Tissue engineering thermoresponsive polymers

Schmaljohann, D. 2005. Thermoresponsive polymers and hydrogels in tissue engineering. e-Polymers No. 021. 

Bmshes grafted to latex particles [279, 280] polymer-protected gold nanoparticles [281, 282] various copolymers [45, 49, 55,259] drug delivery, tissue engineering [45], thermoresponsive gels [130]... 

Several polymers have been designed to exhibit thermoresponsive behavior near physiological temperatures with demonstrated suitability for cell encapsulation and tissue engineering. Two examples of common polymers are the triblock copolymer, poly(ethylene glycol)-fi-poly(propylene)-fi-poly(ethylene glycol), commercially known as Pluronics and poly(N-isopropylacrylamide) (pNiPAAm). Specifically,... 

Thermoresponsive polymers are promising for biomedical applications, including as smart dmg/gene delivery systems, injectable tissue engineering scaffolds, and cell culture and separation sheets/ However, either the most frequently studied thermoresponsive polymers such as poly(N-isopropylacrylamide) (PNlPAAm), oligopoly(ethylene glycol), poly(N,N -diethylacrylamide), and poly(2-carboxyisopropylacrylamide) are non-degradable or the lower critical solution temperature (LCST) cannot be tuned. 

There are two main applications of thermoresponsive polymers in tissue engineering [1] as substrates that enable the cell growth and proliferation and [2] as injectable gels. The cells can be well encapsulated with the polymer and then when injected into the body due to change in LCST of the polymer, it forms a physical gel and the cells get encapsulated within the 3D structure of the gel. The in situ formation of cell/scaffold contrast by thermoresponsive systems can be used to deliver growth factors, cells to the desired site [20]. 

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