continuous shaking. I use the enzyme at 10mg/ml stock conc, usually in a final enzyme conc of 1 mg/ml.
Also, I don't know if your final application will support this, but have you considered 30-40uM pore mesh filtration and density gradient centrifugation in addition to enzyme digestion, to further clean up your prep?
Finally, there are a number of ways to dissolve the alginate matrix itself if you need to get that out of the way: in fact these matrices are now used for 3D cell culture too!

Hi Ainhoa! You might want to try using the enzyme (Col XI) both with and without hyaluronidase (I use it without). XI works great on lung, liver and kidney tissue.
I did not factor in the alginate matrix swelling etc - so you might want to try using the enzyme in regular 1x PBS - at a higher concentration (2mg final instead of 1), just in case those additional ions are required for optimal enzyme activity (i.e. to compensate for any reduced enzyme activity).
Also, this will be some extra work, but you could just try gelling the beads in HBSS -when you originally encapsulate your cells. HBSS already has Ca (and Mg), so you may have to tweak your protocol some. Your cells will be happy, your bead size may vary from what you have right now, and the enzyme will work - so you'll just have to get an optimal balance. The final in vivo instillation can then be in the regular sterile/USP saline, though I believe Sigma has a USp grade HBSS too.
Hope this helps - let us know!
-sam