title: Collagen-coated polylactide microcarriers/chitosan hydrogel composite: injectable scaffold for cartilage regeneration.
abstract: A novel structure of injectable scaffold is designed and fabricated by combining collagen-coated polylactide (PLA) microcarriers and crosslinkable chitosan hydrogel. The collagen-coated PLA microcarriers were firstly mixed with the hydrogel precursor, a thickening agent of konjac glucomannan (KGM), and redox initiators of ammonium persulfate and tetramethylethylenediamine (TMEDA). The mixture was then injected into a mold and incubated at 37 degrees C to obtain the composite scaffold. The hydrogel can deliver the collagen-coated PLA microcarriers to the desired site and, after gelation, will prevent them from uncontrolled movement. On the other hand, the collagen-coated PLA microcarriers can substantially enhance the mechanical properties of the composite system. It was found that the microcarriers suspended stably in 0.6% KGM/1% chitosan derivative (CML) solution at 37 degrees C at least for 15 min. The dynamic elastic modulus (G') of the composite scaffold increased along with the increase of the microcarrier content. G' of the composite scaffold with 10% microcarriers was measured as 0.87-2.15 MPa at a frequency range of 0.1-100 rad/s, which was 120-90 times higher than that of its hydrogel system alone (12.1-24.4 kPa). In vitro culture of chondrocytes/composite scaffold showed that the cell metabolic activity increased rapidly before day 9, then leveled off. Cells in the hydrogel could attach and grow on the surface of the collagen-coated PLA microcarriers to form confluent cell layers after days 9-12. These features make the composite scaffold to be injectable and applicable in either tissue engineering, or regenerative medicine, and in particular, in orthopaedics.
authors.affiliation: Key Laboratory of Macromolecule Synthesis and Functionalization, Ministry of Education, Zhejiang University, Hangzhou 310027, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Hong
authors.forename: Yihong
authors.initials: Y
authors.lastname: Gong
authors.forename: Changyou
authors.initials: C
authors.lastname: Gao
authors.forename: Jiacong
authors.initials: J
authors.lastname: Shen
mesh_terms: D000818:Animals; D002356:Cartilage / Q000502:physiology*; D002478:Cells, Cultured; D048271:Chitosan; D003094:Collagen; D004337:Drug Carriers / Q000737:chemistry*; D006801:Humans; D020100:Hydrogels / Q000008:administration & dosage* / Q000737:chemistry; D011091:Polyesters; D012038:Regeneration; D023822:Tissue Engineering / Q000379:methods*