Abstract
Ultrasound-responsive microspheres (MPs) derived from natural polysaccharides and injectable hydrogels have been widely investigated as a biocompatible, biodegradable, and controllable drug delivery system and cell scaffolds for tissue engineering. In this study, kartogenin (KGN) loaded poly (lactide-co-glycolic acid) (PLGA) MPs (MPs@KGN) were fabricated by premix membrane emulsification (PME) method which were sonicated by an ultrasound transducer. Furthermore, carboxymethyl chitosan-oxidized chondroitin sulfate (CMC-OCS) hydrogel were prepared via the Schiff’ base reaction-embedded MPs to produce a CMC-OCS/MPs scaffold. In the current work, morphology, mechanical property, porosity determination, swelling property, in vitro degradation, KGN release from scaffolds, cytotoxicity, and cell bioactivity were investigated. The results showed that MPs presented an obvious collapse after ultrasound treatment. The embedded PLGA MPs could enhance the compressive elastic modulus of soft CMC-OCS hydrogel. The cumulative release KGN from MPs exhibited a slow rate which would display an appropriate collapse after ultrasound, allowing KGN to maintain a continuous concentration for at least 28 days. Moreover, the composite CMC-OCS@MPs scaffolds exhibited faster gelation, lower swelling ratio, and lower in vitro degradation. CCK-8 and LIVE/DEAD staining showed these scaffolds did not influence rabbit bone marrow mesenchymal stem cells (rBMMSCs) proliferation. Then these scaffolds were cultured with rBMMSCs for 2 weeks, and the immunofluorescent staining of collagen II (COL-2) showed that CMC-OCS hydrogel embedded with MPs@KGN (CMC-OCS@MPs@KGN) with ultrasound had the ability to increase the COL-2 synthesis. Overall, due to the improved mechanical property and the ability of sustained KGN release, this injectable hydrogel with ultrasound-responsive property is a promising system for cartilage tissue engineering.
Highlights
Introduction distributed under the terms andInjuries to articular cartilage are a common health problem, causing pain and disability in all age groups [1]
The rheological results further demonstrated that the storage modulus (G0 ) and loss modulus (G00 ) of carboxymethyl chitosan-oxidized chondroitin sulfate (CMC-OCS) and CMC-OCS@KGN hydrogel scaffolds remained constant within the strain range of 0.01% to 5%, and it was detected that the value of G0 was lower than G00, indicating that the structure was damaged under large deformations (Figure 4E)
To evaluate the effect of the scaffolds or scaffolds incorporating with ultrasound differentiation of rabbit bone marrow mesenchymal stem cells (rBMMSCs) in vitro, they were stained with collagen II (COL-2) immunoon differentiation of rBMMSCs in vitro, they were stained with collagen II (COL-2) imhistochemistry after 14 days
Summary
KGNloading loadingwere wereprepared preparedby bythe thepremix premixmemmemThe PLGA. MPs with with and brane emulsification method. 5 min in structure ture showing an evident collapse. MPs and the yellow arrow represents ultrasound for min. General,owing owingto totheir theirhigh highsurface surface area to volume ratio of the larger size of MPs, the drug loading rate would be increased [35]. The KGN loading content was measured through UV spectrophotometry at 279 nm and area to volume ratio of the larger size of MPs, the drug loading rate would be increased [35]. The KGN loading content was measured through UV spectrophotometry at 279 nm and the concentration was calculated by the standard curve. The encapsulation efficiency and andconcentration drug loading was capacity of PLGA.
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