Author(s)

Kazuaki Muramatsu, Yuji Saito, Takuya Wada, Hiroyuki Hirai, Fujio Miyawaki

Division of Life Science and Engineering, School of Science and Engineering, Tokyo Denki University, Saitama, Japan.

Novel poly(N-isopropylacrylamide-co-N-tert-butylacrylamide)-grafted hyaluronan [P(NIPAAm-co-NtBAAm)-g-HA] has been developed as a modified derivative to improve phase-transition characteristics of PNIPAAm-g-HA, which has a lower critical solution temperature (LCST) of approximately 32°C. This promising self-assembling biomaterial has potential as an injectable scaffold for in situ cartilage tissue engineering. LCST of the P(NIPAAm-co-NtBAAm)-g-HA decreased to approximately 3.6°C compared to that of the original PNIPAAm-g-HA. This modification enabled self-assembly at body temperatures lower than the temperature of the parental PNIPAAm-g-HA molecule. Cytotoxicity and acute systemic toxicity assays revealed that P(NIPAAm-co-NtBAAm)-g-HA was not hazardous. The DNA content of chondrogenic differentiated mesenchymal stem/stromal cells (MSCs) embedded in the gels was higher than that of biomaterial-free aggregates during the culture periods. Cartilage-related genes were also expressed in chondrogenic differentiated MSCs embedded in the P (NIPAAm-co-NtBAAm)-g-HA hydrogel. Specifically, an increased expression of SRY-related HMG box-containing gene 9 (Sox9) observed in the hydrogel group compared to controls. These data suggest that P(NIPAAm-co-NtBAAm)-g-HA is a promising injectable scaffold with thermoresponsive properties suitable for in situ cartilage tissue engineering.

Thermally Responsive Material; Cartilage Tissue Engineering; Biocompatibility; Mesenchymal Cells

Muramatsu, K. , Saito, Y. , Wada, T. , Hirai, H. and Miyawaki, F. (2012) Poly(N-isopropylacrylamide-co-N-tert-butylacrylamide)- grafted hyaluronan as an injectable and self-assembling scaffold for cartilage tissue engineering. Journal of Biomedical Science and Engineering, 5, 639-646. doi: 10.4236/jbise.2012.511079.