Human histology and persistence of various injectable filler substances for soft tissue augmentation

The following is an abstract presented at the 33rd Annual Meeting of the Association of German Plastic Surgeons in Heidelberg, Germany, on 21 September 2002 and published online on 4 December 2003 by researchers at the University of California, San Diego, and the Institute of Pathology, Frankfurt.

An increasing number of soft tissue filler substances have been introduced to the beauty market outside the US which lack experimental and clinical data in support of their claim. Ten commercially available filler substances were examined for biocompatibility and durability: 0.1 cc of each substance was injected deep intradermally into the volar forearm of one of the authors and observed for clinical reaction and permanence. At one, three, six, and nine months the test sites were excised, histologically examined, and graded according to foreign body reactions classification. Collagen (Zyplast) was phagocytosed at six months and hyaluronic acid (Restylane) at nine months. PMMA microspheres (Artecoll) had encapsulated with connective tissue, macrophages, and sporadic giant cells. Silicone oil (PMS 350) was clinically inconspicuous but dissipated into the tissue, causing a chronic foreign body reaction.

Polylactic acid microspheres (New-Fill) induced a mild inflammatory response and had disappeared clinically at four months. Dextran microspheres (Reviderm intra) induced a pronounced foreign body reaction and had disappeared at six months. Polymethylacrylate particles (Dermalive) induced the lowest cellular reaction but had disappeared clinically at six months. Polyacrylamide (Aquamid) was well tolerated and remained palpable to a lessening degree over the entire testing period. Histologically, it dissipated more slowly and was kept in place through fine fibrous capsules. Polyvinylhydroxide microspheres suspended in acrylamide (Evolution) were well tolerated, slowly diminishing over nine months. Calcium hydroxylapatite microspheres (Radiance FN) induced almost no foreign body reaction but were absorbed by the skin at 12 months. Host defence mechanisms react differently to the various filler materials, but all substances – resorbable or nonresorbable – appeared to be clinically and histologically safe, although all exhibit undesirable side effects.

Since the mechanism of late inflammation or granuloma formation is still unknown, early histological findings are not useful in predicting possible late reactions to filler substances.

Comment

This is an ambitious experiment and comparative studies for treatments for New-Fill will be important for patient choice. Dr Lemperle holds the patent rights for Artecoll.

Lemperle G., Morhenn V and Charrier U. Human histology and persistence of various injectable filler substances for soft tissue augmentation. 33rd Annual Meeting of the Association of German Plastic Surgeons in Heidelberg, Germany, 21 September 2002.