The design of biodegradable microcarriers for induced cell aggregation.

PLLA microspheres were aminolyzed in hexanediamine/propanol solution to introduce free amino groups on their surface, which were further transferred into aldehyde groups by a treatment of glutaraldehyde. Chitosan-graft-lactose was then covalently coupled via Schiff base formation. Morphological variation and chitosan-graft-lactose immobilization were characterized. In vitro culture of rabbit auricular chondrocytes demonstrated that the PLLA microcarriers could effectively support the cell attachment and particularly induce cell aggregation on their surface. The formed cell aggregates/microcarriers composite showed higher viability and extracellular matrix production. Thus, the PLLA microcarriers can be potentially used as an injectable delivery system for cartilage repair.