Thermosensitive injectable hyaluronic acid hydrogel for adipose tissue engineering

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Tissue Engineering

Background:

• Hyaluronic acid (HA) is a biocompatible polysaccharide with limitations in stability and injectability.
• Developing injectable, thermosensitive hydrogels is crucial for advanced drug delivery and tissue regeneration.
• Poly(N-isopropylacrylamide) (PNIPAAm) is a well-known thermoresponsive polymer, but its direct application can be limited.

Purpose of the Study:

• To synthesize and characterize novel thermosensitive copolymer hydrogels based on aminated hyaluronic acid and poly(N-isopropylacrylamide) (AHA-g-PNIPAAm).
• To evaluate the physicochemical properties, including thermosensitivity, swelling, and enzymatic degradation, of the synthesized hydrogels.
• To assess the cytocompatibility and potential application of AHA-g-PNIPAAm hydrogels in adipose tissue engineering.

Main Methods:

• Synthesis of aminated hyaluronic acid (AHA) and carboxylic end-capped PNIPAAm (PNIPAAm-COOH).
• Coupling of PNIPAAm-COOH to AHA via amide linkages to form AHA-g-PNIPAAm copolymers.
• Characterization using Nuclear Magnetic Resonance (NMR) spectroscopy, rheological analysis, Scanning Electron Microscopy (SEM), and swelling studies.
• In vitro cell viability assays using human adipose-derived stem cells (ASCs) and in vivo preliminary studies.

Main Results:

• Successfully synthesized AHA-g-PNIPAAm copolymers with tunable PNIPAAm content.
• The hydrogels exhibited a lower critical solution temperature (LCST) around 30°C, demonstrating thermosensitivity.
• Increased PNIPAAm content enhanced enzymatic resistance and reduced equilibrium swelling ratios.
• SEM confirmed a porous 3D hydrogel structure, with pore size dependent on PNIPAAm ratio.
• ASCs encapsulated within the hydrogels showed non-cytotoxicity and maintained high viability.
• Preliminary in vivo studies indicated the potential of AHA-g-PNIPAAm as an injectable scaffold for adipose tissue engineering.

Conclusions:

• AHA-g-PNIPAAm copolymers represent a promising class of injectable, thermosensitive hydrogels.
• These hydrogels possess tunable properties, including enhanced enzymatic resistance and controlled swelling.
• The non-cytotoxic nature and cell viability preservation support their use in regenerative medicine.
• AHA-g-PNIPAAm hydrogels show significant potential as versatile delivery vehicles for cells and pharmaceuticals in tissue engineering applications.