Acrylamide, acrylic acid and N-isopropylacrylamide hydrogels as osmotic tissue expanders.
OBJECTIVE
Osmotically active tissue expanders allow the harvesting of soft tissue for reconstruction after different injuries. However, their expansion properties could be improved. Thus, our goal was to examine the in vivo applicability of acrylamide (AAm), acrylic acid (AAc) and N- isopropylacrylamide (NIPAAm) hydrogels.


METHODS
Cylinders of AAm, AAc and NIPAAm hydrogels were implanted under the skin of rats in the dorsal region. The diameter and the length of the cylinders were measured daily. After removal of the hydrogels, their mass and rheological properties were determined. Further, biopsies were taken from the adjacent tissue for histological analysis.


RESULTS
The hydrogels reached the peak of swelling by the end of the 2nd postoperative week. The wet mass of the removed cylinders was 25 times their dry mass prior to implantation. NIPAAm polymers exhibited the most favourable visco-elastic properties, with the highest tendency to retain their preformed shape. The histological analysis revealed serious tissue damage when the AAc devices were used, whereas the AAm and NIPAAm did not result in such lesions.


CONCLUSIONS
In view of its mechanical and biological properties, NIPAAm hydrogel seems to be the most appropriate of these materials for application in plastic and reconstructive surgery.
Department of Plastic Surgery, University of Szeged, Szeged, Hungary.
J
J
Varga
L
L
Janovak
E
E
Varga
G
G
Eros
I
I
Dekany
L
L
Kemeny
D020106:Acrylamide / Q000009:adverse effects / Q000737:chemistry; D000178:Acrylamides / Q000009:adverse effects / Q000737:chemistry; D000179:Acrylates / Q000009:adverse effects / Q000737:chemistry; D000818:Animals; D001672:Biocompatible Materials / Q000009:adverse effects / Q000737:chemistry*; D004548:Elasticity; D020100:Hydrogels; D008297:Male; D009995:Osmosis; D051381:Rats; D017208:Rats, Wistar; D019651:Plastic Surgery Procedures / Q000009:adverse effects / Q000379:methods*; D012212:Rheology; D015626:Tissue Expansion / Q000009:adverse effects / Q000379:methods*; D015625:Tissue Expansion Devices / Q000009:adverse effects; D014783:Viscosity
D000178:Acrylamides; D000179:Acrylates; D001672:Biocompatible Materials; D020100:Hydrogels; D020106:Acrylamide; C067295:N-isopropylacrylamide; C036658:acrylic acid