Abstract
Background
Hyaluronic acid (HA) hydrogels are becoming an increasingly attractive choice for the creation of new biomaterials useful in wound care, tissue engineering and regenerative medicine, because of their high level of biocompatibility and biodegradability, and for their ability to imitate the environment of the extracellular matrix (ECM). Due to the poor biomechanical properties of native hyaluronan, a variety of chemical modifications have been devised to provide mechanically and chemically stiffer materials.
Methods
In this work, 200 kDa hyaluronic acid was modified with coumarin moieties via a functional linker (FID119) and photo-polymerised into networks through a [2+2] cycloaddition reaction using near-UV light (lmax=365 nm). This method allows to obtain “wall-to-wall” hydrogels starting from moderately viscous solutions. FID119 can therefore be deposited in the cartilage defect as an aqueous solution and can be polymerised in situ after UV irradiation.
Results
With a HA molar derivatisation ranging from 10% to 40% and a concentration varying from 10 mg/mL to 40 mg/mL, hydrogels exhibited a wide range of physical properties. When a suspension of human dermal fibroblasts was photo-encapsulated within the hydrogels, cells retained a rounded morphology throughout the period of culture and showed no spreading. Cells remained viable after 48 hours encapsulation, confirming that their viability was affected neither by the polymerisation process nor by UV irradiation. In this study we have also evaluated the proliferation of fibroblasts encapsulated in HA-hydrogels at different degree of reticulation, concentrations and polymerisation time. By means of the resazurin reduction assay (Alamar Blue) it has been shown that encapsulated fibroblasts showed overall lower metabolic activity compared to fibroblasts cultured in traditional 2D tissue culture plastic dishes, in all the tested conditions.
Conclusions
This work represents a first step towards the development and characterisation of new HA-based advanced biomaterial to be used as scaffolds in cartilage regeneration. The screening of the different FID119 preparations led to the selection of three prototypes representing the best compromise between physical-chemical properties and biocompatibility.
Level of Evidence
III.
