Optimal Pore Size of Honeycomb Polylactic Acid Films for In Vitro Cartilage Formation by Synovial Mesenchymal Stem Cells

Abstract

Background. Tissue engineering of cartilage requires the selection of an appropriate artificial scaffold. Polylactic acid (PLA) honeycomb films are expected to be highly biodegradable and cell adhesive due to their high porosity. The purpose of this study was to determine the optimal pore size of honeycomb PLA films for in vitro cartilage formation using synovial mesenchymal stem cells (MSCs). Methods. Suspensions of human synovial MSCs were plated on PLA films with different pore sizes (no pores, or with 5 μm or 20 μm pores) and then observed by scanning electron microscopy. The numbers of cells remaining in the film and passing through the film were quantified. One day after plating, the medium was switched to chondrogenic induction medium, and the films were time-lapse imaged and observed histologically. Results. The 5 μm pore film showed MSCs with pseudopodia that extended between several pores, while the 20 μm pore film showed MSC bodies submerged into the pores. The number of adhered MSCs was significantly lower for the film without pores, while the number of MSCs that passed through the film was significantly higher for the 20 μm pore film. MSCs that were induced to form cartilage peeled off as a sheet from the poreless film after one day. MSCs formed thicker cartilage at two weeks when growing on the 5 μm pore films than on the 20 μm pore films. Conclusions. Honeycomb PLA films with 5 μm pores were suitable for in vitro cartilage formation by synovial MSCs.

Honeycomb-Structured Porous Films from Poly(3-hydroxybutyrate) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate): Physicochemical Characterization and Mesenchymal Stem Cells Behavior

“…Smaller pores (5 µm) of PLA films, which are similar to PHB by physical characteristics, allows for the formation of thicker tissue during cartilage formation than bigger pores (20 µm). The presence of pores allows cells to be retained on the film and control the area of tissue formation, whereas cells tend to detach from flat film surfaces [33]. In our research, we did not observe the effect of various copolymers on cell behavior, but we can see the effect of pore sizes on cell flattening.…”

Biocompatibility of ABS and PLA Polymers with Dental Pulp Stem Cells Enhance Their Potential Biomedical Applications

“…Salerno et al (2013) produced macroporous PLA scaffolds that enabled uniform cell adhesion, colonization, and proliferation of rat MSCs, promising for bone and cartilage regeneration [42]. Yagi et al (2021) reported that honeycomb PLA films with 5 µm pores facilitated superior cell adhesion and cartilage formation using synovial MSCs, demonstrating their potential for in vitro cartilage engineering [43]. The adhesion, proliferation, and survival of MSCs on PLA surfaces were also previously observed in DPSCs [40,44,45] and human Periodontal Ligament Stem cells (PDLSC), which are also dental MSCs [37].…”

Scanning electron microscopy analysis of synovial and adipose mesenchymal stem cells adhering to cartilage

“…The cells were post-fixed with 1% OsO4 buffered with 0.1 M phosphate buffer for 2 h, dehydrated in a graded series of ethanol, and then dried in a critical point drying apparatus (HCP-2; Hitachi, Tokyo, Japan) with liquid CO2. The specimens were spatter-coated with platinum and examined using scanning electron microscopy (S-4500; Hitachi, Tokyo, Japan) [ 17 , 18 ].…”