Tissue engineering reversible

PEO-PPO-PEO triblock copolymers (Pluronics or Poloxamers) form reversible physically cross-linked hydrogels under certain concentration range and temperature. The use of this system in tissue engineering is scarce because of its inability to degrade. Di- or tri-block copolymers of PEG with PLA have been developed to overcome this problem. Multiple blocks of PEG and PLA, synthesized by condensation reaction of L-lactic acid in the presence of succinic acid. 

Park, H., Kang, S. W., Kim, B. S., Mooney, D. J. Lee, K. Y. (2009a) Shear-reversibly crosslinked alginate hydrogels for tissue engineering. Macromol Biosci, 9, 895-901. 

Temperature-responsive hydrogels, mostly based on PNlPAAm and its derivatives, are widely studied and used for a variety of applications, including drug delivery and tissue engineering. If the temperature of the environment is raised to a critical value known as lower critical solution temperature (LCST), these networks tend to shrink or collapse and the systems undergo a reversible... 

Because of their transient and reversible cross-linking, supramolecular polymer networks are responsive [4] to external stimuli such as variation in temperature [31], pH [32], polarity of the solvent [33], redox reactions [34], and competitive ligation [35]. This tunability makes them useful for a plethora of applications. They can be used as drug delivery systems [36] and as matrixes in tissue engineering [37]. Drugs and cells can be encapsulated and protected within these materials and... 

Tissue engineering scaffold for DNA delivery by cationic polymers. Biomimetic scaffolds can be encapsulated with growth factors and MSCs are seeded onto their surface [top]. Polymeric release bottom left) consists in the entrapment of the complexes between cationic polymers and DNA within the biomaterial for release into the environment. Conversely, substrate-mediated delivery bottom right), also termed reverse transfection delivery, employs the immobilization of complexes to the biomaterial. MSCs can internalize the complexes either directiy or by degrading the linkage between the biomaterial and DNA complexes. 

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