Does anyone have a good method for extracting polymer from explanted polymer implants with substantial tissue ingrowth? The polymer can not be physically separated from the tissue, ideally the method would be chemical extraction. Specifically the polymer is poly(lactic acid) or polylactide. I have paraffin blocks of tissue that have been used for histology of the constructs, but I would love to be able to run GPC on the polymer remaining in the block samples. If anyone has any advice please let me know, I am curious how much polymer I will need to extract. Thanks!
I think this question is most relevant for tissue engineering, bioengineering, regenerative medicine, and looking at biodegradable implants in vivo. Tissue could be human or animal.
For GPC measurements you will need a solution of PLA, so you could use an organic solvent that dissolves the polymer and does not dissolve the rest of the materials that are present in your sample. Maybe DMSO? Just a thought.
Hexan is a good solvent for paraffin, but is a no-solvent for PLLA.
Try to remove the paraffin and then dissolve the polymer in methylen chloride or THF.
I think, that you can use the procedure of tissue removing given in this paper: Lam et al., Evaluation of polycaprolactone scaffold degradation for 6 months in vitro and in vivo. J. Biomed. Mater. Res., (2009) 90A: 906–919.
Regarding to minimal amount of polymer, it depends on used GPC system and measurements parameters. In our lab we need at least 0.5-1ml solution of PLA or other polymer in solvent, (ie THF, CHCl3) with concentration 1-2mg/ml.
Hi Kevin,
I think you should try to dissolve the polymer in the appropiate solvent (such as chlorofrom), and check whether you do not destroy the remaining tissue.
Let me know if this help.
We have used a collagenase digestion to remove fibrous tissue from polymer/tissue explants (see Journal of Surgical Research. Volume 184 (2013) pp. 766-773.) With this technique, we can recover and characterize the polymer implant by mechanical testing, GPC, SEM, etc. However, this may be best suited for fresh explants. In your case, you will likely need to remove the paraffin first.
As an alternative, since GPC only requires a few milligrams of polymer, you could try direct extraction of the paraffin block with a solvent like hexane to remove the paraffin and lipids, followed by your solvent of choice (ex. chloroform) to extract the PLA from the residual tissue. After extraction of the polymer, you can recover the polymer by evaporating the extraction solvent and then proceed with your GPC experiment. Note: There are may different forms of PLA that vary in solubility in different solvents, but none of them should be soluble in hexane.
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