2.5. HA-L-PNIPAM and HA-Based Hydrogel Formulation with Lyophilized FE002 Primary Chondroprogenitors

Lyophilized HA-L-PNIPAM was resuspended at 3.7% w/v in an aqueous solvent composed of distilled water and PBS in equal proportions. Linear HA (2200–2400 kDa MW) was resuspended separately at 1.0% w/v in the same aqueous solvent. Both hydrogel formulations were simultaneously autoclaved at 121 °C for 12 min before further use, in order to obtain sterile formulations. All characterization experiments were performed using steam-sterilized hydrogels. Then, the preparation of the combination products was realized by direct incorporation of the FE002 lyophilized chondroprogenitors or of the corresponding control lyophilizates following a method described previously [24]. Briefly, both hydrogel types were loaded into 3 mL Luer-Lok syringes mounted with 18G blunt-fill needles. Following dispensing of the hydrogels in the appropriate lyophilizate vials and after gentle mechanical homogenization using the tips of the needles, the reconstituted combination products were loaded into the Luer-Lok syringes for further experimental use.