Hydrogel‐filled polylactide porous scaffolds for cartilage tissue engineering

Abstract

Polymer porous scaffolds and hydrogels have been separately employed as analogues of the native extra-cellular matrix (ECM). However, both of these two kinds of materials have their own advantages and shortcomings. In this work, an attempt to combine the advantages of these two kinds of materials is carried out. Poly-L-lactide (PLLA) scaffolds with good mechanical properties were prepared by thermally induced phase separation, which were then filled with hydrogel aiming at entrapment of cells within a support of predefined shape. Agar, which has a function to promote chondrogenesis, was selected to entrap chondrocytes, acting as analogues of native ECM. A straight forward merit of this construct is that both mechanical strength and macroscopic shape, and analogous ECM can be simultaneously achieved. The morphology and distribution of the chondrocytes were studied by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The cell growth behaviors were determined by MTT assay and collagen and glycosaminoglycan (GAG) secretion. After culture for 7 and 14 days, the cells in the construct were round and surrounded by the hydrogel. The MTT viability and the cell secretion in the chondrocytes/agar/scaffold construct were also higher than that of the chondrocytes/scaffold construct (control). Gelatin was further introduced into the construct, yielding improved GAG secretion and cytoviability. After implantation in the subcutaneous dorsum of nude mice for 4 weeks, cartilage-like specimens maintaining their original rectangular shapes were harvested. Histological examination showed that new cartilage was regenerated and a large quantity of collagen and GAG were secreted, while the cells in the control PLLA scaffold turned to be fibroblast-like with less secretion of extracellular matrices. The method provides a useful pathway of scaffold preparation and cell transplantation, which can achieve suitable mechanical properties and good cell performance simultaneously.

Method to Analyze Three-Dimensional Cell Distribution and Infiltration in Degradable Scaffolds

“…22,24,52,53 Unfortunately, these methods fail to provide information on the location, distribution, and infiltration of cells into constructs. In fact, early research conducted for each seeding method showed little variation, with efficiencies of approximately 50%, consistent with unmodified PLGA saltleached scaffolds using these methods, although in disagreement with analysis of the sections of the scaffold.…”

Cell-Derived Polymer/Extracellular Matrix Composite Scaffolds for Cartilage Regeneration, Part 1: Investigation of Cocultures and Seeding Densities for Improved Extracellular Matrix Deposition

“…This is due to the round shaped cells that often take upon gel encapsulation, which has been shown to be beneficial for the chondrogenic phenotype. 51 However, when studying the influences of cocultures on matrix production, hydrogels may potentially restrict the dispersion of cells and secreted factors and thus alter the effects of coculture. 52 For this reason, this study set forth to examine the interaction of chondrocytes and MSCs in a highly porous, fibrous scaffold focusing on the production of the ECM within the scaffold.…”

Optimization of a natural collagen scaffold to aid cell–matrix penetration for urologic tissue engineering

“…Most importantly, the matrix needs to have a three-dimensional (3-D) structure with high porosity, but at the same time, maintaining a normal tensile strength. A 3-D scaffold with higher porosity and relative larger pore size (50-200 mM) promotes cell proliferation, migration and infiltration into the matrix, and appears to allow abundant cell loading onto the scaffold, thereby promoting in vivo tissue regeneration and wound healing [23][24][25][26]. Such a scaffold would also allow the host cells to participate in the tissue remodeling processes by infiltration or migration into the matrix from the wound edges.…”